Document:

<PAGE>

                                                                   EXHIBIT 10.19

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                              PURCHASE AGREEMENT
                          (IMPROVEMENTS - BUILDING 3)

                                   BETWEEN

                           BNP LEASING CORPORATION

                                  ("BNPLC")

                                     AND

                           ZHONE TECHNOLOGIES, INC.

                                  ("Zhone")

                                August 1, 2000

                            (Oakland, California)

==============================================================================
<PAGE>

                               TABLE OF CONTENTS
                               -----------------

<TABLE>
<CAPTION>
                                                                                                                Page
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<S>                                                                                                             <C>
1    Zhone's Options and Obligations on the Designated Sale Date...............................................   2
     (A)    Right to Purchase; Initial Remarketing Rights; Supplemental Payment Obligation.....................   2
            ------------------------------------------------------------------------------
     (B)    Determinations Concerning Price and the Supplemental Payment.......................................   3
            ------------------------------------------------------------
     (C)    Designation of the Purchaser.......................................................................   7
            ----------------------------
     (D)    Effect of the Purchase Option and Zhone's Initial Remarketing Rights on Subsequent Title              8
            ----------------------------------------------------------------------------------------
            Encumbrances.......................................................................................
            ------------
     (E)    Security for the Purchase Option and Zhone's Initial Remarketing Rights............................   8
            -----------------------------------------------------------------------
     (F)    Delivery of Books and Records If BNPLC Retains the Building 3 Property.............................   8
            ----------------------------------------------------------------------

2    Zhone's Rights and Options After the Designated Sale Date.................................................   9
     (A)    Zhone's Extended Right to Remarket.................................................................   9
            ----------------------------------
     (B)    Definition of Minimum Extended Remarketing Price...................................................   9
            ------------------------------------------------
     (C)    BNPLC's Right to Sell..............................................................................  10
            ---------------------
     (D)    Zhone's Right to Excess Sales Proceeds.............................................................  11
            --------------------------------------
     (E)    Permitted Transfers During Zhone's Extended Remarketing Period.....................................  12
            --------------------------------------------------------------

3    Terms of Conveyance Upon Purchase.........................................................................  12

4    Survival and Termination of the Rights and Obligations of Zhone and BNPLC.................................  12
     (A)    Status of this Agreement Generally.................................................................  12
            ----------------------------------
     (B)    Election by Zhone to Terminate the Building 3 Supplemental Payment Obligation Prior to the
            ------------------------------------------------------------------------------------------
            Designated Sale Date and the Building 3 Base Rent Commencement Date................................  13
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     (C)    Automatic Termination of Zhone's Rights............................................................  14
            ---------------------------------------
     (D)    Conditions to Zhone's Rights Relative to State and Local Subdivision Requirements..................  14
            ---------------------------------------------------------------------------------
     (E)    Termination of Zhone's Extended Remarketing Rights to Permit a Sale by BNPLC.......................  15
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     (F)    Payment Only to BNPLC..............................................................................  15
            ---------------------
     (G)    Remedies Under the other Operative Documents.......................................................  15
            --------------------------------------------
     (H)    Occupancy by Zhone Prior to Closing of a Sale......................................................  15
            ---------------------------------------------
     (I)    Preferential Payments to BNPLC.....................................................................  16
            ------------------------------

5.   Security for Zhone's Obligations; Return of Funds.........................................................  16

6    Certain Remedies Cumulative...............................................................................  17

7    Attorneys' Fees and Legal Expenses........................................................................  17

8    Estoppel Certificate......................................................................................  17

9    Successors and Assigns....................................................................................  17

10   Amendment and Restatement.................................................................................  17
</TABLE>

[Improvements - Building 3]
<PAGE>

                            Exhibits and Schedules
                            ----------------------

Exhibit A......................................................Legal Description
---------

Exhibit B...........................................Grant Deed Form Requirements
---------

Exhibit C............................................Bill of Sale and Assignment
---------

Exhibit D..........................................Acknowledgment and Disclaimer
---------

Exhibit E................................................Secretary's Certificate
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Exhibit F.................................Certificate Concerning Tax Withholding
---------

Exhibit G...............................Notice by Zhone of Election to Terminate
---------

[Improvements - Building 3]
<PAGE>

                              PURCHASE AGREEMENT
                          (IMPROVEMENTS - BUILDING 3)

     This PURCHASE AGREEMENT (IMPROVEMENTS - BUILDING 3) (this "Agreement") is
made and dated as of August 1, 2000 (the "Effective Date") by and between BNP
LEASING CORPORATION, a Delaware corporation ("BNPLC"), and ZHONE TECHNOLOGIES,
INC., a Delaware corporation ("Zhone").

                                   RECITALS

     Contemporaneously with the execution of this Agreement, BNPLC and Zhone are
executing a Common Definitions and Provisions Agreement (Improvements - Building
3) dated as of the Effective Date (the "Building 3 CDPA"), which by this
reference is incorporated into and made a part of this Agreement for all
purposes. As used in this Agreement, capitalized terms defined in the Building 3
CDPA and not otherwise defined in this Agreement are intended to have the
respective meanings assigned to them in the Building 3 CDPA.

     Zhone and BNPLC previously executed that Purchase Agreement (Phase I -
Improvements) dated as of January 20, 2000 (the "Prior Purchase Agreement").
Zhone and BNPLC have agreed to amend, restate and replace the Prior Purchase
Agreement with this Agreement and the Buildings 1&2 Purchase Agreement as
provided in Paragraph 10 below.

     Pursuant to the Acquisition Contract, which covers the Land described in
Exhibit A, BNPLC has acquired the Land and any appurtenances thereto from
---------
Seller.  Contemporaneously with this Agreement, BNPLC and Zhone are executing a
Lease Agreement (Improvements - Building 3) (the "Building 3 Lease"), under
which BNPLC is leasing to Zhone the Improvements on the portion of the Land
designated as the Building 3 Site in Exhibit A (the "Building 3 Site"), and
                                     ---------
BNPLC is agreeing to provide funding for the construction and completion of such
Improvements, all of which will be owned by BNPLC. Also contemporaneously with
this Agreement, BNPLC and Zhone are executing a Lease Agreement (Improvements -
Buildings 1&2) (the "Buildings 1&2 Lease"), under which BNPLC is leasing to
Zhone the Improvements on all the Land other than the Building 3 Site, and BNPLC
is agreeing to provide funding for the construction and completion of such
Improvements, all of which will be owned by BNPLC.

     All of BNPLC's interests in the Improvements covered by the Building 3
Lease and in all other real and personal property from time to time covered by
the Building 3 Lease and included within the "Property" as defined therein are
hereinafter collectively referred to as the "Building 3 Property".  All of
BNPLC's interests in the Improvements covered by the Buildings 1&2 Lease and in
all other real and personal property from time to time covered by the Buildings
1&2 Lease and included within the "Property" as defined therein are hereinafter
collectively referred to as the "Buildings 1&2 Property". Together, the Building
3 Property and the Buildings 1&2 Property are hereinafter called the "Combined
Properties".  The Combined Properties do not include the Land itself, it being
understood that the Land Purchase Agreement constitutes a separate agreement
providing for the possible sale of the Land and the appurtenances thereto, and
only the Land and the appurtenances thereto, from BNPLC to Zhone or a third
party designated by Zhone.

                                  AGREEMENTS

     1    Zhone's Options and Obligations on the Designated Sale Date.
<PAGE>

          (A)  Right to Purchase; Initial Remarketing Rights; Supplemental
               -----------------------------------------------------------
Payment Obligation. Whether or not an Event of Default shall have occurred and
------------------
be continuing or the Building 3 Lease shall have been terminated, but subject to
Paragraph 4 below:

               (1)  Zhone shall have the right (the "Purchase Option") to
     purchase or cause an Affiliate of Zhone to purchase the Building 3 Property
     and BNPLC's interest in Building 3 Escrowed Proceeds, if any, on the
     Designated Sale Date for a cash price equal to the Building 3 Break Even
     Amount (as defined below).

               (2)  If neither Zhone nor an Affiliate of Zhone purchases the
     Building 3 Property and BNPLC's interest in any Building 3 Escrowed
     Proceeds on the Designated Sale Date as provided in the preceding
     subparagraph 1(A)(1), then Zhone shall have the following rights
     (collectively, "Zhone's Initial Remarketing Rights"):

                    (a)  First, Zhone shall have the right (but not the
          obligation) to cause an Applicable Purchaser who is not an Affiliate
          of Zhone to purchase the Building 3 Property and BNPLC's interest in
          any Building 3 Escrowed Proceeds on the Designated Sale Date for a
          cash purchase price equal to the Building 3 Third Party Price (as
          defined below). If, however, (i) the Building 3 Break Even Amount
          exceeds the sum of any Building 3 Third Party Price tendered or to be
          tendered to BNPLC and any Building 3 Supplemental Payment paid to
          BNPLC on the Designated Sale Date itself, and (ii) the Buildings 1&2
          Break Even Amount (under and as defined in the Buildings 1&2 Purchase
          Agreement) exceeds the sum of any Buildings 1&2 Third Party Price
          (under and as defined in the Buildings 1&2 Purchase Agreement)
          tendered or to be tendered to BNPLC and any Buildings 1&2 Supplemental
          Payment (under and as defined in the Buildings 1&2 Purchase Agreement)
          paid to BNPLC on the Designated Sale Date itself, then BNPLC may
          affirmatively elect to decline such tender from the Applicable
          Purchaser and to keep the Building 3 Property (together with any
          Building 3 Escrowed Proceeds) rather than sell to the Applicable
          Purchaser (a "Voluntary Retention of the Property").  But if BNPLC
          elects a Voluntary Retention of the Property hereunder, BNPLC must
          also elect a Voluntary Retention of the Property under and as defined
          in the Buildings 1&2 Purchase Agreement.

                    (b)  Second, if the Building 3 Third Party Price actually
          paid by an Applicable Purchaser to BNPLC on the Designated Sale Date
          exceeds the Building 3 Break Even Amount, Zhone shall be entitled to
          such excess, subject, however, to BNPLC's right to offset against such
          excess any and all sums that are then due from Zhone to BNPLC under
          the other Building 3 Operative Documents.  (In no event shall BNPLC be
          entitled to retain any such excess to recover any part of BNPLC's
          investment in the Buildings 1&2 Property that the Buildings 1&2
          Operative Documents do not entitle BNPLC to recover from Zhone.)

               (3)  If for any reason whatsoever neither Zhone nor an Applicable
     Purchaser pays to BNPLC a net cash price for the Building 3 Property (or
     allocated thereto as described in subparagraph 1(B)(2)) on the Designated
     Sale Date equal to or in excess of the Building 3 Break Even Amount
     pursuant to this Agreement, then Zhone shall have the obligation (the
     "Building 3 Supplemental Payment Obligation") to pay to BNPLC on the
     Designated Sale Date a supplemental payment (the "Building 3 Supplemental
     Payment") equal to the lesser of (1) the amount by which the Building 3
     Break Even Amount on the Designated Sale Date exceeds such net cash price
     (if any) for the Building 3 Property (or allocated thereto) actually
     received by BNPLC on the Designated Sale Date (such excess being
     hereinafter called a "Deficiency") or (2) the Maximum Remarketing
     Obligation. As used herein, the "Maximum Remarketing Obligation" means a
     dollar amount equal to the product of (i) Stipulated Loss Value on the
     Designated Sale Date, times (ii) 100% minus the Residual Risk Percentage;

[Improvements - Building 3]             2
<PAGE>

     provided, however, that the "Maximum Remarketing Obligation" will equal the
     Building 3 Break Even Amount, if (but only if):

                         (x)  Zhone shall have elected to accelerate the
               Designated Sale Date as provided in clause (2) of the definition
               of Designated Sale Date in the Building 3 CDPA when no "Event of
               Default" under and as defined in the Buildings 1&2 Lease
               Agreement has occurred and is continuing; or

                         (y)  an "Event of Default" under and as defined in the
               Building 3 Lease has occurred and is continuing on the Designated
               Sale Date, other than an Issue 97-1 Non-performance-related
               Subjective Event of Default or a Buildings 1&2 Cross-Default.

     BNPLC acknowledges that the proviso at the end of the preceding sentence
     shall not cause the Maximum Remarketing Obligation to exceed the product of
     (i) Stipulated Loss Value on the Designated Sale Date, times (ii) 100%
     minus the Residual Risk Percentage, solely by reason of an Issue 97-1 Non-
     performance-related Subjective Event of Default or a Buildings 1&2 Cross-
     Default.

     Without limiting the generality of the foregoing, the Building 3
     Supplemental Payment shall be required even if BNPLC does not sell the
     Building 3 Property to Zhone or an Applicable Purchaser on the Designated
     Sale Date because of (A) a Voluntary Retention of the Property, or (B) a
     failure of Zhone to exercise, or decision by Zhone not to exercise, the
     Purchase Option or Zhone's Initial Remarketing Rights in accordance with
     the terms and conditions set forth in  subparagraph 4(D) and other
     provisions of this Agreement.   If any Building 3 Supplemental Payment or
     portion thereof is not actually paid to BNPLC on the Designated Sale Date,
     Zhone shall pay interest on the past due amount computed at the Default
     Rate from the Designated Sale Date.  Zhone acknowledges that it is
     undertaking the Building 3 Supplemental Payment Obligation in consideration
     of the rights afforded to it by this Agreement, but that such obligation is
     not contingent upon any exercise by Zhone of such rights or upon any
     purchase of the Building 3 Property by Zhone or an Applicable Purchaser.

          (B)  Determinations Concerning Price and the Supplemental Payment.
               ------------------------------------------------------------

               (1)  Determination of the Building 3 Break Even Amount. As used
                    -------------------------------------------------
     herein, "Building 3 Break Even Amount" means an amount equal to Stipulated
     Loss Value, plus any out-of-pocket costs and expenses (including appraisal
                 ----
     costs, withholding taxes (if any) not constituting Excluded Taxes, and
     Attorneys' Fees) incurred by BNPLC in connection with any sale of BNPLC's
     interests in the Building 3 Property under this Agreement or in connection
     with collecting payments due hereunder, and plus an amount equal to the
                                             --------
     Balance of Unpaid Construction-Period Indemnity Payments, but less the
                                                               --------
     aggregate amounts (if any) of Direct Payments to Participants and Deposit
     Taker Losses.  As used herein, the "Balance of Unpaid Construction-Period
     Indemnity Payments" means an amount equal to the sum of Construction-Period
     Indemnity Payments, if any, that Zhone declined to pay pursuant to

     subparagraph 5(d)(ii) of the Building 3 Lease, plus interest accruing at
     ---------------------                          ----
     the Default Rate, compounded annually, on each such payment from the date
     such payment would have become due but for Zhone's right to decline to pay
     it as described in subparagraph 5(d)(ii) of the Building 3 Lease.  If,
                        ---------------------
     however, Losses for which Zhone has so declined to pay any Construction-
     Period Indemnity Payment consist of claims against BNPLC or another
     Interested Party that have not been liquidated prior to the Designated Sale
     Date (and, thus, such Losses have yet to be fixed in amount as of the
     Designated Sale Date), then Zhone may elect to exclude any Construction-
     Period Indemnity Payment attributable to such Losses by providing to BNPLC,
     for the benefit of BNPLC and other Interested Parties, a written agreement
     to indemnify and defend BNPLC and other Interested Parties against such
     Losses.  To be effective  hereunder for purposes of reducing the Balance of
     Unpaid Construction-Period Indemnity

[Improvements - Building 3]            3
<PAGE>

     Payments (and, thus, the Building 3 Break Even Amount), any such written
     indemnity must be fully executed and delivered by Zhone on or prior to the
     Designated Sale Date, must include provisions comparable to subparagraphs
                                                                 -------------
     5(c)(ii), (iii), (iv) and (v) of the Building 3 Lease and otherwise must be
     -----------------------------
     in form and substance satisfactory to BNPLC.

               (2)  Determination of Building 3 Third Party Price.  As used in
                    ---------------------------------------------
     subparagraph 1(A)(2)(a) and other provisions of this Agreement, "Building 3
     Third Party Price" means the amount determined as follows:

               (a)  For purposes of both the Buildings 1&2 Purchase Agreement
          and this Agreement, Zhone may give a notice (a "Remarketing Notice")
          to BNPLC and to each of the Participants no earlier than one hundred
          eighty days before the Designated Sale Date and no later than twenty
          days before the Designated Sale Date, specifying (i) an amount as the
          Buildings 1&2 Third Party Price that Zhone believes in good faith to
          constitute reasonably equivalent value for the Buildings 1&2 Property
          and any Buildings 1&2 Escrowed Proceeds, and (ii) an amount as the
          Building 3 Third Party Price that Zhone believes in good faith to
          constitute reasonably equivalent value for the Building 3 Property and
          any Building 3 Escrowed Proceeds. Once given, a Remarketing Notice
          shall not be rescinded, replaced or modified without BNPLC's written
          consent. If (1) the Buildings 1&2 Third Party Price specified by Zhone
          in a Remarketing Notice, when added to any Buildings 1&2 Supplemental
          Payment that Zhone must pay to BNPLC on the Designated Sale Date, is
          equal to or greater than the Buildings 1&2 Break Even Amount
          calculated on the Designated Sale Date, and (2) the Building 3 Third
          Party Price specified by Zhone in the same Remarketing Notice, when
          added to any Building 3 Supplemental Payment that Zhone must pay to
          BNPLC on the Designated Sale Date, is equal to or greater than the
          Building 3 Break Even Amount calculated on the Designated Sale Date,
          then the Remarketing Notice will control for purposes of establishing
          the Buildings 1&2 Third Party Price under the Buildings 1&2 Purchase
          Agreement and for purposes of establishing the Building 3 Third Party
          Price under this Agreement. Otherwise, however:

          .    the Buildings 1&2 Third Party Price will be established for
               purposes of the Buildings 1&2 Purchase Agreement as the greater
               of (A) any amount specified as the Buildings 1&2 Third Party
               Price by Zhone in a Remarketing Notice, or (B) the lesser of (i)
               the Buildings 1&2 Break Even Amount, or (ii) the Assumed
               Conditions Market Value (as defined below) allocated to the
               Buildings 1&2 Property; and

          .    the Building 3 Third Party Price will be established for purposes
               of this Agreement as the greater of (A) any amount specified as
               the Building 3 Third Party Price by Zhone in a Remarketing
               Notice, or (B) the lesser of (i) the Building 3 Break Even
               Amount, or (ii) the Assumed Conditions Market Value allocated to
               the Building 3 Property.

          As used in this Agreement (and in the Buildings 1&2 Purchase
          Agreement) "Assumed Conditions Market Value" means (and all appraisers
          and other persons involved in the determination of the Assumed
          Conditions Market Value will be so advised) the price that would be
          agreed upon between a willing buyer, under no compulsion to buy, and a
          willing seller, under no compulsion to sell, for the Combined
          Properties, calculated under the assumptions (whether or not then
          accurate) that Zhone's representations in the Buildings 1&2 Operative
          Documents and the Building 3 Operative Documents are true and correct;
          that Zhone has complied with all of the requirements of the Buildings
          1&2 Operative Documents and Building 3 Operative Documents, including
          requirements to maintain the Combined Properties in compliance with
          Applicable Laws [including Environmental Laws], and has completed the
          repairs or restoration

[Improvements - Building 3]            4
<PAGE>

          which according to the Buildings 1&2 Lease or the Building 3 Lease
          Zhone will provide after any damage or destruction of the Combined
          Properties by fire or other casualty or after any partial taking of
          the Combined Properties or any conveyance in lieu of such a partial
          taking; that no lien or other encumbrance against the Combined
          Properties exists other than Permitted Encumbrances; that Zhone, as
          the owner or lessee of any other property in the vicinity of the
          Combined Properties, will cooperate to permit the future development
          or use thereof in accordance with the requirements of the Closing
          Certificate and Agreement; that the construction, use and maintenance
          of Improvements on the Land that are contemplated in the Operative
          Documents will not be hindered or delayed because of any failure of
          Zhone to plan and provide for adequate utilities, water and parking;
          and that any purchaser of the Combined Properties will receive copies
          of Zhone's books and records which are necessary or useful to a future
          owner's or occupant's use of the Combined Properties. After it is
          calculated for the Combined Properties, taken together, the Assumed
          Conditions Market Value will be allocated, for purposes of this
          Agreement and the Buildings 1&2 Purchase Agreement (and all appraisers
          and other persons involved in the determination of the Assumed
          Conditions Market Value will be so advised), between the Buildings 1&2
          Property and the Building 3 Property as if each was a stand-alone
          facility benefitted by easements and restrictive covenants that
          provide for ingress, egress, parking, utilities and lateral support
          and that provide for common area maintenance and security, the
          maintenance of appropriate insurance, the application of insurance
          proceeds, the application of condemnation proceeds and the fair and
          appropriate allocation of shared costs, all as may be necessary or
          appropriate for the normal operation, maintenance, repair, improvement
          and ownership of the Buildings 1&2 Property and the Building 3
          Property in order that such properties could, if separately owned,
          share the common facilities that they actually do share or are
          designed to share. In no event will the Assumed Conditions Market
          Value so allocated to the Buildings 1&2 Property plus the Assumed
          Conditions Market Value so allocated to the Building 3 Property be
          less than the Assumed Conditions Market Value of the Combined
          Properties.

               (b)  If concerned that a Remarking Notice alone will not be
          determinative of the Buildings 1&2 Third Party Price and the Building
          3 Third Party Price as provided in subparagraph (a), Zhone may, for
          purposes of both the Buildings 1&2 Purchase Agreement and this
          Agreement, give a notice (an "Appraisal Notice") to BNPLC and to each
          of the Participants no earlier than one hundred eighty days before the
          Designated Sale Date and no later than twenty days before the
          Designated Sale Date, stating that Zhone elects to have made a
          determination of Assumed Conditions Market Value and an allocation
          thereof between the Buildings 1&2 Property and the Building 3
          Property, in accordance with the following procedures (the "Appraisal
          Procedures"):

                    (1)  Zhone and BNPLC shall each appoint a real estate
               appraiser who is familiar with properties in the vicinity of the
               Combined Properties.  Each party will make the appointment no
               later than ten days after receipt of notice from the other party
               that the appraisal process described in these provisions has been
               invoked.  The agreement of the two appraisers as to the amount of
               Assumed Conditions Market Value and the allocation thereof
               between the Buildings 1&2 Property and the Building 3 Property
               will be binding upon Zhone and BNPLC.  If the two appraisers do
               not, however, agree upon Assumed Conditions Market Value or the
               allocation thereof within thirty days following their
               appointment, they shall within another ten days agree upon a
               third real estate appraiser.  Immediately thereafter, each of the
               first two appraisers will submit his best estimate of the
               appropriate Assumed Conditions Market Value and the allocation
               thereof between the Buildings 1&2 Property and the Building 3
               Property

[Improvements - Building 3]            5
<PAGE>

               (together with a written report supporting such estimate) to the
               third appraiser and the third appraiser will choose between the
               two estimates. The estimate chosen by the third appraiser will be
               binding upon Zhone and BNPLC. Notification in writing of the
               Assumed Conditions Market Value and the allocation thereof shall
               be made to Zhone and BNPLC within thirty days following the
               selection of the third appraiser.

                    (2)  If appraisers must be selected under the procedure set
               out above and either BNPLC or Zhone fails to appoint an appraiser
               or fails to notify the other party of such appointment within
               fifteen days after receipt of notice that the prescribed time for
               appointing the appraisers has passed, then the other party's
               appraiser will determine the Assumed Conditions Market Value and
               the proper allocation thereof.  All appraisers selected for these
               Appraisal Procedures will be disinterested, reputable, qualified
               real estate appraisers with the designation of MAI or equivalent
               and with at least 10 years experience in appraising properties
               comparable to the Land in the San Francisco Bay area.

                    (3)  If a third appraiser must be chosen under the Appraisal
               Procedures set out above, he will be chosen on the basis of
               objectivity and competence, not on the basis of his relationship
               with the other appraisers or with BNPLC or Zhone, and the first
               two appraisers will be so advised.  Although the first two
               appraisers will be instructed to attempt in good faith to agree
               upon the third appraiser, if for any reason they cannot agree
               within the prescribed time, either Zhone or BNPLC may require the
               first two appraisers to immediately submit his or her choice for
               the third appraiser to the then highest ranking officer of the
               California Bar Association who will agree to help and who has no
               attorney/client or other significant relationship to either Zhone
               or BNPLC.  Such officer will have complete discretion to select
               the most objective and competent third appraiser from between the
               choices of each of the first two appraisers, and will be
               instructed to do so within ten days after such choices are
               submitted to him.

                    (4)  Either Zhone or BNPLC may notify the appraiser selected
               by the other party to demand the submission of an estimate of
               Assumed Conditions Market Value and the allocation thereof or a
               choice of a third appraiser as required under the procedure
               described above; and if the submission of such an estimate or
               choice is required but the other party's appraiser fails to
               comply with the demand within fifteen days after receipt of such
               notice, then the Assumed Conditions Market Value and allocation
               thereof, or choice of the third appraiser, as the case may be,
               selected by the other appraiser (i.e., the notifying party's
               appraiser) will be binding upon Zhone and BNPLC.

          All appraisal and other costs of the Appraisal Procedures shall be
          paid by Zhone.

               (c)  If for any reason whatsoever, including any acceleration of
          the Designated Sale Date, the Building 3 Third Party Price is not
          established before the Designated Sale Date by a Remarketing Notice
          alone pursuant to subparagraph (a) and is not otherwise established
          before the Designated Sale Date by the Appraisal Procedures outlined
          in subparagraph (b), then the Building 3 Third Party Price will, for
          purposes of subparagraph 1(A)(2)(a), be the amount equal to the lesser
          of (1) the Building 3 Break Even Amount on the Designated Sale Date,
          or (2) the Assumed Conditions Market Value allocable to the Building 3
          Property as determined by BNPLC in its sole good faith discretion.
          Without limiting the foregoing, for the purposes of determining the
          Building 3 Third Party Price pursuant to the preceding sentence, BNPLC
          shall be entitled to determine in its sole good faith discretion the
          amount of the Assumed Conditions Market Value and the allocation
          thereof between the Buildings 1&2 Property and the Building 3

[Improvements - Building 3]            6
<PAGE>

          Property.  Further, any determinations of BNPLC pursuant to this
          subparagraph (c) will also control for purposes of establishing the
          Assumed Conditions Market Value and allocation thereof as elements of
          the Minimum Extended Remarketing Price (as defined below); provided,
          however, that if Zhone did deliver an Appraisal Notice at least twenty
          days prior to the Designated Sale Date, then Zhone may require the
          continuation of the Appraisal Procedures outlined in subparagraph (b)
          after the Designated Sale Date only for the purpose of establishing
          the Minimum Extended Remarketing Price hereunder and the Minimum
          Extended Remarketing Price under and as defined in the Buildings 1&2
          Purchase Agreement.  Effective upon, but only upon, any conclusion of
          the Appraisal Procedures after the Designated Sale Date, BNPLC's
          determination of the Assumed Conditions Market Value and of the
          allocation thereof between the Buildings 1&2 Property and the Building
          3 Property will be superseded by the determinations thereof made in
          accordance with the Appraisal Procedures for purposes of calculating
          the Minimum Extended Remarketing Price.

          (C)  Designation of the Purchaser. To give BNPLC the opportunity
               ----------------------------
before the Designated Sale Date to prepare the deed and other documents that
BNPLC must tender pursuant to Paragraph 3 (collectively, the "Sale Closing
Documents"), Zhone must, by a notice to BNPLC given at least seven days prior to
the Designated Sale Date, specify irrevocably, unequivocally and with
particularity the party who will purchase the Building 3 Property pursuant to
this Agreement. If for any reason Zhone fails to so specify a party who will in
accordance with the terms and conditions set forth herein purchase the Building
3 Property (be it Zhone itself, an Affiliate of Zhone or another Applicable
Purchaser), BNPLC shall be entitled to postpone the tender of the Sale Closing
Documents until a date after the Designated Sale Date and not more than twenty
days after Zhone finally does so specify a party, but such postponement will not
relieve or postpone or affect the obligation of Zhone to make a Building 3
Supplemental Payment as provided in Paragraph 1(A)(3).

          (D)  Effect of the Purchase Option and Zhone's Initial Remarketing
               -------------------------------------------------------------
Rights on Subsequent Title Encumbrances.  Any conveyance of the Building 3
---------------------------------------
Property to Zhone or any Applicable Purchaser pursuant to this Paragraph 1(A)
shall cut off and terminate any interest in the Building 3 Property claimed by,
through or under BNPLC, including any interest claimed by the Participants and
including any Liens Removable by BNPLC (such as, but not limited to, any
judgment liens established against the Building 3 Property because of a judgment
rendered against BNPLC and any leasehold or other interests conveyed by BNPLC in
the ordinary course of BNPLC's business), but not including personal obligations
of Zhone to BNPLC under the Building 3 Operative Documents or the Other
Operative Documents  (including obligations arising under the indemnities in the
Building 3 Lease).  Anyone accepting or taking any interest in the Building 3
Property by or through BNPLC after the date of this Agreement shall acquire such
interest subject to the Purchase Option and Zhone's Initial Remarketing Rights.
Further, Zhone and any Applicable Purchaser shall be entitled to pay any payment
required by this Agreement for the purchase of the Building 3 Property directly
to BNPLC notwithstanding any prior conveyance or assignment by BNPLC, voluntary
or otherwise, of any right or interest in this Agreement or the Building 3
Property, and neither Zhone nor any Applicable Purchaser shall be responsible
for the proper distribution or application of any such payments by BNPLC; and
any such payment to BNPLC shall discharge the obligation of Zhone to cause such
payment to all Persons claiming an interest in such payment.  Contemporaneously
with the execution of this Agreement, the parties shall record a memorandum of
this Agreement for purposes of effecting constructive notice to all Persons of
Zhone's rights under this Agreement, including its rights under this
subparagraph.

          (E)  Security for the Purchase Option and Zhone's Initial Remarketing
               ----------------------------------------------------------------
Rights.  To secure BNPLC's obligation to sell the Building 3 Property pursuant
------
to Paragraph 1(A) and to pay any damages to Zhone caused by a breach of such
obligations, including any such breach caused by a rejection or termination of
this Agreement in any bankruptcy or insolvency proceeding instituted by or
against BNPLC, as debtor, BNPLC does hereby grant to Zhone a lien and security
interest against all rights, title and interests of BNPLC from time to time in
and to the Building 3 Property.  Zhone may enforce such lien and security
interest judicially after any

[Improvements - Building 3]            7
<PAGE>

such breach by BNPLC, but not otherwise. Contemporaneously with the execution of
this Agreement, Zhone and BNPLC will execute a memorandum of this Agreement
which is in recordable form and which specifically references the lien granted
in this subparagraph, and Zhone shall be entitled to record such memorandum at
any time prior to the Designated Sale Date. However, nothing in this
subparagraph shall be construed as a waiver by Zhone of any right Zhone may have
at law or in equity to the following remedies, whether because of BNPLC's
failure to remove a Lien Removable by BNPLC or because of any other default by
BNPLC under this Agreement: (i) the recovery of monetary damages, (ii)
injunctive relief in case of the violation, or attempted or threatened
violation, by BNPLC of any of the express covenants, agreements, conditions or
provisions of this Agreement which are binding upon BNPLC, or (iii) a decree
compelling performance by BNPLC of any of the express covenants, agreements,
conditions or provisions of this Agreement which are binding upon BNPLC.

          (F)  Delivery of Books and Records If BNPLC Retains the Building 3
               -------------------------------------------------------------
Property. Unless Zhone or its Affiliate or another Applicable Purchaser
--------
purchases the Building 3 Property pursuant to Paragraph 1(A), promptly after the
Designated Sale Date Zhone shall deliver to BNPLC copies of all plans and
specifications for the Building 3 Property prepared in connection with the
construction contemplated by the Construction Management Agreement and the
Building 3 Lease, together with all other books and records of Zhone which will
be necessary or useful to any future owner's or occupant's use of the Building 3
Property.

     2    Zhone's Rights and Options After the Designated Sale Date.

          (A)  Zhone's Extended Right to Remarket.  During the two years
               ----------------------------------
following the Designated Sale Date ("Zhone's Extended Remarketing Period"),
Zhone shall have the right ("Zhone's Extended Remarketing Right") to cause an
Applicable Purchaser who is not an Affiliate of Zhone to purchase the Building 3
Property for a cash purchase price not below the Minimum Extended Remarketing
Price (as defined below).  Zhone's Extended Remarketing Right shall, however, be
subject to all of the following conditions:

               (1)  The Building 3 Property and BNPLC's interest in Building 3
     Escrowed Proceeds, if any, shall not have been sold on the Designated Sale
     Date as provided in Paragraph 1 or within the thirty days thereafter as
     provided in subparagraph 4(C).

               (2)  No Voluntary Retention of the Property shall have occurred
     as described in subparagraph 1(A)(2)(a).

               (3)  Zhone's Extended Remarketing Right shall not have been
     terminated pursuant to subparagraph 4(C) below because of Zhone's failure
     to make any Building 3 Supplemental Payment required on the Designated Sale
     Date.

               (4)  Zhone's Extended Remarketing Right shall not have been
     terminated by BNPLC pursuant to subparagraph 4(E) below to facilitate
     BNPLC's sale of the Building 3 Property to a third party in accordance with
     subparagraph 2(C).

               (5)  At least thirty days prior to the date upon which BNPLC is
     to convey the Building 3 Property to an Applicable Purchaser because of
     Zhone's exercise of Zhone's Extended Remarketing Right (the "Final Sale
     Date"), Zhone shall have notified BNPLC of (x) the date proposed by Zhone
     as the Final Sale Date (which must be a Business Day), (y) the full legal
     name of the Applicable Purchaser and such other information as will be
     required to prepare the Sale Closing Documents, and (z) the amount of the
     purchase price that the Applicable Purchaser will pay (consistent with the
     minimum required pursuant to the other provisions of this subparagraph
     2(A)) for the Building 3 Property.

               (6)  Zhone shall have satisfied the obligations imposed upon it
     by

[Improvements - Building 3]             8
<PAGE>

     subparagraph 4(D).

               (7)  The sale of the Building 3 Property to the Applicable
     Purchaser hereunder, or the simultaneous sale of the Buildings 1&2 Property
     to the Applicable Purchaser under the Buildings 1&2 Purchase Agreement as
     required by subparagraph 4(D), shall generate excess sale proceeds to which
     Zhone is entitled under subparagraph 2(D) of this Agreement or under
     subparagraph 2(D) of the Buildings 1&2 Purchase Agreement or under both
     subparagraphs.

          (B)  Definition of Minimum Extended Remarketing Price. As used
               ------------------------------------------------
herein, "Minimum Extended Remarketing Price" means, subject to reduction as
provided in subparagraph 2(C) below (if applicable), an amount equal to the sum
of the following:

               (1)  the lesser of (a) the amount by which the Building 3 Break
     Even Amount on the Designated Sale Date exceeds any Building 3 Supplemental
     Payment actually paid to BNPLC on the Designated Sale Date itself, or (b)
     the Assumed Conditions Market Value allocated to the Building 3 Property as
     of the Designated Sale Date, determined as described in subparagraph
     1(B)(2), plus
              ----

               (2)  interest on the lesser of the amounts described in the
     preceding clause (1) computed at the Default Rate for the period commencing
     on the Designated Sale Date and ending on the Final Sale Date, plus
                                                                    ----

               (3)  all out-of-pocket costs and expenses (including withholding
     taxes [if any], other than Excluded Taxes, and Attorneys' Fees) incurred by
     BNPLC in connection with the sale to the Applicable Purchaser, to the
     extent not already included in the computation of the Minimum Extended
     Remarketing Price, and plus
                        --------

               (4)  the sum of all Impositions, insurance premiums and other
     Losses of every kind suffered or incurred by BNPLC or any other Interested
     Party with respect to the ownership, operation, construction or maintenance
     of the Building 3 Property on or after the Designated Sale Date (except to
     the extent already reimbursed by any lessee of the Building 3 Property
     after the Designated Sale Date), together with interest on such
     Impositions, insurance premiums and other Losses computed at the Default
     Rate from the date paid or incurred to the Final Sale Date.

If, however, Losses described in the preceding clause (4) consist of claims
against BNPLC or another Interested Party that have not been liquidated prior to
the Final Sale Date (and, thus, such Losses have yet to be fixed in amount as of
the Final Sale Date), then Zhone may elect to exclude any such Losses from the
computation of the Minimum Extended Remarketing Price by providing to BNPLC, for
the benefit of BNPLC and other Interested Parties, a written agreement to
indemnify and defend BNPLC and other Interested Parties against such Losses.  To
be effective  hereunder for purposes of reducing the Minimum Extended
Remarketing Price (and, thus, the Building 3 Break Even Amount), any such
written indemnity must be fully executed and delivered by Zhone on or prior to
the Final Sale Date, must include provisions comparable to subparagraphs
                                                           -------------
5(c)(ii), (iii), (iv) and (v) of the Building 3 Lease and otherwise must be in
-----------------------------
form and substance satisfactory to BNPLC.

          (C)  BNPLC's Right to Sell  . After the Designated Sale Date, if the
               ---------------------
Building 3 Property has not already been sold by BNPLC pursuant to Paragraph 1
or this Paragraph 2, BNPLC shall have the right to sell the Combined Properties
or offer the Combined Properties for sale to any third party on any terms
believed to be appropriate by BNPLC in its sole good faith business judgment;
provided, however, that so long as the conditions to Zhone's Extended
Remarketing Rights specified in subparagraph 2(A) continue to be satisfied:

               (1)  BNPLC shall not sell the Combined Properties to an Affiliate
     of BNPLC on

[Improvements - Building 3]             9
<PAGE>

     terms less favorable than those which BNPLC would require from a
     prospective purchaser not an Affiliate of BNPLC;

               (2)  If BNPLC receives or desires to make a written proposal
     (whether in the form of a "letter of intent" or other nonbinding expression
     of interest or in the form of a more definitive purchase and sale
     agreement) for a sale of the Combined Properties to a prospective purchaser
     (a "Third Party Sale Proposal"), and if on the basis of such Third Party
     Sale Proposal BNPLC expects to enter into or to pursue negotiations for a
     definitive purchase and sale agreement with the prospective purchaser, then
     prior to executing any such definitive agreement, BNPLC shall submit the
     Third Party Sale Proposal to Zhone with a notice (the "Third Party Sale
     Notice") explaining that:

                    (A)  if BNPLC and the prospective purchaser reach agreement
          on other terms and conditions to be incorporated into a definitive
          purchase and sale agreement, BNPLC is then prepared to accept (i) a
          price for the Buildings 1&2 Property (or allocated thereto) not below
          an amount specified in such Third Party Sale Notice (the "Buildings
          1&2 Third Party Target Price"), and (ii) a price for the Building 3
          Property (or allocated thereto) not below an amount specified in such
          Third Party Sale Notice (the "Building 3 Third Party Target Price");
          and

                    (B)  Zhone's Extended Remarketing Right may be terminated
          pursuant to subparagraph 4(E) of this Agreement, and Zhone's Extended
          Remarketing Right under and as defined in the Buildings 1&2 Purchase
          Agreement may be terminated pursuant to subparagraph 4(E) thereof,
          unless within ninety days after the date of such Third Party Sale
          Notice Zhone causes an Applicable Purchaser to consummate a purchase
          of the Combined Properties under Paragraph 2 of this Agreement and
          Paragraph 2 of the Buildings 1&2 Purchase Agreement; and

               (3)  If BNPLC does sell the Combined Properties to a third party
     pursuant to this subparagraph during Zhone's Extended Remarketing Period,
     then for purposes of subparagraphs 2(D) and 4(E) of this Agreement and of
     subparagraphs 2(D) and 4(E) of the Buildings 1&2 Purchase Agreement, BNPLC
     may allocate the total price paid by the third party for the Combined
     Properties between the Buildings 1&2 Property and the Building 3 Property
     in accordance with any agreement for the allocation reached by BNPLC and
     the third party.  Absent such an agreement, however, the total price paid
     by the third party for the Combined Properties will be allocated between
     the Buildings 1&2 Property and the Building 3 Property in the same
     proportion that the Assumed Conditions Market Value of the Combined
     Properties is allocated pursuant to this Agreement and the Buildings 1&2
     Purchase Agreement.

For a period of ninety days (but only ninety days) after the date of any Third
Party Sale Notice, the Minimum Extended Remarketing Price shall be limited in
amount so that it does not exceed the Building 3 Third Party Target Price
specified by BNPLC therein.  Accordingly, if BNPLC has delivered a Third Party
Sale Notice specifying a Building 3 Third Party Target Price below the Minimum
Extended Remarketing Price calculated as provided in subparagraph 2(B) within
the ninety days prior to the Final Sale Date for any sale to an Applicable
Purchaser by BNPLC pursuant to this Paragraph 2, then the Minimum Extended
Remarketing Price applicable to such sale shall be reduced to the amount of the
Building 3 Third Party Target Price so specified.  Such a reduction, however,
will apply only to a sale to an Applicable Purchaser actually consummated within
the ninety days after the date of the applicable Third Party Sale Notice.

          (D)  Zhone's Right to Excess Sales Proceeds. If the cash price
               --------------------------------------
actually paid to BNPLC by any third party for the Building 3 Property (or
allocated thereto) during Zhone's Extended Remarketing Period, including any
price paid by an Applicable Purchaser purchasing from BNPLC pursuant to this
Paragraph 2,

[Improvements - Building 3]             10
<PAGE>

exceeds the Minimum Extended Remarketing Price (calculated as provided in
subparagraph 2(B), without reduction pursuant to subparagraph 2(C)), then Zhone
shall be entitled to the excess; provided, that BNPLC may offset and retain from
the excess any and all sums that are then due and unpaid from Zhone to BNPLC
under any of the Building 3 Operative Documents or the Other Operative
Documents. (But in no event shall BNPLC be entitled to retain any such excess to
recover any part of BNPLC's investment in the Buildings 1&2 Property that the
Buildings 1&2 Operative Documents do not entitle BNPLC to recover from Zhone.)

          (E)  Permitted Transfers During Zhone's Extended Remarketing Period.
               --------------------------------------------------------------
Any "Permitted Transfer" described in clause (6) of the definition thereof in
                                      ----------
the Building 3 CDPA to an Affiliate of BNPLC or that covers BNPLC's entire fee
estate in the Improvements included in the Building 3 Property will be subject
to Zhone's Extended Remarketing Right if, at the time of the Permitted Transfer,
Zhone's Extended Remarketing Right has not expired or been terminated as
provided herein. Any other Permitted Transfer described in clause (6) of the
definition thereof, however, will not be subject to Zhone's Extended Remarketing
Right. Thus, for example, BNPLC's conveyance of a utility easement or space
lease more than thirty days after the Designated Sale Date to a Person not an
Affiliate of BNPLC shall not be subject to Zhone's Extended Remarketing Right,
though following the conveyance of the lesser estate, Zhone's Extended
Remarketing Right may continue to apply to BNPLC's remaining interest in the
Building 3 Property.

     3    Terms of Conveyance Upon Purchase. As necessary to consummate any
sale of the Building 3 Property to Zhone or an Applicable Purchaser pursuant to
this Agreement, BNPLC must, subject to any postponement permitted by
subparagraph 1(C) and to Zhone's satisfaction of its obligations set forth in
subparagraph 4(D), immediately after the tender of the purchase price and any
other payments to BNPLC required pursuant to Paragraph 1 or Paragraph 2, as
applicable, convey all of BNPLC's right, title and interest in the Building 3
Property to Zhone or the Applicable Purchaser, as the case may be, by BNPLC's
execution, acknowledgment (where appropriate) and delivery of the Sale Closing
Documents. Such conveyance by BNPLC will be subject only to the Permitted
Encumbrances and any other encumbrances that do not constitute Liens Removable
by BNPLC. However, such conveyance shall not include the rights of BNPLC or
other Interested Parties under the indemnities provided in the Building 3
Operative Documents and the Other Operative Documents, including rights to any
payments then due from Zhone under the indemnities or that may become due
thereafter because of any expense or liability incurred by BNPLC or another
Interested Party resulting in whole or in part from events or circumstances
occurring or alleged to have occurred before such conveyance. All costs, both
foreseen and unforeseen, of any purchase by Zhone or an Applicable Purchaser
hereunder shall be the responsibility of the purchaser. The Sale Closing
Documents used to accomplish such conveyance shall consist of the following: (1)
a Corporation Grant Deed (conveying both the Buildings 1&2 Property and the
Building 3 Property simultaneously to the same grantee as required to satisfy
the condition set forth in subparagraph 4(D)) in the form attached as Exhibit
                                                                      -------
B-1 or Exhibit B-2 or Exhibit B-4, as required by Exhibit B, (2) if required by
---    -----------    -----------
Exhibit B, an extension of the Land Lease in the form attached as Exhibit B-3,
---------                                                         -----------
(3) a Bill of Sale and Assignment in the form attached as Exhibit C, (4) an
                                                          ---------
Acknowledgment of Disclaimer of Representations and Warranties, in the form
attached as Exhibit D, which Zhone or the Applicable Purchaser must execute and
            ---------
return to BNPLC, (5) a Secretary's Certificate in the form attached as Exhibit
                                                                       -------
E, and (6) a certificate concerning tax withholding in the form attached as
-
Exhibit F. If for any reason BNPLC fails to tender the Sale Closing Documents
---------
as required by this Paragraph 3, BNPLC may cure such refusal at any time before
thirty days after receipt of a demand for such cure from Zhone.

     4    Survival and Termination of the Rights and Obligations of Zhone and
          BNPLC.

          (A)  Status of this Agreement Generally. Except as expressly provided
               ----------------------------------
herein, this Agreement shall not terminate; nor shall Zhone have any right to
terminate this Agreement; nor shall Zhone be entitled to any reduction of the
Building 3 Break Even Amount, any Deficiency, the Maximum Remarketing
Obligation, any Building 3 Supplemental Payment or the Minimum Extended
Remarketing Price hereunder; nor shall the obligations of Zhone to BNPLC under
Paragraph 1 be affected, by reason of (i) any damage to or the

[Improvements - Building 3]             11
<PAGE>

destruction of all or any part of the Building 3 Property from whatever cause
(though it is understood that Zhone will receive any remaining Building 3
Escrowed Proceeds yet to be applied as provided in the Building 3 Lease that may
result from such damage if Zhone purchases the Building 3 Property and the
Building 3 Escrowed Proceeds as herein provided), (ii) the taking of or damage
to the Building 3 Property or any portion thereof by eminent domain or otherwise
for any reason (though it is understood that Zhone will receive any remaining
Building 3 Escrowed Proceeds yet to be applied as provided in the Building 3
Lease that may result from such taking or damage if Zhone purchases the Building
3 Property and the Building 3 Escrowed Proceeds as herein provided), (iii) the
prohibition, limitation or restriction of Zhone's use of all or any portion of
the Building 3 Property or any interference with such use by governmental action
or otherwise, (iv) any eviction of Zhone or any party claiming under Zhone by
paramount title or otherwise, (v) Zhone's prior acquisition or ownership of any
interest in the Building 3 Property, (vi) any default on the part of BNPLC under
this Agreement, the Building 3 Lease or any other agreement to which BNPLC is a
party, or (vii) any other cause, whether similar or dissimilar to the foregoing,
any existing or future law to the contrary notwithstanding. It is the intention
of the parties hereto that the obligation of Zhone to make any Building 3
Supplemental Payment as provided in Paragraph 1 shall be a separate and
independent covenant and agreement from BNPLC's obligations under this Agreement
or any other agreement between BNPLC and Zhone; provided, however, that nothing
in this subparagraph shall excuse BNPLC from its obligation to tender the Sale
Closing Documents in substantially the form attached hereto as exhibits when
required by Paragraph 3. Nothing in this subparagraph shall be construed as a
waiver by Zhone of any right Zhone may have at law or in equity to the following
remedies, whether because of BNPLC's failure to remove a Lien Removable by BNPLC
or because of any other default by BNPLC under this Agreement: (i) the recovery
of monetary damages, (ii) injunctive relief in case of the violation, or
attempted or threatened violation, by BNPLC of any of the express covenants,
agreements, conditions or provisions of this Agreement which are binding upon
BNPLC, or (iii) a decree compelling performance by BNPLC of any of the express
covenants, agreements, conditions or provisions of this Agreement which are
binding upon BNPLC.

          (B)  Election by Zhone to Terminate the Building 3 Supplemental
               ----------------------------------------------------------
Payment Obligation Prior to the Designated Sale Date and the Building 3 Base
----------------------------------------------------------------------------
Rent Commencement Date. At any time prior to the Building 3 Base Rent
----------------------
Commencement Date, Zhone may elect to terminate its Building 3 Supplemental
Payment Obligation, subject to the following conditions:

          (1)  To be effective, any such election to terminate must be made by
     giving notice thereof to BNPLC and the Participants in the form attached as
     Exhibit G (a) prior to the Building 3 Base Rent Commencement Date and (b)
     ---------
     only after (x) Zhone shall have given Notice of Zhone's Election to
     Terminate pursuant to Paragraph 4(D) of the Construction Management
                           --------------
     Agreement, (y) BNPLC shall have given any FOCB Notice as provided in
     Paragraph 4(E) of the Construction Management Agreement, or (z) BNPLC shall
     --------------
     have given notice of its election to accelerate the Designated Sale Date
     when an Event of Default has occurred and is continuing as provided in
     clause (3) of the definition of Designated Sale Date in the Building 3
     CDPA.

          (2)  No termination pursuant to this subparagraph 4(B) shall be
     effective, notwithstanding any notice Zhone may have given as described in
     the preceding clause (1), unless contemporaneously with the giving of the
     notice (and in any event prior to both the Designated Sale Date and the
     Building 3 Base Rent Commencement Date) Zhone shall deliver to BNPLC an
     Issue 97-10 Prepayment.

          (3)  If for any reason whatsoever, including any bona fide dispute
     over the amount of any required Issue 97-10 Prepayment, BNPLC does not
     receive both the notice described in the preceding clause (1) and a full
     Issue 97-10 Prepayment as described in the preceding clause (2) prior to
     both the Building 3 Supplemental Payment Date and the Building 3 Base Rent
     Commencement Date, then without any notice or other action by the parties
     to this Agreement Zhone shall cease to have any option

[Improvements - Building 3]             12
<PAGE>

     to terminate the Building 3 Supplemental Payment Obligation pursuant to
     this subparagraph 4(B). Zhone may, however, pay any amount claimed by BNPLC
     to constitute a required Issue 97-10 Prepayment in order to preserve
     Zhone's option to terminate the Building 3 Supplemental Payment Obligation
     without waiving its right to continue any bona fide dispute over such
     amount and without waiving its right to recover any excess paid to BNPLC if
     Zhone subsequently establishes that the amount claimed by BNPLC was
     excessive.

          (C)  Automatic Termination of Zhone's Rights.
               ---------------------------------------

          (1)  Without limiting BNPLC's right to enforce Zhone's obligation to
     pay any Building 3 Supplemental Payment or other amounts required by this
     Agreement, the Purchase Option, Zhone's Initial Remarketing Rights and
     Zhone's Extended Remarketing Rights shall all terminate automatically if
     BNPLC shall elect a Voluntary Retention of the Property as provided in
     subparagraph 1(A)(2)(a).

          (2)  Without limiting BNPLC's right to enforce Zhone's obligation to
     pay any Building 3 Supplemental Payment or other amounts required by this
     Agreement, the Purchase Option, Zhone's Initial Remarketing Rights and
     Zhone's Extended Remarketing Rights shall all terminate automatically if
     Zhone shall fail to pay the full amount of any Building 3 Supplemental
     Payment required by subparagraph 1(A)(3) on the Designated Sale Date. If,
     however, the Building 3 Supplemental Payment Obligation is effectively
     terminated pursuant to subparagraph 4(B) prior to the Designated Sale Date,
     thereby excusing Zhone from the obligation to make any Building 3
     Supplemental Payment that would otherwise be required by subparagraph
     1(A)(3), then neither the Purchase Option, nor Zhone's Initial Remarketing
     Rights nor Zhone's Extended Remarketing Rights will automatically terminate
     pursuant to this subparagraph 4(C)(2). Further, notwithstanding anything in
     this subparagraph 4(C) to the contrary, even after a failure to pay any
     required Building 3 Supplemental Payment on the Designated Sale Date, on
     any Business Day within thirty days after the Designated Sale Date Zhone or
     its designee may tender to BNPLC the full Building 3 Break Even Amount
     (calculated as of the Designated Sale Date) and the full Buildings 1&2
     Break Even Amount (calculated as of the Designated Sale Date), together
     with interest on the total Building 3 Break Even Amount and Buildings 1&2
     Break Even Amount computed at the Default Rate from the Designated Sale
     Date to the date of tender, and together with all other amounts then due
     under any of the Building 3 Operative Documents and the Other Operative
     Documents, and if presented with such a tender within thirty days after the
     Designated Sale Date, BNPLC must accept the tender and promptly thereafter
     deliver to Zhone or its designee all Buildings 1&2 Escrowed Proceeds (if
     any), Building 3 Escrowed Proceeds (if any), the Buildings 1&2 Sale Closing
     Documents listed in Paragraph 3 of the Buildings 1&2 Purchase Agreement and
     the Building 3 Sale Closing Documents required by Paragraph 3 of this
     Agreement.

          (D)  Conditions to Zhone's Rights Relative to State and Local
               --------------------------------------------------------
Subdivision Requirements.  Simultaneously with any sale hereunder of the
------------------------
Building 3 Property by BNPLC to Zhone because of Zhone's exercise of the
Purchase Option, Zhone must also acquire, on and subject to the terms and
conditions set forth in the Buildings 1&2 Purchase Agreement, the Buildings 1&2
Property.  Simultaneously with any sale hereunder of the Building 3 Property by
BNPLC to an Applicable Purchaser because of Zhone's exercise of the Purchase
Option, Zhone's Initial Remarketing Right or Zhone's Extended Remarketing Right,
Zhone must cause the same Applicable Purchaser to acquire, on and subject to the
terms and conditions set forth in the Buildings 1&2 Purchase Agreement, the
Buildings 1&2 Property.  If, in addition to the simultaneous acquisition of both
the Combined Properties by the same purchaser, other requirements of state or
local subdivision laws and ordinances must be satisfied to permit a lawful
conveyance by BNPLC of the Building 3 Property in connection with Zhone's
exercise of the Purchase Option, Zhone's Initial Remarketing Right or Zhone's
Extended Remarketing Right, then Zhone must also comply or cause an Applicable
Purchaser to comply with such other requirements.  Zhone's right to require any
tender by BNPLC of the Sale Closing Documents in connection with

[Improvements - Building 3]              13
<PAGE>

Zhone's exercise of the Purchase Option, Zhone's Initial Remarketing Right or
Zhone's Extended Remarketing Right shall be conditioned upon Zhone's
satisfaction of the requirements of this subparagraph 4(D). Nothing contained in
this subparagraph 4(D) shall be construed to obligate Zhone to exercise its
Purchase Option, Zhone's Initial Remarketing Rights or Zhone's Extended
Remarketing Rights or shall create any claim on the part of BNPLC against Zhone
in the event Zhone does not exercise its Purchase Option, Zhone's Initial
Remarketing Rights or Zhone's Extended Remarketing Rights, for payment of any
sum other than the Building 3 Supplemental Payment as provided in subparagraph
1(A)(3).

          (E)  Termination of Zhone's Extended Remarketing Rights to Permit a
               --------------------------------------------------------------
Sale by BNPLC. At any time after the Designated Sale Date and more than ninety
-------------
days after BNPLC has delivered a Third Party Sale Notice to Zhone as described
in subparagraph 2(C)(2), BNPLC may terminate Zhone's Extended Remarketing Rights
(both under and as defined in this Agreement and under and as defined in the
Buildings 1&2 Purchase Agreement) contemporaneously with the consummation of a
sale of the Combined Properties by BNPLC to any third party (be it the
prospective purchaser named in the Third Party Sale Notice or another third
party).  However, as a condition to such termination, (1) the price paid by the
third party to BNPLC for the Buildings 1&2 Property (or allocated thereto) must
equal or exceed the Buildings 1&2 Third Party Target Price specified in the
Third Party Sale Notice, and (2) the price paid by the third party to BNPLC for
the Building 3 Property (or allocated thereto) must equal or exceed the Building
3 Third Party Target Price specified in the Third Party Sale Notice.  This
subparagraph is intended to establish the requirements for a sale by BNPLC of
the Combined Properties, unencumbered by Zhone's Extended Remarketing Rights,
pursuant to subparagraph 2(C).

          (F)  Payment Only to BNPLC. Except for Direct Payments to
               ---------------------
Participants, all amounts payable under this Agreement by Zhone and, if
applicable, by an Applicable Purchaser must be paid directly to BNPLC, and no
payment to any other party shall be effective for the purposes of this
Agreement. (This provision shall not, however, limit Zhone's right to deduct
Deposit Taker Losses when calculating the Building 3 Break Even Amount, as
provided in subparagraph 1(B)(1).)  In addition to any payments required under
subparagraph 1(A), on the Designated Sale Date Zhone must pay all amounts then
due to BNPLC under the Building 3 Operative Documents or under the Other
Operative Documents.

          (G)  Remedies Under the other Operative Documents. No repossession
               --------------------------------------------
of or re-entering upon the Building 3 Property or exercise of any other remedies
available to BNPLC under the other Building 3 Operative Documents or the Other
Operative Documents shall terminate Zhone's rights or obligations hereunder, all
of which shall survive BNPLC's exercise of remedies under those other documents.
Zhone acknowledges that the consideration for this Agreement is separate and
independent of the consideration for the Building 3 Lease, the Construction
Management Agreement and the Closing Certificate, and Zhone's obligations
hereunder shall not be affected or impaired by any event or circumstance that
would excuse Zhone from performance of its obligations under such other Building
3 Operative Documents or any of the Other Operative Documents.

          (H)  Occupancy by Zhone Prior to Closing of a Sale. Prior to the
               ---------------------------------------------
closing of any sale of the Building 3 Property to Zhone or an Applicable
Purchaser hereunder, Zhone's occupancy of the Building 3 Land and Building 3
Improvements and its use of the Building 3 Property shall continue to be subject
to the terms and conditions of the Building 3 Lease, including the terms setting
forth Zhone's obligation to pay rent, prior to any termination or expiration of
the Building 3 Lease pursuant to its express terms and conditions.

          (I)  Preferential Payments to BNPLC.  If any payment to BNPLC by an
               ------------------------------
Applicable Purchaser hereunder is held to constitute a preference or a voidable
transfer under Applicable Law, or must for any other reason be refunded by BNPLC
to the Applicable Purchaser or to another Person, and if such payment to BNPLC
reduced or had the effect of reducing a Building 3 Supplemental Payment or
increased or had the

  [Improvements - Building 3]         14
<PAGE>

effect of increasing any excess sale proceeds paid to Zhone pursuant to
subparagraph 1(A)(2)(b) or pursuant to subparagraph 2(D), then Zhone shall pay
to BNPLC upon demand an amount equal to the reduction of the Building 3
Supplemental Payment or to the increase of the excess sale proceeds paid to
Zhone, as applicable, and this Agreement shall continue to be effective or shall
be reinstated as necessary to permit BNPLC to enforce its right to collect such
amount from Zhone.

     5    Security for Zhone's Obligations; Return of Funds.  Zhone's
obligations under this Agreement are secured by the Building 3 Pledge Agreement,
reference to which is hereby made for a description of the Collateral covered
thereby and the rights and remedies provided to BNPLC thereby. Although the
collateral agent appointed for BNPLC as provided in the Building 3 Pledge
Agreement shall be entitled to hold all Collateral as security for the full and
faithful performance by Zhone of Zhone's covenants and obligations under this
Agreement, the Collateral shall not be considered an advance payment of the
Building 3 Break Even Amount or any Building 3 Supplemental Payment or a measure
of BNPLC's damages should Zhone breach this Agreement.  If Zhone does breach
this Agreement and fails to cure the same within any time specified herein for
the cure, BNPLC may, from time to time, without prejudice to any other remedy
and without notice to Zhone, require the collateral agent to immediately apply
the proceeds of any disposition of the Collateral (and any cash included in the
Collateral) to amounts then due hereunder from Zhone.  If by a Permitted
Transfer BNPLC conveys its interest in the Building 3 Property before the
Designated Sale Date, BNPLC may also assign BNPLC's interest in the Collateral
to the transferee.  BNPLC shall be entitled to return any Collateral not sold or
used to satisfy the obligations secured by the Building 3 Pledge Agreement
directly to Zhone notwithstanding any prior actual or attempted conveyance or
assignment by Zhone, voluntary or otherwise, of any right to receive the same;
neither BNPLC nor the collateral agent named in the Building 3 Pledge Agreement
shall be responsible for the proper distribution or application by Zhone of any
such Collateral returned to Zhone; and any such return of Collateral to Zhone
shall discharge any obligation of BNPLC to deliver such Collateral to all
Persons claiming an interest in the Collateral.  Further, BNPLC shall be
entitled to deliver any Building 3 Escrowed Proceeds it holds on the Designated
Sale Date directly to Zhone or to any Applicable Purchaser purchasing BNPLC's
interest in the Building 3 Property and the Building 3 Escrowed Proceeds
pursuant to this Agreement notwithstanding any prior actual or attempted
conveyance or assignment by Zhone, voluntary or otherwise, of any right to
receive the same; BNPLC shall not be responsible for the proper distribution or
application by Zhone or any Applicable Purchaser of any such Building 3 Escrowed
Proceeds paid over to Zhone or the Applicable Purchaser; and any such payment of
Building 3 Escrowed Proceeds to Zhone or an Applicable Purchaser shall discharge
any obligation of BNPLC to deliver the same to all Persons claiming an interest
therein.

     6    Certain Remedies Cumulative.  No right or remedy herein conferred upon
or reserved to BNPLC is intended to be exclusive of any other right or remedy
BNPLC has with respect to the Building 3 Property, and each and every right and
remedy shall be cumulative and in addition to any other right or remedy given
hereunder or now or hereafter existing at law or in equity or by statute. In
addition to other remedies available under this Agreement, either party shall be
entitled, to the extent permitted by applicable law, to a decree compelling
performance of any of the other party's agreements hereunder.

     7    Attorneys' Fees and Legal Expenses.  If either party to this Agreement
commences any legal action or other proceeding to enforce any of the terms of
this Agreement, or because of any breach by the other party or dispute
hereunder, the party prevailing in such action or proceeding shall be entitled
to recover from the other party all Attorneys' Fees incurred in connection
therewith, whether or not such controversy, claim or dispute is prosecuted to a
final judgment.  Any such Attorneys' Fees incurred by either party in enforcing
a judgment in its favor under this Agreement shall be recoverable separately
from such judgment, and the obligation for such Attorneys' Fees is intended to
be severable from other provisions of this Agreement and not to be merged into
any such judgment.

  [Improvements - Building 3]         15
<PAGE>

     8    Estoppel Certificate. Upon request by BNPLC, Zhone shall execute,
acknowledge and deliver a written statement certifying that this Agreement is
unmodified and in full effect (or, if there have been modifications, that this
Agreement is in full effect as modified, and setting forth such modification)
and either stating that no default exists hereunder or specifying each such
default of which Zhone has knowledge. Any such statement may be relied upon by
any Participant or prospective purchaser or assignee of BNPLC with respect to
the Building 3 Property.

     9    Successors and Assigns. The terms, provisions, covenants and
conditions hereof shall be binding upon Zhone and BNPLC and their respective
permitted successors and assigns and shall inure to the benefit of Zhone and
BNPLC and all permitted transferees, mortgagees, successors and assignees of
Zhone and BNPLC with respect to the Building 3 Property; provided, that (A) the
rights of BNPLC hereunder shall not pass to Zhone or any Applicable Purchaser or
any subsequent owner claiming through Zhone or an Applicable Purchaser, (B)
BNPLC shall not assign this Agreement or any rights hereunder except pursuant to
a Permitted Transfer, and (C) Zhone shall not assign this Agreement or any
rights hereunder without the prior written consent of BNPLC.

     10   Amendment and Restatement. Together, this Agreement and the Buildings
1&2 Purchase Agreement amend, restate and replace the Prior Purchase Agreement
referenced in the recitals at the beginning of this agreement.

                                    [Signature pages follow.]

  [Improvements - Building 3]         16
<PAGE>

     IN WITNESS WHEREOF, Zhone and BNPLC have caused this Purchase Agreement
(Improvements - Building 3) to be executed as of August 1, 2000.

                                   "Zhone"

                                   ZHONE TECHNOLOGIES, INC.

                                   By:  /s/  Bruce Ruberg
                                        ---------------------------------
                                        Name:  Bruce Ruberg
                                        ---------------------------------
                                        Title: Corporate Controller
                                        ---------------------------------
<PAGE>

[Continuation of signature pages to Purchase Agreement (Improvements - Building
3) dated to be effective as of August 1, 2000]

                                   "BNPLC"

                                   BNP LEASING CORPORATION

                                   By: /s/  Lloyd G. Cox
                                       ----------------------------------------
                                       Lloyd G. Cox, Vice President
<PAGE>

                                   Exhibit A
                                   ---------

                               LEGAL DESCRIPTION

The real property located in the City of Oakland, County of Alameda, State of
California, described as follows:

Being a portion of Lot 12, as shown on Parcel Map No. 6003, filed in Book 205 of
Parcel Maps, at Pages 94 through 98, Alameda County Records, more particularly
described as follows:

Commencing at the most southerly corner of said Lot 12; Thence along the
southwesterly line of said Lot 12, North 33 (degrees) 50' 24" West, 628.68 feet
to the point of beginning; Thence continuing along the southwesterly line of
said Lot 12, North 33(degrees) 50' 24" West, 1029.21 feet; Thence along the
southeasterly line of said Lot 12, South 56(degrees) 09' 36" West 14.00 feet;
Thence along the southwesterly line of said Lot 12, North 33(degrees) 50' 24"
West, 253.55 feet to the beginning of a curve, concave southwesterly, having a
radius of 392.21 feet; Thence northerly along the arc of said curve, through a
central angle of 3(degrees) 51' 45", an arc distance of 26.44 feet to the
intersection of a line drawn parallel with and 85.00 feet southeasterly of the
northwesterly line of said Lot 12, a radial line through said point bears North
52(degrees) 17' 51" East; Thence parallel with the northwesterly line of said
Lot 12, North 56(degrees) 09' 36" East, 476.93 feet to a point that is 5 feet
southwesterly of the northeasterly line of said Lot 12; Thence along a line that
is parallel with and 5 feet southwesterly of the said northeasterly line of Lot
12, South 40(degrees) 00' 30" East, 69.44 feet to the beginning of a curve,
concave southwesterly, having a radius of 1949.00 feet; Thence southeasterly
along the arc of said curve, through a central angle of 6(degrees) 10' 18", an
arc distance of 209.94 feet; Thence continuing along a line that is parallel
with and 5 feet southwesterly of the said northeasterly line of Lot 12, South
33(degrees)50' 12" East, 1030.61 feet to the intersection with a line drawn
perpendicular with the southwesterly line of said Lot 12, distant thereon 628.68
feet from the most southerly corner of said Lot 12; Thence southwesterly along
said perpendicular line, South 56(degrees) 09' 36" West, 480.72 feet to the
Point of Beginning.

The basis of bearings for Parcel Map No. 6003 is the North American Datum of
1983, Zone 3, 1984 Adjustment Published in 1986, as shown on Record of Survey
990, filed in Book 18 of Records of Survey, at Pages 50 through 60, Alameda
County Records. All distances in this description are grid distances. To convert
to ground distances, multiply grid distances by 1.0000708. Assessor's Parcel No.
041-3902-015 (Portion)

  [Improvements - Building 3]
<PAGE>

[SUBSTITUTE A PAGE COPIED FROM A SURVEY OF THE LAND, MARKED TO SHOW THE
"BUILDING 3 SITE" HERE.]

[Improvements - Building 3]
<PAGE>

                                    Exhibit B
                                    ---------

        Requirements Re: Form of Grant Deed and Extension of Land Lease

The form of deed to be used to convey BNPLC's interest in the Improvements to
Zhone or an Applicable Purchaser will depend upon whether BNPLC's interest in
the Land has been or is being conveyed at the same time to the same party.

If BNPLC's interests in both the Land and the Improvements are to be conveyed to
Zhone or an Applicable Purchaser at the same time, because sales under this
Building 3 Purchase Agreement, the Buildings 1&2 Purchase Agreement and the Land
Purchase Agreement (covering the Land) are all being consummated at the same
time and to the same party, then the one deed in form attached as Exhibit B-1
                                                                  -----------
will be used to convey both.

If, however, a sale of BNPLC's interest in the Land pursuant to the Land
Purchase Agreement has not been consummated before, and is not being consummated
contemporaneously with sales of BNPLC's interest in the Improvements under this
Building 3 Purchase Agreement and under the Buildings 1&2 Purchase Agreement,
then BNPLC's interest in the Improvements will be conveyed by a deed in the form
attached as Exhibit B-2.  In such a case, if Zhone has requested it in writing
            -----------
at least thirty days prior to the delivery of such a deed, BNPLC shall also
tender an amendment to the Land Lease in the form attached as Exhibit B-3, which
                                                              -----------
will extend the term of the Land Lease at a base rent equal to fair market
rental value of the Land, determined as provided in such amendment.  In such a
case, it is understood that if Zhone designates an Applicable Purchaser to
purchase BNPLC's interest in the Improvements, Zhone may sublease the Land to
the Applicable Purchaser under (and subject to the terms and conditions of) the
Land Lease.  (Presumably, the Applicable Purchaser will require a sublease of
the Land from Zhone as a condition to purchasing the Improvements.)  But in no
event will BNPLC be required to do more than tender an extension of the Land
Lease (as provided in this paragraph) to facilitate the use and enjoyment of the
Improvements by Zhone or any Applicable Purchaser claiming through Zhone.
Without limiting the generality of the foregoing, it is understood that BNPLC
will not otherwise be required to grant any lease or other interest in the Land
to any such Applicable Purchaser.

Finally, BNPLC's interest in the Improvements will be conveyed by a deed in the
form attached as Exhibit B-3 if BNPLC's interest in the Land has been sold
                 -----------
pursuant to the Land Purchase Agreement before a sale of BNPLC's interest in the
Improvements under this Agreement and the Buildings 1&2 Purchase Agreement, or
if BNPLC's interest in the Improvements is being sold contemporaneously with a
sale of BNPLC's interest in the Land, but the purchaser of the Improvements is
not the same as the purchaser of the Land.

[Improvements - Building 3]
<PAGE>

                                  Exhibit B-1
                                  -----------

                            CORPORATION GRANT DEED

RECORDING REQUESTED BY
AND WHEN RECORDED MAIL TO:
-------------------------

NAME: [Zhone or the Applicable Purchaser]
ADDRESS:  ___________________
ATTN:     ___________________
CITY:     ___________________
STATE:___________________
Zip:      ___________________

MAIL TAX STATEMENTS TO:
----------------------

NAME: [Zhone or the Applicable Purchaser]
ADDRESS:  ___________________
ATTN:     ___________________
CITY:     ___________________
STATE:___________________
Zip:      ___________________

                            CORPORATION GRANT DEED
                       (Covering Land and Improvements)

FOR A VALUABLE CONSIDERATION, receipt of which is hereby acknowledged, BNP
LEASING CORPORATION, a Delaware corporation ("Grantor"), hereby grants to [Zhone
or the Applicable Purchaser] ("Grantee") all of Grantor's interest in the land
situated in Oakland, California, described on Annex A attached hereto and hereby
made a part hereof and all improvements on such land, together with the any
other right, title and interest of Grantor in and to any easements, rights-of-
way, privileges and other rights appurtenant to such land or the improvements
thereon; provided, however, that this grant is subject to the encumbrances
described on Annex B (the "Permitted Encumbrances"). Grantee hereby assumes the
obligations (including any personal obligations) of Grantor, if any, created by
or under, and agrees to be bound by the terms and conditions of, the Permitted
Encumbrances to the extent that the same concern or apply to the land or
improvements conveyed by this deed.

[Improvements - Building 3]
<PAGE>

                                    BNP LEASING CORPORATION

Date: As of ____________            By:     ___________________________________
                                            Its:

                                    Attest: ___________________________________
                                            Its:

                                    [Zhone or Applicable Purchaser]

Date: As of ____________            By:     ___________________________________
                                            Its:

                                    Attest: ___________________________________
                                            Its:

STATE OF ____________  )
                       )  SS
COUNTY OF ___________  )

     On ___________________ before me,______________, personally
appeared___________ and________________, personally known to me (or proved to me
on the basis of satisfactory evidence) to be the persons whose names are
subscribed to the within instrument and acknowledged to me that they executed
the same in their authorized capacities, and that by their signatures on the
instrument the person, or the entity upon behalf of which the persons acted,
executed the instrument.

     WITNESS my hand and official seal.

     Signature__________________________________

[Improvements - Building 3]

                             Exhibit B-1 - Page 2
<PAGE>

STATE OF ____________  )
                       )  SS
COUNTY OF ___________  )

     On ___________________ before me,______________, personally
appeared___________ and________________, personally known to me (or proved to me
on the basis of satisfactory evidence) to be the persons whose names are
subscribed to the within instrument and acknowledged to me that they executed
the same in their authorized capacities, and that by their signatures on the
instrument the person, or the entity upon behalf of which the persons acted,
executed the instrument.

     WITNESS my hand and official seal.

     Signature_______________________________

[Improvements - Building 3]

                             Exhibit B-1 - Page 3
<PAGE>

                                    Annex A

                               LEGAL DESCRIPTION

[DRAFTING NOTE: TO THE EXTENT THAT THE "LAND" COVERED BY THE LAND LEASE CHANGES
 -------------
FROM TIME TO TIME BECAUSE OF ADJUSTMENTS FOR WHICH ZHONE REQUESTS BNPLC'S
CONSENT OR APPROVAL, SO TOO WILL THE DESCRIPTION OF THE LAND BELOW CHANGE. ANY
SUCH CHANGES WILL BE INCORPORATED INTO THE DESCRIPTION BELOW AND THIS "DRAFTING
NOTE" WILL BE DELETED BEFORE THE DEED TO WHICH THIS DESCRIPTION IS ATTACHED IS
ACTUALLY EXECUTED AND DELIVERED.]

The real property located in the City of Oakland, County of Alameda, State of
California, described as follows:

Being a portion of Lot 12, as shown on Parcel Map No. 6003, filed in Book 205 of
Parcel Maps, at Pages 94 through 98, Alameda County Records, more particularly
described as follows:

Commencing at the most southerly corner of said Lot 12; Thence along the
southwesterly line of said Lot 12, North 33(degrees) 50' 24" West, 628.68 feet
to the point of beginning; Thence continuing along the southwesterly line of
said Lot 12, North 33(degrees) 50' 24" West, 1029.21 feet; Thence along the
southeasterly line of said Lot 12, South 56(degrees) 09' 36" West 14.00 feet;
Thence along the southwesterly line of said Lot 12, North 33(degrees) 50' 24"
West, 253.55 feet to the beginning of a curve, concave southwesterly, having a
radius of 392.21 feet; Thence northerly along the arc of said curve, through a
central angle of 3(degrees) 51' 45", an arc distance of 26.44 feet to the
intersection of a line drawn parallel with and 85.00 feet southeasterly of the
northwesterly line of said Lot 12, a radial line through said point bears North
52(degrees) 17' 51" East; Thence parallel with the northwesterly line of said
Lot 12, North 56(degrees) 09' 36" East, 476.93 feet to a point that is 5 feet
southwesterly of the northeasterly line of said Lot 12; Thence along a line that
is parallel with and 5 feet southwesterly of the said northeasterly line of Lot
12, South 40(degrees) 00' 30" East, 69.44 feet to the beginning of a curve,
concave southwesterly, having a radius of 1949.00 feet; Thence southeasterly
along the arc of said curve, through a central angle of 6(degrees) 10' 18", an
arc distance of 209.94 feet; Thence continuing along a line that is parallel
with and 5 feet southwesterly of the said northeasterly line of Lot 12, South
33(degrees)50' 12" East, 1030.61 feet to the intersection with a line drawn
perpendicular with the southwesterly line of said Lot 12, distant thereon 628.68
feet from the most southerly corner of said Lot 12; Thence southwesterly along
said perpendicular line, South 56(degrees) 09' 36" West, 480.72 feet to the
Point of Beginning.

The basis of bearings for Parcel Map No. 6003 is the North American Datum of
1983, Zone 3, 1984 Adjustment Published in 1986, as shown on Record of Survey
990, filed in Book 18 of Records of Survey, at Pages 50 through 60, Alameda
County Records. All distances in this description are grid distances. To convert
to ground distances, multiply grid distances by 1.0000708.

Assessor's Parcel No. 041-3902-015 (Portion)

[Improvements - Building 3]

                             Exhibit B-1 - Page 4
<PAGE>

                                    Annex B

                            Permitted Encumbrances

[DRAFTING NOTE: TO THE EXTENT THAT ENCUMBRANCES (OTHER THAN "LIENS REMOVABLE BY
 -------------
BNPLC") ARE IDENTIFIED IN ADDITION TO THOSE DESCRIBED BELOW, SUCH ADDITIONAL
ENCUMBRANCES WILL BE ADDED TO THE LIST BELOW AND THIS "DRAFTING NOTE" WILL BE
DELETED BEFORE THIS DEED IS ACTUALLY EXECUTED AND DELIVERED BY BNPLC. SUCH
ADDITIONAL ENCUMBRANCES WOULD INCLUDE ANY NEW ENCUMBRANCES APPROVED BY BNPLC AS
"PERMITTED ENCUMBRANCES" UNDER THE LAND LEASE, THE BUILDINGS 1&2 LEASE OR THE
BUILDING 3 LEASE FROM TIME TO TIME OR BECAUSE OF ZHONE'S REQUEST FOR BNPLC'S
CONSENT OR APPROVAL TO AN ADJUSTMENT.]

     This conveyance is subject to all encumbrances not constituting a "Lien
Removable by BNPLC" (as defined in the Common Definitions and Provisions
Agreement (Improvements - Building 3) incorporated by reference into the Lease
Agreement (Improvements - Building 3) referenced in the last item of the list
below), including the following matters to the extent the same are still valid
and in force:

1.   County and city taxes for the Fiscal Year 2000 - 2001, a lien not yet due
     or payable.

2.   The Lien of Supplemental Taxes, if any, assessed pursuant to the provisions
     of Chapter 3.5, Revenue and Taxation Code, Sections 75 et seq., resulting
     from changes of ownership or completion of construction on or after the
     date hereof.

3.   Easement, upon the terms, covenants and conditions thereof, for the
     purposes stated therein and incidental purposes created in that certain
     instrument

     Recorded    :  FEBRUARY 11, 1974, REEL 3608, IMAGE 3, SERIES NO. 74-16523,
                    OFFICIAL RECORDS
     Granted to  :  THE PACIFIC TELEPHONE AND TELEGRAPH COMPANY, A
                    CORPORATION
     Purpose     :  COMMUNICATION FACILITIES
     Affects     :  A SOUTHWESTERLY PORTION OF SAID LAND

4.   Terms, covenants, conditions and reservations as contained in the Port
     Ordinance No. 2832.  An Ordinance establishing standards and restrictions
     regulating the use of land and the design and construction of structures
     and other improvements in the Oakland Airport Business Park, and repealing
     Port Ordinance No. 1343, as amended, recorded MAY 10, 1990, SERIES NO.
     90130204, OFFICIAL RECORDS.

     Amendment Port Ordinance No. 3146, recorded SEPTEMBER 30, 1993, SERIES NO.
     93348032, OFFICIAL RECORDS.

5.   Terms and conditions of the City of Oakland Redevelopment Project adopted
     by Ordinance No. 11824, C.M.S., as disclosed in the "Notice of Adoption of
     the Coliseum Area Redevelopment Plan, Termination of the 77/th/ Avenue
     Industrial Redevelopment Project and Amendment of the Elmhurst
     Redevelopment Plan," recorded JULY 31, 1995, SERIES NO. 95167161, OFFICIAL
     RECORDS. Amendment recorded SEPTEMBER 9, 1997, SERIES NO. 97-231187,
     OFFICIAL RECORDS.

[Improvements - Building 3]

                             Exhibit B-1 - Page 5
<PAGE>

6.   The Lease Agreement (Land), the Lease Agreement (Improvements - Buildings
     1&2) and the Lease Agreement (Improvements - Building 3), all dated as of
     August 1, 2000 and all between BNP Leasing Corporation, as lessor, and
     Zhone Technologies, Inc., as lessee.

[Improvements - Building 3]

                             Exhibit B-1 - page 6
<PAGE>

                                    Exhibit B-2
                                    -----------

                            CORPORATION GRANT DEED

RECORDING REQUESTED BY
AND WHEN RECORDED MAIL TO:
-------------------------

NAME:  [Zhone or the Applicable Purchaser]
ADDRESS:  ___________________
ATTN:     ___________________
CITY:     ___________________
STATE:  ___________________
Zip:      ___________________

MAIL TAX STATEMENTS TO:
----------------------

NAME:  [Zhone or the Applicable Purchaser]
ADDRESS:  ___________________
ATTN:     ___________________
CITY:     ___________________
STATE:  ___________________
Zip:      ___________________

                            CORPORATION GRANT DEED
        (Covering Improvements but not the Land under the Improvements)

FOR A VALUABLE CONSIDERATION, receipt of which is hereby acknowledged, BNP
LEASING CORPORATION, a Delaware corporation ("Grantor"), hereby grants to [Zhone
or the Applicable Purchaser] ("Grantee") all of Grantor's interest in the
buildings and other improvements (the "Improvements") on the land situated in
Oakland, California, described on Annex A attached hereto and hereby made a part
hereof (the "Land"), together with the any other right, title and interest of
Grantor in and to any easements, rights-of-way, privileges and other rights
appurtenant to the Improvements; provided, however, that this grant is subject
to the encumbrances described on Annex B (the "Permitted Encumbrances") and any
reservations or qualifications set forth below. Grantee hereby assumes the
obligations (including any personal obligations) of Grantor, if any, created by
or under, and agrees to be bound by the terms and conditions of, the Permitted
Encumbrances to the extent that the same concern or apply to the Improvements.

Although this deed conveys Grantor's interest in the Improvements, this deed
does not convey any interest in the Land under the Improvements or any rights or
easements appurtenant to Improvements. Grantor retains and reserves all right,
title and interest of  Grantor in and to the Land and any rights and easements
appurtenant to Land.  Further, this deed does not convey any right of access
over or right to use the Land, it being understood that the right of Grantee or
its successors and assigns to maintain or use the improvements conveyed hereby
on the Land shall be on and subject to the terms and conditions of any separate
ground lease or deed that Grantee may from time to time obtain, authorizing use
of the Land by Grantee. [DRAFTING NOTE: IF ZHONE DESIGNATES AN APPLICABLE
                         -------------
PURCHASER AS GRANTEE (RATHER THAN DESIGNATING ITSELF TO BE THE GRANTEE), THE
FOLLOWING WILL BE ADDED TO THIS DEED:

     Unless Grantee has obtained or is (contemporaneously with the delivery of
this deed) obtaining a sublease under a separate existing ground lease that is
sufficient to authorize Grantee to maintain the Improvements on the Land,
Grantee shall remove or abandon the Improvements promptly upon request of the
owner of the Land. Nothing herein or in the agreements pursuant to which this
deed is being delivered shall be construed as an obligation on the part of
Grantor to deliver or cooperate reasonably in obtaining for Grantee any deed or
ground lease covering the Land described in

  [Improvements - Building 3]
<PAGE>

Annex A.]

[Improvements - Building 3]

                             Exhibit B-2 - Page 2
<PAGE>

                                    BNP LEASING CORPORATION

Date: As of ____________            By:     ___________________________________
                                            Its:

                                    Attest: ___________________________________
                                            Its:

                                    [Zhone or Applicable Purchaser]

Date: As of ____________            By:     ___________________________________
                                            Its:

                                    Attest: ___________________________________
                                            Its:

STATE OF ____________  )
                       )  SS
COUNTY OF ___________  )

     On ___________________ before me,______________, personally
appeared___________ and________________, personally known to me (or proved to me
on the basis of satisfactory evidence) to be the persons whose names are
subscribed to the within instrument and acknowledged to me that they executed
the same in their authorized capacities, and that by their signatures on the
instrument the person, or the entity upon behalf of which the persons acted,
executed the instrument.

     WITNESS my hand and official seal.

     Signature_____________________________

[Improvements - Building 3]

                             Exhibit B-2 - Page 3
<PAGE>

STATE OF ____________  )
                       )  SS
COUNTY OF ___________  )

     On ___________________ before me,______________, personally
appeared___________ and________________, personally known to me (or proved to me
on the basis of satisfactory evidence) to be the persons whose names are
subscribed to the within instrument and acknowledged to me that they executed
the same in their authorized capacities, and that by their signatures on the
instrument the person, or the entity upon behalf of which the persons acted,
executed the instrument.

     WITNESS my hand and official seal.

     Signature_______________________________

[Improvements - Building 3]

                             Exhibit B-2 - Page 4
<PAGE>

                                    Annex A

                               LEGAL DESCRIPTION

[DRAFTING NOTE: TO THE EXTENT THAT THE "LAND" COVERED BY THE LAND LEASE CHANGES
 --------------
FROM TIME TO TIME BECAUSE OF ADJUSTMENTS FOR WHICH ZHONE REQUESTS BNPLC'S
CONSENT OR APPROVAL, SO TOO WILL THE DESCRIPTION OF THE LAND BELOW CHANGE. ANY
SUCH CHANGES WILL BE INCORPORATED INTO THE DESCRIPTION BELOW AND THIS "DRAFTING
NOTE" WILL BE DELETED BEFORE THE DEED TO WHICH THIS DESCRIPTION IS ATTACHED IS
ACTUALLY EXECUTED AND DELIVERED.]

The real property located in the City of Oakland, County of Alameda, State of
California, described as follows:

Being a portion of Lot 12, as shown on Parcel Map No. 6003, filed in Book 205 of
Parcel Maps, at Pages 94 through 98, Alameda County Records, more particularly
described as follows:

Commencing at the most southerly corner of said Lot 12; Thence along the
southwesterly line of said Lot 12, North 33(degrees) 50' 24" West, 628.68 feet
to the point of beginning; Thence continuing along the southwesterly line of
said Lot 12, North 33(degrees) 50' 24" West, 1029.21 feet; Thence along the
southeasterly line of said Lot 12, South 56(degrees) 09' 36" West 14.00 feet;
Thence along the southwesterly line of said Lot 12, North 33(degrees) 50' 24"
West, 253.55 feet to the beginning of a curve, concave southwesterly, having a
radius of 392.21 feet; Thence northerly along the arc of said curve, through a
central angle of 3(degrees) 51' 45", an arc distance of 26.44 feet to the
intersection of a line drawn parallel with and 85.00 feet southeasterly of the
northwesterly line of said Lot 12, a radial line through said point bears North
52(degrees) 17' 51" East; Thence parallel with the northwesterly line of said
Lot 12, North 56(degrees) 09' 36" East, 476.93 feet to a point that is 5 feet
southwesterly of the northeasterly line of said Lot 12; Thence along a line that
is parallel with and 5 feet southwesterly of the said northeasterly line of Lot
12, South 40(degrees) 00' 30" East, 69.44 feet to the beginning of a curve,
concave southwesterly, having a radius of 1949.00 feet; Thence southeasterly
along the arc of said curve, through a central angle of 6(degrees) 10' 18", an
arc distance of 209.94 feet; Thence continuing along a line that is parallel
with and 5 feet southwesterly of the said northeasterly line of Lot 12, South
33(degrees)50' 12" East, 1030.61 feet to the intersection with a line drawn
perpendicular with the southwesterly line of said Lot 12, distant thereon 628.68
feet from the most southerly corner of said Lot 12; Thence southwesterly along
said perpendicular line, South 56(degrees) 09' 36" West, 480.72 feet to the
Point of Beginning.

The basis of bearings for Parcel Map No. 6003 is the North American Datum of
1983, Zone 3, 1984 Adjustment Published in 1986, as shown on Record of Survey
990, filed in Book 18 of Records of Survey, at Pages 50 through 60, Alameda
County Records. All distances in this description are grid distances. To convert
to ground distances, multiply grid distances by 1.0000708.

Assessor's Parcel No. 041-3902-015 (Portion)

[Improvements - Building 3]

                             Exhibit B-2 - Page 5

<PAGE>

                                    Annex B

                            Permitted Encumbrances

[DRAFTING NOTE: TO THE EXTENT THAT ENCUMBRANCES (OTHER THAN "LIENS REMOVABLE BY
 --------------
BNPLC") ARE IDENTIFIED IN ADDITION TO THOSE DESCRIBED BELOW, SUCH ADDITIONAL
ENCUMBRANCES WILL BE ADDED TO THE LIST BELOW AND THIS "DRAFTING NOTE" WILL BE
DELETED BEFORE THIS DEED IS ACTUALLY EXECUTED AND DELIVERED BY BNPLC. SUCH
ADDITIONAL ENCUMBRANCES WOULD INCLUDE ANY NEW ENCUMBRANCES APPROVED BY BNPLC AS
"PERMITTED ENCUMBRANCES" UNDER THE LAND LEASE, THE BUILDINGS 1&2 LEASE OR THE
BUILDING 3 LEASE FROM TIME TO TIME OR BECAUSE OF ZHONE'S REQUEST FOR BNPLC'S
CONSENT OR APPROVAL TO AN ADJUSTMENT.]

     This conveyance is subject to all encumbrances not constituting a "Lien
Removable by BNPLC" (as defined in the Common Definitions and Provisions
Agreement (Improvements - Building 3) incorporated by reference into the Lease
Agreement (Improvements - Building 3) referenced in the last item of the list
below), including the following matters to the extent the same are still valid
and in force:

1.   County and city taxes for the Fiscal Year 2000 - 2001, a lien not yet due
     or payable.

2.   The Lien of Supplemental Taxes, if any, assessed pursuant to the provisions
     of Chapter 3.5, Revenue and Taxation Code, Sections 75 et seq., resulting
     from changes of ownership or completion of construction on or after the
     date hereof.

3.   Easement, upon the terms, covenants and conditions thereof, for the
     purposes stated therein and incidental purposes created in that certain
     instrument

     Recorded    :  FEBRUARY 11, 1974, REEL 3608, IMAGE 3, SERIES NO. 74-
                    16523, OFFICIAL RECORDS
     Granted to  :  THE PACIFIC TELEPHONE AND TELEGRAPH COMPANY, A CORPORATION
     Purpose     :  COMMUNICATION FACILITIES
     Affects     :  A SOUTHWESTERLY PORTION OF SAID LAND

4.   Terms, covenants, conditions and reservations as contained in the Port
     Ordinance No. 2832. An Ordinance establishing standards and restrictions
     regulating the use of land and the design and construction of structures
     and other improvements in the Oakland Airport Business Park, and repealing
     Port Ordinance No. 1343, as amended, recorded MAY 10, 1990, SERIES NO.
     90130204, OFFICIAL RECORDS.

     Amendment Port Ordinance No. 3146, recorded SEPTEMBER 30, 1993, SERIES NO.
     93348032, OFFICIAL RECORDS.

5.   Terms and conditions of the City of Oakland Redevelopment Project adopted
     by Ordinance No. 11824, C.M.S., as disclosed in the "Notice of Adoption of
     the Coliseum Area Redevelopment Plan, Termination of the 77/th/ Avenue
     Industrial Redevelopment Project and Amendment of the Elmhurst
     Redevelopment Plan," recorded JULY 31, 1995, SERIES NO. 95167161, OFFICIAL
     RECORDS.
     Amendment recorded SEPTEMBER 9, 1997, SERIES NO. 97-231187, OFFICIAL
     RECORDS.

[Improvements - Building 3]

                             Exhibit B-2 - Page 6
<PAGE>

6.   The Lease Agreement (Land), the Lease Agreement (Improvements - Buildings
     1&2) and the Lease Agreement (Improvements - Building 3), all dated as of
     August 1, 2000 and all between BNP Leasing Corporation, as lessor, and
     Zhone Technologies, Inc., as lessee.

[Improvements - Building 3]

                             Exhibit B-2 - Page 7
<PAGE>

                                  Exhibit B-3
                                  -----------

                      AMENDMENT TO LEASE AGREEMENT (LAND)

     This AMENDMENT TO LEASE AGREEMENT LAND (this "Amendment"), by and between
BNP LEASING CORPORATION, a Delaware corporation ("BNPLC"), whose address is
12201 Merit Drive, Suite 860, Dallas, Texas 75251, and [Zhone or any permitted
assignee of Zhone which has become the tenant under the Land Lease], a
___________ ("Lessee"), whose address is ____________________. as of
____________, ____ (the "Effective Date").

                                   RECITALS

     This Amendment is being executed pursuant to a Purchase Agreement (Land)
dated as of August 1, 2000 (the "Land Purchase Agreement"), between BNP Leasing
Corporation and Zhone Technologies, Inc., covering the land described in Annex 1
                                                                         -------
attached hereto (the "Land"). Incorporated by reference into the Land Purchase
Agreement is a Common Definitions and Provisions Agreement (Land) dated as of
the effective date of the Land Purchase Agreement (the "Land CDPA"), between BNP
Leasing Corporation and Zhone Technologies, Inc. The Land CDPA is hereby
incorporated into and made a part of this Amendment for all purposes.
Capitalized terms defined in the Land CDPA and used but not otherwise defined
herein are intended in this Amendment to have the respective meanings ascribed
to them in the Land CDPA. The provisions in Article II of the Land CDPA are
intended to apply to this Amendment as if set forth herein and as if this Ground
Lease were one of the "Land Operative Documents" as defined therein.

     Lessee is currently the tenant under the Land Lease, which covers the Land
described in Annex 1. Lessee and BNPLC have reached agreement as to the terms
             -------
and conditions upon which they will extend the Land Lease Land for a term of
just less that 35 years, and by this Amendment Lessee and BNPLC desire to
evidence such agreement.

                                  AGREEMENTS

     NOW, THEREFORE, Lessee and BNPLC agree as follows:

     1.   The term of the Land Lease is extended so that (unless the Land Lease
is terminated earlier in accordance with its terms) the term of the Land Lease
will end on the first day of the last calendar month prior to the thirty-fifth
anniversary of the date of this Amendment.

     2.   From and after the Designated Sale Date, Base Rent required by the
Land Lease must be paid by Lessee in monthly installments, with each installment
due on the first day of every calendar month, in arrears, without offset, demand
or deduction, in an amount equal to the Fair Rental Value as defined in Annex 2
                                                                        -------
attached hereto.

     3.   Lessee waives (A) any right to terminate the Land Lease as provided in
Paragraph 1(d) thereof, and (B) any right to further extend the Land Lease,
pursuant to Paragraph 1(c) thereof or otherwise.
     4.   Except as provided herein, the Land Lease will continue on all of the
same terms and conditions as are set forth therein.

[Improvements - Building 3]

<PAGE>

                         [The signature pages follow.]

[Improvements - Building 3]

                             Exhibit B-3 - Page
<PAGE>

     IN WITNESS WHEREOF, this Land Lease Amendment is hereby executed in
multiple originals as of the date first written above.

                         "Lessor"

                         [Zhone or its permitted assignee under the Land Lease]

                         By:______________________________________________
                              Name:_______________________________________
                              Title:______________________________________

  [Improvements - Building 3]

                             Exhibit B-3 - Page 3
<PAGE>

[Continuation of signature pages to Land Lease Amendment dated as of
___________, ____]

                                 "BNPLC"

                                 BNP LEASING CORPORATION

                                 By:____________________________________
                                     Name:______________________________
                                     Title:_____________________________

[Improvements - Building 3]

                             Exhibit B-3 - Page 4
<PAGE>

STATE OF ___________     )
                         )
COUNTY OF _____________  )

     On _____________, _____, before me, ________________________, personally
appeared ____________________________, personally known to me (or proved to me
on the basis of satisfactory evidence) to be the person whose name is subscribed
to the within instrument and acknowledged to me that he executed the same in his
authorized capacity, and that by his signature on the instrument the person, or
the entity upon behalf of which the person acted, executed the instrument.

                         WITNESS my hand and official seal.

                         Signature _____________________________

[Improvements - Building 3]

                             Exhibit B-3 - Page 5
<PAGE>

STATE OF ________    )
                     )
COUNTY OF __________ )

     On ___________, _____, before me, ________________________, personally
appeared ____________, personally known to me (or proved to me on the basis of
satisfactory evidence) to be the person whose name is subscribed to the within
instrument and acknowledged to me that he executed the same in his authorized
capacity, and that by his signature on the instrument the person, or the entity
upon behalf of which the person acted, executed the instrument.

                         WITNESS my hand and official seal.

                         Signature _________________________________

[Improvements - Building 3]

                             Exhibit B-3 - Page 6
<PAGE>

                                    Annex 1
                                    -------

                               Legal Description

[DRAFTING NOTE: TO THE EXTENT THAT THE "LAND" COVERED BY THE LAND LEASE CHANGES
 --------------
FROM TIME TO TIME BECAUSE OF ADJUSTMENTS FOR WHICH ZHONE REQUESTS BNPLC'S
CONSENT OR APPROVAL, SO TOO WILL THE DESCRIPTION OF THE LAND BELOW CHANGE. ANY
SUCH CHANGES WILL BE INCORPORATED INTO THE DESCRIPTION BELOW AND THIS "DRAFTING
NOTE" WILL BE DELETED BEFORE THE DEED TO WHICH THIS DESCRIPTION IS ATTACHED IS
ACTUALLY EXECUTED AND DELIVERED.]

The real property located in the City of Oakland, County of Alameda, State of
California, described as follows:

Being a portion of Lot 12, as shown on Parcel Map No. 6003, filed in Book 205 of
Parcel Maps, at Pages 94 through 98, Alameda County Records, more particularly
described as follows:

Commencing at the most southerly corner of said Lot 12; Thence along the
southwesterly line of said Lot 12, North 33(degrees) 50' 24" West, 628.68 feet
to the point of beginning; Thence continuing along the southwesterly line of
said Lot 12, North 33(degrees) 50' 24" West, 1029.21 feet; Thence along the
southeasterly line of said Lot 12, South 56(degrees) 09' 36" West 14.00 feet;
Thence along the southwesterly line of said Lot 12, North 33(degrees) 50' 24"
West, 253.55 feet to the beginning of a curve, concave southwesterly, having a
radius of 392.21 feet; Thence northerly along the arc of said curve, through a
central angle of 3(degrees) 51' 45", an arc distance of 26.44 feet to the
intersection of a line drawn parallel with and 85.00 feet southeasterly of the
northwesterly line of said Lot 12, a radial line through said point bears North
52(degrees) 17' 51" East; Thence parallel with the northwesterly line of said
Lot 12, North 56(degrees) 09' 36" East, 476.93 feet to a point that is 5 feet
southwesterly of the northeasterly line of said Lot 12; Thence along a line that
is parallel with and 5 feet southwesterly of the said northeasterly line of Lot
12, South 40(degrees) 00' 30" East, 69.44 feet to the beginning of a curve,
concave southwesterly, having a radius of 1949.00 feet; Thence southeasterly
along the arc of said curve, through a central angle of 6(degrees) 10' 18", an
arc distance of 209.94 feet; Thence continuing along a line that is parallel
with and 5 feet southwesterly of the said northeasterly line of Lot 12, South
33(degrees)50' 12" East, 1030.61 feet to the intersection with a line drawn
perpendicular with the southwesterly line of said Lot 12, distant thereon 628.68
feet from the most southerly corner of said Lot 12; Thence southwesterly along
said perpendicular line, South 56(degrees) 09' 36" West, 480.72 feet to the
Point of Beginning.

The basis of bearings for Parcel Map No. 6003 is the North American Datum of
1983, Zone 3, 1984 Adjustment Published in 1986, as shown on Record of Survey
990, filed in Book 18 of Records of Survey, at Pages 50 through 60, Alameda
County Records. All distances in this description are grid distances. To convert
to ground distances, multiply grid distances by 1.0000708.

Assessor's Parcel No. 041-3902-015 (Portion)

[Improvements - Building 3]

                             Exhibit B-3 - Page 7
<PAGE>

                                    Annex 2
                                    -------

                      DETERMINATION OF FAIR RENTAL VALUE

     Each monthly payment of Base Rent will equal the Fair Rental Value,
computed as of the most recent Rental Determination Date (defined below) when
such payment becomes due. As used in this Annex:

          "Fair Rental Value" means (and all appraisers and other persons
     involved in the determination of the Fair Rental Value will be so advised)
     the monthly rent, as determined in accordance with this Annex, that would
     be agreed upon between a willing tenant, under no compulsion to lease, and
     a willing landlord, under no compulsion to lease, for unimproved land
                                                           ----------
     comparable in size and location to the Land, exclusive of any improvements,
     at the time a determination is required hereunder and taking into
     consideration the condition of the Land, the encumbrances affecting the
     title to the Land and all applicable zoning, land use approvals and other
     governmental permits relating to the Land at the time of such
     determination; and

          "Rental Determination Date" means the Designated Sale Date and each
     fifth anniversary of the Designated Sale Date.

     If Lessee and BNPLC have not agreed upon Fair Rental Value as of any Rental
Determination Date within one hundred eighty days after the such date, then Fair
Rental Value will be determined as follows:

          (a) Lessee and BNPLC shall each appoint a real estate appraiser who is
     familiar with rental values for properties in the vicinity of the Land and
     who has not previously acted for either party. Each party will make the
     appointment no later than ten days after receipt of notice from the other
     party that the appraisal process described in this Annex has been invoked.
     The agreement of the two appraisers as to Fair Rental Value will be binding
     upon Lessee and BNPLC. If the two appraisers cannot agree upon the Fair
     Rental Value within ten days following their appointment, they shall within
     another ten days agree upon a third real estate appraiser. Immediately
     thereafter, each of the first two appraisers will submit his best estimate
     of the appropriate Fair Rental Value (together with a written report
     supporting such estimate) to the third appraiser and the third appraiser
     will choose between the two estimates. The estimate of Fair Rental Value
     chosen by the third appraiser as the closest to the prevailing annual fair
     rental value will be binding upon Lessee and BNPLC. Notification in writing
     of this estimate shall be made to Lessee and BNPLC within fifteen days
     following the selection of the third appraiser.

          (b) If appraisers must be selected under the procedure set out above
     and either BNPLC or Lessee fails to appoint an appraiser or fails to notify
     the other party of such appointment within fifteen days after receipt of
     notice that the prescribed time for appointing the appraisers has passed,
     then the other party's appraiser will determine the Fair Rental Value. All
     appraisers selected for the appraisal process set out in this Annex will be
     disinterested, reputable, qualified real estate appraisers with the
     designation of MAI or equivalent and with at least 5 years experience in
     appraising properties comparable to the Land.

          (c) If a third appraiser must be chosen under the procedure set out
     above, he or she will be chosen on the basis of objectivity and competence,
     not on the basis of his relationship with the other appraisers or the
     parties to the Land Lease, and the first two appraisers will be so advised.
     Although the first two appraisers will be instructed to attempt in good
     faith to agree upon the third appraiser, if for

[Improvements - Building 3]

Exhibit B-3 - Page 8
<PAGE>

     any reason they cannot agree within the prescribed time, either Lessee and
     BNPLC may require the first two appraisers to immediately submit its top
     choice for the third appraiser to the then highest ranking officer of the
     California Bar Association who will agree to help and who has no
     attorney/client or other significant relationship to either Lessee or
     BNPLC. Such officer will have complete discretion to select the most
     objective and competent third appraiser from between the choices of each of
     the first two appraisers, and will do so within twenty days after such
     choices are submitted to him.

          (d) Either Lessee or BNPLC may notify the appraiser selected by the
     other party to demand the submission of an estimate of Fair Rental Value or
     a choice of a third appraiser as required under the procedure described
     above; and if the submission of such an estimate or choice is required but
     the other party's appraiser fails to comply with the demand within fifteen
     days after receipt of such notice, then the Fair Rental Value or choice of
     the third appraiser, as the case may be, selected by the other appraiser
     (i.e., the notifying party's appraiser) will be binding upon Lessee and
     BNPLC.

          (e) Lessee and BNPLC shall each bear the expense of the appraiser
     appointed by it, and the expense of the third appraiser and of any officer
     of the California Bar Association who participates in the appraisal process
     described above will be shared equally by Lessee and BNPLC.

     If the Fair Rental Value as of any Rental Determination Date has not been
established by agreement of the parties or in accordance with the foregoing
procedures prior to the due date for any monthly installment of Base Rent that
is dependent upon such Fair Rental Value, then no later than such due date
Lessee shall make an estimated payment of Base Rent equal to 150% of the monthly
Base Rent required for latest full calendar month prior to such Rental
Determination Date. Thereafter, if the Fair Rental Value is established to be
greater than the estimated payments made by Lessee, Lessee will pay over any
resulting underpayment to BNPLC upon demand. If, on the other hand, the Fair
Rental Value is later established to be less than the estimated payments made by
Lessee, Lessee may offset any resulting overpayment of Base Rent against future
installments of Base Rent as they become due.

[Improvements - Building 3]

                             Exhibit B-3 - Page 9
<PAGE>

                                  Exhibit B-4
                                  -----------

                            CORPORATION GRANT DEED

RECORDING REQUESTED BY
AND WHEN RECORDED MAIL TO:
-------------------------

NAME:  [Zhone or the Applicable Purchaser]
ADDRESS:  ___________________
ATTN:     ___________________
CITY:     ___________________
STATE:_____________________
Zip:      ___________________

MAIL TAX STATEMENTS TO:
----------------------

NAME:  [Zhone or the Applicable Purchaser]
ADDRESS:  ___________________
ATTN:     ___________________
CITY:     ___________________
STATE:_____________________
Zip:      ___________________

                            CORPORATION GRANT DEED
          (Covering Improvements but not Land under the Improvements)

FOR A VALUABLE CONSIDERATION, receipt of which is hereby acknowledged, BNP
LEASING CORPORATION, a Delaware corporation ("Grantor"), hereby grants to [Zhone
or the Applicable Purchaser] ("Grantee") all of Grantor's interest in the
buildings and other improvements (the "Improvements") on the land situated in
Oakland, California, described on Annex A attached hereto and hereby made a part
hereof (the "Land"), together with the any other right, title and interest of
Grantor in and to any easements, rights-of-way, privileges and other rights
appurtenant to the Improvements; provided, however, that this grant is subject
to the encumbrances described on Annex B (the "Permitted Encumbrances") and any
reservations or qualifications set forth below. Grantee hereby assumes the
obligations (including any personal obligations) of Grantor, if any, created by
or under, and agrees to be bound by the terms and conditions of, the Permitted
Encumbrances to the extent that the same concern or apply to the Improvements.

Although this deed conveys Grantor's interest in the Improvements on the Land,
this deed does not convey any interest in the Land itself or any rights or
easements appurtenant to Land. Prior to or contemporaneously with the delivery
of this deed, Grantor has conveyed or is conveying the Land and appurtenant
rights and easements to another party, subject to the terms and conditions of a
Ground Lease dated ________, filed or to be filed for record in the Santa Clara
County records. Grantor is assigning it's rights as lessee under the Ground
Lease to Grantee by a separate instrument dated of even date herewith.

[Improvements - Building 3]
<PAGE>

                                    BNP LEASING CORPORATION

Date: As of ____________            By:     _________________________________
                                            Its:

                                    Attest: _________________________________
                                            Its:

                                    [Zhone or Applicable Purchaser]

Date: As of ____________            By:     _________________________________
                                            Its:

                                    Attest: _________________________________
                                            Its:

STATE OF ____________    )
                         )  SS
COUNTY OF _____________  )

     On ___________________ before me,______________, personally
appeared___________ and________________, personally known to me (or proved to me
on the basis of satisfactory evidence) to be the persons whose names are
subscribed to the within instrument and acknowledged to me that they executed
the same in their authorized capacities, and that by their signatures on the
instrument the person, or the entity upon behalf of which the persons acted,
executed the instrument.

     WITNESS my hand and official seal.

     Signature ______________________________

[Improvements - Building 3]

                             Exhibit B-4 - Page 2
<PAGE>

STATE OF ____________    )
                         )  SS
COUNTY OF _____________  )

     On ___________________ before me,______________, personally
appeared___________ and________________, personally known to me (or proved to me
on the basis of satisfactory evidence) to be the persons whose names are
subscribed to the within instrument and acknowledged to me that they executed
the same in their authorized capacities, and that by their signatures on the
instrument the person, or the entity upon behalf of which the persons acted,
executed the instrument.

     WITNESS my hand and official seal.

     Signature_________________________________

[Improvements - Building 3]

                             Exhibit B-4 - Page 3
<PAGE>

                                    Annex A

                               LEGAL DESCRIPTION

[DRAFTING NOTE: TO THE EXTENT THAT THE "LAND" COVERED BY THE LAND LEASE CHANGES
 --------------
FROM TIME TO TIME BECAUSE OF ADJUSTMENTS FOR WHICH ZHONE REQUESTS BNPLC'S
CONSENT OR APPROVAL, SO TOO WILL THE DESCRIPTION OF THE LAND BELOW CHANGE. ANY
SUCH CHANGES WILL BE INCORPORATED INTO THE DESCRIPTION BELOW AND THIS "DRAFTING
NOTE" WILL BE DELETED BEFORE THE DEED TO WHICH THIS DESCRIPTION IS ATTACHED IS
ACTUALLY EXECUTED AND DELIVERED.]

The real property located in the City of Oakland, County of Alameda, State of
California, described as follows:

Being a portion of Lot 12, as shown on Parcel Map No. 6003, filed in Book 205 of
Parcel Maps, at Pages 94 through 98, Alameda County Records, more particularly
described as follows:

Commencing at the most southerly corner of said Lot 12; Thence along the
southwesterly line of said Lot 12, North 33(degrees) 50' 24" West, 628.68 feet
to the point of beginning; Thence continuing along the southwesterly line of
said Lot 12, North 33(degrees) 50' 24" West, 1029.21 feet; Thence along the
southeasterly line of said Lot 12, South 56(degrees) 09' 36" West 14.00 feet;
Thence along the southwesterly line of said Lot 12, North 33(degrees) 50' 24"
West, 253.55 feet to the beginning of a curve, concave southwesterly, having a
radius of 392.21 feet; Thence northerly along the arc of said curve, through a
central angle of 3(degrees) 51' 45", an arc distance of 26.44 feet to the
intersection of a line drawn parallel with and 85.00 feet southeasterly of the
northwesterly line of said Lot 12, a radial line through said point bears North
52(degrees) 17' 51" East; Thence parallel with the northwesterly line of said
Lot 12, North 56(degrees) 09' 36" East, 476.93 feet to a point that is 5 feet
southwesterly of the northeasterly line of said Lot 12; Thence along a line that
is parallel with and 5 feet southwesterly of the said northeasterly line of Lot
12, South 40(degrees) 00' 30" East, 69.44 feet to the beginning of a curve,
concave southwesterly, having a radius of 1949.00 feet; Thence southeasterly
along the arc of said curve, through a central angle of 6(degrees) 10' 18", an
arc distance of 209.94 feet; Thence continuing along a line that is parallel
with and 5 feet southwesterly of the said northeasterly line of Lot 12, South
33(degrees) 50' 12" East, 1030.61 feet to the intersection with a line drawn
perpendicular with the southwesterly line of said Lot 12, distant thereon 628.68
feet from the most southerly corner of said Lot 12; Thence southwesterly along
said perpendicular line, South 56(degrees) 09' 36" West, 480.72 feet to the
Point of Beginning.

The basis of bearings for Parcel Map No. 6003 is the North American Datum of
1983, Zone 3, 1984 Adjustment Published in 1986, as shown on Record of Survey
990, filed in Book 18 of Records of Survey, at Pages 50 through 60, Alameda
County Records. All distances in this description are grid distances. To convert
to ground distances, multiply grid distances by 1.0000708.

Assessor's Parcel No. 041-3902-015 (Portion)

[Improvements - Building 3]

                             Exhibit B-4 - Page 4
<PAGE>

                                    Annex B

                            Permitted Encumbrances

[DRAFTING NOTE: TO THE EXTENT THAT ENCUMBRANCES (OTHER THAN "LIENS REMOVABLE BY
 --------------
BNPLC") ARE IDENTIFIED IN ADDITION TO THOSE DESCRIBED BELOW, SUCH ADDITIONAL
ENCUMBRANCES WILL BE ADDED TO THE LIST BELOW AND THIS "DRAFTING NOTE" WILL BE
DELETED BEFORE THIS DEED IS ACTUALLY EXECUTED AND DELIVERED BY BNPLC. SUCH
ADDITIONAL ENCUMBRANCES WOULD INCLUDE ANY NEW ENCUMBRANCES APPROVED BY BNPLC AS
"PERMITTED ENCUMBRANCES" UNDER THE LAND LEASE, THE BUILDINGS 1&2 LEASE OR THE
BUILDING 3 LEASE FROM TIME TO TIME OR BECAUSE OF ZHONE'S REQUEST FOR BNPLC'S
CONSENT OR APPROVAL TO AN ADJUSTMENT.]

     This conveyance is subject to all encumbrances not constituting a "Lien
Removable by BNPLC" (as defined in the Common Definitions and Provisions
Agreement (Land) incorporated by reference into the Lease Agreement (Land)
referenced in the last item of the list below), including the following matters
to the extent the same are still valid and in force:

1.   County and city taxes for the Fiscal Year 2000 - 2001, a lien not yet due
     or payable.

2.   The Lien of Supplemental Taxes, if any, assessed pursuant to the provisions
     of Chapter 3.5, Revenue and Taxation Code, Sections 75 et seq., resulting
     from changes of ownership or completion of construction on or after the
     date hereof.

3.   Easement, upon the terms, covenants and conditions thereof, for the
     purposes stated therein and incidental purposes created in that certain
     instrument

     Recorded      :  FEBRUARY 11, 1974, REEL 3608, IMAGE 3, SERIES NO. 74-
                      16523, OFFICIAL RECORDS
     Granted to    :  THE PACIFIC TELEPHONE AND TELEGRAPH COMPANY, A CORPORATION
     Purpose       :  COMMUNICATION FACILITIES
     Affects       :  A SOUTHWESTERLY PORTION OF SAID LAND

4.   Terms, covenants, conditions and reservations as contained in the Port
     Ordinance No. 2832. An Ordinance establishing standards and restrictions
     regulating the use of land and the design and construction of structures
     and other improvements in the Oakland Airport Business Park, and repealing
     Port Ordinance No. 1343, as amended, recorded MAY 10, 1990, SERIES NO.
     90130204, OFFICIAL RECORDS.

     Amendment Port Ordinance No. 3146, recorded SEPTEMBER 30, 1993, SERIES NO.
     93348032, OFFICIAL RECORDS.

5.   Terms and conditions of the City of Oakland Redevelopment Project adopted
     by Ordinance No. 11824, C.M.S., as disclosed in the "Notice of Adoption of
     the Coliseum Area Redevelopment Plan, Termination of the 77/th/ Avenue
     Industrial Redevelopment Project and Amendment of the Elmhurst
     Redevelopment Plan," recorded JULY 31, 1995, SERIES NO. 95167161, OFFICIAL
     RECORDS.

     Amendment recorded SEPTEMBER 9, 1997, SERIES NO. 97-231187, OFFICIAL
     RECORDS.

[Improvements - Building 3]

                             Exhibit B-4 - Page 5
<PAGE>

6.   The Lease Agreement (Land), the Lease Agreement (Improvements - Buildings
     1&2) and the Lease Agreement (Improvements - Building 3), all dated as of
     August 1, 2000 and all between BNP Leasing Corporation, as lessor, and
     Zhone Technologies, Inc., as lessee.

[Improvements - Building 3]

                             Exhibit B-4 - Page 6
<PAGE>

                                   Exhibit C
                                   ---------

                          BILL OF SALE AND ASSIGNMENT

     Reference is made to: (1) that certain Purchase Agreement (Improvements -
Building 3) between BNP Leasing Corporation ("Assignor") and Zhone Technologies,
Inc., dated as of August 1, 2000, (the "Building 3 Purchase Agreement") and (2)
that certain Lease Agreement (Improvements - Building 3) between Assignor, as
landlord, and Zhone Technologies, Inc., as tenant, dated as of August 1, 2000
(the "Building 3 Lease"). (Capitalized terms used and not otherwise defined in
this document are intended to have the meanings assigned to them in the Common
Definitions and Provisions Agreement (Improvements - Building 3) incorporated by
reference into both the Building 3 Purchase Agreement and Building 3 Lease.)

     As contemplated by the Building 3 Purchase Agreement, Assignor hereby
sells, transfers and assigns unto [Zhone OR THE APPLICABLE PURCHASER, AS THE
CASE MAY BE], a _____________ ("Assignee"), all of Assignor's right, title and
interest in and to the following property, if any, to the extent such property
is assignable:

     (a) the Building 3 Lease [DRAFTING NOTE: THE FOLLOWING WILL BE ADDED ONLY
IF APPLICABLE BECAUSE OF THE SIMULTANEOUS DELIVERY OF A GRANT DEED IN THE FORM
OF EXHIBIT B-3: and the Ground Lease dated _________, between _________, as
   ------------
lessor, and Assignor, as lessee, filed for record on in ___________ of Alameda
County records (the "Ground Lease")];

     (b) any pending or future award made because of any condemnation affecting
the Building 3 Property or because of any conveyance to be made in lieu thereof,
and any unpaid award for damage to the Building 3 Property and any unpaid
proceeds of insurance or claim or cause of action for damage, loss or injury to
the Building 3 Property; and

     (c) all other property included within the definition of "Property" as set
forth in the Building 3 Purchase Agreement, including but not limited to any of
the following transferred to Assignor by the tenant pursuant to Paragraph 7
                                                                -----------
of the Building 3 Lease or otherwise acquired by Assignor, at the time of the
execution and delivery of the Building 3 Lease and Purchase Agreement or
thereafter, by reason of Assignor's status as the owner of any interest in the
Building 3 Property: (1) any goods, equipment, furnishings, furniture, chattels
and tangible personal property of whatever nature that are located on the
Building 3 Property and all renewals or replacements of or substitutions for any
of the foregoing; (ii) the rights of Assignor, existing at the time of the
execution of the Building 3 Lease and Purchase Agreement or thereafter arising,
under Permitted Encumbrances or Development Documents (both as defined in the
Building 3 Lease); and (iii) any other permits, licenses, franchises,
certificates, and other rights and privileges related to the Building 3 Property
that Assignee would have acquired if Assignee had itself acquired the
Improvements covered by the Building 3 Lease and constructed the Improvements
included in the Building 3 Property.

Provided, however, excluded from this conveyance and reserved to Assignor are
any rights or privileges of Assignor under the following ("Excluded Rights"):
(1) the indemnities set forth in the Building 3 Lease or Other Lease Agreements,
whether such rights are presently known or unknown, including rights of the
Assignor to be indemnified against environmental claims of third parties which
may not presently be known, (2) provisions in the Building 3 Lease or Other
Lease Agreements that establish the right of Assignor to recover any accrued
unpaid rent which may be outstanding as of the date hereof, (3) agreements
between Assignor and "BNPLC's Parent" or any "Participant," both as defined in
the Building 3 Lease, or any modification or extension thereof, or (4) any other
instrument being delivered to Assignor contemporaneously herewith pursuant to
the Building 3 Purchase Agreement or the Other Purchase Agreements. To the
extent that this conveyance does include any rights to receive future payments
under the Building 3 Lease, such rights shall be subordinate to

[Improvements - Building 3]
<PAGE>

Assignor's Excluded Rights.

     Assignor does for itself and its successors covenant and agree to warrant
and defend the title to the property assigned herein against the just and lawful
claims and demands of any person claiming under or through a Lien Removable by
BNPLC, but not otherwise.

     Assignee hereby assumes and agrees to keep, perform and fulfill Assignor's
obligations, if any, relating to any permits or contracts, under which Assignor
has rights being assigned herein.

     IN WITNESS WHEREOF, the parties have executed this instrument as of
_______________, _____.

                                 ASSIGNOR:
                                 --------

                                 BNP LEASING CORPORATION a Delaware corporation

                                 By:____________________________________________
                                 Its:___________________________________________

                                 ASSIGNEE:
                                 --------

                                 [Zhone or the Applicable Purchaser], a
                                 ____________________

                                 By:____________________________________________
                                 Its:___________________________________________

[Improvements - Building 3]

                              Exgibit C - Page 2
<PAGE>

STATE OF ____________   )
                        )  SS
COUNTY OF ___________   )

     On ___________________ before me,______________, personally
appeared___________ and________________, personally known to me (or proved to me
on the basis of satisfactory evidence) to be the persons whose names are
subscribed to the within instrument and acknowledged to me that they executed
the same in their authorized capacities, and that by their signatures on the
instrument the person, or the entity upon behalf of which the persons acted,
executed the instrument.

     WITNESS my hand and official seal.

     Signature______________

STATE OF ____________   )
                        )  SS
COUNTY OF ___________   )

     On ___________________ before me,______________, personally
appeared___________ and________________, personally known to me (or proved to me
on the basis of satisfactory evidence) to be the persons whose names are
subscribed to the within instrument and acknowledged to me that they executed
the same in their authorized capacities, and that by their signatures on the
instrument the person, or the entity upon behalf of which the persons acted,
executed the instrument.

     WITNESS my hand and official seal.

     Signature______________

[Improvements - Building 3]

                              Exhibit C - Page 3
<PAGE>

                                    Annex A

                               LEGAL DESCRIPTION

[DRAFTING NOTE: TO THE EXTENT THAT THE "LAND" COVERED BY THE LAND LEASE CHANGES
 --------------
FROM TIME TO TIME BECAUSE OF ADJUSTMENTS FOR WHICH ZHONE REQUESTS BNPLC'S
CONSENT OR APPROVAL, SO TOO WILL THE DESCRIPTION OF THE LAND BELOW CHANGE. ANY
SUCH CHANGES WILL BE INCORPORATED INTO THE DESCRIPTION BELOW AND THIS "DRAFTING
NOTE" WILL BE DELETED BEFORE THE DOCUMENT TO WHICH THIS DESCRIPTION IS ATTACHED
IS ACTUALLY EXECUTED AND DELIVERED.]

The real property located in the City of Oakland, County of Alameda, State of
California, described as follows:

Being a portion of Lot 12, as shown on Parcel Map No. 6003, filed in Book 205 of
Parcel Maps, at Pages 94 through 98, Alameda County Records, more particularly
described as follows:

Commencing at the most southerly corner of said Lot 12; Thence along the
southwesterly line of said Lot 12, North 33(degrees) 50' 24" West, 628.68 feet
to the point of beginning; Thence continuing along the southwesterly line of
said Lot 12, North 33(degrees) 50' 24" West, 1029.21 feet; Thence along the
southeasterly line of said Lot 12, South 56(degrees) 09' 36" West 14.00 feet;
Thence along the southwesterly line of said Lot 12, North 33(degrees) 50' 24"
West, 253.55 feet to the beginning of a curve, concave southwesterly, having a
radius of 392.21 feet; Thence northerly along the arc of said curve, through a
central angle of 3(degrees) 51' 45", an arc distance of 26.44 feet to the
intersection of a line drawn parallel with and 85.00 feet southeasterly of the
northwesterly line of said Lot 12, a radial line through said point bears North
52(degrees) 17' 51" East; Thence parallel with the northwesterly line of said
Lot 12, North 56(degrees) 09' 36" East, 476.93 feet to a point that is 5 feet
southwesterly of the northeasterly line of said Lot 12; Thence along a line that
is parallel with and 5 feet southwesterly of the said northeasterly line of Lot
12, South 40(degrees) 00' 30" East, 69.44 feet to the beginning of a curve,
concave southwesterly, having a radius of 1949.00 feet; Thence southeasterly
along the arc of said curve, through a central angle of 6(degrees) 10' 18", an
arc distance of 209.94 feet; Thence continuing along a line that is parallel
with and 5 feet southwesterly of the said northeasterly line of Lot 12, South
33(degrees) 50' 12" East, 1030.61 feet to the intersection with a line drawn
perpendicular with the southwesterly line of said Lot 12, distant thereon 628.68
feet from the most southerly corner of said Lot 12; Thence southwesterly along
said perpendicular line, South 56(degrees) 09' 36" West, 480.72 feet to the
Point of Beginning.

The basis of bearings for Parcel Map No. 6003 is the North American Datum of
1983, Zone 3, 1984 Adjustment Published in 1986, as shown on Record of Survey
990, filed in Book 18 of Records of Survey, at Pages 50 through 60, Alameda
County Records. All distances in this description are grid distances. To convert
to ground distances, multiply grid distances by 1.0000708.

Assessor's Parcel No. 041-3902-015 (Portion)

[Improvements - Building 3]

                              Exhibit C - Page 4
<PAGE>

                                   Exhibit D
                                   ---------

        ACKNOWLEDGMENT OF DISCLAIMER OF REPRESENTATIONS AND WARRANTIES

     THIS ACKNOWLEDGMENT OF DISCLAIMER OF REPRESENTATIONS AND WARRANTIES (this
"Certificate") is made as of ___________________, ____, by [Zhone or the
Applicable Purchaser, as the case may be], a ___________________ ("Grantee").

     Contemporaneously with the execution of this Certificate, BNP Leasing
Corporation, a Delaware corporation ("BNPLC"), is executing and delivering to
Grantee (1) a corporate grant deed and (2) a Bill of Sale and Assignment (the
foregoing documents and any other documents to be executed in connection
therewith are herein called the "Conveyancing Documents" and any of the
properties, rights or other matters assigned, transferred or conveyed pursuant
thereto are herein collectively called the "Subject Property").

     Notwithstanding any provision contained in the Conveyancing Documents to
the contrary, Grantee acknowledges that BNPLC makes no representations or
warranties of any nature or kind, whether statutory, express or implied, with
respect to environmental matters or the physical condition of the Subject
Property, and Grantee, by acceptance of the Conveyancing Documents, accepts the
Subject Property "AS IS," "WHERE IS," "WITH ALL FAULTS" and without any such
                  -- --    ----- --    ---- --- ------
representation or warranty by Grantor as to environmental matters, the physical
condition of the Subject Property, compliance with subdivision or platting
requirements or construction of any improvements. Without limiting the
generality of the foregoing, Grantee hereby further acknowledges and agrees that
warranties of merchantability and fitness for a particular purpose are excluded
from the transaction contemplated by the Conveyancing Documents, as are any
warranties arising from a course of dealing or usage of trade. Grantee hereby
assumes all risk and liability (and agrees that BNPLC shall not be liable for
any special, direct, indirect, consequential, or other damages) resulting or
arising from or relating to the ownership, use, condition, location,
maintenance, repair, or operation of the Subject Property, except for damages
proximately caused by (and attributed by any applicable principles of
comparative fault to) the Established Misconduct of BNPLC. As used in the
preceding sentence, "Established Misconduct" is intended to have, and be limited
to, the meaning given to it in the Common Definitions and Provisions Agreement
(Improvements - Building 3) incorporated by reference into the Building 3
Purchase Agreement between BNPLC and Zhone Technologies, Inc. dated as of August
1, 2000, pursuant to which Purchase Agreement BNPLC is delivering the
Conveyancing Documents.

     The provisions of this Certificate shall be binding on Grantee, its
successors and assigns and any other party claiming through Grantee. Grantee
hereby acknowledges that BNPLC is entitled to rely and is relying on this
Certificate.

     EXECUTED as of ________________, ____.

                                          [Zhone or the Applicable Purchaser]
                                          By:___________________________________
                                             Name:______________________________
                                             Title:_____________________________

[Improvements - Building 3]
<PAGE>

                                   Exhibit E
                                   ---------

                            SECRETARY'S CERTIFICATE

     The undersigned, [Secretary or Assistant Secretary] of BNP Leasing
Corporation, a Delaware corporation (the "Corporation"), hereby certifies as
follows:

     1.  That he is the duly, elected, qualified and acting Secretary [or
Assistant Secretary] of the Corporation and has custody of the corporate
records, minutes and corporate seal.

     2.  That the following named persons have been properly designated, elected
and assigned to the office in the Corporation as indicated below; that such
persons hold such office at this time and that the specimen signature appearing
beside the name of such officer is his or her true and correct signature.

[The following blanks must be completed with the names and signatures of the
officers who will be signing the deed and other Sale Closing Documents on behalf
of the Corporation.]

Name                     Title                    Signature
----                     -----                    ---------

________________         ________________         ________________

________________         ________________         ________________

     3.  That the resolutions attached hereto and made a part hereof were duly
adopted by the Board of Directors of the Corporation in accordance with the
Corporation's Articles of Incorporation and Bylaws. Such resolutions have not
been amended, modified or rescinded and remain in full force and effect.

     IN WITNESS WHEREOF, I have hereunto signed my name and affixed the seal of
the Corporation on this__, day of____,__.

                           ________________________________
                            [signature and title]

[Improvements - Building 3]
<PAGE>

                           CORPORATE RESOLUTIONS OF
                            BNP LEASING CORPORATION

     WHEREAS, pursuant to that certain Purchase Agreement (Improvements -
Building 3) (herein called the "Purchase Agreement") dated as of August 1, 2000,
by and between BNP Leasing Corporation (the "Corporation") and [Zhone or the
Applicable Purchaser as the case may be] ("Purchaser"), the Corporation agreed
to sell and Purchaser agreed to purchase or cause the Applicable Purchaser (as
defined in the Building 3 Purchase Agreement) to purchase the Corporation's
interest in the property (the "Property") located in Oakland, California more
particularly described therein.

     NOW THEREFORE, BE IT RESOLVED, that the Board of Directors of the
Corporation, in its best business judgment, deems it in the best interest of the
Corporation and its shareholders that the Corporation convey the Property to
Purchaser or the Applicable Purchaser pursuant to and in accordance with the
terms of the Building 3 Purchase Agreement.

     RESOLVED FURTHER, that the proper officers of the Corporation, and each of
them, are hereby authorized and directed in the name and on behalf of the
Corporation to cause the Corporation to fulfill its obligations under the
Building 3 Purchase Agreement.

     RESOLVED FURTHER, that the proper officers of the Corporation, and each of
them, are hereby authorized and directed to take or cause to be taken any and
all actions and to prepare or cause to be prepared and to execute and deliver
any and all deeds and other documents, instruments and agreements that shall be
necessary, advisable or appropriate, in such officer's sole and absolute
discretion, to carry out the intent and to accomplish the purposes of the
foregoing resolutions.

[Improvements - Building 3]

                              Exhibit E - Page 2
<PAGE>

                                   Exhibit F
                                   ---------

                               FIRPTA STATEMENT

     Section 1445 of the Internal Revenue Code of 1986, as amended, provides
that a transferee of a U.S. real property interest must withhold tax if the
transferor is a foreign person. Sections 18805, 18815 and 26131 of the
California Revenue and Taxation Code, as amended, provide that a transferee of a
California real property interest must withhold income tax if the transferor is
a nonresident seller.

     To inform [Zhone or the Applicable Purchaser] (the "Transferee") that
withholding of tax is not required upon the disposition of a California real
property interest by transferor, BNP Leasing Corporation (the "Seller"), the
undersigned hereby certifies the following on behalf of the Seller:

     1. The Seller is not a foreign corporation, foreign partnership, foreign
trust, or foreign estate (as those terms are defined in the Internal Revenue
Code and Income Tax Regulations);

     2. The United States employer identification number for the Seller is
_____________________;

     3. The office address of the Seller is ____________________________________
_________________.

     4. The Seller is qualified to do business in California.

     The Seller understands that this certification may be disclosed to the
Internal Revenue Service and/or to the California Franchise Tax Board by the
Transferee and that any false statement contained herein could be punished by
fine, imprisonment, or both.

     The Seller understands that the Transferee is relying on this affidavit in
determining whether withholding is required upon said transfer.

     Under penalties of perjury I declare that I have examined this
certification and to the best of my knowledge and belief it is true, correct and
complete, and I further declare that I have authority to sign this document on
behalf of the Seller.

     Dated: ___________, ____.

                               By:_____________________________
                               Name:___________________________
                               Title:__________________________

[Improvements - Building 3]
<PAGE>

                                   Exhibit G
                                   ---------

            Notice of Election to Terminate the Purchase Option and
                the Building 3 Supplemental Payment Obligations

BNP Leasing Corporation
12201 Merit Drive
Suite 860
Dallas, Texas 75251
Attention: Lloyd G. Cox

     Re: Purchase Agreement (Improvements - Building 3) dated as of August 1,
2000 (the "Building 3 Purchase Agreement"), between Zhone Technologies, Inc.
("Zhone") and BNP Leasing Corporation ("BNPLC")

Gentlemen:

     Capitalized terms used in this letter are intended to have the meanings
assigned to them in the Building 3 Purchase Agreement referenced above. This
letter shall constitute a notice, given before the Building 3 Base Rent
Commencement Date pursuant to subparagraph 4(B) of the Building 3 Purchase
Agreement, of Zhone's election to terminate the Purchase Option and the Building
3 Supplemental Payment Obligation. Zhone irrevocably elects to terminate the
Purchase Option and the Building 3 Supplemental Payment Obligation effective
immediately, subject only to the conditions described below.

     Zhone acknowledges that the election made by Zhone described above
constitutes an Issue 97-10 Election under and as defined in the Building 3
Operative Documents.

     Zhone also acknowledges that its right to terminate the Purchase Option and
the Building 3 Supplemental Payment Obligation is subject to the condition
precedent that (x) Zhone shall have given Notice of Zhone's Election to
Terminate pursuant to Paragraph 4(D) of the Construction Management Agreement,
                      --------------
or (y) BNPLC shall have given any FOCB Notice as provided in Paragraph 4(E) of
                                                             --------------
the Construction Management Agreement, or (z) BNPLC shall have given notice of
its election to accelerate the Designated Sale Date when an Event of Default has
occurred and is continuing as provided in clause (5) of the definition
Designated Sale Date in the Common Definitions and Provisions Agreement (Phase
I-Improvements). Accordingly, if none of the notices described in the preceding
sentence have been given, the Purchase Option and the Building 3 Supplemental
Payment Obligation shall not terminate by reason of this notice.

     Zhone further acknowledges that no termination of the Purchase Option and
the Building 3 Supplemental Payment Obligation by Zhone pursuant to this notice
shall be effective, unless contemporaneously with the giving of this notice
Zhone shall deliver to BNPLC a full Issue 97-10 Prepayment. Zhone hereby
covenants to pay, if Zhone has not already done so, a full Issue 97-10
Prepayment to BNPLC.

     Finally, Zhone acknowledges that a termination of the Purchase Option and
the Building 3 Supplemental Payment Obligation pursuant to this notice shall
cause the Building 3 Lease to terminate as of the Building 3 Base Rent
Commencement Date pursuant to subparagraph 1(b) of the Building 3 Lease.
                              -----------------

[Improvements - Building 3]
<PAGE>

     Executed this _____ day of ______________, 20___.

                           ZHONE TECHNOLOGIES, INC.

                           Name:________________________________________________
                           Title:_______________________________________________

[cc all Participants]

[Improvements - Building 3]

                              Exhibit G - Page 2<PAGE>

                                                                   Exhibit 10.20

================================================================================

                              PURCHASE AGREEMENT
                                    (LAND)

                                    BETWEEN

                            BNP LEASING CORPORATION

                                   ("BNPLC")

                                      AND

                           ZHONE TECHNOLOGIES, INC.

                                   ("Zhone")

                                August 1, 2000

                             (Oakland, California)

==============================================================================
<PAGE>

                               TABLE OF CONTENTS
                               -----------------

<TABLE>
<CAPTION>
                                                                                                                  Page
                                                                                                                  ----
<S>                                                                                                               <C>
1    Zhone's Options and Obligations on the Designated Sale Date.................................................   1
     (A)    Right to Purchase; Initial Remarketing Rights; Supplemental Payment Obligations......................   1
            -----------------------------------------------------------------------------------------------------
     (B)    Determinations Concerning Price......................................................................   3
            -----------------------------------------------------------------------------------------------------
     (C)    Designation of the Purchaser.........................................................................   4
            -----------------------------------------------------------------------------------------------------
     (D)    Effect of the Purchase Option and Zhone's Initial Remarketing Rights on Subsequent
            -----------------------------------------------------------------------------------
            Title Encumbrances...................................................................................   4
            ------------------
     (E)    Security for the Purchase Option and Zhone's Initial Remarketing Rights..............................   4
            -----------------------------------------------------------------------------------------------------
     (F)    Delivery of Books and Records If BNPLC Retains the Property..........................................   5
            -----------------------------------------------------------------------------------------------------

2    Zhone's Rights and Options After the Designated Sale Date...................................................   5
     (A)    Zhone's Extended Right to Remarket...................................................................   5
            -----------------------------------------------------------------------------------------------------
     (B)    Definition of Minimum Extended Remarketing Price.....................................................   5
            -----------------------------------------------------------------------------------------------------
     (C)    BNPLC's Right to Sell................................................................................   6
            -----------------------------------------------------------------------------------------------------
     (D)    Zhone's Right to Excess Sales Proceeds...............................................................   7
            -----------------------------------------------------------------------------------------------------
     (E)    Permitted Transfers During Zhone's Extended Remarketing Period.......................................   7
            -----------------------------------------------------------------------------------------------------

3    Terms of Conveyance Upon Purchase...........................................................................   7

4     Survival and Termination of the Rights and Obligations of Zhone and BNPLC..................................   8
     (A)    Status of this Agreement Generally...................................................................   8
            -----------------------------------------------------------------------------------------------------
     (B)    Automatic Termination of Zhone's Rights..............................................................   9
            -----------------------------------------------------------------------------------------------------
     (C)    Termination of Zhone's Extended Remarketing Rights to Permit a Sale by BNPLC.........................   9
            -----------------------------------------------------------------------------------------------------
     (D)    Payment Only to BNPLC................................................................................   9
            -----------------------------------------------------------------------------------------------------
     (E)    Remedies Under the other Operative Documents.........................................................   9
            -----------------------------------------------------------------------------------------------------
     (F)    Occupancy by Zhone Prior to Closing of a Sale........................................................   9
            -----------------------------------------------------------------------------------------------------
     (G)    Preferential Payments to BNPLC.......................................................................  10
            -----------------------------------------------------------------------------------------------------

5.   Security for Zhone's Obligations; Return of Funds...........................................................  10

6    Certain Remedies Cumulative.................................................................................  10

7    Attorneys' Fees and Legal Expenses..........................................................................  10

8    Estoppel Certificate........................................................................................  11

9    Successors and Assigns......................................................................................  11

10   Amendment and Restatement...................................................................................  11
</TABLE>

[Land]
<PAGE>

                            Exhibits and Schedules
                            ----------------------

Exhibit A......................................................Legal Description
---------

Exhibit B...................Requirements Re: Form of Grant Deed and Ground Lease
---------

Exhibit C............................................Bill of Sale and Assignment
---------

Exhibit D..........................................Acknowledgment and Disclaimer
---------

Exhibit E................................................Secretary's Certificate
---------

Exhibit F.................................Certificate Concerning Tax Withholding
---------

[Land]
<PAGE>

                              PURCHASE AGREEMENT
                                    (LAND)

     This PURCHASE AGREEMENT (LAND) (this "Agreement") is made and dated as of
August 1, 2000 (the "Effective Date") by and between BNP LEASING CORPORATION, a
Delaware corporation ("BNPLC"), and ZHONE TECHNOLOGIES, INC., a Delaware
corporation ("Zhone").

                                   RECITALS

          Contemporaneously with the execution of this Agreement, BNPLC and
Zhone are executing a Common Definitions and Provisions Agreement (Land) dated
as of the Effective Date (the "Land CDPA"), which by this reference is
incorporated into and made a part of this Agreement for all purposes. As used in
this Agreement, capitalized terms defined in the Land CDPA and not otherwise
defined in this Agreement are intended to have the respective meanings assigned
to them in the Land CDPA.

     Zhone and BNPLC previously executed that Purchase Agreement (Phase I -
Land) dated as of January 20, 2000 (the "Prior Purchase Agreement").  Zhone and
BNPLC have agreed to amend, restate and replace the Prior Purchase Agreement
with this Agreement as provided in Paragraph 10 below.

     Pursuant to the Acquisition Contract, which covers the Land described in
Exhibit A, BNPLC has acquired the Land and any appurtenances thereto from
---------
Seller.  Pursuant to the Lease Agreement (Land) executed by BNPLC and Zhone
contemporaneously with this Agreement (the "Land Lease"), BNPLC is leasing the
Land to Zhone. (All of BNPLC's interests, including those created by the
documents delivered at the closing under the Acquisition Contract, in the Land
and in all other real and personal property from time to time covered by the
Land Lease and included within the "Property" as defined therein are hereinafter
collectively referred to as the "Property". The Property does not include the
Improvements, it being understood that the Other Purchase Agreements constitute
separate agreements providing for the possible sale of the Improvements and the
appurtenances thereto from BNPLC to Zhone or a third party designated by Zhone.)

                                  AGREEMENTS

     1    Zhone's Options and Obligations on the Designated Sale Date.

          (A)  Right to Purchase; Initial Remarketing Rights; Supplemental
               -----------------------------------------------------------
Payment Obligations.  Whether or not an Event of Default shall have occurred
-------------------
and be continuing or the Land Lease shall have been terminated, but subject to
Paragraph 4 below:

               (1)  Zhone shall have the right (the "Purchase Option") to
     purchase or cause an Affiliate of Zhone to purchase the Property and
     BNPLC's interest in Land Escrowed Proceeds, if any, on the Designated Sale
     Date for a cash price equal to the Land Break Even Amount (as defined
     below).

               (2)  If neither Zhone nor an Affiliate of Zhone purchases the
     Property and BNPLC's interest in any Land Escrowed Proceeds on the
     Designated Sale Date as provided in the preceding subparagraph 1(A)(1),
     then Zhone shall have the following rights (collectively, "Zhone's Initial
     Remarketing Rights"):
<PAGE>

                    (a)  First, Zhone shall have the right (but not the
          obligation) to cause an Applicable Purchaser who is not an Affiliate
          of Zhone to purchase the Property and BNPLC's interest in any Land
          Escrowed Proceeds on the Designated Sale Date for a cash purchase
          price equal to the Land Third Party Price (as defined below). If,
          however, the Land Break Even Amount exceeds the sum of any Land Third
          Party Price tendered or to be tendered to BNPLC by an Applicable
          Purchaser and any Land Supplemental Payment paid to BNPLC on the
          Designated Sale Date itself, then BNPLC may affirmatively elect to
          decline such tender from the Applicable Purchaser and to keep the
          Property (together with any Land Escrowed Proceeds) rather than sell
          to the Applicable Purchaser (a "Voluntary Retention of the Property").

                    (b)  Second, if the Land Third Party Price actually paid by
          an Applicable Purchaser to BNPLC on the Designated Sale Date exceeds
          the Land Break Even Amount, Zhone shall be entitled to such excess,
          subject, however, to BNPLC's right to offset against such excess any
          and all sums that are then due from Zhone to BNPLC.

               (3)  If for any reason whatsoever neither Zhone nor an Applicable
     Purchaser pays to BNPLC a net cash price for the Property on the Designated
     Sale Date equal to or in excess of the Land Break Even Amount pursuant to
     this Agreement, then Zhone shall have the obligation (the "Land
     Supplemental Payment Obligation") to pay to BNPLC on the Designated Sale
     Date a supplemental payment (the "Land Supplemental Payment") equal to the
     lesser of (1) the amount by which the Land Break Even Amount on the
     Designated Sale Date exceeds such net cash price (if any) for the Property
     actually received by BNPLC on the Designated Sale Date (such excess being
     hereinafter called a "Deficiency") or (2) the Maximum Remarketing
     Obligation. As used herein, the "Maximum Remarketing Obligation" means a
     dollar amount equal to the product of (i) Stipulated Loss Value on the
     Designated Sale Date, times (ii) 100% minus the Residual Risk Percentage;
     provided, however, that the "Maximum Remarketing Obligation" will equal the
     Land Break Even Amount, if (but only if):

                              (x) Zhone shall have elected to accelerate the
               Designated Sale Date as provided in clause (2) of the definition
               of Designated Sale Date in the Land CDPA; or

                              (y) an "Event of Default" under and as defined in
               the Land Lease has occurred and is continuing on the Designated
               Sale Date, other than an Issue 97-1 Non-performance-related
               Subjective Event of Default.

     Without limiting the generality of the foregoing, the Land Supplemental
     Payment shall be required even if BNPLC does not sell the Property to Zhone
     or an Applicable Purchaser on the Designated Sale Date because of (A) a
     Voluntary Retention of the Property, or (B) a failure of Zhone to exercise,
     or decision by Zhone not to exercise, the Purchase Option or Zhone's
     Initial Remarketing Rights.   If any Land Supplemental Payment or portion
     thereof is not actually paid to BNPLC on the Designated Sale Date, Zhone
     shall pay interest on the past due amount computed at the Default Rate from
     the Designated Sale Date.  Zhone acknowledges that it is undertaking the
     Land Supplemental Payment Obligation in consideration of the rights
     afforded to it by this Agreement, but that such obligation is not
     contingent upon any exercise by Zhone of such rights or upon any purchase
     of the Property by Zhone or an Applicable Purchaser.

          (B)  Determinations Concerning Price.
               -------------------------------

               (1)  Determination of the Land Break Even Amount. As used herein,
                    -------------------------------------------
     "Land Break Even Amount" means an amount equal to Stipulated Loss Value,
     plus all out-of-pocket costs and expenses (including appraisal costs,
     ----
     withholding taxes (if any) not constituting Excluded Taxes, and

[Land]                                 2
<PAGE>

     Attorneys' Fees) incurred by BNPLC in connection with any sale of BNPLC's
     interests in the Property under this Agreement or in connection with
     collecting payments due hereunder, but less the aggregate amounts (if any)
                                        --------
     of Direct Payments to Participants and Deposit Taker Losses.

               (2)  Determination of Land Third Party Price.  As used in
                    ---------------------------------------
     subparagraph 1(A)(2)(a) and other provisions of this Agreement, "Land Third
     Party Price" means the amount determined as follows:

               (a)  Zhone may give a notice (a "Remarketing Notice") to BNPLC
          and to each of the Participants no earlier than one hundred twenty
          days before the Designated Sale Date and no later than ninety days
          before the Designated Sale Date, specifying an amount as the Land
          Third Party Price that Zhone believes in good faith to constitute
          reasonably equivalent value for the Property and any Land Escrowed
          Proceeds. Once given, a Remarketing Notice shall not be rescinded or
          modified without BNPLC's written consent.

               (b)  If BNPLC believes in good faith that the Land Third Party
          Price specified by Zhone in a Remarketing Notice does not constitute
          reasonably equivalent value for the Property and any Land Escrowed
          Proceeds, BNPLC may at any time before sixty days prior to the
          Designated Sale Date respond to the Remarketing Notice with a notice
          back to Zhone, objecting to the Land Third Party Price so specified by
          Zhone. If BNPLC receives a Remarketing Notice, yet does not respond
          with an objection as provided in the preceding sentence, the Land
          Third Party Price suggested by Zhone in the Remarketing Notice will be
          the Land Third Party Price for purposes of this Agreement. If,
          however, BNPLC does respond with an objection as provided in this
          subparagraph, and if Zhone and BNPLC do not otherwise agree in writing
          upon a Land Third Party Price, then the Land Third Party Price will be
          the lesser of (I) fair market value of the Property, plus the amount
          of any Land Escrowed Proceeds, as determined by a professional
          independent appraiser selected by BNPLC, or (II) the Land Break Even
          Amount.

               (c)  If for any reason, including an acceleration of the
          Designated Sale Date as provided in the definition thereof in the Land
          CDPA, Zhone does not deliver a Remarketing Notice to BNPLC within the
          time period specified above, then the Land Third Party Price will be
          an amount determined in good faith by BNPLC as constituting reasonably
          equivalent value for the Property and any Land Escrowed Proceeds, but
          in no event more than the Land Break Even Amount.

     If any payment to BNPLC by an Applicable Purchaser hereunder is held to
     constitute a preference or a voidable transfer under Applicable Law, or
     must for any other reason be refunded by BNPLC to the Applicable Purchaser
     or to another Person, and if such payment to BNPLC reduced or had the
     effect of reducing a Land Supplemental Payment or increased or had the
     effect of increasing any excess sale proceeds paid to Zhone pursuant to
     subparagraph 1(A)(2)(b) or pursuant to subparagraph 2(D), then Zhone shall
     pay to BNPLC upon demand an amount equal to the reduction of the Land
     Supplemental Payment or to the increase of the excess sale proceeds paid to
     Zhone, as applicable, and this Agreement shall continue to be effective or
     shall be reinstated as necessary to permit BNPLC to enforce its right to
     collect such amount from Zhone.

          (C)  Designation of the Purchaser. To give BNPLC the opportunity
               ----------------------------
before the Designated Sale Date to prepare the deed and other documents that
BNPLC must tender pursuant to Paragraph 3 (collectively, the "Land Sale Closing
Documents"), Zhone must, by a notice to BNPLC given at least seven days prior to
the Designated Sale Date, specify irrevocably, unequivocally and with
particularity the party who will purchase the Property pursuant to this
Agreement.  If for any reason Zhone fails to so specify a party who

[Land]                                 3
<PAGE>

will in accordance with the terms and conditions set forth herein purchase the
Property (be it Zhone itself, an Affiliate of Zhone or another Applicable
Purchaser), BNPLC shall be entitled to postpone the tender of the Land Sale
Closing Documents until a date after the Designated Sale Date and not more than
twenty days after Zhone finally does so specify a party, but such postponement
will not relieve or postpone the obligation of Zhone to make a Land Supplemental
Payment as provided in Paragraph 1(A)(3).

          (D)  Effect of the Purchase Option and Zhone's Initial Remarketing
               -------------------------------------------------------------
Rights on Subsequent Title Encumbrances.  Any conveyance of the Property to
---------------------------------------
Zhone or any Applicable Purchaser pursuant to Paragraph 1(A) shall cut off and
terminate any interest in the Property claimed by, through or under BNPLC,
including any interest claimed by the Participants and including any Liens
Removable by BNPLC (such as, but not limited to, any judgment liens established
against the Property because of a judgment rendered against BNPLC and any
leasehold or other interests conveyed by BNPLC in the ordinary course of BNPLC's
business), but not including personal obligations of Zhone to BNPLC under the
Land Operative Documents or the Other Operative Documents (including obligations
arising under the indemnities in the Land Lease).  Anyone accepting or taking
any interest in the Property by or through BNPLC after the date of this
Agreement shall acquire such interest subject to the Purchase Option and Zhone's
Initial Remarketing Rights.  Further, Zhone and any Applicable Purchaser shall
be entitled to pay any payment required by this Agreement for the purchase of
the Property directly to BNPLC notwithstanding any prior conveyance or
assignment by BNPLC, voluntary or otherwise, of any right or interest in this
Agreement or the Property, and neither Zhone nor any Applicable Purchaser shall
be responsible for the proper distribution or application of any such payments
by BNPLC; and any such payment to BNPLC shall discharge the obligation of Zhone
to cause such payment to all Persons claiming an interest in such payment.
Contemporaneously with the execution of this Agreement, the parties shall record
a memorandum of this Agreement for purposes of effecting constructive notice to
all Persons of Zhone's rights under this Agreement, including its rights under
this subparagraph.

          (E)  Security for the Purchase Option and Zhone's Initial Remarketing
               ----------------------------------------------------------------
Rights.  To secure BNPLC's obligation to sell the Property pursuant to
------
Paragraph 1(A) and to pay any damages to Zhone caused by a breach of such
obligations, including any such breach caused by a rejection or termination of
this Agreement in any bankruptcy or insolvency proceeding instituted by or
against BNPLC, as debtor, BNPLC does hereby grant to Zhone a lien and security
interest against all rights, title and interests of BNPLC from time to time in
and to the Property.  Zhone may enforce such lien and security interest
judicially after any such breach by BNPLC, but not otherwise.  Contemporaneously
with the execution of this Agreement, Zhone and BNPLC will execute a memorandum
of this Agreement which is in recordable form and which specifically references
the lien granted in this subparagraph, and Zhone shall be entitled to record
such memorandum at any time prior to the Designated Sale Date.   However,
nothing in this subparagraph shall be construed as a waiver by Zhone of any
right Zhone may have at law or in equity to the following remedies, whether
because of BNPLC's failure to remove a Lien Removable by BNPLC or because of any
other default by BNPLC under this Agreement: (i) the recovery of monetary
damages, (ii) injunctive relief in case of the violation, or attempted or
threatened violation, by BNPLC of any of the express covenants, agreements,
conditions or provisions of this Agreement which are binding upon BNPLC, or
(iii) a decree compelling performance by BNPLC of any of the express covenants,
agreements, conditions or provisions of this Agreement which are binding upon
BNPLC.

          (F)  Delivery of Books and Records If BNPLC Retains the Property.
               -----------------------------------------------------------
Unless Zhone or its Affiliate or another Applicable Purchaser purchases the
Property pursuant to Paragraph 1(A), promptly after the Designated Sale Date
Zhone shall deliver to BNPLC copies of books and records of Zhone which will be
necessary or useful to any future owner's or occupant's use of the Property.

     2    Zhone's Rights and Options After the Designated Sale Date.

[Land]                                 4
<PAGE>

          (A)  Zhone's Extended Right to Remarket.  During the two years
               ----------------------------------
following the Designated Sale Date ("Zhone's Extended Remarketing Period"),
Zhone shall have the right ("Zhone's Extended Remarketing Right") to cause an
Applicable Purchaser who is not an Affiliate of Zhone to purchase the Property
for a cash purchase price not below the Minimum Extended Remarketing Price (as
defined below).  Zhone's Extended Remarketing Right shall, however, be subject
to all of the following conditions:

               (1)  The Property and BNPLC's interest in Land Escrowed Proceeds,
     if any, shall not have been sold on the Designated Sale Date as provided in
     Paragraph 1 or within the thirty days thereafter as provided in
     subparagraph 4(B).

               (2)  No Voluntary Retention of the Property shall have occurred
     as described in subparagraph 1(A)(2)(a).

               (3)  Zhone's Extended Remarketing Right shall not have been
     terminated pursuant to subparagraph 4(B) below because of Zhone's failure
     to make any Land Supplemental Payment required on the Designated Sale Date.

               (4)  Zhone's Extended Remarketing Right shall not have been
     terminated by BNPLC pursuant to subparagraph 4(C) below to facilitate
     BNPLC's sale of the Property to a third party in accordance with
     subparagraph 2(C).

               (5)  At least thirty days prior to the date upon which BNPLC is
     to convey the Property to an Applicable Purchaser because of Zhone's
     exercise of Zhone's Extended Remarketing Right (the "Final Sale Date"),
     Zhone shall have notified BNPLC of (x) the date proposed by Zhone as the
     Final Sale Date (which must be a Business Day), (y) the full legal name of
     the Applicable Purchaser and such other information as will be required to
     prepare the Land Sale Closing Documents, and (z) the amount of the purchase
     price that the Applicable Purchaser will pay (consistent with the minimum
     required pursuant to the other provisions of this subparagraph 2(A)) for
     the Property.

          (B)  Definition of Minimum Extended Remarketing Price. As used herein,
               ------------------------------------------------
"Minimum Extended Remarketing Price" means, subject to reduction as provided in
subparagraph 2(C) below, an amount equal to the sum of the following:

               (1)  the amount by which the Land Break Even Amount computed on
     the Designated Sale Date exceeds any Land Supplemental Payment actually
     paid to BNPLC on the Designated Sale Date, together with interest on such
     excess computed at the Default Rate from the period commencing on the
     Designated Sale Date and ending on the Final Sale Date, plus
                                                             ----

               (2)  all out-of-pocket costs and expenses (including withholding
     taxes [if any], other than Excluded Taxes, and Attorneys' Fees) incurred by
     BNPLC in connection with the sale to the Applicable Purchaser, to the
     extent not already included in the computation of Land Break Even Amount,
     and plus
     --------

               (3)  the sum of all Impositions, insurance premiums and other
     Losses of every kind suffered or incurred by BNPLC or any other Interested
     Party with respect to the ownership, operation or maintenance of the
     Property on or after the Designated Sale Date (except to the extent already
     reimbursed by any lessee of the Property after the Designated Sale Date),
     together with interest on such Impositions, insurance premiums and other
     Losses computed at the Default Rate from the date paid or incurred to the
     Final Sale Date.

[Land]                                 5
<PAGE>

If, however, Losses described in the preceding clause (3) consist of claims
against BNPLC or another Interested Party that have not been liquidated prior to
the Final Sale Date (and, thus, such Losses have yet to be fixed in amount as of
the Final Sale Date), then Zhone may elect to exclude any such Losses from the
computation of the Minimum Extended Remarketing Price by providing to BNPLC, for
the benefit of BNPLC and other Interested Parties, a written agreement to
indemnify and defend BNPLC and other Interested Parties against such Losses. To
be effective hereunder for purposes of reducing the Minimum Extended Remarketing
Price (and, thus, the Land Break Even Amount), any such written indemnity must
be fully executed and delivered by Zhone on or prior to the Final Sale Date,
must include provisions comparable to subparagraphs 5(c)(ii), (iii), (iv) and
                                      ---------------------------------------
(v) of the Land Lease and otherwise must be in form and substance satisfactory
---
to BNPLC.

          (C)  BNPLC's Right to Sell. After the Designated Sale Date, if the
               ---------------------
Property has not already been sold by BNPLC pursuant to Paragraph 1 or this
Paragraph 2, BNPLC shall have the right to sell the Property or offer the
Property for sale to any third party on any terms believed to be appropriate by
BNPLC in its sole good faith business judgment; provided, however, that so long
as the conditions to Zhone's Extended Remarketing Rights specified in
subparagraph 2(A) continue to be satisfied:

               (1)  BNPLC shall not sell the Property to an Affiliate of BNPLC
     on terms less favorable than those which BNPLC would require from a
     prospective purchaser not an Affiliate of BNPLC;

               (2)  If BNPLC receives or desires to make a written proposal
     (whether in the form of a "letter of intent" or other nonbinding expression
     of interest or in the form of a more definitive purchase and sale
     agreement) for a sale of the Property to a prospective purchaser (a "Third
     Party Sale Proposal"), and if on the basis of such Third Party Sale
     Proposal BNPLC expects to enter into or to pursue negotiations for a
     definitive purchase and sale agreement with the prospective purchaser, then
     prior to executing any such definitive agreement, BNPLC shall submit the
     Third Party Sale Proposal to Zhone with a notice (the "Third Party Sale
     Notice") explaining that:

                    (A)  if BNPLC and the prospective purchaser reach agreement
          on other terms and conditions to be incorporated into a definitive
          purchase and sale agreement, BNPLC is then prepared to accept a price
          for the Property not below an amount specified in such Third Party
          Sale Notice (the "Land Third Party Target Price"); and

                    (B)  Zhone's Extended Remarketing Right may be terminated
          pursuant to subparagraph 4(C) of this Agreement, unless within ninety
          days after the date of such Third Party Sale Notice Zhone causes an
          Applicable Purchaser to consummate a purchase of the Property under
          Paragraph 2 of this Agreement.

For a period of ninety days (but only ninety days) after the date of any Third
Party Sale Notice, the Minimum Extended Remarketing Price shall be limited in
amount so that it does not exceed the Third Party Target Price specified by
BNPLC therein.  Accordingly, if BNPLC has delivered a Third Party Sale Notice
specifying a Third Party Target Price below the Minimum Extended Remarketing
Price calculated as provided in subparagraph 2(B) within the ninety days prior
to the Final Sale Date for any sale to an Applicable Purchaser by BNPLC pursuant
to this Paragraph 2, then the Minimum Extended Remarketing Price applicable to
such sale shall be reduced to the amount of the Third Party Target Price so
specified.  Such a reduction, however, will apply only to a sale to an
Applicable Purchaser actually consummated within the ninety days after the date
of the applicable Third Party Sale Notice.

          (D)  Zhone's Right to Excess Sales Proceeds. If the cash price
               --------------------------------------
actually paid to BNPLC by any third party for the Property during Zhone's
Extended Remarketing Period, including any price paid by an

[Land]                                 6
<PAGE>

Applicable Purchaser purchasing from BNPLC pursuant to this Paragraph 2, exceeds
the Minimum Extended Remarketing Price (calculated as provided in subparagraph
2(B), without reduction pursuant to subparagraph 2(C)), then Zhone shall be
entitled to the excess; provided, that BNPLC may offset and retain from the
excess any and all sums that are then due and unpaid from Zhone to BNPLC under
any of the Land Operative Documents or the Other Operative Documents.

          (E)  Permitted Transfers During Zhone's Extended Remarketing Period.
               --------------------------------------------------------------
Any "Permitted Transfer" described in clause (6) of the definition thereof in
                                      ----------
the Land CDPA to an Affiliate of BNPLC or that covers BNPLC's entire interest in
the Land will be subject to Zhone's Extended Remarketing Right if, at the time
of the Permitted Transfer, Zhone's Extended Remarketing Right has not expired or
been terminated as provided herein. Any other Permitted Transfer described in
clause (6) of the definition thereof, however, will not be subject to Zhone's
Extended Remarketing Right. Thus, for example, BNPLC's conveyance of a utility
easement or space lease more than thirty days after the Designated Sale Date to
a Person not an Affiliate of BNPLC shall not be subject to Zhone's Extended
Remarketing Right, though following the conveyance of the lesser estate, Zhone's
Extended Remarketing Right may continue to apply to BNPLC's remaining interest
in the Property.

     3    Terms of Conveyance Upon Purchase. As necessary to consummate any sale
of the Property to Zhone or an Applicable Purchaser pursuant to this Agreement,
BNPLC must, subject to any postponement permitted by subparagraph 1(C),
immediately after the tender of the purchase price and any other payments to
BNPLC required pursuant to Paragraph 1 or Paragraph 2, as applicable, convey all
of BNPLC's right, title and interest in the Property to Zhone or the Applicable
Purchaser, as the case may be, by BNPLC's execution, acknowledgment (where
appropriate) and delivery of the Land Sale Closing Documents. Such conveyance by
BNPLC will be subject only to the Permitted Encumbrances and any other
encumbrances that do not constitute Liens Removable by BNPLC. However, such
conveyance shall not include the rights of BNPLC or other Interested Parties
under the indemnities provided in the Land Operative Documents and the Other
Operative Documents, including rights to any payments then due from Zhone under
the indemnities or that may become due thereafter because of any expense or
liability incurred by BNPLC or another Interested Party resulting in whole or in
part from events or circumstances occurring or alleged to have occurred before
such conveyance. All costs, both foreseen and unforeseen, of any purchase by
Zhone or an Applicable Purchaser hereunder shall be the responsibility of the
purchaser. The Land Sale Closing Documents used to accomplish such conveyance
shall consist of the following: (1) a Corporation Grant Deed in the form
attached as Exhibit B-1 or Exhibit B-2 or Exhibit B-4, as required by Exhibit B,
            -----------    -----------    -----------                 ---------
(2) if required by Exhibit B, a Ground Lease in the form attached as Exhibit
                   ---------                                         -------
B-3, which Zhone or the Applicable Purchase must execute and return to BNPLC,
---
(3) a Bill of Sale and Assignment in the form attached as Exhibit C, (4) an
                                                          ---------
Acknowledgment of Disclaimer of Representations and Warranties, in the form
attached as Exhibit D, which Zhone or the Applicable Purchaser must execute and
            ---------
return to BNPLC, (5) a Secretary's Certificate in the form attached as Exhibit
                                                                       -------
E, and (6) a certificate concerning tax withholding in the form attached as
-
Exhibit F. If for any reason BNPLC fails to tender the Land Sale Closing
---------
Documents as required by this Paragraph 3, BNPLC may cure such refusal at any
time before thirty days after receipt of a demand for such cure from Zhone.

     4    Survival and Termination of the Rights and Obligations of Zhone and
BNPLC.

          (A)  Status of this Agreement Generally. Except as expressly provided
               ----------------------------------
herein, this Agreement shall not terminate; nor shall Zhone have any right to
terminate this Agreement; nor shall Zhone be entitled to any reduction of the
Land Break Even Amount, any Deficiency, the Maximum Remarketing Obligation, any
Land Supplemental Payment or the Minimum Extended Remarketing Price hereunder;
nor shall the obligations of Zhone to BNPLC under Paragraph 1 be affected, by
reason of (i) any damage to or the destruction of all or any part of the
Property from whatever cause (though it is understood that Zhone will receive
any remaining Land Escrowed Proceeds yet to be applied as provided in the Land
Lease that may result

[Land]                                 7
<PAGE>

from such damage if Zhone purchases the Property and the Land Escrowed Proceeds
as herein provided), (ii) the taking of or damage to the Property or any portion
thereof by eminent domain or otherwise for any reason (though it is understood
that Zhone will receive any remaining Land Escrowed Proceeds yet to be applied
as provided in the Land Lease that may result from such taking or damage if
Zhone purchases the Property and the Land Escrowed Proceeds as herein provided),
(iii) the prohibition, limitation or restriction of Zhone's use of all or any
portion of the Property or any interference with such use by governmental action
or otherwise, (iv) any eviction of Zhone or any party claiming under Zhone by
paramount title or otherwise, (v) Zhone's prior acquisition or ownership of any
interest in the Property, (vi) any default on the part of BNPLC under this
Agreement, the Land Lease or any other agreement to which BNPLC is a party, or
(vii) any other cause, whether similar or dissimilar to the foregoing, any
existing or future law to the contrary notwithstanding. It is the intention of
the parties hereto that the obligation of Zhone to make any Land Supplemental
Payment as provided in Paragraph 1 shall be a separate and independent covenant
and agreement from BNPLC's obligations under this Agreement or any other
agreement between BNPLC and Zhone; provided, however, that nothing in this
subparagraph shall excuse BNPLC from its obligation to tender the Land Sale
Closing Documents in substantially the form attached hereto as exhibits when
required by Paragraph 3. Nothing in this subparagraph shall be construed as a
waiver by Zhone of any right Zhone may have at law or in equity to the following
remedies, whether because of BNPLC's failure to remove a Lien Removable by BNPLC
or because of any other default by BNPLC under this Agreement: (i) the recovery
of monetary damages, (ii) injunctive relief in case of the violation, or
attempted or threatened violation, by BNPLC of any of the express covenants,
agreements, conditions or provisions of this Agreement which are binding upon
BNPLC, or (iii) a decree compelling performance by BNPLC of any of the express
covenants, agreements, conditions or provisions of this Agreement which are
binding upon BNPLC.

          (B)  Automatic Termination of Zhone's Rights. Without limiting BNPLC'S
               ---------------------------------------
right to enforce Zhone's obligation to pay any Land Supplemental Payment or
other amounts required by this Agreement, the Purchase Option, Zhone's Initial
Remarketing Rights and Zhone's Extended Remarketing Rights shall all terminate
automatically if Zhone shall fail to pay the full amount of any Land
Supplemental Payment required by subparagraph 1(A)(3) on the Designated Sale
Date or if BNPLC shall elect a Voluntary Retention of the Property as provided
in subparagraph 1(A)(2)(a). However, notwithstanding anything in this
subparagraph to the contrary, even after a failure to pay any required Land
Supplemental Payment on the Designated Sale Date, on any Business Day within
thirty days after the Designated Sale Date Zhone or its designee may tender to
BNPLC the full Land Break Even Amount (calculated as of the Designated Sale
Date), together with interest on the total Land Break Even Amount computed at
the Default Rate from the Designated Sale Date to the date of tender, and
together with all other amounts then due under any of the Land Operative
Documents and the Other Operative Documents, and if presented with such a tender
within thirty days after the Designated Sale Date, BNPLC must accept the tender
and promptly thereafter deliver to Zhone or its designee all Land Escrowed
Proceeds (if any) and the Land Sale Closing Documents required by Paragraph 3 of
this Agreement.

          (C)  Termination of Zhone's Extended Remarketing Rights to Permit a
               --------------------------------------------------------------
Sale by BNPLC. At any time more than ninety days after BNPLC has delivered a
-------------
Third Party Sale Notice to Zhone as described in subparagraph 2(C)(2), BNPLC may
terminate Zhone's Extended Remarketing Rights contemporaneously with the
consummation of a sale of the Property by BNPLC to any third party (be it the
prospective purchaser named in the Third Party Sale Notice or another third
party) at a price equal to or in excess of the Third Party Target Price
specified in the Third Party Sale Notice, so as to permit the sale of the
Property unencumbered by Zhone's Extended Remarketing Rights.

          (D)  Payment Only to BNPLC. Except for Direct Payments to
               ---------------------
Participants, all amounts payable under this Agreement by Zhone and, if
applicable, by an Applicable Purchaser must be paid directly to BNPLC, and no
payment to any other party shall be effective for the purposes of this
Agreement. (This provision shall not, however, limit Zhone's right to deduct
Deposit Taker Losses when calculating the Land Break Even Amount, as provided in
subparagraph 1(B)(1).)  In addition to any payments required under subparagraph
1(A),

[Land]                                 8
<PAGE>

on the Designated Sale Date Zhone must pay all amounts then due to BNPLC
under the Other Operative Documents.

          (E)  Remedies Under the other Operative Documents. No repossession
               --------------------------------------------
of or re-entering upon the Property or exercise of any other remedies available
to BNPLC under the other Land Operative Documents or the Other Operative
Documents shall terminate Zhone's rights or obligations hereunder, all of which
shall survive BNPLC's exercise of remedies under those other documents. Zhone
acknowledges that the consideration for this Agreement is separate and
independent of the consideration for the Land Lease and the Closing Certificate,
and Zhone's obligations hereunder shall not be affected or impaired by any event
or circumstance that would excuse Zhone from performance of its obligations
under such other Land Operative Documents or any of the Other Operative
Documents.

          (F)  Occupancy by Zhone Prior to Closing of a Sale. Prior to the
               ---------------------------------------------
closing of any sale of the Property to Zhone or an Applicable Purchaser
hereunder, Zhone's occupancy and use of the Property shall continue to be
subject to the terms and conditions of the Land Lease, including the terms
setting forth Zhone's obligation to pay rent, so long as the Land Lease has not
been terminated or expired in accordance with its express terms and conditions.

          (G)  Preferential Payments to BNPLC.  If any payment to BNPLC by an
               ------------------------------
Applicable Purchaser hereunder is held to constitute a preference or a voidable
transfer under Applicable Law, or must for any other reason be refunded by BNPLC
to the Applicable Purchaser or to another Person, and if such payment to BNPLC
reduced or had the effect of reducing a Land Supplemental Payment or increased
or had the effect of increasing any excess sale proceeds paid to Zhone pursuant
to subparagraph 1(A)(2)(b) or pursuant to subparagraph 2(D), then Zhone shall
pay to BNPLC upon demand an amount equal to the reduction of the Land
Supplemental Payment or to the increase of the excess sale proceeds paid to
Zhone, as applicable, and this Agreement shall continue to be effective or shall
be reinstated as necessary to permit BNPLC to enforce its right to collect such
amount from Zhone.

     5    Security for Zhone's Obligations; Return of Funds.   Zhone's
obligations under this Agreement are secured by the Land Pledge Agreement,
reference to which is hereby made for a description of the Collateral covered
thereby and the rights and remedies provided to BNPLC thereby. Although the
collateral agent appointed for BNPLC as provided in the Land Pledge Agreement
shall be entitled to hold all Collateral as security for the full and faithful
performance by Zhone of Zhone's covenants and obligations under this Agreement,
the Collateral shall not be considered an advance payment of the Land Break Even
Amount or any Land Supplemental Payment or a measure of BNPLC's damages should
Zhone breach this Agreement.  If Zhone does breach this Agreement and fails to
cure the same within any time specified herein for the cure, BNPLC may, from
time to time, without prejudice to any other remedy and without notice to Zhone,
require the collateral agent to immediately apply the proceeds of any
disposition of the Collateral (and any cash included in the Collateral) to
amounts then due hereunder from Zhone.  If by a Permitted Transfer BNPLC conveys
its interest in the Property before the Designated Sale Date, BNPLC may also
assign BNPLC's interest in the Collateral to the transferee.  BNPLC shall be
entitled to return any Collateral not sold or used to satisfy the obligations
secured by the Land Pledge Agreement directly to Zhone notwithstanding any prior
actual or attempted conveyance or assignment by Zhone, voluntary or otherwise,
of any right to receive the same; neither BNPLC nor the collateral agent named
in the Land Pledge Agreement shall be responsible for the proper distribution or
application by Zhone of any such Collateral returned to Zhone; and any such
return of Collateral to Zhone shall discharge any obligation of BNPLC to deliver
such Collateral to all Persons claiming an interest in the Collateral.  Further,
BNPLC shall be entitled to deliver any Land Escrowed Proceeds it holds on the
Designated Sale Date directly to Zhone or to any Applicable Purchaser purchasing
BNPLC's interest in the Property and the Land Escrowed Proceeds pursuant to this
Agreement notwithstanding any prior actual or attempted conveyance or assignment
by Zhone, voluntary or otherwise, of any right to receive the same; BNPLC shall
not be

[Land]                                 9
<PAGE>

responsible for the proper distribution or application by Zhone or any
Applicable Purchaser of any such Land Escrowed Proceeds paid over to Zhone or
the Applicable Purchaser; and any such payment of Land Escrowed Proceeds to
Zhone or an Applicable Purchaser shall discharge any obligation of BNPLC to
deliver the same to all Persons claiming an interest therein.

     6    Certain Remedies Cumulative. No right or remedy herein conferred upon
or reserved to BNPLC is intended to be exclusive of any other right or remedy
BNPLC has with respect to the Property, and each and every right and remedy
shall be cumulative and in addition to any other right or remedy given hereunder
or now or hereafter existing at law or in equity or by statute. In addition to
other remedies available under this Agreement, either party shall be entitled,
to the extent permitted by applicable law, to a decree compelling performance of
any of the other party's agreements hereunder.

     7    Attorneys' Fees and Legal Expenses. If either party to this Agreement
commences any legal action or other proceeding to enforce any of the terms of
this Agreement, or because of any breach by the other party or dispute
hereunder, the party prevailing in such action or proceeding shall be entitled
to recover from the other party all Attorneys' Fees incurred in connection
therewith, whether or not such controversy, claim or dispute is prosecuted to a
final judgment.  Any such Attorneys' Fees incurred by either party in enforcing
a judgment in its favor under this Agreement shall be recoverable separately
from such judgment, and the obligation for such Attorneys' Fees is intended to
be severable from other provisions of this Agreement and not to be merged into
any such judgment.

     8    Estoppel Certificate. Upon request by BNPLC, Zhone shall execute,
acknowledge and deliver a written statement certifying that this Agreement is
unmodified and in full effect (or, if there have been modifications, that this
Agreement is in full effect as modified, and setting forth such modification)
and either stating that no default exists hereunder or specifying each such
default of which Zhone has knowledge. Any such statement may be relied upon by
any Participant or prospective purchaser or assignee of BNPLC with respect to
the Property.

     9    Successors and Assigns. The terms, provisions, covenants and
conditions hereof shall be binding upon Zhone and BNPLC and their respective
permitted successors and assigns and shall inure to the benefit of Zhone and
BNPLC and all permitted transferees, mortgagees, successors and assignees of
Zhone and BNPLC with respect to the Property; provided, that (A) the rights of
BNPLC hereunder shall not pass to Zhone or any Applicable Purchaser or any
subsequent owner claiming through Zhone or an Applicable Purchaser, (B) BNPLC
shall not assign this Agreement or any rights hereunder except pursuant to a
Permitted Transfer, and (C) Zhone shall not assign this Agreement or any rights
hereunder without the prior written consent of BNPLC.

     10    Amendment and Restatement. This Agreement amends, restates and
replaces the Prior Purchase Agreement referenced in the recitals at the
beginning of this agreement.

                           [Signature pages follow.]

[Land]                                 10
<PAGE>

     IN WITNESS WHEREOF, Zhone and BNPLC have caused this Purchase Agreement
(Land) to be executed as of August 1, 2000.

                                   "Zhone"

                                   ZHONE TECHNOLOGIES, INC.

                                   By:  /s/  Bruce Ruberg
                                        ----------------------------------
                                        Name:  Bruce Ruberg
                                             -----------------------------
                                        Title:  Corporate Controller
                                              ----------------------------
<PAGE>

[Continuation of signature pages to Purchase Agreement (Land) dated to be
effective August 1, 2000]

                                   "BNPLC"

                                   BNP LEASING CORPORATION

                                   By: /s/  Lloyd G. Cox
                                       ------------------------------------
                                       Lloyd G. Cox, Vice President
<PAGE>

                                   Exhibit A
                                   ---------

                               LEGAL DESCRIPTION

The real property located in the City of Oakland, County of Alameda, State of
California, described as follows:

Being a portion of Lot 12, as shown on Parcel Map No. 6003, filed in Book 205 of
Parcel Maps, at Pages 94 through 98, Alameda County Records, more particularly
described as follows:

Commencing at the most southerly corner of said Lot 12; Thence along the
southwesterly line of said Lot 12, North 33(degrees) 50' 24" West, 628.68 feet
to the point of beginning; Thence continuing along the southwesterly line of
said Lot 12, North 33(degrees) 50' 24" West, 1029.21 feet; Thence along the
southeasterly line of said Lot 12, South 56(degrees) 09' 36" West 14.00 feet;
Thence along the southwesterly line of said Lot 12, North 33(degrees) 50' 24"
West, 253.55 feet to the beginning of a curve, concave southwesterly, having a
radius of 392.21 feet; Thence northerly along the arc of said curve, through a
central angle of 3(degrees) 51' 45", an arc distance of 26.44 feet to the
intersection of a line drawn parallel with and 85.00 feet southeasterly of the
northwesterly line of said Lot 12, a radial line through said point bears North
52(degrees) 17' 51" East; Thence parallel with the northwesterly line of said
Lot 12, North 56(degrees) 09' 36" East, 476.93 feet to a point that is 5 feet
southwesterly of the northeasterly line of said Lot 12; Thence along a line that
is parallel with and 5 feet southwesterly of the said northeasterly line of Lot
12, South 40(degrees) 00' 30" East, 69.44 feet to the beginning of a curve,
concave southwesterly, having a radius of 1949.00 feet; Thence southeasterly
along the arc of said curve, through a central angle of 6(degrees) 10' 18", an
arc distance of 209.94 feet; Thence continuing along a line that is parallel
with and 5 feet southwesterly of the said northeasterly line of Lot 12, South
33(degrees)50' 12" East, 1030.61 feet to the intersection with a line drawn
perpendicular with the southwesterly line of said Lot 12, distant thereon 628.68
feet from the most southerly corner of said Lot 12; Thence southwesterly along
said perpendicular line, South 56(degrees) 09' 36" West, 480.72 feet to the
Point of Beginning.

The basis of bearings for Parcel Map No. 6003 is the North American Datum of
1983, Zone 3, 1984 Adjustment Published in 1986, as shown on Record of Survey
990, filed in Book 18 of Records of Survey, at Pages 50 through 60, Alameda
County Records.  All distances in this description are grid distances.  To
convert to ground distances, multiply grid distances by 1.0000708.

Assessor's Parcel No. 041-3902-015 (Portion)

[Land]
<PAGE>

[SUBSTITUTE A PAGE COPIED FROM A SURVEY OF THE LAND, MARKED TO SHOW THE
"BUILDING 3 SITE" HERE.]

[Land]
<PAGE>

                                   Exhibit B
                                   ---------

             Requirements Re: Form of Grant Deed and Ground Lease

The form of deed to be used to convey BNPLC's interest in the Land to Zhone or
an Applicable Purchaser will depend upon whether BNPLC's interest in the
Improvements has been or is being conveyed at the same time to the same party.

If BNPLC's interests in both the Land and the Improvements are to be conveyed to
Zhone or an Applicable Purchaser at the same time, because a sale under this
Land Purchase Agreement and sales under the Other Purchase Agreements (covering
the Improvements) are being consummated at the same time and to the same party,
then the one deed in form attached as Exhibit B-1 will be used to convey both.
                                      -----------

If, however, a sale of BNPLC's interest in the Improvements pursuant to the
Other Purchase Agreements has not been consummated before, and is not being
consummated contemporaneously with the sale of BNPLC's interest in the Land
under this Agreement, then BNPLC's interest in the Land will be conveyed by a
deed in the form attached as Exhibit B-2, and BNPLC and the grantee under such
                             -----------
deed shall, as a condition to BNPLC's obligation to deliver the deed, execute
and deliver a Ground Lease covering the Land in the form attached hereto as
Exhibit B-3.
-----------

Finally, BNPLC's interest in the Land will be conveyed by a deed in the form
attached as Exhibit B-4 if BNPLC's interest in the Improvements has been sold
            -----------
pursuant to the Other Purchase Agreements before a sale of BNPLC's interest in
the Land under this Agreement, or if BNPLC's interest in the Improvements is
being sold contemporaneously with a sale of BNPLC's interest in the Land, but
the purchaser of the Improvements is not the same as the purchaser of the Land.

[Land]
<PAGE>

                                  Exhibit B-1
                                  -----------

                            CORPORATION GRANT DEED

RECORDING REQUESTED BY
AND WHEN RECORDED MAIL TO:
-------------------------

NAME:  [Zhone or the Applicable Purchaser]
ADDRESS:  ____________________________
ATTN:     ____________________________
CITY:     ____________________________
STATE:_____________________
Zip:      ____________________________

MAIL TAX STATEMENTS TO:
----------------------

NAME:  [Zhone or the Applicable Purchaser]
ADDRESS:  ____________________________
ATTN:     ____________________________
CITY:     ____________________________
STATE:_____________________
Zip:      ____________________________

                            CORPORATION GRANT DEED
                       (Covering Land and Improvements)

FOR A VALUABLE CONSIDERATION, receipt of which is hereby acknowledged, BNP
LEASING CORPORATION, a Delaware corporation ("Grantor"), hereby grants to [Zhone
or the Applicable Purchaser] ("Grantee") all of Grantor's interest in the land
situated in Oakland, California, described on Annex A attached hereto and hereby
made a part hereof and all improvements on such land, together with the any
other right, title and interest of Grantor in and to any easements, rights-of-
way, privileges and other rights appurtenant to such land or the improvements
thereon; provided, however, that this grant is subject to the encumbrances
described on Annex B (the "Permitted Encumbrances"). Grantee hereby assumes the
obligations (including any personal obligations) of Grantor, if any, created by
or under, and agrees to be bound by the terms and conditions of, the Permitted
Encumbrances to the extent that the same concern or apply to the land or
improvements conveyed by this deed.

[Land]
<PAGE>

                                    BNP LEASING CORPORATION

Date: As of ____________            By:     ____________________________________
                                            Its:

                                    Attest: ____________________________________
                                            Its:

                                    [Zhone or Applicable Purchaser]

Date: As of ____________            By:     ____________________________________
                                            Its:

                                    Attest: ____________________________________
                                            Its:

STATE OF ____________  )
                       )  SS
COUNTY OF ___________  )

     On ________________ before me,__________, personally appeared_________ and
________________, personally known to me (or proved to me on the basis of
satisfactory evidence) to be the persons whose names are subscribed to the
within instrument and acknowledged to me that they executed the same in their
authorized capacities, and that by their signatures on the instrument the
person, or the entity upon behalf of which the persons acted, executed the
instrument.

     WITNESS my hand and official seal.

     Signature _______________________

STATE OF ____________  )
                       )  SS
COUNTY OF ___________  )

     On _________________ before me,________, personally appeared_________ and
________________, personally known to me (or proved to me on the basis of
satisfactory evidence) to be the persons whose names are subscribed to the
within instrument and acknowledged to me that they executed the same in their
authorized capacities, and that by their signatures on the instrument the
person, or the entity upon behalf of which the persons acted, executed the
instrument.

     WITNESS my hand and official seal.

     Signature _______________________

[Land]                       Exhibit B-1 - Page 2
<PAGE>

                                    Annex A

                               LEGAL DESCRIPTION

[DRAFTING NOTE: TO THE EXTENT THAT THE "LAND" COVERED BY THE LAND LEASE CHANGES
 --------------
FROM TIME TO TIME BECAUSE OF ADJUSTMENTS FOR WHICH ZHONE REQUESTS BNPLC'S
CONSENT OR APPROVAL, SO TOO WILL THE DESCRIPTION OF THE LAND BELOW CHANGE. ANY
SUCH CHANGES WILL BE INCORPORATED INTO THE DESCRIPTION BELOW AND THIS "DRAFTING
NOTE" WILL BE DELETED BEFORE THE DEED TO WHICH THIS DESCRIPTION IS ATTACHED IS
ACTUALLY EXECUTED AND DELIVERED.]

The real property located in the City of Oakland, County of Alameda, State of
California, described as follows:

Being a portion of Lot 12, as shown on Parcel Map No. 6003, filed in Book 205 of
Parcel Maps, at Pages 94 through 98, Alameda County Records, more particularly
described as follows:

Commencing at the most southerly corner of said Lot 12; Thence along the
southwesterly line of said Lot 12, North 33(degrees) 50' 24" West, 628.68 feet
to the point of beginning; Thence continuing along the southwesterly line of
said Lot 12, North 33(degrees) 50' 24" West, 1029.21 feet; Thence along the
southeasterly line of said Lot 12, South 56(degrees) 09' 36" West 14.00 feet;
Thence along the southwesterly line of said Lot 12, North 33(degrees) 50' 24"
West, 253.55 feet to the beginning of a curve, concave southwesterly, having a
radius of 392.21 feet; Thence northerly along the arc of said curve, through a
central angle of 3(degrees) 51' 45", an arc distance of 26.44 feet to the
intersection of a line drawn parallel with and 85.00 feet southeasterly of the
northwesterly line of said Lot 12, a radial line through said point bears North
52(degrees) 17' 51" East; Thence parallel with the northwesterly line of said
Lot 12, North 56(degrees) 09' 36" East, 476.93 feet to a point that is 5 feet
southwesterly of the northeasterly line of said Lot 12; Thence along a line that
is parallel with and 5 feet southwesterly of the said northeasterly line of Lot
12, South 40(degrees) 00' 30" East, 69.44 feet to the beginning of a curve,
concave southwesterly, having a radius of 1949.00 feet; Thence southeasterly
along the arc of said curve, through a central angle of 6(degrees) 10' 18", an
arc distance of 209.94 feet; Thence continuing along a line that is parallel
with and 5 feet southwesterly of the said northeasterly line of Lot 12, South
33(degrees)50' 12" East, 1030.61 feet to the intersection with a line drawn
perpendicular with the southwesterly line of said Lot 12, distant thereon 628.68
feet from the most southerly corner of said Lot 12; Thence southwesterly along
said perpendicular line, South 56(degrees) 09' 36" West, 480.72 feet to the
Point of Beginning.

The basis of bearings for Parcel Map No. 6003 is the North American Datum of
1983, Zone 3, 1984 Adjustment Published in 1986, as shown on Record of Survey
990, filed in Book 18 of Records of Survey, at Pages 50 through 60, Alameda
County Records.  All distances in this description are grid distances.  To
convert to ground distances, multiply grid distances by 1.0000708.

Assessor's Parcel No. 041-3902-015 (Portion)

[Land]                       Exhibit B-1 - Page 3
<PAGE>

                                    Annex B

                            Permitted Encumbrances

[DRAFTING NOTE: TO THE EXTENT THAT ENCUMBRANCES (OTHER THAN "LIENS REMOVABLE BY
 --------------
BNPLC") ARE IDENTIFIED IN ADDITION TO THOSE DESCRIBED BELOW, SUCH ADDITIONAL
ENCUMBRANCES WILL BE ADDED TO THE LIST BELOW AND THIS "DRAFTING NOTE" WILL BE
DELETED BEFORE THIS DEED IS ACTUALLY EXECUTED AND DELIVERED BY BNPLC. SUCH
ADDITIONAL ENCUMBRANCES WOULD INCLUDE ANY NEW ENCUMBRANCES APPROVED BY BNPLC AS
"PERMITTED ENCUMBRANCES" UNDER THE LAND LEASE OR THE OTHER LEASE AGREEMENTS FROM
TIME TO TIME OR BECAUSE OF ZHONE'S REQUEST FOR BNPLC'S CONSENT OR APPROVAL TO AN
ADJUSTMENT.]

     This conveyance is subject to all encumbrances not constituting a "Lien
Removable by BNPLC" (as defined in the Common Definitions and Provisions
Agreement (Land) incorporated by reference into the Lease Agreement (Land)
referenced in the last item of the list below), including the following matters
to the extent the same are still valid and in force:

1.   County and city taxes for the Fiscal Year 2000 - 2001, a lien not yet due
     or payable.

2.   The Lien of Supplemental Taxes, if any, assessed pursuant to the provisions
     of Chapter 3.5, Revenue and Taxation Code, Sections 75 et seq., resulting
     from changes of ownership or completion of construction on or after the
     date hereof.

3.   Easement, upon the terms, covenants and conditions thereof, for the
     purposes stated therein and incidental purposes created in that certain
     instrument

     Recorded             :       FEBRUARY 11, 1974, REEL 3608, IMAGE 3, SERIES
                                  NO. 74-16523, OFFICIAL RECORDS
     Granted to           :       THE PACIFIC TELEPHONE AND TELEGRAPH COMPANY, A
                                  CORPORATION
     Purpose       :      COMMUNICATION FACILITIES
     Affects       :      A SOUTHWESTERLY PORTION OF SAID LAND

4.   Terms, covenants, conditions and reservations as contained in the Port
     Ordinance No. 2832.  An Ordinance establishing standards and restrictions
     regulating the use of land and the design and construction of structures
     and other improvements in the Oakland Airport Business Park, and repealing
     Port Ordinance No. 1343, as amended, recorded MAY 10, 1990, SERIES NO.
     90130204, OFFICIAL RECORDS.

     Amendment Port Ordinance No. 3146, recorded SEPTEMBER 30, 1993, SERIES NO.
     93348032, OFFICIAL RECORDS.

5.   Terms and conditions of the City of Oakland Redevelopment Project adopted
     by Ordinance No. 11824, C.M.S., as disclosed in the "Notice of Adoption of
     the Coliseum Area Redevelopment Plan, Termination of the 77/th/ Avenue
     Industrial Redevelopment Project and Amendment of the Elmhurst
     Redevelopment Plan," recorded JULY 31, 1995, SERIES NO. 95167161, OFFICIAL
     RECORDS.

     Amendment recorded SEPTEMBER 9, 1997, SERIES NO. 97-231187, OFFICIAL
     RECORDS.

[Land]                       Exhibit B-1 - Page 4
<PAGE>

6.   The Lease Agreement (Land), the Lease Agreement (Improvements - Buildings
     1&2) and the Lease Agreement (Improvements - Building 3), all dated as of
     August 1, 2000 and all between BNP Leasing Corporation, as lessor, and
     Zhone Technologies, Inc., as lessee.

[Land]                       Exhibit B-1 - Page 5
<PAGE>

                                  Exhibit B-2
                                  -----------

                            CORPORATION GRANT DEED

RECORDING REQUESTED BY
AND WHEN RECORDED MAIL TO:
-------------------------

NAME:  [Zhone or the Applicable Purchaser]
ADDRESS:  ____________________________
ATTN:     ____________________________
CITY:     ____________________________
STATE:_____________________
Zip:      ____________________________

MAIL TAX STATEMENTS TO:
----------------------

NAME:  [Zhone or the Applicable Purchaser]
ADDRESS:  ____________________________
ATTN:     ____________________________
CITY:     ____________________________
STATE:_____________________
Zip:      ____________________________

                            CORPORATION GRANT DEED
             (Covering Land but not the Improvements On the Land)

FOR A VALUABLE CONSIDERATION, receipt of which is hereby acknowledged, BNP
LEASING CORPORATION, a Delaware corporation ("Grantor"), hereby grants to [Zhone
or the Applicable Purchaser] ("Grantee") all of Grantor's interest in the land
situated in Oakland, California, described on Annex A attached hereto and hereby
made a part hereof (the "Land"), together with the any other right, title and
interest of Grantor in and to any easements, rights-of-way, privileges and other
rights appurtenant to the Land; provided, however, that this grant is subject to
the encumbrances described on Annex B (the "Permitted Encumbrances") and any
reservations or qualifications set forth below. Grantee hereby assumes the
obligations (including any personal obligations) of Grantor, if any, created by
or under, and agrees to be bound by the terms and conditions of, the Permitted
Encumbrances to the extent that the same concern or apply to the Land.

Although this deed conveys Grantor's interest in the Land itself, this deed does
not convey any interest in any buildings or other improvements on the Land
(collectively, "Improvements") or any rights or easements appurtenant to
Improvements. Grantor retains and reserves all right, title and interest of
Grantor in and to Improvements and any rights and easements appurtenant to
Improvements, together with a leasehold estate in and to the Land and any rights
and easements appurtenant to the Land, which leasehold estate will permit the
construction, maintenance and use of Improvements by Grantor and Grantor's
successors and assigns on and subject to the terms and conditions set forth in
the Ground Lease dated of even date herewith, executed by Grantee, as lessor,
and Grantor, as lessee.  Reference is made to such Ground Lease, all the terms
and conditions of which are incorporated into this deed as if set forth herein.

[Land]
<PAGE>

                                    BNP LEASING CORPORATION

Date: As of ____________            By:     ___________________________________
                                            Its:

                                    Attest: ___________________________________
                                            Its:

                                    [Zhone or Applicable Purchaser]

Date: As of ____________            By:     ___________________________________
                                            Its:

                                    Attest: ___________________________________
                                            Its:

STATE OF ____________  )
                       )  SS
COUNTY OF ___________  )

     On ______________ before me,____________, personally appeared________ and
________________, personally known to me (or proved to me on the basis of
satisfactory evidence) to be the persons whose names are subscribed to the
within instrument and acknowledged to me that they executed the same in their
authorized capacities, and that by their signatures on the instrument the
person, or the entity upon behalf of which the persons acted, executed the
instrument.

     WITNESS my hand and official seal.

     Signature ______________________

STATE OF ____________  )
                       )  SS
COUNTY OF ___________  )

     On ________________ before me,___________, personally appeared_________ and
_______________, personally known to me (or proved to me on the basis of
satisfactory evidence) to be the persons whose names are subscribed to the
within instrument and acknowledged to me that they executed the same in their
authorized capacities, and that by their signatures on the instrument the
person, or the entity upon behalf of which the persons acted, executed the
instrument.

     WITNESS my hand and official seal.

     Signature ______________________

[Land]                       Exhibit B-2 - Page 2
<PAGE>

                                    Annex A

                               LEGAL DESCRIPTION

[DRAFTING NOTE: TO THE EXTENT THAT THE "LAND" COVERED BY THE LAND LEASE CHANGES
 --------------
FROM TIME TO TIME BECAUSE OF ADJUSTMENTS FOR WHICH ZHONE REQUESTS BNPLC'S
CONSENT OR APPROVAL, SO TOO WILL THE DESCRIPTION OF THE LAND BELOW CHANGE. ANY
SUCH CHANGES WILL BE INCORPORATED INTO THE DESCRIPTION BELOW AND THIS "DRAFTING
NOTE" WILL BE DELETED BEFORE THE DEED TO WHICH THIS DESCRIPTION IS ATTACHED IS
ACTUALLY EXECUTED AND DELIVERED.]

The real property located in the City of Oakland, County of Alameda, State of
California, described as follows:

Being a portion of Lot 12, as shown on Parcel Map No. 6003, filed in Book 205 of
Parcel Maps, at Pages 94 through 98, Alameda County Records, more particularly
described as follows:

Commencing at the most southerly corner of said Lot 12; Thence along the
southwesterly line of said Lot 12, North 33(degrees) 50' 24" West, 628.68 feet
to the point of beginning; Thence continuing along the southwesterly line of
said Lot 12, North 33(degrees) 50' 24" West, 1029.21 feet; Thence along the
southeasterly line of said Lot 12, South 56(degrees) 09' 36" West 14.00 feet;
Thence along the southwesterly line of said Lot 12, North 33(degrees) 50' 24"
West, 253.55 feet to the beginning of a curve, concave southwesterly, having a
radius of 392.21 feet; Thence northerly along the arc of said curve, through a
central angle of 3(degrees) 51' 45", an arc distance of 26.44 feet to the
intersection of a line drawn parallel with and 85.00 feet southeasterly of the
northwesterly line of said Lot 12, a radial line through said point bears North
52(degrees) 17' 51" East; Thence parallel with the northwesterly line of said
Lot 12, North 56(degrees) 09' 36" East, 476.93 feet to a point that is 5 feet
southwesterly of the northeasterly line of said Lot 12; Thence along a line that
is parallel with and 5 feet southwesterly of the said northeasterly line of Lot
12, South 40(degrees) 00' 30" East, 69.44 feet to the beginning of a curve,
concave southwesterly, having a radius of 1949.00 feet; Thence southeasterly
along the arc of said curve, through a central angle of 6(degrees) 10' 18", an
arc distance of 209.94 feet; Thence continuing along a line that is parallel
with and 5 feet southwesterly of the said northeasterly line of Lot 12, South
33(degrees)50' 12" East, 1030.61 feet to the intersection with a line drawn
perpendicular with the southwesterly line of said Lot 12, distant thereon 628.68
feet from the most southerly corner of said Lot 12; Thence southwesterly along
said perpendicular line, South 56(degrees) 09' 36" West, 480.72 feet to the
Point of Beginning.

The basis of bearings for Parcel Map No. 6003 is the North American Datum of
1983, Zone 3, 1984 Adjustment Published in 1986, as shown on Record of Survey
990, filed in Book 18 of Records of Survey, at Pages 50 through 60, Alameda
County Records.  All distances in this description are grid distances.  To
convert to ground distances, multiply grid distances by 1.0000708.

Assessor's Parcel No. 041-3902-015 (Portion)

[Land]                       Exhibit B-2 - Page 3
<PAGE>

                                    Annex B

                            Permitted Encumbrances

[DRAFTING NOTE: TO THE EXTENT THAT ENCUMBRANCES (OTHER THAN "LIENS REMOVABLE BY
 --------------
BNPLC") ARE IDENTIFIED IN ADDITION TO THOSE DESCRIBED BELOW, SUCH ADDITIONAL
ENCUMBRANCES WILL BE ADDED TO THE LIST BELOW AND THIS "DRAFTING NOTE" WILL BE
DELETED BEFORE THIS DEED IS ACTUALLY EXECUTED AND DELIVERED BY BNPLC. SUCH
ADDITIONAL ENCUMBRANCES WOULD INCLUDE ANY NEW ENCUMBRANCES APPROVED BY BNPLC AS
"PERMITTED ENCUMBRANCES" UNDER THE LAND LEASE OR THE OTHER LEASE AGREEMENTS FROM
TIME TO TIME OR BECAUSE OF ZHONE'S REQUEST FOR BNPLC'S CONSENT OR APPROVAL TO AN
ADJUSTMENT.]

     This conveyance is subject to all encumbrances not constituting a "Lien
Removable by BNPLC" (as defined in the Common Definitions and Provisions
Agreement (Land) incorporated by reference into the Lease Agreement (Land)
referenced in the last item of the list below), including the following matters
to the extent the same are still valid and in force:

1.   County and city taxes for the Fiscal Year 2000 - 2001, a lien not yet due
     or payable.

2.   The Lien of Supplemental Taxes, if any, assessed pursuant to the provisions
     of Chapter 3.5, Revenue and Taxation Code, Sections 75 et seq., resulting
     from changes of ownership or completion of construction on or after the
     date hereof.

3.   Easement, upon the terms, covenants and conditions thereof, for the
     purposes stated therein and incidental purposes created in that certain
     instrument

     Recorded             :       FEBRUARY 11, 1974, REEL 3608, IMAGE 3, SERIES
                                  NO. 74-16523, OFFICIAL RECORDS
     Granted to           :       THE PACIFIC TELEPHONE AND TELEGRAPH COMPANY, A
                                  CORPORATION
     Purpose       :      COMMUNICATION FACILITIES
     Affects              :       A SOUTHWESTERLY PORTION OF SAID LAND

4.   Terms, covenants, conditions and reservations as contained in the Port
     Ordinance No. 2832.  An Ordinance establishing standards and restrictions
     regulating the use of land and the design and construction of structures
     and other improvements in the Oakland Airport Business Park, and repealing
     Port Ordinance No. 1343, as amended, recorded MAY 10, 1990, SERIES NO.
     90130204, OFFICIAL RECORDS.

     Amendment Port Ordinance No. 3146, recorded SEPTEMBER 30, 1993, SERIES NO.
     93348032, OFFICIAL RECORDS.

5.   Terms and conditions of the City of Oakland Redevelopment Project adopted
     by Ordinance No. 11824, C.M.S., as disclosed in the "Notice of Adoption of
     the Coliseum Area Redevelopment Plan, Termination of the 77/th/ Avenue
     Industrial Redevelopment Project and Amendment of the Elmhurst
     Redevelopment Plan," recorded JULY 31, 1995, SERIES NO. 95167161, OFFICIAL
     RECORDS.

     Amendment recorded SEPTEMBER 9, 1997, SERIES NO. 97-231187, OFFICIAL
     RECORDS.

6.   The Lease Agreement (Land), the Lease Agreement (Improvements - Buildings
     1&2) and the Lease

[Land]                       Exhibit B-2 - Page 4
<PAGE>

     Agreement (Improvements - Building 3), all dated as of August 1, 2000 and
     all between BNP Leasing Corporation, as lessor, and Zhone Technologies,
     Inc., as lessee

[Land]                       Exhibit B-2 - Page 5
<PAGE>

                                  Exhibit B-3
                                  -----------

                                 GROUND LEASE

     This GROUND LEASE (this "Ground Lease"), by and between BNP LEASING
CORPORATION, a Delaware corporation ("BNPLC"), whose address is 12201 Merit
Drive, Suite 860, Dallas, Texas 75251, and [Zhone or the Applicable Purchaser],
a ___________ ("Lessor"), whose address is ____________________. as of
____________, ____ (the "GL Effective Date").

                                   RECITALS

     This Ground Lease is being executed pursuant to a Purchase Agreement (Land)
dated as of August 1, 2000 (the "Land Purchase Agreement"), between BNP Leasing
Corporation and Zhone Technologies, Inc., covering the land described in Annex 1
                                                                         -------
attached hereto (the "Land").  Incorporated by reference into the Land Purchase
Agreement is a Common Definitions and Provisions Agreement (Land) dated as of
the effective date of the Land Purchase Agreement (the "Land CDPA"), between BNP
Leasing Corporation and Zhone Technologies, Inc.  The Land CDPA is hereby
incorporated into and made a part of this Ground Lease for all purposes.
Capitalized terms defined in the Land CDPA and used but not otherwise defined
herein are intended in this Ground Lease to have the respective meanings
ascribed to them in the Land CDPA.  The provisions in Article II of the Land
CDPA are intended to apply to this Ground Lease as if set forth herein and as if
this Ground Lease were one of the "Land Operative Documents" as defined therein.

     Lessor and BNPLC have reached agreement as to the terms and conditions upon
which Lessor is willing to lease the Land described in Annex 1 to BNPLC for a
                                                       -------
term of just less that 35 years, and by this Ground Lease Lessor and BNPLC
desire to evidence such agreement.

                               GRANTING CLAUSES

     NOW, THEREFORE, in consideration of the rent to be paid and the covenants
and agreements to be performed by BNPLC, as hereinafter set forth, Lessor does
hereby LEASE, DEMISE and LET unto BNPLC for the term hereinafter set forth the
Land, together with:

          (1)  all easements and rights-of-way now owned or hereafter acquired
     by Lessor for use in connection with the Land or as a means of access
     thereto; and

          (2)  all right, title and interest of Lessor, now owned or hereafter
     acquired, in and to (A) any land lying within the right-of-way of any
     street, open or proposed, adjoining the Land, (B) any and all sidewalks and
     alleys adjacent to the Land and (C) any strips and gores between the Land
     and any abutting land not owned by Lessor.

The Land and all of the property described in the preceding clauses (1) and (2)
are hereinafter referred to collectively as the "Real Property".

     To the extent, but only to the extent, that assignable rights or interests
in, to or under the following have been or will be acquired by Lessor as the
owner of any interest in the Real Property, Lessor also hereby

[Land]
<PAGE>

grants and assigns to BNPLC for the term of this Ground Lease (and thereafter,
if BNPLC purchases the Real Property from Lessor pursuant to the Repurchase
Option described in Paragraph 12) the right to use and enjoy (and, in the case
of contract rights, to enforce) such rights or interests of Lessor:

          (a)  the Permitted Encumbrances; and

          (b)  any general intangibles, permits, licenses, franchises,
     certificates, and other rights and privileges related to the Real Property
     that BNPLC have retained (rather than conveyed to Lessor) if Lessor had not
     acquired the fee estate in the Real Property from BNPLC (excluding,
     however, any rights and privileges of Lessor under this Ground Lease or
     under the Land Operative Documents or the Other Operative Documents).

Such rights and interests of Lessor, whether now existing or hereafter arising,
are hereinafter collectively called the "GL Personal Property".  The Real
Property and the GL Personal Property are hereinafter sometimes collectively
called the "GL Property."

     Provided, however, the leasehold estate conveyed hereby and BNPLC's rights
hereunder are expressly made subject and subordinate to the Permitted
Encumbrances, including those listed on Annex 2.  FURTHER, IF AND SO LONG AS THE
                                        -------
OTHER LEASE AGREEMENTS AND THE OTHER PURCHASE AGREEMENTS (BOTH AS DEFINED IN THE
-     -     -                  -     -        -
LAND CDPA) REMAIN IN FORCE, THE RIGHTS AND OBLIGATIONS OF LESSOR AND BNPLC
-    ----                                                 -          -----
HEREUNDER SHALL BE SUBJECT TO ANY CONTRARY PROVISIONS THEREIN.  ACCORDINGLY,
BNPLC'S RIGHTS UNDER PARAGRAPH 7 BELOW SHALL BE SUBJECT TO THE PROVISIONS
-----
GOVERNING INSURANCE AND CONDEMNATION IN THE OTHER LEASE AGREEMENTS, IF AND SO
                                            -     -     -
LONG AS THE OTHER LEASE AGREEMENTS REMAINS IN FORCE.
            -     -     -

                         GENERAL TERMS AND CONDITIONS

     The GL Property is leased by Lessor to BNPLC and is accepted and is to be
used and possessed by BNPLC upon and subject to the following terms and
conditions:

     1    Ground Lease Term and Early Termination by BNPLC.  The term of this
Ground Lease (the "Ground Lease Term") shall commence on and include the GL
Effective Date and end on last Business Day prior to the thirty-fifth
anniversary of the GL Effective Date.  However, subject to the prior approval of
any Leasehold Mortgagee, BNPLC shall have the right to terminate this Ground
Lease by giving a notice to Lessor stating that BNPLC unequivocally elects to
terminate effective as of a date specified in such notice, which may be any date
more than thirty days after the notice and after the expiration or termination
of the Lease pursuant to its terms.

     2    No Other Ground Lease Termination. Except as expressly provided
herein, this Ground Lease shall not terminate, nor shall Lessor have any right
to terminate this Ground Lease, nor shall the obligations of Lessor under this
Ground Lease be excused, for any reason whatsoever, including any of the
following: (i) any damage to or the destruction of all or any part of the GL
Property from whatever cause, (ii) the taking of the GL Property or any portion
thereof by eminent domain or otherwise for any reason, (iii) any default on the
part of BNPLC under this Ground Lease or under any other agreement to which
Lessor and BNPLC are parties, or (iv) any other cause whether similar or
dissimilar to the foregoing, any existing or future law to the contrary
notwithstanding. It is the intention of the parties hereto that the obligations
of Lessor hereunder shall be separate and independent of the covenants and
agreements of BNPLC. However, nothing in this Paragraph shall be construed as a
waiver by Lessor of any right Lessor may have at law or in equity to recover
monetary damages for any default under this Ground Lease by BNPLC.

[Land]                       Exhibit B-3 - Page 2
<PAGE>

     3    Ground Lease Rent. On each anniversary of the GL Effective Date, BNPLC
shall make a payment to Lessor of rent for the then preceding year ("Ground
Lease Rent"), in currency that at the time of payment is legal tender for public
and private debts in the United States of America.  Each such payment of Ground
Lease Rent shall equal the Fair Rental Value, determined as provided in Annex 3.
                                                                        -------

     4    Use of GL Property.

          (A)  Permitted Uses and Construction of Improvements.    Subject to
               -----------------------------------------------
the Permitted Encumbrances and the terms hereof, BNPLC may use and occupy the GL
Property for any purpose permitted by Applicable Laws and may construct,
maintain and use any Improvements on the Land which are permitted by Applicable
Laws.

          (B)  Cooperation by Lessor and its Affiliates.
               ----------------------------------------

          (1)   After the expiration or any earlier termination of the Lease, if
     a use of the GL Property by BNPLC or any new Improvements or any removal or
     modification of Improvements proposed by BNPLC would violate any Permitted
     Encumbrance or Applicable Law unless Lessor or any of its Affiliates, as an
     owner of adjacent property or otherwise, gave its consent or approval
     thereto or agreed to join in a modification of a Permitted Encumbrance,
     then Lessor shall give and cause its Affiliates to give such consent or
     approval or join in such modification.

          (2)   To the extent, if any, that any Permitted Encumbrance or
     Applicable Law requires the consent or approval of Lessor or any of its
     Affiliates or of the City of Oakland or any other Person to an assignment
     of this Ground Lease or a transfer of any interest in the GL Property by
     BNPLC or its successors or assigns, Lessor will without charge give and
     cause its Affiliates to give such consent or approval and will cooperate in
     any way reasonably requested by BNPLC to assist BNPLC to obtain such
     consent or approval from the City or any other Person; provided, however,
     the assignment or transfer is not then prohibited by the Lease.

          (3)   Lessor's obligations under this subparagraph 4(B) shall be
     binding upon any successor or assign of Lessor with respect to the Land and
     other properties encumbered by the Permitted Encumbrances, and such
     obligations shall survive any sale of Lessor's interest in the GL Property
     to BNPLC because of BNPLC's exercise of the Repurchase Option (as defined
     in Paragraph 12).

          (C)  Title to Improvements.  Any and all Improvements of whatever
               ---------------------
nature at any time constructed, placed or maintained upon any part of the Land
shall be and remain the property of BNPLC and BNPLC's sublessee's, assignees,
licensees and concessionaires, as their interests may appear; provided, any such
Improvements which remain on the Land when this Ground Lease expires or is
terminated shall become and thereupon be the property of Lessor, free and clear
of any Liens Removable by BNPLC.  It is the intention of Lessor and BNPLC that
severance of fee title to the Land and the Improvements shall not change the
character of the Improvements as real property.  BNPLC may at any time after
Lessor ceases to have possession of the GL Property as tenant under the Lease
and prior to the expiration or termination of this Ground Lease remove all or
any Improvements from the Land without the consent of Lessor and without any
obligation to Lessor or its Affiliates to provide compensation or to construct
other Improvements on or about the Land.

     5    Assignment and Subletting; Pass Through of BNPLC's Liability Insurance
and Indemnity Rights.  BNPLC may sublet or assign this Ground Lease without the
consent of Lessor or any of its Affiliates, subject only to limitations set
forth in the Lease for the benefit of Lessor so long as those limitations remain
in force.

[Land]                       Exhibit B-3 - Page 3
<PAGE>

     To the extent that BNPLC may from time to time after the expiration or
earlier termination of the Other Lease Agreements require any subtenant to agree
to maintain liability insurance against claims of third parties and agree to
make BNPLC an additional or named insured under such insurance, BNPLC shall also
require the subtenant to agree to make Lessor an additional or named insured.
However, BNPLC shall have no liability to Lessor for a breach by the subtenant
of any such agreements, and to the extent that BNPLC's rights as an additional
or named insured are subject to exceptions or limitations concerning BNPLC's own
acts or omissions or the acts or omissions of anyone other than the subtenant,
so too may Lessor's rights as an additional or named insured be subject to
exceptions or limitations concerning Lessor's own acts or omissions or the acts
or omissions of anyone other than the subtenant.

     To the extent that BNPLC may itself from time to time after the expiration
or earlier termination of the Other Lease Agreements maintain liability
insurance against claims of third parties which may arise because of any
occurrence on or alleged to have occurred on or about the GL Property, BNPLC
shall cause Lessor to be an additional or named insured under such insurance,
provided Lessor pays or reimburses BNPLC for any additional insurance premium
required to have Lessor made an insured.

     To the extent that BNPLC may from time to time after the expiration or
earlier termination of the Other Lease Agreements require any subtenant to agree
to indemnify BNPLC against Environmental Losses or other Losses concerning the
GL Property, BNPLC shall also require the subtenant to agree to indemnify
Lessor.  However, BNPLC shall have no liability to Lessor for a breach by the
subtenant of any such agreement, and to the extent that BNPLC's rights as an
indemnitee of the subtenant are subject to exceptions or limitations concerning
BNPLC's own acts or omissions or the acts or omissions of anyone other than the
subtenant, so too may Lessor's rights as an indemnitee be subject to exceptions
or limitations concerning Lessor's own acts or omissions or the acts or
omissions of anyone other than the subtenant.

     6    Representations, Warranties and Covenants of Lessor Concerning the
Property.  Lessor represents, warrants and covenants as follows:

          (A)  Title to the Property. This Ground Lease shall vest in BNPLC good
               ---------------------
and marketable title to a leasehold estate in the Land, subject only to the
terms and conditions hereof, the Permitted Encumbrances and any Liens Removable
by BNPLC.  Lessor shall not, without the prior consent of BNPLC, create, place
or authorize, or through any act or failure to act, acquiesce in the placing of,
any deed of trust, mortgage or other Lien, whether statutory, constitutional or
contractual against or covering the GL Property or any part thereof (other than
Permitted Encumbrances and Liens Removable by BNPLC), regardless of whether the
same are expressly or otherwise subordinate to the Land Operative Documents or
the Other Operative Documents or to BNPLC's interest in the Property.

          (B)  Modification of Permitted Encumbrances.   Without the prior
               --------------------------------------
consent of BNPLC, Lessor shall not enter into, initiate, approve or consent to
any modification of any Permitted Encumbrance that would create or expand or
purport to create or expand obligations or restrictions which would encumber the
GL Property or any improvements constructed thereon.

          (C)  Performance and Preservation of the Permitted Encumbrances for
               --------------------------------------------------------------
the Benefit of BNPLC.  Not only during the term of the Other Lease Agreements,
--------------------
but thereafter throughout the term of this Ground Lease, Lessor shall comply
with and perform the obligations imposed by the Permitted Encumbrances upon
Lessor or upon any owner of the Land, and shall do whatever is required to
preserve the rights and benefits conferred or intended to be conferred by the
Permitted Encumbrances, as necessary to facilitate the construction of the
Construction Projects on the Land as contemplated in the Other Lease Agreements
and the use of the Improvements included in the Construction Projects by BNPLC
and its successors, assigns and subtenants under

[LAND]                       Exhibit B-3 - Page 4
<PAGE>

this Ground Lease after the expiration or any earlier termination of the Other
Lease Agreements. Further, if Lessor or any Affiliate of Lessor now or hereafter
owns, acquires or leases land (other than the Land) that is the subject of a
Permitted Encumbrance, then Lessor shall, and shall cause its Affiliate to,
assume liability for and indemnify BNPLC and other Interested Parties and defend
and hold them harmless from and against all Losses (including Losses caused by
any decline in the value of the Property or of the Improvements) that they would
not have incurred or suffered but for (i) a termination of such Permitted
Encumbrance, to which Lessor or its Affiliate agreed, or which resulted from a
breach thereof by Lessor or its Affiliate, or (ii) a refusal of Lessor or its
Affiliate to agree to any waiver or modification requested by BNPLC of
restrictions upon the Property or the transfer thereof imposed by such Permitted
Encumbrance, or (iii) anything done, authorized or suffered by Lessor or its
Affiliate in violation of such Permitted Encumbrance. Lessor's obligations under
this subparagraph 6(C) shall be binding upon any successor or assign of Lessor
or its Affiliates with respect to their interest in properties subject to the
Permitted Encumbrances.

     7    Insurance and Condemnation.

          (A)  Entitlement to Insurance and Condemnation Proceeds.  All
               --------------------------------------------------
insurance and condemnation proceeds payable with respect to any damage to or
taking of the GL Property shall be payable to and become the property of BNPLC;
provided, however, Lessor shall be entitled to receive condemnation proceeds
awarded for the value of Lessor's remainder interest in the Land exclusive of
the Improvements.  BNPLC is authorized to take all action necessary on behalf of
both BNPLC and Lessor (as lessor under this Ground Lease) to collect insurance
and condemnation proceeds.

          (B)  Collection of Insurance Proceeds.  In the event any of the GL
               --------------------------------
Property is destroyed or damaged by fire, explosion, windstorm, hail or by any
other casualty against which insurance shall have been required hereunder, (i)
BNPLC may make proof of loss, (ii) each insurance company concerned is hereby
authorized and directed to make payment for such loss directly to BNPLC for
application as required by subparagraph 7(A), and (iii) BNPLC's consent must be
obtained for any settlement, adjustment or compromise of any claims for loss,
damage or destruction under any policy or policies of insurance.

          (C)  Collection of Condemnation Proceeds.  All proceeds of
               -----------------------------------
condemnation awards or proceeds of sale in lieu of condemnation with respect to
the GL Property and all judgments, decrees and awards for injury or damage to
the GL Property shall be paid to BNPLC and applied as provided in subparagraph
7(A) above.  BNPLC is hereby authorized, in the name of Lessor, to execute and
deliver valid acquittances for, and to appeal from, any such judgment, decree or
award concerning condemnation of any of the GL Property.  BNPLC shall not be, in
any event or circumstances, liable or responsible for failure to collect, or to
exercise diligence in the collection of, any such proceeds, judgments, decrees
or awards.

     8    Leasehold Mortgages.

          (A)  By Leasehold Mortgage BNPLC may encumber BNPLC's leasehold estate
in the GL Property created by this Ground Lease, as well as BNPLC's rights and
interests in buildings, fixtures, equipment and Improvements situated on the
Land and rents, issues, profits, revenues and other income to be derived by
BNPLC therefrom.

          (B)  Any Leasehold Mortgagee or other party, including any corporation
formed by a Leasehold Mortgagee, may become the legal owner of the leasehold
estate created by this Ground Lease, and of the Improvements, equipment,
fixtures and other property assigned as additional security pursuant to a
Leasehold Mortgage, by foreclosure of a Leasehold Mortgage or as a result of the
assignment or conveyance in lieu of foreclosure.  Further, any such Leasehold
Mortgagee or other party may itself, after becoming the legal owner and holder
of the leasehold estate created by this Ground Lease, or of any Improvements,
equipment,

[LAND]                       Exhibit B-3 - Page 5
<PAGE>

fixtures and other property assigned as additional security pursuant to a
Leasehold Mortgage, convey or pledge the same without the consent of Lessor.

          (C)  Lessor shall serve notice of any default by BNPLC hereunder upon
any Leasehold Mortgagee.  No notice of a default by BNPLC shall be deemed
effective until it is so served.  Any Leasehold Mortgagee shall have the right
to correct or cure any such default within the same period of time after receipt
of such notice as is given to BNPLC under this Ground Lease to correct or cure
defaults, plus an additional period of thirty days thereafter.  Lessor will
accept performance by any Leasehold Mortgagee of any covenant, condition or
agreement on BNPLC's part to be performed hereunder with the same force and
effect as though performed by BNPLC.

          (D)  If this Ground Lease should terminate by reason of a
disaffirmance or rejection of this Ground Lease by BNPLC or any receiver,
liquidator or trustee for the property of BNPLC, or by any governmental
authority which had taken possession of the business or property of BNPLC by
reason of the insolvency or alleged insolvency of BNPLC, then:

          (1)  Lessor shall give notice thereof to each Leasehold Mortgagee; and
     upon request of any Leasehold Mortgagee made within sixty days after Lessor
     has given such notice, Lessor shall enter into a new ground lease of the GL
     Property with such Leasehold Mortgagee for the remainder of the Ground
     Lease Term, at the same Ground Lease Rent and on the same terms and
     conditions as contained in this Ground Lease.

          (2)  The estate of the Leasehold Mortgagee, as lessee under the new
     lease, shall have priority equal to the estate of BNPLC hereunder.  That
     is, there shall be no charge, lien or burden upon the GL Property prior to
     or superior to the estate granted by such new lease which was not prior to
     or superior to the estate of BNPLC under this Ground Lease as of the date
     immediately preceding the termination of this Ground Lease.

          (3)  Notwithstanding the foregoing, if Lessor shall receive requests
     to enter into a new ground lease from more than one Leasehold Mortgagee,
     Lessor shall be required to enter into only one new ground lease, and the
     new ground lease shall be to the requesting Leasehold Mortgagee who holds
     the highest priority lien or interest in BNPLC's leasehold estate in the
     Land. If the liens or security interests of two or more such requesting
     Leasehold Mortgagees which shared the highest priority just prior to the
     termination of this Ground Lease, the new ground lease shall name all such
     Leasehold Mortgagees as co-tenants thereunder.

          (E)  If BNPLC has agreed with any Leasehold Mortgagee that such
Leasehold Mortgagee's consent will be required to any modification or early
termination of this Ground Lease by BNPLC, and if Lessor has been notified of
such agreement, such consent will be required.

          (F)  No Leasehold Mortgagee will assume any liability under this
Ground Lease either by virtue of its Leasehold Mortgage or by any subsequent
receipt or collection of rents or profits generated from the GL Property, unless
and until the Leasehold Mortgagee acquires BNPLC's leasehold estate in the GL
Property at foreclosure or by deed in lieu of foreclosure.

          (G)  Although the foregoing provisions concerning Leasehold Mortgages
and Leasehold Mortgagees will be self operative, Lessor agrees to include, in
addition to the items specified in Paragraph 11, confirmation of the foregoing
in any statement provided to a Leasehold Mortgagee or prospective Leasehold
Mortgagee pursuant to Paragraph 11.

[LAND]                       Exhibit B-3 - Page 6
<PAGE>

     9    Events of Default.

          (A)  Definition of Ground Lease Default.  Each of the following events
               ----------------------------------
shall be deemed to be a "Ground Lease Default" by BNPLC under this Ground Lease:

          (1)  BNPLC shall fail to pay when due any installment of Ground Lease
     Rent due hereunder and such failure shall continue for sixty days after
     BNPLC receives notice thereof.

          (2)  BNPLC shall fail to comply with any term, provision or covenant
     of this Ground Lease (other than as described in the other clauses of this
     subparagraph 9(A)), and shall not cure such failure prior to the earlier of
     (A) ninety days after notice thereof is sent to BNPLC, or (B) the date any
     writ or order is issued for the levy or sale of any property owned by
     Lessor or its Affiliates (including the GL Property) because of such
     failure or any criminal action is instituted against BNPLC or any of its
     directors, officers or employees because of such failure; provided,
     however, that so long as no such writ or order is issued and no such
     criminal actions is instituted, if such failure is susceptible of cure but
     cannot with reasonable diligence be cured within such ninety day period,
     and if BNPLC shall promptly have commenced to cure the same and shall
     thereafter prosecute the curing thereof with reasonable diligence, the
     period within which such failure may be cured shall be extended for such
     further period as shall be necessary for the curing thereof with reasonable
     diligence.

          (B)  Remedy.  Upon the occurrence of a Ground Lease Default which is
               ------
not cured within any applicable period expressly permitted by subparagraph 9(A),
Lessor's sole and exclusive remedies shall be to sue BNPLC for the collection of
any amount due under this Ground Lease, to sue for the specific enforcement of
BNPLC's obligations hereunder, or to enjoin the continuation of the Ground Lease
Default; provided, however, no limitation of Lessor's remedies contained herein
will prevent Lessor from recovering any reasonable costs Lessor may incur to
mitigate its damages by curing a Ground Lease Default that BNPLC has failed to
cure itself (so long as the cure by Lessor is pursued in a lawful manner and the
costs Lessor seeks to recover do not exceed the actual damages to be mitigated).
Lessor may not terminate this Ground Lease or BNPLC's right to possession under
this Ground Lease.  Any judgment which Lessor may obtain against BNPLC for
amounts due under this Ground Lease may be collected only through resort of a
judgement lien against BNPLC's interest in the GL Property and any Improvements.
BNPLC shall have no personal liability for the payment amounts due under this or
for the performance of any obligations of BNPLC under this Ground Lease.

     10   Quiet Enjoyment.  Neither Lessor nor any third party lawfully claiming
any right or interest in the GL Property shall during the Ground Lease Term
disturb BNPLC's peaceable and quiet enjoyment of the GL Property; however, such
enjoyment shall be subject to the terms, provisions, covenants, agreements and
conditions of this Ground Lease and the Permitted Encumbrances, to which this
Ground Lease is subject and subordinate as hereinabove set forth.

     11   Estoppel Certificate.  Lessor shall from time to time, within ten days
after receipt of request by BNPLC, deliver a statement in writing certifying:

          (A)  that this Ground Lease is unmodified and in full force and effect
(or if modified that this Ground Lease as so modified is in full force and
effect);

          (B)  that to the knowledge of Lessor BNPLC has not previously assigned
or hypothecated its rights or interests under this Ground Lease, except as is
described in such statement with as much specificity as Lessor is able to
provide;

          (C)  the term of this Ground Lease and the Ground Lease Rent then in
effect and any

[LAND]                       Exhibit B-3 - Page 7
<PAGE>

additional charges;

          (D)  that BNPLC is not in default under any provision of this Ground
Lease (or if in default, the nature thereof in detail) and a statement as to any
outstanding obligations on the part of Lessor or BNPLC; and

          (E)  such other matters as are reasonably requested by BNPLC.

Lessor's failure to deliver such statement within such time shall be conclusive
upon BNPLC (i) that this Ground Lease is in full force and effect, without
modification except as may be represented by BNPLC, (ii) that there are no
uncured defaults in BNPLC's performance hereunder.

     12   Option to Repurchase.  Subject to the terms and conditions set forth
in Annex 4, BNPLC (and any assignee of BNPLC's entire interest in the GL
   -------
Property, but not any subtenant or assignee of a lesser interest) shall have the
option (the "Repurchase Option") to purchase Lessor's interest in the GL
Property. To secure BNPLC's right to recover any damages caused by a breach of
the Repurchase Option or other provisions of this Ground Lease by Lessor,
including any such breach caused by a rejection or termination of this Ground
Lease in any bankruptcy or insolvency proceeding instituted by or against
Lessor, as debtor, Lessor does hereby grant to BNPLC a lien and security
interest against the Land and against all rights, title and interests of Lessor
from time to time in and to the GL Property.

                         [The signature pages follow.]

[LAND]                       Exhibit B-3 - Page 8
<PAGE>

     IN WITNESS WHEREOF, this Ground Lease is hereby executed in multiple
originals as of the date first written above.

                                 "Lessor"

                                 [Zhone or the Applicable Purchaser]

                                 By: _______________________________________
                                     Name :_________________________________
                                     Title: ________________________________

[LAND]                       Exhibit B-3 - Page 9
<PAGE>

[Continuation of signature pages to GROUND LEASE dated as of ___________, ____]

                                 "BNPLC"

                                 BNP LEASING CORPORATION

                                 By: _______________________________________
                                     Name: _________________________________
                                     Title: ________________________________

[LAND]                       Exhibit B-3 - Page 10
<PAGE>

STATE OF ___________     )
                         )
COUNTY OF _____________  )

     On _____________, _____, before me, ________________________, personally
appeared ____________________________, personally known to me (or proved to me
on the basis of satisfactory evidence) to be the person whose name is subscribed
to the within instrument and acknowledged to me that he executed the same in his
authorized capacity, and that by his signature on the instrument the person, or
the entity upon behalf of which the person acted, executed the instrument.

                         WITNESS my hand and official seal.

                         Signature ____________________________________

[LAND]                       Exhibit B-3 - Page 11
<PAGE>

STATE OF ________     )
                      )
COUNTY OF __________  )

     On ___________, _____, before me, ________________________, personally
appeared ____________, personally known to me (or proved to me on the basis of
satisfactory evidence) to be the person whose name is subscribed to the within
instrument and acknowledged to me that he executed the same in his authorized
capacity, and that by his signature on the instrument the person, or the entity
upon behalf of which the person acted, executed the instrument.

                         WITNESS my hand and official seal.

                         Signature ________________________________

[LAND]                       Exhibit B-3 - Page 12
<PAGE>

                                    Annex 1
                                    -------

                               Legal Description

[DRAFTING NOTE: TO THE EXTENT THAT THE "LAND" COVERED BY THE LAND LEASE CHANGES
 --------------
FROM TIME TO TIME BECAUSE OF ADJUSTMENTS FOR WHICH ZHONE REQUESTS BNPLC'S
CONSENT OR APPROVAL, SO TOO WILL THE DESCRIPTION OF THE LAND BELOW CHANGE. ANY
SUCH CHANGES WILL BE INCORPORATED INTO THE DESCRIPTION BELOW AND THIS "DRAFTING
NOTE" WILL BE DELETED BEFORE THE DEED TO WHICH THIS DESCRIPTION IS ATTACHED IS
ACTUALLY EXECUTED AND DELIVERED.]

The real property located in the City of Oakland, County of Alameda, State of
California, described as follows:

Being a portion of Lot 12, as shown on Parcel Map No. 6003, filed in Book 205 of
Parcel Maps, at Pages 94 through 98, Alameda County Records, more particularly
described as follows:

Commencing at the most southerly corner of said Lot 12; Thence along the
southwesterly line of said Lot 12, North 33(degrees) 50' 24" West, 628.68 feet
to the point of beginning; Thence continuing along the southwesterly line of
said Lot 12, North 33(degrees) 50' 24" West, 1029.21 feet; Thence along the
southeasterly line of said Lot 12, South 56(degrees) 09' 36" West 14.00 feet;
Thence along the southwesterly line of said Lot 12, North 33(degrees) 50' 24"
West, 253.55 feet to the beginning of a curve, concave southwesterly, having a
radius of 392.21 feet; Thence northerly along the arc of said curve, through a
central angle of 3(degrees) 51' 45", an arc distance of 26.44 feet to the
intersection of a line drawn parallel with and 85.00 feet southeasterly of the
northwesterly line of said Lot 12, a radial line through said point bears North
52(degrees) 17' 51" East; Thence parallel with the northwesterly line of said
Lot 12, North 56(degrees) 09' 36" East, 476.93 feet to a point that is 5 feet
southwesterly of the northeasterly line of said Lot 12; Thence along a line that
is parallel with and 5 feet southwesterly of the said northeasterly line of Lot
12, South 40(degrees) 00' 30" East, 69.44 feet to the beginning of a curve,
concave southwesterly, having a radius of 1949.00 feet; Thence southeasterly
along the arc of said curve, through a central angle of 6(degrees) 10' 18", an
arc distance of 209.94 feet; Thence continuing along a line that is parallel
with and 5 feet southwesterly of the said northeasterly line of Lot 12, South
33(degrees)50' 12" East, 1030.61 feet to the intersection with a line drawn
perpendicular with the southwesterly line of said Lot 12, distant thereon 628.68
feet from the most southerly corner of said Lot 12; Thence southwesterly along
said perpendicular line, South 56(degrees) 09' 36" West, 480.72 feet to the
Point of Beginning.

The basis of bearings for Parcel Map No. 6003 is the North American Datum of
1983, Zone 3, 1984 Adjustment Published in 1986, as shown on Record of Survey
990, filed in Book 18 of Records of Survey, at Pages 50 through 60, Alameda
County Records.  All distances in this description are grid distances.  To
convert to ground distances, multiply grid distances by 1.0000708.

Assessor's Parcel No. 041-3902-015 (Portion)

[LAND]                       Exhibit B-3 - Page 13
<PAGE>

                                    Annex 2
                                    -------

                            Permitted Encumbrances

The leasehold and other interests in the Land hereby conveyed by Lessor are
conveyed subject to the following matters to the extent the same are still valid
and in force:

[THE SAME LIST OF PERMITTED ENCUMBRANCES ATTACHED TO THE GRANT DEED FROM BNPLC
TO ZHONE OR THE APPLICABLE PURCHASER SHALL BE INSERTED HERE.]

[LAND]                       Exhibit B-3 - Page 14
<PAGE>

                                    Annex 3
                                    -------

                      DETERMINATION OF FAIR RENTAL VALUE

     Each annual payment of Ground Lease Rent will equal the Fair Rental Value,
computed as of the most recent Rental Determination Date when such payment
becomes due.  As used in this Annex:

          "Fair Rental Value" means (and all appraisers and other persons
     involved in the determination of the Fair Rental Value will be so advised)
     the annual rent, as determined in accordance with this Annex, that would be
     agreed upon between a willing tenant, under no compulsion to lease, and a
     willing landlord, under no compulsion to lease, for unimproved land
                                                         ----------
     comparable in size and location to the Land, exclusive of any Improvements
     but assuming that there is no higher and better use for such land than as a
     site for improvements of comparable size and utility to the Improvements,
     at the time a determination is required hereunder and taking into
     consideration the condition of the Land, the encumbrances affecting the
     title to the Land and all applicable zoning, land use approvals and other
     governmental permits relating to the Land at the time of such
     determination; and

          "Rental Determination Date" means the GL Effective Date and each fifth
     anniversary of the GL Effective Date.

     If Lessor and BNPLC have not agreed upon Fair Rental Value as of any Rental
Determination Date within one hundred eighty days after the such date, then Fair
Rental Value will be determined as follows:

          (a)  Lessor and BNPLC shall each appoint a real estate appraiser who
     is familiar with rental values for properties in the vicinity of the Land
     and who has not previously acted for either party.  Each party will make
     the appointment no later than ten days after receipt of notice from the
     other party that the appraisal process described in this Annex has been
     invoked.  The agreement of the two appraisers as to Fair Rental Value will
     be binding upon Lessor and BNPLC.  If the two appraisers cannot agree upon
     the Fair Rental Value within ten days following their appointment, they
     shall within another ten days agree upon a third real estate appraiser.
     Immediately thereafter, each of the first two appraisers will submit his
     best estimate of the appropriate Fair Rental Value (together with a written
     report supporting such estimate) to the third appraiser and the third
     appraiser will choose between the two estimates.  The estimate of Fair
     Rental Value chosen by the third appraiser as the closest to the prevailing
     annual fair rental value will be binding upon Lessor and BNPLC.
     Notification in writing of this estimate shall be made to Lessor and BNPLC
     within fifteen days following the selection of the third appraiser.

          (b)  If appraisers must be selected under the procedure set out above
     and either BNPLC or Lessor fails to appoint an appraiser or fails to notify
     the other party of such appointment within fifteen days after receipt of
     notice that the prescribed time for appointing the appraisers has passed,
     then the other party's appraiser will determine the Fair Rental Value.  All
     appraisers selected for the appraisal process set out in this Annex will be
     disinterested, reputable, qualified real estate appraisers with the
     designation of MAI or equivalent and with at least 5 years experience in
     appraising properties comparable to the Land.

          (c)  If a third appraiser must be chosen under the procedure set out
     above, he or she will be chosen on the basis of objectivity and competence,
     not on the basis of his relationship with the other appraisers or the
     parties to this Ground Lease, and the first two appraisers will be so
     advised.  Although the first two appraisers will be instructed to attempt
     in good faith to agree upon the third appraiser, if for any reason they
     cannot agree within the prescribed time, either Lessor and BNPLC may
     require the

[LAND]                       Exhibit B-3 - Page 15
<PAGE>

     first two appraisers to immediately submit its top choice for the third
     appraiser to the then highest ranking officer of the California Bar
     Association who will agree to help and who has no attorney/client or other
     significant relationship to either Lessor or BNPLC. Such officer will have
     complete discretion to select the most objective and competent third
     appraiser from between the choices of each of the first two appraisers, and
     will do so within twenty days after such choices are submitted to him.

          (d)  Either Lessor or BNPLC may notify the appraiser selected by the
     other party to demand the submission of an estimate of Fair Rental Value or
     a choice of a third appraiser as required under the procedure described
     above; and if the submission of such an estimate or choice is required but
     the other party's appraiser fails to comply with the demand within fifteen
     days after receipt of such notice, then the Fair Rental Value or choice of
     the third appraiser, as the case may be, selected by the other appraiser
     (i.e., the notifying party's appraiser) will be binding upon Lessor and
     BNPLC.

          (e)  Lessor and BNPLC shall each bear the expense of the appraiser
     appointed by it, and the expense of the third appraiser and of any officer
     of the California Bar Association who participates in the appraisal process
     described above will be shared equally by Lessor and BNPLC.

[LAND]                       Exhibit B-3 - Page 16
<PAGE>

                                    Annex 4
                                    -------

                               REPURCHASE OPTION

     Subject to the terms of this Annex, BNPLC shall have an option (the
"Option") to buy Lessor's fee interest in the GL Property at any time during the
term of this Ground Lease for a purchase price (the "Option Price") to Lessor
equal to the fair market value of the GL Property, determined as described in
the next paragraph.

     For the purposes of this Annex, "fair market value" of the GL Property
means (and all appraisers and other persons involved in the determination of the
Option Price will be so advised) the price that would be agreed upon between a
willing buyer, under no compulsion to buy, and a willing seller, under no
compulsion to sell, for the Land, exclusive of any Improvements as if the Land
were unimproved, but assuming that there is no higher and better use for the
     ----------
Land than as a site for the construction of improvements of comparable size and
utility to the Improvements, at the time of BNPLC's exercise of the Option and
taking into consideration the encumbrances affecting the title to the Land and
all applicable zoning, land use approvals and other governmental permits
relating to the Land at the time of the exercise of the Option.

     If BNPLC exercises the Option, which BNPLC may do by notifying Lessor that
BNPLC has elected to buy Lessor's interest in the GL Property as provided
herein, then:

          (a)  To the extent, if any, required as a condition imposed by law to
     the conveyance of the fee interest in the GL Property to BNPLC, Lessor
     shall promptly at its expense do whatever is necessary to obtain approvals
     of a new Parcel Map or lot line adjustments.

          (b)  Upon BNPLC's tender of the Option Price to Lessor, Lessor will
     convey to BNPLC by general warranty deed and assignment, subject only to
     the Permitted Encumbrances, good and marketable title to the fee estate in
     the Land, to Lessor's interest in all other GL Property and, to the extent
     still in force, to Lessor's Extended Remarketing Rights under the Land
     Purchase Agreement.

          (c)  BNPLC's obligation to close the purchase shall be subject to the
     following terms and conditions, all of which are for the benefit of BNPLC:
     (1) BNPLC shall have been furnished with evidence satisfactory to BNPLC
     that Lessor can convey title as required by the preceding subparagraph; (2)
     nothing shall have occurred or been discovered after BNPLC exercised the
     Option that could significantly and adversely affect title to the GL
     Property or BNPLC's use thereof, (3) all of the representations of Lessor
     in this Ground Lease shall continue to be true as if made effective on the
     date of the closing and, with respect to any such representations which may
     be limited to the knowledge of Lessor or any of Lessor's representatives,
     would continue to be true on the date of the closing if all relevant facts
     and circumstances were known to Lessor and such representatives, (4) BNPLC
     shall find the Option Price acceptable after it is determined as provided
     in this Annex, and (5) BNPLC shall have been tendered the deed and other
     documents which are described in this Annex as documents to be delivered to
     BNPLC at the closing of BNPLC's purchase.

          (d)  Closing of the purchase will be scheduled on the first Business
     Day following thirty days after the Option Price is established in
     accordance with the terms and conditions of this Annex and after any
     approvals described in subparagraph (a) above are obtained, and prior to
     closing BNPLC's occupancy of the GL Property shall continue to be subject
     to the terms and conditions of this Ground Lease, including the terms
     setting forth BNPLC's obligation to pay rent.  Closing shall take place at
     the offices of any title insurance company reasonably selected by BNPLC to
     insure title under the title insurance policy described below.

[Land]                       Exhibit B-3 - Page 17
<PAGE>

          (e)  Any transfer taxes or notices or registrations required by law in
     connection with the sale contemplated by this Annex will be the
     responsibility of Lessor.

          (f)  Lessor will deliver a certificate of nonforeign status to BNPLC
     at closing as needed to comply with the provisions of the Foreign Investors
     Real Property Tax Act (FIRPTA) or any comparable federal, state or local
     law in effect at the time.

          (g)  Lessor will also pay for and deliver to BNPLC at the closing an
     owner's title insurance policy in the full amount of the Option Price,
     issued by a title insurance company designated by BNPLC (or written
     confirmation from the title company that it is then prepared to issue such
     a policy), and subject only to standard printed exceptions which the title
     insurance company refuses to delete or modify in a manner acceptable to
     BNPLC and to Permitted Encumbrances.

          (h)  Lessor shall also deliver at the closing all other documents or
     things reasonably required to be delivered to BNPLC or by the title
     insurance company to evidence Lessor's ability to transfer the GL Property
     to BNPLC.

     If Lessor and BNPLC do not otherwise agree upon the amount of the Option
Price within twenty days after BNPLC exercises the Option, the Option Price
shall be determined in accordance with the following procedure:

               (1)  Lessor and BNPLC shall each appoint a real estate appraiser
          who is familiar with properties in the vicinity of the Land and who
          has not previously acted for either party.  Each party will make the
          appointment no later than ten days after receipt of notice from the
          other party that the appraisal process described in this Annex has
          been invoked.  The agreement of the two appraisers as to the Option
          Price will be binding upon Lessor and BNPLC.  If the two appraisers
          cannot agree upon the Option Price within ten days following their
          appointment, they shall within another ten days agree upon a third
          real estate appraiser.  Immediately thereafter, each of the first two
          appraisers will submit his best estimate of the appropriate Option
          Price (together with a written report supporting such estimate) to the
          third appraiser and the third appraiser will choose between the two
          estimates.  The estimate of Option Price chosen by the third appraiser
          as the closest to the prevailing  fair market value will be binding
          upon Lessor and BNPLC.  Notification in writing of the Option Price
          shall be made to Lessor and BNPLC within fifteen days following the
          selection of the third appraiser.

               (2)  If appraisers must be selected under the procedure set out
          above and either BNPLC or Lessor fails to appoint an appraiser or
          fails to notify the other party of such appointment within fifteen
          days after receipt of notice that the prescribed time for appointing
          the appraisers has passed, then the other party's appraiser will
          determine the Option Price.  All appraisers selected for the appraisal
          process set out in this Annex will be disinterested, reputable,
          qualified real estate appraisers with the designation of MAI or
          equivalent and with at least 5 years experience in appraising
          properties comparable to the Land.

               (3)  If a third appraiser must be chosen under the procedure set
          out above, he will be chosen on the basis of objectivity and
          competence, not on the basis of his relationship with the other
          appraisers or the parties to this Ground Lease, and the first two
          appraisers will be so advised.  Although the first two appraisers will
          be instructed to attempt in good faith to agree upon the third
          appraiser, if for any reason they cannot agree within the prescribed
          time, either Lessor and BNPLC may require the first two appraisers to
          immediately submit its top choice for

[Land]                       Exhibit B-3 - Page 18
<PAGE>

          the third appraiser to the then highest ranking officer of the
          California Bar Association who will agree to help and who has no
          attorney/client or other significant relationship to either Lessor or
          BNPLC. Such officer will have complete discretion to select the most
          objective and competent third appraiser from between the choices of
          each of the first two appraisers, and will do so within ten days after
          such choices are submitted to him.

               (4)  Either Lessor or BNPLC may notify the appraiser selected by
          the other party to demand the submission of an estimate of Option
          Price or a choice of a third appraiser as required under the procedure
          described above; and if the submission of such an estimate or choice
          is required but the other party's appraiser fails to comply with the
          demand within fifteen days after receipt of such notice, then the
          Option Price or choice of the third appraiser, as the case may be,
          selected by the other appraiser (i.e., the notifying party's
          appraiser) will be binding upon Lessor and BNPLC.

               (5)  Lessor and BNPLC shall each bear the expense of the
          appraiser appointed by it, and the expense of the third appraiser and
          of any officer of the California Bar Association who participates in
          the appraisal process described above will be shared equally by Lessor
          and BNPLC.

[Land]                       Exhibit B-3 - Page 19
<PAGE>

                                  Exhibit B-4
                                  -----------

                            CORPORATION GRANT DEED

RECORDING REQUESTED BY
AND WHEN RECORDED MAIL TO:
-------------------------

NAME:  [Zhone or the Applicable Purchaser]
ADDRESS:  ____________________________
ATTN:     ____________________________
CITY:     ____________________________
STATE:________________________
Zip:      ____________________________

MAIL TAX STATEMENTS TO:
----------------------

NAME:  [Zhone or the Applicable Purchaser]
ADDRESS:  ____________________________
ATTN:     ____________________________
CITY:     ____________________________
STATE:________________________
Zip:      ____________________________

                            CORPORATION GRANT DEED
             (Covering Land but not the Improvements On the Land)

FOR A VALUABLE CONSIDERATION, receipt of which is hereby acknowledged, BNP
LEASING CORPORATION, a Delaware corporation ("Grantor"), hereby grants to [Zhone
or the Applicable Purchaser] ("Grantee") all of Grantor's interest in the land
situated in Oakland, California, described on Annex A attached hereto and hereby
made a part hereof (the "Land"), together with the any other right, title and
interest of Grantor in and to any easements, rights-of-way, privileges and other
rights appurtenant to the Land; provided, however, that this grant is subject to
the encumbrances described on Annex B (the "Permitted Encumbrances") and any
reservations or qualifications set forth below. Grantee hereby assumes the
obligations (including any personal obligations) of Grantor, if any, created by
or under, and agrees to be bound by the terms and conditions of, the Permitted
Encumbrances to the extent that the same concern or apply to the Land.

Although this deed conveys Grantor's interest in the Land itself, this deed does
not convey any interest in any buildings or other improvements on the Land
(collectively, "Improvements") or any rights or easements appurtenant to
Improvements. Prior to or contemporaneously with the delivery of this deed,
Grantor has conveyed or is conveying the Improvements and appurtenant rights and
easements to another party.

[Land]
<PAGE>

                                    BNP LEASING CORPORATION

Date: As of ____________            By:     __________________________________
                                            Its:

                                    Attest: __________________________________
                                            Its:

                                    [Zhone or Applicable Purchaser]

Date: As of ____________            By:     __________________________________
                                            Its:

                                    Attest: __________________________________
                                            Its:

STATE OF ____________  )
                       )  SS
COUNTY OF ___________  )

     On ________________ before me,___________, personally appeared_______ and
_______________, personally known to me (or proved to me on the basis of
satisfactory evidence) to be the persons whose names are subscribed to the
within instrument and acknowledged to me that they executed the same in their
authorized capacities, and that by their signatures on the instrument the
person, or the entity upon behalf of which the persons acted, executed the
instrument.

     WITNESS my hand and official seal.

     Signature __________________________

STATE OF ____________  )
                       )  SS
COUNTY OF ___________  )

     On ______________ before me,_____________, personally appeared________ and
______________, personally known to me (or proved to me on the basis of
satisfactory evidence) to be the persons whose names are subscribed to the
within instrument and acknowledged to me that they executed the same in their
authorized capacities, and that by their signatures on the instrument the
person, or the entity upon behalf of which the persons acted, executed the
instrument.

     WITNESS my hand and official seal.

     Signature __________________________

[Land]                       Exhibit B-4 - Page 2
<PAGE>

                                    Annex A

                               LEGAL DESCRIPTION

[DRAFTING NOTE: TO THE EXTENT THAT THE "LAND" COVERED BY THE LAND LEASE CHANGES
 --------------
FROM TIME TO TIME BECAUSE OF ADJUSTMENTS FOR WHICH ZHONE REQUESTS BNPLC'S
CONSENT OR APPROVAL, SO TOO WILL THE DESCRIPTION OF THE LAND BELOW CHANGE. ANY
SUCH CHANGES WILL BE INCORPORATED INTO THE DESCRIPTION BELOW AND THIS "DRAFTING
NOTE" WILL BE DELETED BEFORE THE DEED TO WHICH THIS DESCRIPTION IS ATTACHED IS
ACTUALLY EXECUTED AND DELIVERED.]

The real property located in the City of Oakland, County of Alameda, State of
California, described as follows:

Being a portion of Lot 12, as shown on Parcel Map No. 6003, filed in Book 205 of
Parcel Maps, at Pages 94 through 98, Alameda County Records, more particularly
described as follows:

Commencing at the most southerly corner of said Lot 12; Thence along the
southwesterly line of said Lot 12, North 33(degrees) 50' 24" West, 628.68 feet
to the point of beginning; Thence continuing along the southwesterly line of
said Lot 12, North 33(degrees) 50' 24" West, 1029.21 feet; Thence along the
southeasterly line of said Lot 12, South 56(degrees) 09' 36" West 14.00 feet;
Thence along the southwesterly line of said Lot 12, North 33(degrees) 50' 24"
West, 253.55 feet to the beginning of a curve, concave southwesterly, having a
radius of 392.21 feet; Thence northerly along the arc of said curve, through a
central angle of 3(degrees) 51' 45", an arc distance of 26.44 feet to the
intersection of a line drawn parallel with and 85.00 feet southeasterly of the
northwesterly line of said Lot 12, a radial line through said point bears North
52(degrees) 17' 51" East; Thence parallel with the northwesterly line of said
Lot 12, North 56(degrees) 09' 36" East, 476.93 feet to a point that is 5 feet
southwesterly of the northeasterly line of said Lot 12; Thence along a line that
is parallel with and 5 feet southwesterly of the said northeasterly line of Lot
12, South 40(degrees) 00' 30" East, 69.44 feet to the beginning of a curve,
concave southwesterly, having a radius of 1949.00 feet; Thence southeasterly
along the arc of said curve, through a central angle of 6(degrees) 10' 18", an
arc distance of 209.94 feet; Thence continuing along a line that is parallel
with and 5 feet southwesterly of the said northeasterly line of Lot 12, South
33(degrees)50' 12" East, 1030.61 feet to the intersection with a line drawn
perpendicular with the southwesterly line of said Lot 12, distant thereon 628.68
feet from the most southerly corner of said Lot 12; Thence southwesterly along
said perpendicular line, South 56(degrees) 09' 36" West, 480.72 feet to the
Point of Beginning.

The basis of bearings for Parcel Map No. 6003 is the North American Datum of
1983, Zone 3, 1984 Adjustment Published in 1986, as shown on Record of Survey
990, filed in Book 18 of Records of Survey, at Pages 50 through 60, Alameda
County Records.  All distances in this description are grid distances.  To
convert to ground distances, multiply grid distances by 1.0000708.

Assessor's Parcel No. 041-3902-015 (Portion)

[Land]                       Exhibit B-4 - Page 3
<PAGE>

                                    Annex B

                            Permitted Encumbrances

[DRAFTING NOTE: TO THE EXTENT THAT ENCUMBRANCES (OTHER THAN "LIENS REMOVABLE BY
 --------------
BNPLC") ARE IDENTIFIED IN ADDITION TO THOSE DESCRIBED BELOW, SUCH ADDITIONAL
ENCUMBRANCES WILL BE ADDED TO THE LIST BELOW AND THIS "DRAFTING NOTE" WILL BE
DELETED BEFORE THIS DEED IS ACTUALLY EXECUTED AND DELIVERED BY BNPLC. SUCH
ADDITIONAL ENCUMBRANCES WOULD INCLUDE ANY NEW ENCUMBRANCES APPROVED BY BNPLC AS
"PERMITTED ENCUMBRANCES" UNDER THE LAND LEASE OR THE OTHER LEASE AGREEMENTS FROM
TIME TO TIME OR BECAUSE OF ZHONE'S REQUEST FOR BNPLC'S CONSENT OR APPROVAL TO AN
ADJUSTMENT.]

     This conveyance is subject to all encumbrances not constituting a "Lien
Removable by BNPLC" (as defined in the Common Definitions and Provisions
Agreement (Land) incorporated by reference into the Lease Agreement (Land)
referenced in the last item of the list below), including the following matters
to the extent the same are still valid and in force:

1.   County and city taxes for the Fiscal Year 2000 - 2001, a lien not yet due
     or payable.

2.   The Lien of Supplemental Taxes, if any, assessed pursuant to the provisions
     of Chapter 3.5, Revenue and Taxation Code, Sections 75 et seq., resulting
     from changes of ownership or completion of construction on or after the
     date hereof.

3.   Easement, upon the terms, covenants and conditions thereof, for the
     purposes stated therein and incidental purposes created in that certain
     instrument

     Recorded            :        FEBRUARY 11, 1974, REEL 3608, IMAGE 3,
                                  SERIES NO. 74-16523, OFFICIAL RECORDS
     Granted to          :        THE PACIFIC TELEPHONE AND TELEGRAPH COMPANY, A
                                  CORPORATION
     Purpose       :     COMMUNICATION FACILITIES
     Affects             :  A SOUTHWESTERLY PORTION OF SAID LAND

4.   Terms, covenants, conditions and reservations as contained in the Port
     Ordinance No. 2832.  An Ordinance establishing standards and restrictions
     regulating the use of land and the design and construction of structures
     and other improvements in the Oakland Airport Business Park, and repealing
     Port Ordinance No. 1343, as amended, recorded MAY 10, 1990, SERIES NO.
     90130204, OFFICIAL RECORDS.

     Amendment Port Ordinance No. 3146, recorded SEPTEMBER 30, 1993, SERIES NO.
     93348032, OFFICIAL RECORDS.

5.   Terms and conditions of the City of Oakland Redevelopment Project adopted
     by Ordinance No. 11824, C.M.S., as disclosed in the "Notice of Adoption of
     the Coliseum Area Redevelopment Plan, Termination of the 77/th/ Avenue
     Industrial Redevelopment Project and Amendment of the Elmhurst
     Redevelopment Plan," recorded JULY 31, 1995, SERIES NO. 95167161, OFFICIAL
     RECORDS.

     Amendment recorded SEPTEMBER 9, 1997, SERIES NO. 97-231187, OFFICIAL
     RECORDS.

6.   The Lease Agreement (Land), the Lease Agreement (Improvements - Buildings
     1&2) and the Lease Agreement (Improvements - Building 3), all dated as of
     August 1, 2000 and all between BNP Leasing

[Land]                       Exhibit B-4 - Page 4
<PAGE>

     Corporation, as lessor, and Zhone Technologies, Inc., as lessee.

[Land]                       Exhibit B-4 - Page 5
<PAGE>

                                   Exhibit C
                                   ---------

                          BILL OF SALE AND ASSIGNMENT

     Reference is made to: (1) that certain Purchase Agreement (Land) between
BNP Leasing Corporation ("Assignor") and Zhone Technologies, Inc., dated as of
August 1, 2000, (the "Land Purchase Agreement") and (2) that certain Lease
Agreement (Land) between Assignor, as landlord, and Zhone Technologies, Inc., as
tenant, dated as of August 1, 2000 (the "Land Lease"). (Capitalized terms used
and not otherwise defined in this document are intended to have the meanings
assigned to them in the Common Definitions and Provisions Agreement (Land)
incorporated by reference into both the Land Purchase Agreement and Land Lease.)

     As contemplated by the Land Purchase Agreement, Assignor hereby sells,
transfers and assigns unto [Zhone OR THE APPLICABLE PURCHASER, AS THE CASE MAY
BE], a _____________ ("Assignee"), all of Assignor's right, title and interest
in and to the following property, if any, to the extent such property is
assignable:

     (a)  the Land Lease;

     (b) cany pending or future award made because of any condemnation affecting
the Property or because of any conveyance to be made in lieu thereof, and any
unpaid award for damage to the Property and any unpaid proceeds of insurance or
claim or cause of action for damage, loss or injury to the Property; and

     (c) call other property included within the definition of "Property" as set
forth in the Land Purchase Agreement.

Provided, however, excluded from this conveyance and reserved to Assignor are
any rights or privileges of Assignor under the following ("Excluded Rights"):
(1) the indemnities set forth in the Land Lease or Other Lease Agreements,
whether such rights are presently known or unknown, including rights of the
Assignor to be indemnified against environmental claims of third parties which
may not presently be known, (2) provisions in the Land Lease or Other Lease
Agreements that establish the right of Assignor to recover any accrued unpaid
rent which may be outstanding as of the date hereof, (3) agreements between
Assignor and "BNPLC's Parent" or any "Participant," both as defined in the Land
Lease, or any modification or extension thereof, or (4) any other instrument
being delivered to Assignor contemporaneously herewith pursuant to the Land
Purchase Agreement or the Other Purchase Agreements. To the extent that this
conveyance does include any rights to receive future payments under the Land
Lease, such rights shall be subordinate to Assignor's Excluded Rights.

     Assignor does for itself and its successors covenant and agree to warrant
and defend the title to the property assigned herein against the just and lawful
claims and demands of any person claiming under or through a Lien Removable by
BNPLC, but not otherwise.

     Assignee hereby assumes and agrees to keep, perform and fulfill Assignor's
obligations, if any, relating to any permits or contracts, under which Assignor
has rights being assigned herein.

     IN WITNESS WHEREOF, the parties have executed this instrument as of
_______________, _____.

                                   ASSIGNOR:
                                   --------

[Land]
<PAGE>

                                 BNP LEASING CORPORATION a Delaware corporation

                                 By:___________________________________________
                                 Its:__________________________________________

                                 ASSIGNEE:
                                 --------

                                 [Zhone or the Applicable Purchaser], a
                                 ____________________

                                 By:___________________________________________
                                 Its:__________________________________________

[Land]                       Exhibit C - Page 2
<PAGE>

STATE OF ____________   )
                        )  SS
COUNTY OF ___________   )

     On _______________ before me,__________, personally appeared________ and
______________, personally known to me (or proved to me on the basis of
satisfactory evidence) to be the persons whose names are subscribed to the
within instrument and acknowledged to me that they executed the same in their
authorized capacities, and that by their signatures on the instrument the
person, or the entity upon behalf of which the persons acted, executed the
instrument.

     WITNESS my hand and official seal.

     Signature _______________________

STATE OF ____________   )
                        )  SS
COUNTY OF ___________   )

     On _______________ before me,____________, personally appeared_________ and
______________, personally known to me (or proved to me on the basis of
satisfactory evidence) to be the persons whose names are subscribed to the
within instrument and acknowledged to me that they executed the same in their
authorized capacities, and that by their signatures on the instrument the
person, or the entity upon behalf of which the persons acted, executed the
instrument.

     WITNESS my hand and official seal.

     Signature _______________________

[Land]                       Exhibit C - Page 3
<PAGE>

                                    Annex A

                               LEGAL DESCRIPTION

[DRAFTING NOTE: TO THE EXTENT THAT THE "LAND" COVERED BY THE LAND LEASE CHANGES
 --------------
FROM TIME TO TIME BECAUSE OF ADJUSTMENTS FOR WHICH ZHONE REQUESTS BNPLC'S
CONSENT OR APPROVAL, SO TOO WILL THE DESCRIPTION OF THE LAND BELOW CHANGE. ANY
SUCH CHANGES WILL BE INCORPORATED INTO THE DESCRIPTION BELOW AND THIS "DRAFTING
NOTE" WILL BE DELETED BEFORE THE DOCUMENT TO WHICH THIS DESCRIPTION IS ATTACHED
IS ACTUALLY EXECUTED AND DELIVERED.]

The real property located in the City of Oakland, County of Alameda, State of
California, described as follows:

Being a portion of Lot 12, as shown on Parcel Map No. 6003, filed in Book 205 of
Parcel Maps, at Pages 94 through 98, Alameda County Records, more particularly
described as follows:

Commencing at the most southerly corner of said Lot 12; Thence along the
southwesterly line of said Lot 12, North 33(degrees) 50' 24" West, 628.68 feet
to the point of beginning; Thence continuing along the southwesterly line of
said Lot 12, North 33(degrees) 50' 24" West, 1029.21 feet; Thence along the
southeasterly line of said Lot 12, South 56(degrees) 09' 36" West 14.00 feet;
Thence along the southwesterly line of said Lot 12, North 33(degrees) 50' 24"
West, 253.55 feet to the beginning of a curve, concave southwesterly, having a
radius of 392.21 feet; Thence northerly along the arc of said curve, through a
central angle of 3(degrees) 51' 45", an arc distance of 26.44 feet to the
intersection of a line drawn parallel with and 85.00 feet southeasterly of the
northwesterly line of said Lot 12, a radial line through said point bears North
52(degrees) 17' 51" East; Thence parallel with the northwesterly line of said
Lot 12, North 56(degrees) 09' 36" East, 476.93 feet to a point that is 5 feet
southwesterly of the northeasterly line of said Lot 12; Thence along a line that
is parallel with and 5 feet southwesterly of the said northeasterly line of Lot
12, South 40(degrees) 00' 30" East, 69.44 feet to the beginning of a curve,
concave southwesterly, having a radius of 1949.00 feet; Thence southeasterly
along the arc of said curve, through a central angle of 6(degrees) 10' 18", an
arc distance of 209.94 feet; Thence continuing along a line that is parallel
with and 5 feet southwesterly of the said northeasterly line of Lot 12, South
33(degrees)50' 12" East, 1030.61 feet to the intersection with a line drawn
perpendicular with the southwesterly line of said Lot 12, distant thereon 628.68
feet from the most southerly corner of said Lot 12; Thence southwesterly along
said perpendicular line, South 56(degrees) 09' 36" West, 480.72 feet to the
Point of Beginning.

The basis of bearings for Parcel Map No. 6003 is the North American Datum of
1983, Zone 3, 1984 Adjustment Published in 1986, as shown on Record of Survey
990, filed in Book 18 of Records of Survey, at Pages 50 through 60, Alameda
County Records.  All distances in this description are grid distances.  To
convert to ground distances, multiply grid distances by 1.0000708.

Assessor's Parcel No. 041-3902-015 (Portion)

[Land]                       Exhibit C - Page 4
<PAGE>

                                   Exhibit D
                                   ---------

        ACKNOWLEDGMENT OF DISCLAIMER OF REPRESENTATIONS AND WARRANTIES

     THIS ACKNOWLEDGMENT OF DISCLAIMER OF REPRESENTATIONS AND WARRANTIES (this
"Certificate") is made as of ___________________, ____, by [Zhone or the
Applicable Purchaser, as the case may be], a ___________________ ("Grantee").

     Contemporaneously with the execution of this Certificate, BNP Leasing
Corporation, a Delaware corporation ("BNPLC"), is executing and delivering to
Grantee (1) a corporate grant deed and (2) a Bill of Sale and Assignment (the
foregoing documents and any other documents to be executed in connection
therewith are herein called the "Conveyancing Documents" and any of the
properties, rights or other matters assigned, transferred or conveyed pursuant
thereto are herein collectively called the "Subject Property").

     Notwithstanding any provision contained in the Conveyancing Documents to
the contrary, Grantee acknowledges that BNPLC makes no representations or
warranties of any nature or kind, whether statutory, express or implied, with
respect to environmental matters or the physical condition of the Subject
Property, and Grantee, by acceptance of the Conveyancing Documents, accepts the
Subject Property "AS IS," "WHERE IS," "WITH ALL FAULTS" and without any such
                  -- --    ----- --    ---- --- ------
representation or warranty by Grantor as to environmental matters, the physical
condition of the Subject Property, compliance with subdivision or platting
requirements or construction of any improvements. Without limiting the
generality of the foregoing, Grantee hereby further acknowledges and agrees that
warranties of merchantability and fitness for a particular purpose are excluded
from the transaction contemplated by the Conveyancing Documents, as are any
warranties arising from a course of dealing or usage of trade. Grantee hereby
assumes all risk and liability (and agrees that BNPLC shall not be liable for
any special, direct, indirect, consequential, or other damages) resulting or
arising from or relating to the ownership, use, condition, location,
maintenance, repair, or operation of the Subject Property, except for damages
proximately caused by (and attributed by any applicable principles of
comparative fault to) the Established Misconduct of BNPLC. As used in the
preceding sentence, "Established Misconduct" is intended to have, and be limited
to, the meaning given to it in the Common Definitions and Provisions Agreement
(Land) incorporated by reference into the Land Purchase Agreement between BNPLC
and Zhone Technologies, Inc. dated as of August 1, 2000, pursuant to which
Purchase Agreement BNPLC is delivering the Conveyancing Documents.

     The provisions of this Certificate shall be binding on Grantee, its
successors and assigns and any other party claiming through Grantee. Grantee
hereby acknowledges that BNPLC is entitled to rely and is relying on this
Certificate.

     EXECUTED as of ________________, ____.

                                 [Zhone or the Applicable Purchaser]
                                 By:________________________________________
                                    Name:___________________________________
                                    Title:__________________________________

[Land]
<PAGE>

                                   Exhibit E
                                   ---------

                            SECRETARY'S CERTIFICATE

     The undersigned, [Secretary or Assistant Secretary] of BNP Leasing
Corporation, a Delaware corporation (the "Corporation"), hereby certifies as
follows:

     1.   That he is the duly, elected, qualified and acting Secretary [or
Assistant Secretary] of the Corporation and has custody of the corporate
records, minutes and corporate seal.

     2.   That the following named persons have been properly designated,
elected and assigned to the office in the Corporation as indicated below; that
such persons hold such office at this time and that the specimen signature
appearing beside the name of such officer is his or her true and correct
signature.

[The following blanks must be completed with the names and signatures of the
officers who will be signing the deed and other Land Sale Closing Documents on
behalf of the Corporation.]

Name                        Title                        Signature
----                        -----                        ---------

______________________      _____________________        _______________________

______________________      _____________________        _______________________

     3.   That the resolutions attached hereto and made a part hereof were duly
adopted by the Board of Directors of the Corporation in accordance with the
Corporation's Articles of Incorporation and Bylaws. Such resolutions have not
been amended, modified or rescinded and remain in full force and effect.

     IN WITNESS WHEREOF, I have hereunto signed my name and affixed the seal of
the Corporation on this__, day of____,__.

                            __________________________________
                            [signature and title]

[Land]
<PAGE>

                           CORPORATE RESOLUTIONS OF
                            BNP LEASING CORPORATION

     WHEREAS, pursuant to that certain Purchase Agreement (Land) (herein called
the "Purchase Agreement") dated as of August 1, 2000, by and between BNP Leasing
Corporation (the "Corporation") and [Zhone or the Applicable Purchaser as the
case may be] ("Purchaser"), the Corporation agreed to sell and Purchaser agreed
to purchase or cause the Applicable Purchaser (as defined in the Land Purchase
Agreement) to purchase the Corporation's interest in the property (the
"Property") located in Oakland, California more particularly described therein.

     NOW THEREFORE, BE IT RESOLVED, that the Board of Directors of the
Corporation, in its best business judgment, deems it in the best interest of the
Corporation and its shareholders that the Corporation convey the Property to
Purchaser or the Applicable Purchaser pursuant to and in accordance with the
terms of the Land Purchase Agreement.

     RESOLVED FURTHER, that the proper officers of the Corporation, and each of
them, are hereby authorized and directed in the name and on behalf of the
Corporation to cause the Corporation to fulfill its obligations under the Land
Purchase Agreement.

     RESOLVED FURTHER, that the proper officers of the Corporation, and each of
them, are hereby authorized and directed to take or cause to be taken any and
all actions and to prepare or cause to be prepared and to execute and deliver
any and all deeds and other documents, instruments and agreements that shall be
necessary, advisable or appropriate, in such officer's sole and absolute
discretion, to carry out the intent and to accomplish the purposes of the
foregoing resolutions.

[Land]                       Exhibit E - Page 2
<PAGE>

                                   Exhibit F
                                   ---------

                               FIRPTA STATEMENT

     Section 1445 of the Internal Revenue Code of 1986, as amended, provides
that a transferee of a U.S. real property interest must withhold tax if the
transferor is a foreign person. Sections 18805, 18815 and 26131 of the
California Revenue and Taxation Code, as amended, provide that a transferee of a
California real property interest must withhold income tax if the transferor is
a nonresident seller.

     To inform [Zhone or the Applicable Purchaser] (the "Transferee") that
withholding of tax is not required upon the disposition of a California real
property interest by transferor, BNP Leasing Corporation (the "Seller"), the
undersigned hereby certifies the following on behalf of the Seller:

     1.   The Seller is not a foreign corporation, foreign partnership, foreign
trust, or foreign estate (as those terms are defined in the Internal Revenue
Code and Income Tax Regulations);

     2.   The United States employer identification number for the Seller is
_____________________;

     3.   The office address of the Seller is ____________ ___________________
_________________.

     4.   The Seller is qualified to do business in California.

     The Seller understands that this certification may be disclosed to the
Internal Revenue Service and/or to the California Franchise Tax Board by the
Transferee and that any false statement contained herein could be punished by
fine, imprisonment, or both.

     The Seller understands that the Transferee is relying on this affidavit in
determining whether withholding is required upon said transfer.

     Under penalties of perjury I declare that I have examined this
certification and to the best of my knowledge and belief it is true, correct and
complete, and I further declare that I have authority to sign this document on
behalf of the Seller.

     Dated: ___________, ____.

                                    By:_______________________________
                                    Name:_____________________________
                                    Title:____________________________

[Land]

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