Document:

<PAGE>

                                                                    EXHIBIT 10.4

                                    FORM OF
                              CORVIS CORPORATION
                         EMPLOYEE STOCK PURCHASE PLAN
                         ----------------------------

<PAGE>

                              CORVIS CORPORATION
                         EMPLOYEE STOCK PURCHASE PLAN
                         ----------------------------

     1.   Purpose; Effective Date.  The Corvis Corporation Employee Stock
          -----------------------
Purchase Plan has been established to provide employees of Corvis Corporation
("Corvis") and its Participating Subsidiaries (as defined below) with an
opportunity to become owners of Corvis through the purchase of shares of Corvis'
common stock ("Stock"). For purposes of the Plan, the term "Participating
Subsidiary" means any corporation in which Corvis has, either directly or
indirectly, at least a 50 percent ownership interest and which has been
designated by Corvis as a Participating Subsidiary. It is intended that the
Plan, and all rights granted hereunder, will meet the requirements of an
"employee stock purchase plan" within the meaning of section 423 of the Internal
Revenue Code of 1986, as amended (the "Code"). The Plan, in all respects, shall
be interpreted and construed so as to be consistent with such requirements. The
Plan shall be effective as of the date of the final prospectus relating to the
initial public offering of the Stock (the "Effective Date") and shall remain in
effect until all shares reserved for issuance hereunder have been issued or
until the Plan is otherwise terminated in accordance with the provisions of
Section 10 hereof.

     2.   Administration by Committee; Authority. The Plan shall be administered
          --------------------------------------
by the Compensation Committee of Corvis' Board of Directors (the "Committee").
Subject to the terms and conditions of the Plan, the Committee shall have the
authority to (a) manage and control the operation of the Plan; (b) conclusively
interpret and construe the provisions of the Plan, and prescribe, amend and
rescind rules, regulations and procedures relating to the Plan; (c) correct any
defect or omission and reconcile any inconsistency in the Plan; and (d) make all
other determinations and take all other actions as it deems necessary or
desirable for the implementation and administration of the Plan.  The
determination of the Committee on matters within its authority shall be
conclusive and binding on Corvis, the Participating Subsidiaries and all other
persons.

     3.   Participation.  Subject to the terms and conditions of the Plan, each
          -------------
regular, full-time or part-time employee of Corvis and the Participating
Subsidiaries who regularly works more than 20 hours per week shall be eligible
to participate in the Plan for an Offering Period (as defined below) if, as of
the first day of the Offering Period, he is employed by Corvis or a
Participating Subsidiary.  For purposes of the Plan, an "Offering Period" means
(1) the period beginning on the Effective Date ending on the June 30 or December
31 which is nearest to the 24 month anniversary of the Effective Date (but not
more than 27 months after the Effective Date),  (2) the six month period
beginning on the first January 1 or July 1 next following the Effective Date and
ending on the next following June 30 or December 31, as applicable, and (3) the
six month period commencing on the first July 1 or January 1, as applicable,
immediately following the last day of the Offering Period described in paragraph
(2) and ending on the next following June 30 or December 31, as applicable, and
each six month period thereafter.  An employee who is eligible to participate in
the Plan for an Offering Period may elect to become a "Participant" in the Plan
for that Offering Period by completing and filing with Corvis, or its designee,
an "Election Form" which authorizes payroll deductions from the Participant's
pay.  Subject to the
<PAGE>

terms and conditions of the Plan, deductions pursuant to a Participant's
Election Form shall commence with the first payroll period ending after the
first day of the Offering Period, shall continue until the Participant
terminates participation in the Plan in accordance herewith or until the Plan is
terminated, whichever occurs first, and shall be credited to his Plan Account
(as described in paragraph 6(d)). An eligible employee may participate in the
Plan only through payroll deductions. Other contributions will not be accepted.
All Election Forms shall be filed in accordance with uniform and
nondiscriminatory rules established by the Committee.

     4.   Shares Subject to Plan.
          ----------------------

     (a)  Number of Shares Reserved. The shares of Stock which may be issued
          -------------------------
          under the Plan shall be shares currently authorized but unissued or
          currently held or subsequently acquired by Corvis as treasury shares,
          including shares purchased in the open market or in private
          transactions. Subject to the provisions of paragraph 4(c), the number
          of shares of Stock which may be issued under the Plan during any
          calendar year shall not exceed 2,000,000 shares, provided however,
          that total number of shares of Stock which may be issued under the
          Plan during the term of the Plan may not exceed 10,000,000 in the
          aggregate.

     (b)  Reusage of Shares.  In the event of the expiration, withdrawal or
          -----------------
          other cancellation of an Option (as defined in Section 5) under the
          Plan, the number of shares of Stock that were subject to the Option
          but not delivered shall again be available for issuance under the
          Plan.

     (c)  Adjustments to Shares Reserved. In the event of any transaction
          ------------------------------
          involving Corvis (including, without limitation, any merger,
          consolidation, reorganization, recapitalization, spinoff, stock
          dividend, extraordinary cash dividend, stock split, reverse stock
          split, combination, exchange or other distribution with respect to
          shares of Stock or other change in the corporate structure or
          capitalization affecting the Stock), the Committee may make
          adjustments to Options under the Plan to preserve the benefits or
          potential benefits of the Options. Action by the Committee may include
          (i) adjustment of the number and kind of shares which are or may be
          subject to Options under the Plan (ii) adjustment of the number and
          kind of shares subject to outstanding Options under the Plan, (iii)
          adjustment to the exercise price of outstanding Options under the
          Plan, and (iv) any other adjustments that the Committee determines to
          be equitable.

     (d)  Insufficient Shares.  If, on an Exercise Date (as defined in paragraph
          -------------------
          8(a)), Participants in the aggregate have outstanding Options to
          purchase more shares of Stock than are then available for purchase
          under the Plan, each Participant shall be eligible to purchase a
          reduced number of shares of Stock on a pro rata basis and any excess
          payroll deductions shall be returned to such Participants, without
          interest, all as provided by uniform and nondiscriminatory rules
          adopted by the Committee.

                                      -3-
<PAGE>

     5.   Grant of Options.  As of the first day of each Offering Period (the
          ----------------
"Grant Date"), each employee who is a Participant for such Offering Period shall
be deemed to have been granted an "Option" under the Plan; provided, however,
that:

     (a)  no Participant shall be granted an Option to purchase shares of Stock
          on any Grant Date if such Participant, immediately after the Option is
          granted, owns stock possessing 5% or more of the total combined voting
          power or value of all classes of stock of Corvis or any subsidiary of
          Corvis (determined in accordance with section 424(f) of the Code (each
          a "Subsidiary")); and

     (b)  no Participant may purchase under the Plan (or any other employee
          stock purchase plan of Corvis or any Subsidiary) more than $25,000 of
          Fair Market Value (as defined in paragraph 9(h)) of shares of Stock
          (determined at the Grant Date) for each calendar year.

The provisions of paragraph 5(b) shall be interpreted in accordance with section
423(b)(8) of the Code.  For purposes of this Section 5, the rules of section
424(d) of the Code shall apply in determining the stock ownership of an
individual, and Stock which the Participant may purchase under outstanding
Options shall be treated as Stock owned by the Participant.

     6.   Payroll Deductions.
          ------------------

     (a)  Source and Amount of Payroll Deductions. Payroll deductions shall be
          ---------------------------------------
          made from the Base Earnings (as defined in paragraph 6(e)) paid to
          each Participant for each payroll period in such amounts as the
          Participant shall authorize in his Election Form. Subject to the
          provisions of Section 5, the Committee may, from time to time,
          establish uniform and nondiscriminatory minimum and maximum payroll
          deductions for any period. Unless otherwise specified by the
          Committee, payroll deductions for any payroll period must be made in
          whole percentage increments and may not exceed 15% of the
          Participant's Base Earnings for that payroll period.

     (b)  Insufficient Pay. If a Participant's Base Earnings are insufficient in
          ----------------
          any payroll period to allow the entire payroll deduction contemplated
          under the Plan, no deduction will be made for such payroll period.
          Payroll deductions will resume with the next payroll period in which
          the Participant has Base Earnings sufficient to allow for the
          deductions. Payroll deductions under the Plan shall be made in any
          payroll period only after other withholdings, deductions, garnishments
          and the like have been made, and only if the remaining Base Earnings
          are sufficient to allow the entire payroll deduction contemplated.

     (c)  Changes to Deductions.  Subject to any minimum and maximum deductions
          ---------------------
          established by the Committee and the terms and conditions of the Plan,
          a

                                      -4-
<PAGE>

          Participant may change the amount of his payroll deduction for any
          payroll period occurring within an Offering Period (but not
          retroactively and not more than twice during any Offering Period) by
          filing a new Election Form with Corvis or its designated recordkeeper
          in accordance with uniform and nondiscriminatory rules established by
          the Committee. Any change to payroll deductions for an Offering Period
          shall be implemented as soon as administratively feasible.

     (d)  Plan Accounts.  The Committee shall cause a separate bookkeeping
          -------------
          account (a "Plan Account") to be maintained for each Participant,
          which Plan Account will reflect the accumulated payroll deductions
          made on behalf of the Participant from time to time, reduced for any
          distributions from such Plan Account pursuant to the provisions of the
          Plan.

     (e)  Base Earnings. For purposes of the Plan, the term "Base Earnings" for
          -------------
          any period shall have the usual meaning given to that term by Corvis
          from time to time which are payable to a Participant for that period.

     7.   Termination of Participation.
          ----------------------------

     (a)  Voluntary Termination.  A Participant, at any time and for any reason,
          ---------------------
          may voluntarily terminate participation in the Plan by written
          notification of withdrawal delivered to the appropriate payroll office
          at least 10 business days (or such other period provided by the
          Committee) before the next payroll period.

     (b)  Automatic Termination.  Except as provided in paragraphs (c) or (d), a
          ---------------------
          Participant's participation in the Plan shall be automatically
          terminated immediately upon termination of his employment with Corvis
          and the Participating Subsidiaries for any reason.

     (c)  Special Rule for Death.  Notwithstanding the provisions of paragraph
          ----------------------
          (b) if a Participant's termination of employment with Corvis and the
          Participating Subsidiaries occurs on account of death, the
          Participant's beneficiary may elect to continue to participate in the
          Plan (but only to the extent of the Participant's Plan Account balance
          as of the date of his death) through the Exercise Date coincident with
          or next following the Participant's death, at which time the
          Participant's participation in the Plan shall automatically terminate.
          Any election pursuant to the preceding sentence must be made within 30
          days after the Participant's death; provided, however, that if the
          Participant's death occurs less than 30 days prior to the next
          Exercise Date, the beneficiary's election must be made no later than
          the Exercise Date coincident with or next following the Participant's
          death. If the beneficiary does not elect to continue participation in
          the Plan pursuant to the foregoing provisions of this paragraph (c),
          the Participant's participation in the Plan will be deemed to have
          terminated as of the date of his death and any

                                      -5-
<PAGE>

          existing account balance will be refunded to the beneficiary in cash
          without interest.

     (d)  Special Rule for Retirement.  Notwithstanding the provisions of
          ---------------------------
          paragraph (b), if a Participant's termination of employment with
          Corvis and the Participating Subsidiaries occurs on account of
          Retirement (as defined below) within three months prior to an Exercise
          Date, the Participant may elect to continue to participate in the Plan
          (but only to the extent of his Plan Account balance as of the date of
          his Retirement) through the Exercise Date coincident with or next
          following his Retirement, at which time the Participant's
          participation in the Plan shall automatically terminate. For purposes
          of the Plan, the term "Retirement" means the Participant's termination
          of employment with Corvis and the Participating Subsidiaries on or
          after the Participant attains age 65. A Participant will be deemed to
          have elected to continue participation in accordance with this
          paragraph (d) if, as of the Exercise Date coincident with or next
          following his Retirement, he has not given notice of his cessation of
          Plan participation in accordance with the terms of the Plan.

     (e)  Effect of Termination.  In the event a Participant's participation
          ---------------------
          in the Plan is terminated for any reason, payroll deductions shall
          immediately cease and any amounts then credited to the Participant's
          Plan Account shall be returned to the Participant, without interest,
          as soon as practicable thereafter. A Participant whose participation
          in the Plan has terminated may not rejoin the Plan until the next
          Offering Period following the date of such termination, subject to the
          terms and conditions of the Plan.

     8.   Exercise of Option/Purchase of Shares.
          -------------------------------------

     (a)  Exercise of Option.  On each June 30 and December 31 (or, if such day
          ------------------
          is not a business day, the next preceding business day) (each an
          "Exercise Date"), each Participant who is then employed by Corvis or a
          Participating Subsidiary (or who is otherwise eligible to exercise an
          Option pursuant to paragraph 7(c)) shall be deemed to have exercised
          his Option with respect to that number of shares of Stock equal to the
          quotient of (i) the balance in the Participant's Plan Account as of
          the Exercise Date and (ii) the Exercise Price. For purposes of the
          Plan, the "Exercise Price" shall be the lesser of (1) 85% of the Fair
          Market Value of a share of Stock on the Grant Date, or (2) 85% of the
          Fair Market Value of a share of Stock on the Exercise Date, rounded up
          to the nearest 1/8 point, but in no event less than the par value of a
          share of Stock. In the event of overlapping or concurrent Offering
          Periods, Options shall be exercised in the order granted.

     (b)  Statements.  As soon as practicable after each Exercise Date, a
          ----------
          statement shall be delivered to each Participant which shall include
          the number of shares of Stock purchased on the Exercise Date on behalf
          of such Participant under the Plan.

                                      -6-
<PAGE>

     (c)  Certificates.  When requested by a Participant, a stock certificate
          ------------
          for whole shares of Stock purchased by the Participant under the Plan
          shall be issued in the name of the Participant or, if so specified in
          the Participant's Election Form, in the Participant's name and the
          name of another person as joint tenants with right of survivorship or
          as tenants in common. The value of any fractional shares shall be paid
          to the Participant in cash.

     (d)  Excess Plan Account Balances. Any amounts remaining in a Participant's
          ----------------------------
          Plan Account as of any Exercise Date after the purchase of shares
          described herein shall remain in the Participant's Plan Account and
          shall be used as of the next Exercise Date to purchase shares of Stock
          in accordance with the terms of the Plan; provided, however, that
          nothing in this paragraph (d) shall affect a Participant's right to
          cease participation in the Plan in accordance with the terms hereof.

     9.   Miscellaneous.
          -------------

     (a)  Compliance with Applicable Laws; Limits on Issuance.  Notwithstanding
          ---------------------------------------------------
          any other provision of the Plan, Corvis shall have no obligation to
          issue any shares of Stock under the Plan unless such issuance would
          comply with all applicable laws and the applicable regulations or
          requirements of any securities exchange or similar entity. Prior to
          the issuance of any shares of Stock under the Plan, Corvis may require
          a written statement that the recipient is acquiring the shares for
          investment and not for the purpose or with the intention of
          distributing the shares and will not dispose of them in violation of
          the registration requirements of the Securities Act of 1933.

     (b)  Transferability.  Neither the right of a Participant to purchase
          ---------------
          shares of Stock hereunder, nor his Plan Account balance, may be
          transferred, pledged or assigned by the Participant other than by will
          or the laws of descent and distribution and his rights hereunder may
          be exercised during his lifetime only by him.

     (c)  Notices.  Any notice or document required to be filed with the
          -------
          Committee under or with respect to the Plan will be properly filed if
          delivered or mailed by registered mail, postage prepaid, to the
          Committee at Corvis' principal executive offices. The Committee may,
          by advance written notice to affected persons, revise any notice
          procedure from time to time. Any notice required under the Plan may be
          waived by the person entitled to notice.

     (d)  Withholding.  All amounts withheld pursuant to the Plan, shares of
          -----------
          Stock issued hereunder and any payments pursuant to the Plan are
          subject to withholding of all applicable taxes and Corvis and its
          subsidiaries shall have the right to withhold from any payment or
          distribution of shares or to collect as a condition of any

                                      -7-
<PAGE>

          payment or distribution under the Plan, as applicable, any taxes
          required by law to be withheld. To the extent provided by the
          Committee, a Participant may elect to have any distribution of shares
          otherwise required to be made pursuant to the Plan to be withheld or
          to surrender to Corvis or its subsidiaries shares of Stock already
          owned by the Participant to fulfill any tax withholding obligation;
          provided, however, in no event shall the fair market value of the
          number of shares so withheld (or accepted) exceed the amount necessary
          to meet the minimum Federal, state and local marginal tax rates then
          in effect that are applicable to the Participant and to the particular
          transaction.

     (e)  Limitation of Implied Rights. The Plan does not constitute a contract
          ----------------------------
          of employment or continued service and participation in the Plan will
          not give any employee the right to be retained in the employ of Corvis
          or any Participating Subsidiary or any right or claim to any benefit
          under the Plan unless such right or claim has specifically accrued
          under the terms of the Plan. Participation in the Plan by a
          Participant shall not create any rights in such Participant as a
          stockholder of Corvis until shares of Stock are registered in the name
          of the Participant.

     (f)  Evidence.  Evidence required of anyone under the Plan may be by
          --------
          certificate, affidavit, document or other information which the person
          acting on it considers pertinent and reliable, and signed, made or
          presented by the proper party or parties.

     (g)  Gender and Number.  Where the context admits, words in one gender
          -----------------
          shall include the other gender, words in the singular shall include
          the plural and the plural shall include the singular.

     (h)  Definition of Fair Market Value. For purposes of the Plan, the "Fair
          -------------------------------
          Market Value" of a share of Stock as of any date shall be the closing
          market composite price for such Stock as reported on the Nasdaq
          National Market on that date or, if Stock is not traded on that date,
          on the immediately preceding date on which Stock was traded. In the
          event that the Stock is not listed for trading on a national exchange
          or quoted on an inter-dealer quotation system, the Fair Market Value
          shall be determined by the Committee. Notwithstanding the foregoing,
          the "Fair Market Value" of a share of Stock for the Grant Date
          occurring on the Effective Date shall be the per share "Price to
          Public" shown on the cover page of the final Prospectus filed in
          connection with Corvis' initial public offering.

     10.  Amendment or Termination of Plan.   The Board may, at any time and in
          --------------------------------
any manner, amend, suspend or terminate the Plan or any election outstanding
under the Plan; provided, however, that no such amendment shall be made without
approval of Corvis' stockholders to the extent such approval would be required
under section 423 of the Code, the

                                      -8-
<PAGE>

rules of any securities exchange or similar entity on which the Stock is listed
or otherwise by applicable law.

                                      -9-<PAGE>

                                                                    EXHIBIT 10.7

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

                             PROCUREMENT AGREEMENT

                                    BETWEEN

                    BROADWING COMMUNICATIONS SERVICES  INC.

                                      AND

                               CORVIS CORPORATION

                              DATED MARCH 17, 2000
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

                               TABLE OF CONTENTS

                                                                            Page
                                                                            ----

                Recital                                                        1
Article 1       Laboratory System                                              1
Article 2       Transport Field Trial                                          2
Article 3       Reserved                                                       4
Article 4       Volume Deployment; Quantities and Delivery Schedules           5
Article 5       Commercial Testing; Product Discontinuation                    7
Article 6       Pricing, Invoicing, Payment and Other Financial Terms          8
Article 7       Term                                                           9
Article 8       Documentation and Reports                                      9
Article 9       Delivery and Installation                                      9
Article 10      Force Majeure                                                 10
Article 11      Training                                                      10
Article 12      Software License                                              11
Article 13      Software Changes                                              13
Article 14      Product Changes                                               13
Article 15      Proprietary Information                                       15
Article 16      Warranties, and Warranty Exclusions and Limitations           16
Article 17      Representations and Other Warranties                          18
Article 18      Remedies and Limitations                                      18
Article 19      Support and Other Services                                    20
Article 20      Insurance                                                     20
Article 21      Indemnification                                               21
Article 22      Patents, Copyright and Trade Secrets                          21
Article 23      Termination                                                   22
Article 24      Dispute Resolution                                            23
Article 25      Notice and Representatives of the Parties                     24
Article 26      General                                                       25
Article 27      Incorporation of Documents                                    26
Article 28      Definitions                                                   26
Article 29      Entire Agreement                                              29

<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

                             PROCUREMENT AGREEMENT
                 BETWEEN BROADWING COMMUNICATIONS SERVICES INC.
                             AND CORVIS CORPORATION

     THIS PROCUREMENT AGREEMENT ("Agreement"), made effective as of this 17th
day of March, 2000 ("Effective Date"), by and between Broadwing Communications
Services Inc., a Delaware  corporation, having its principal place of business
at 1122 Capital of Texas Highway South, Austin, Texas 78746-6426  (hereinafter
referred to as "Customer"), and Corvis Corporation, a Delaware corporation,
having its principal place of business at 7015 Albert Einstein Drive, Columbia,
MD 21046-9400 (hereinafter referred to as "Corvis").

     A.  Customer is a leading telecommunications service provider offering a
         broad range of telecommunications services requiring ever-increasing
         bandwidth.

     B.  Corvis is a manufacturer of next-generation optical network equipment
         whose ultra-long transmission capacity and high channel count products
         coupled with its optical router create substantially greater capacity
         while simultaneously reducing the overall cost-per-bit to the lowest
         levels in the industry.

     C.  Customer desires to deploy commercially, and Corvis desires to supply,
         Corvis equipment and software in Customer's network contingent upon
         such equipment and software performing in accordance with the Transport
         Field Trial Test Criteria, as defined below.

     NOW, THEREFORE, in consideration of the foregoing premises and the
representations, warranties, covenants and agreements herein contained, the
parties agree as follows:

DEFINITIONS:  Defined terms and definitions are set forth in Article 28 of this
Agreement.

ARTICLE 1. LABORATORY SYSTEM.

     1.1  Equipment and Software.  Corvis [*] to Customer, and Customer [*], the
     Equipment and Software identified in Attachment 1 (the "Laboratory System")
     for the prices set forth in such attachment.

     1.2  [*]

     1.3  Shipment of Laboratory System.  Corvis will ship to Customer the
     Laboratory System by the date for such delivery set forth in Attachment
     1.3.

     1.4  [*]

                                       1
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

ARTICLE 2.  TRANSPORT FIELD TRIAL.

2.1  Scope.  Customer will conduct a field trial of the Corvis transport
equipment and software by deploying Corvis Equipment and Software in the
configuration set out in Attachment 2 ("Transport Field Trial") to determine
whether such Equipment and Software (the "Transport Field Trial Equipment and
Software") fulfill the test criteria set forth in Attachment 2 ("Transport Field
Trial Test Criteria").

2.2  Equipment and Software

          (a) Corvis will sell to Customer, and Customer will purchase, the
          Transport Field Trial Equipment and Software identified in Attachment
          2 for the prices set forth in such attachment.

          (b)  In connection with the Transport Field Trial, Corvis will provide
          Customer required installation services, maintenance, training, and
          technical support [*].

2.3  Payment

          (a)  [*], Customer will pay Corvis, within [*] after the Effective
          Date, an amount equal to [*] of the Equipment and license fees for
          Transport Field Trial Software to be paid by Customer to Corvis for
          the Transport Field Trial Equipment and Software as specified in
          Attachment 2.

          (b)  Customer will pay [*] the purchase price for the Transport Field
          Trial Equipment and license fees for Transport Field Trial Software
          [*] the Transport Field Trial, which will be deemed to occur on the
          date the Transport Field Trial Equipment and Software meet the
          Transport Field Trial Test Criteria.

          (c)  Should the Transport Field Trial not be successfully completed
          (as described above)[*] after system turn-up, either party may elect
          to terminate the Transport Field Trial upon written notice to the
          other party. In the event of such termination, Customer will promptly
          return the Transport Field Trial Equipment and Software to Corvis [*].
          [*]

     2.4  Shipment of Transport Field Trial Equipment and Software. Corvis will
     ship to Customer the Transport Field Trial Equipment and Software by the
     date for such shipment set forth in Attachment 1.3.

     2.5  Duration of Transport Field Trial.  Customer will complete the
     Transport Field Trial as soon as practicable, but in any event not later
     than [*] after delivery, installation and turn-up of the Transport Field
     Trial Equipment and Software. If the Transport Field Trial Equipment and
     Software fulfill the Transport Field Trial Test Criteria, Customer will,
     [*]

                                       2
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

     thereafter, commence deployment of Corvis Transport Equipment and
     Software in its network pursuant to Article 4. Customer will acknowledge in
     writing the successful completion of the Transport Field Trial [*] after
     such completion.

ARTICLE 3.  RESERVED.

ARTICLE 4.  VOLUME DEPLOYMENT; QUANTITIES AND DELIVERY SCHEDULES.

     4.1  Initial Deployment.  Upon successful completion of the Transport Field
     Trial, Customer will purchase from Corvis and deploy the Corvis Transport
     Equipment and Software in quantities and in configurations priced at
     U.S.$200,000,000.00 (the "Minimum Deployment Commitment"), U.S.
     $100,000,000.00 of which (the "First Year Deployment Commitment") must be
     ordered within 12 months after the successful completion of the Field Trial
     with delivery no later than [*] after such 12 month period, in each case
     based on the prices and license fees set forth in Attachment 6. Customer
     will be [*] in accordance with the terms and conditions of Attachment 6.

     4.2  (a)  Quantity Forecast.  By the [*] business day of each [*] (the
               [*] hereafter being "[*]"), Customer will provide to Corvis a [*]
               month rolling forecast (the "Rolling Forecast") of deliveries for
               the [*] period commencing at the beginning of the [*] after the
               [*] in which the forecast is made the Rolling Forecast ([*]
               through [*]) will show the quantity of each Product by product
               code which Customer anticipates it will need to be delivered
               during the specified [*].

          (b)  Initial Rolling Forecast; Capacity.  Notwithstanding anything to
               the contrary contained herein, the parties shall discuss the
               initial Rolling Forecast issued under this Agreement to better
               anticipate Product requirements and availability.

     4.3  During the Term of this Agreement, Customer will issue Purchase Orders
     specifying the Products ordered, the quantities necessary, the delivery
     site or sites (hereinafter the "Specified Site[s]") for the Products and
     its proposed delivery schedule.

     4.4  All deliveries of Products will be made [*]. Customer agrees to pay
     [*] charges. The preceding provisions of this clause are valid for
     deliveries in the United States, its possessions and territories only. All
     deliveries outside the aforementioned areas will be mutually agreed upon on
     a case by case basis.

                                       3
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

     4.5  Customer will have the right to alter the destination site at least
     [*] prior to Corvis' scheduled shipment date for Products, without cost or
     expense to Customer, by timely transmitting Notice to Corvis of the new
     Specified Site(s).

     4.6  Corvis will execute and deliver to Customer an order acknowledgment
     within [*] after Corvis' receipt of each Purchase Order or, if Corvis
     cannot meet the proposed delivery times, the parties shall mutually agree
     to appropriate delivery times. If Corvis and Customer cannot agree upon
     delivery times, Corvis shall have the right to reject a Purchase Order.
     Product order lead times shall be [*] unless otherwise specified by Corvis.

     4.7  Customer will purchase on-site installation spares parts and
     components of the Equipment ("Spares Kits" or "Kits") reasonably designated
     by Corvis and agreed upon by Corvis and Customer from time to time as the
     quantity necessary to enable Corvis to provide the warranty and support
     services required by this Agreement. The quantity and locations of the Kits
     may change with installation requirements and changes in the topology of
     Customer's network.

     4.8  [*]

     4.9  [*]

ARTICLE 5.  CUSTOMER TESTING; PRODUCT DISCONTINUATION.

     5.1  Customer will have [*] after receipt of Product at its location to
     perform any acceptance testing that Customer wishes to perform to confirm
     that the Product complies with its applicable Technical Requirements.
     Unless Customer notifies Corvis within that [*] period of any defects in
     such Product, Customer will be deemed to have accepted the Product.
     Customer's inspection or failure to inspect and/or its acceptance of any
     Product will not relieve Corvis of its warranty obligations in respect of
     such Product.

     5.2  Corvis will notify Customer promptly upon learning of any material
     defects in any of the Products.

     5.3  (a)  Corvis will support all Licensed Software and Equipment for its
          expected useful life, as set forth in Attachment 5.3 ("Product Life"),
          subject to the support limitations for Licensed Software contained in
          Attachment 19.

          (b)  If Corvis discontinues manufacture and/or support of the
          Equipment, Corvis will at Customer's request, to the extent of Corvis'
          legal rights to do so, without obligation or charge to Customer
          deliver to Customer all of the technical information owned and
          possessed by Corvis relating to the manufacture and/or support of the
          Equipment, in the form being used in Corvis' factories in its day-to-

                                       4
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

          day operations of manufacture, or arrange for the replacement and
          repair spare parts for the Equipment to Customer's reasonable
          satisfaction. Customer may use such technical information only to
          manufacture, have manufactured, obtain such spare parts from other
          sources in connection with the Equipment and System Software obtained
          from Corvis and owned and operated or licensed by Customer. Title to
          Corvis' technical information and intellectual property rights will
          remain with Corvis.

ARTICLE 6.  PRICING, INVOICING, PAYMENT AND OTHER FINANCIAL TERMS.

     6.1  Prices for Products are set forth in Attachment 6.  In addition,
     Customer will pay the right to use fee (the "Right to Use Fee") for the
     Equipment and/or Software and intellectual property associated with Corvis
     Equipment as specified in Attachment 6.

     6.2  The prices in this Agreement do not include any federal, state or
     local sales, use, excise or similar taxes, however designated, which may be
     levied or assessed on the Products or Services provided hereunder, and any
     personal property taxes levied or assessed on Products which has been
     delivered but as to which title has not passed to Customer. With respect to
     such taxes, Customer will either furnish Corvis with an appropriate
     exemption certificate applicable thereto, or pay to Corvis, such amounts as
     Corvis may by law be required to collect or pay.

     6.3  Payment terms are set forth as follows:

          (a)  Customer will remit payment to Corvis for invoiced amounts within
          [*] after the receipt of the invoice, which will be issued upon
          shipment of the Product or completion of Services, as applicable.
          Charges for Services and Equipment will be invoiced and paid
          separately by Customer.

          (b)  Customer will not be required to pay for Products or Services
          which are rightfully rejected.

     6.4  In the event Corvis fails to receive payment from Customer as required
     herein, Customer will have [*] calendar days to cure such non-payment after
     its notice of non-payment from Corvis. Payments provided for in this
     Agreement, when overdue, will bear interest at a rate per month equal to
     [*] % for the time period from and including the due date until payment is
     received by Corvis.

     6.5  Invoicing instructions will be as follows:

     Original Invoice Sent To:

                                       5
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

     Broadwing Communication Services
     Attn: Accounts Payable
     1122 Capital of Texas Highway South
     Austin, Texas 78746

ARTICLE 7.  TERM.

     Subject to the terms and conditions of this Agreement, the initial term of
     this Agreement will be two (2) years from the successful completion of the
     Transport Field Trial ("Initial Term"). [*] The Initial Term in combination
     with any extensions is also referred to in this Agreement as the "Term".

ARTICLE 8.  DOCUMENTATION AND REPORTS.

     Corvis will provide to Customer, one electronic copy of the Documentation
     necessary to operate and maintain the Products provided hereunder for each
     Specified Site at which such Product is installed. Corvis will provide
     Customer with (a) updates to the Documentation, as such updates are made
     generally available, and (b) new and/or revised data incorporating any
     changes to the Products which affect form, fit, or function,[*]. Such
     Documentation may be reproduced by Customer for its internal use, provided
     that any copyright notice of such Documentation is copied as well. Soft
     copies of such Documentation will be available upon Customer's request.
     Such Documentation will be used solely for Customer's internal use only on
     a need-to-know and need-to-use basis.

ARTICLE 9.  DELIVERY AND INSTALLATION.

     9.1  Corvis will mark each shipment to Customer with Corvis name, the
     Purchase Order number, and the identity and quantity of Product. Final
     destination, interim staging area or any special shipping instructions and
     any applicable charge will be specified on each Purchase Order.

     9.2  Corvis will perform installation services for the Products at Corvis'
     then standard rates for such services and on terms and conditions agreed by
     the parties.

ARTICLE 10.  FORCE MAJEURE

                                       6
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

     10.1  Except as otherwise provided herein, neither Corvis nor Customer will
     be liable to the other for any delay in performing in accordance with this
     Agreement if such delay arises out of an Act of God including fire, flood,
     earthquake, explosion, casualty, or accident, or out of war, riot, civil
     commotion, labor dispute, the requirement of any governmental agency or
     instrumentality, industry-wide shortages of raw materials or transportation
     facilities, or any other cause beyond the control of the party claiming
     force majeure.

     10.2  The party asserting that an event of force majeure has occurred will
     send the other party prompt notice thereof setting forth a description of
     the event of force majeure, an estimate of its effect upon the party's
     ability to perform its obligations under this Agreement and the duration or
     expected duration thereof.

     10.3  The party asserting that an event of force majeure has occurred will
     be excused, on a day-to-day basis, from the performance of its obligations
     under this Agreement to the extent prevented or delayed by such event (and
     the other party likewise will be excused, on a day-to-day basis, from the
     performance of its obligations under this Agreement to the extent such
     party's obligations related to the obligations are so prevented or
     delayed); provided, however, that the party asserting the occurrence of a
     force majeure event will use diligent efforts to avoid or remove such force
     majeure event.

ARTICLE 11.  TRAINING.

     11.1  Corvis will provide, upon Customer's request and at the time or times
     required by Customer during the Term of this Agreement, training classes
     and training materials for Customer personnel. Training will take place at
     the Corvis facilities in Columbia, MD. The training programs necessary for
     full installation, operation and maintenance of the Corvis Products are
     summarized in Attachment 11.1, which shall be subject to change by Corvis
     from time to time to reflect updates to the training methodology and
     courses. Such training will be kept current to encompass the latest
     Licensed Software and Equipment, or any other Software revision level
     and/or Equipment revision level directed by Customer. Subject to the
     foregoing, course content and material will be designed [*]. Customer will
     have the right to copy Corvis' training materials for its internal use
     provided that any copyright notice included in such material is copied as
     well. Courses will be limited to a maximum of [*] attendees in each course
     session. Corvis will provide [*] a total of [*] seats in the aggregate to
     Corvis training programs that will train attendees in the installation,
     testing or operation of Corvis Equipment. Such training programs will be
     offered [*] by Customer of the Corvis equipment. Corvis will implement
     commencing in [*] training and certification programs and will certify that
     participants in such training courses received information sufficient for
     installation, testing or operation of Corvis Equipment and Corvis will
     provide that the [*] individuals utilizing the [*] seats provided by Corvis
     as set out above are provided training sufficient to certify them. Such
     certification shall not make Corvis liable for any negligence of or damage
     caused by such certified individuals. Subsequent training

                                       7
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

     programs will be charged at a rate of U.S.$[*] per person-day of training.
     In all cases, Customer is obligated to pay for all travel and lodging of
     Customer personnel. All training will be conducted at Corvis' Maryland
     location, [*].

     11.2  Corvis will certify attendees upon successful completion of the
     course. Such course content and materials [*] Customer for its internal use
     only.

ARTICLE 12.  SOFTWARE LICENSE.

     12.1  Subject to payment of any and all applicable license fees set out in
     Attachment 6, Corvis grants to Customer a perpetual (subject to termination
     pursuant to the terms of this Agreement), personal, nontransferable (except
     as provided in this Agreement), and nonexclusive license (or, with respect
     to the Third Party Software, a sublicense) to use the Software and its
     related Documentation provided pursuant to the terms of this Agreement. Use
     of the Software is restricted to the specified number of Network Elements
     or the designated equipment, as applicable ("Designated Equipment") set
     forth on Customer's Purchase Order(s). If a Designated Equipment becomes
     inoperative, Customer will have the right to use the Software on comparable
     backup equipment until such Designated Equipment is restored to operable
     status. [*] The license grants Customer no right to and Customer will not
     sublicense such Software, or modify, decompile, or disassemble Software
     furnished as object code to generate corresponding Source Code. Customer
     and its customers will be entitled to modify only the user-controlled
     features of the Software as provided for in the related Documentation. With
     respect to any Third Party Software, in addition to the terms and
     conditions herein, Customer will abide by the applicable terms and
     conditions for such Third Party Software. Attachment 12.1 lists the Third
     Party Software licenses that are applicable as of the date of this
     Agreement.

     12.2  The CEM Software provided for use on Sun Workstations may only be
     used on such workstation if such Software is the only software running on
     such workstation and access to such workstation is password protected.

     12.3  All Software (whether or not part of firmware) and its related
     documentation furnished by Corvis, and all copies thereof made by Customer,
     including translations, compilations, and partial copies, are and will
     remain the exclusive property of Corvis and its licensors. Customer will
     hold such Software and related documentation in strict confidence, and will
     not, without Corvis' prior written consent, disclose, provide, provide
     access to, or otherwise make available, in whole or in part, any Software
     or related documentation including any description of the [*] sections of
     the Software to anyone, except to its employees, and those agents and
     subcontractors that are not competitors of Corvis having a need-to-know for
     purposes of operating or maintaining the related Product, and except to its
     customers to the extent necessary to permit them to utilize customer-
     controlled features in accordance with the applicable Documentation. Such
     availability shall be limited to only those portions of

                                       8
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

     the Software and its related documentation for which there is a need-to-
     know for purposes of operating or maintaining the related Product. All
     persons to whom the Software and relative documentation is made available
     shall have agreed in writing to obligations of confidentiality at least as
     protective as those set forth herein. Customer shall maintain an accurate
     and complete list of all persons having access to the Software and its
     related documentation and shall maintain a log of persons accessing the
     Software and its related documentation and the nature of the access, e.g.,
     edit, view, copy, etc. Customer shall provide Corvis with prompt written
     notice of any unauthorized use of the Software and its related
     documentation and fully cooperate with Corvis in enforcing Corvis'
     proprietary rights in the Software and its related documentation.

     Customer shall not, and shall not permit any other person to copy,
     duplicate, modify, alter, enhance, revise, summarize, or prepare derivative
     works from any portion of the [*] sections of the Software. Customer will
     not copy Software embodied in firmware. Customer will not make any copies
     of any other Software or related documentation except as necessary for
     maintaining archival copies in accordance with Customer's customary
     practices. Such archival copies shall be stored in a locked and secured
     container. Customer will reproduce and include any Corvis copyright and
     proprietary notice on all such necessary copies of the Software and its
     related documentation. Customer will take appropriate action, by
     instruction, agreement, or otherwise, with the persons permitted access to
     the Software and related documentation to enable Customer to satisfy its
     obligations under this Agreement. When the Software and related
     documentation are no longer needed by Customer, or if Customer's license is
     canceled or terminated, Customer will return all copies of such Software
     and related documentation to Corvis or follow written disposition
     instructions provided by Corvis.

     12.4  Subject to Corvis' approval which will not be unreasonably withheld,
     Customer may transfer its right-to-use Software furnished under this
     Agreement without the payment of an additional right-to-use fee by third
     party transferee, except for additional fees which would have been
     applicable to Customer with respect to usage sensitive factors (e.g.,
     feature pricing based on activation level). Such transfer can be made to
     another end user for their own internal use, but not to any competitor of
     Corvis and only under the following conditions:

          (a)  Such Software will be used only within the United States and such
          other countries for which such Software may be licensed from time to
          time under the terms of this Agreement.

          (b)  The right to use such Software may be transferred only together
          with the Designated Equipment with which Customer has a right to use
          such Software, as long as such transfer of the Designated Equipment is
          permitted pursuant to Section 15.3, and such right to use the Software
          will continue to be limited to use with such Designated Equipment;

                                       9
<PAGE>

 Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

           (c)  Before any such Software will be transferred, Customer will
           notify Corvis in writing of such intended transfer and the transferee
           will have agreed in writing (a copy of which will be provided to
           Corvis before such transfer) to the terms of this Agreement and any
           amendments thereto.

     12.5  Subject to Section 12.2, upon advance written notice to Corvis,
     Customer may physically transfer Software or optional feature packages, for
     which Customer has the right to use, from one Customer-owned workstation
     computer and relocate them to another Customer-owned workstation computer,
     provided that (a) the Product from which the Software has been transferred
     will cease to be Designated Equipment for such transferred Software and the
     workstation to which the Software has been transferred will thereafter be
     deemed to be the Designated Equipment, and (b) the Software delivered by
     Corvis pursuant to a Purchase Order will not be resident at any time on
     more than the total number of items of Designated Equipment for such
     Software set forth on the applicable Purchase Order. Customer will not be
     required to pay additional right-to-use fees as a result of such
     relocation, except for additional fees which would have been applicable to
     Customer with respect to usage sensitive factors.

     12.6  Provided that Customer has proceeded with volume deployment pursuant
     to Section 4, Corvis and Customer will enter into an escrow agreement, in
     the form set forth in Attachment 12.6 and acceptable to both parties
     ("Escrow Agreement"). The escrow agent for the Escrow Agreement will be [*]
     or another escrow agent acceptable to both parties. Corvis will bear the
     cost of providing Corvis' Source Code to the Escrow Agent. Customer will
     pay the Escrow Agent's charges, including any costs associated with testing
     the Source Code in Escrow or with release of such Source Code. Upon
     execution of the Escrow Agreement by both parties, Corvis will place in
     escrow the source code version of the Software (excluding Third Party
     Software). Thereafter, Corvis will supplement the materials in escrow to
     include upgrades and new releases of the Software (excluding Third Party
     Software) then in use by Customer. The Escrow Agreement will provide for
     the availability of the materials in escrow, subject to the terms and
     conditions of the Escrow Agreement.

ARTICLE 13.  SOFTWARE CHANGES.

     13.1  Corvis will furnish to Customer preliminary planning information and
     documentation for new releases of the Software. Such information will be
     provided [*] to Customer. New generally available releases of the Software
     may be licensed by Customer at Corvis' then-current standard license fees,
     except to the extent such releases are included in the Maintenance and
     Support Services then in effect pursuant to the terms of this Agreement.

     13.2  Software licensed to Customer under this Agreement may contain
     supplemental optional features or enhancements that are separately priced.
     Customer agrees not to

                                       10
<PAGE>

 Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

     activate such optional feature or enhancements without written
     authorization from Corvis and Customer's payment of the appropriate license
     fees. If, in spite of Customer's best efforts to comply with this
     restriction, such features are activated, Customer agrees to so notify
     Corvis promptly and to pay Corvis the license fees for the activated
     features as well as the reasonable cost of money not exceeding the prime
     rate of interest for the period in which such features were activated.
     Corvis will have the right to audit Customer's usage of Corvis Equipment
     and Software to assure compliance with the terms of this Agreement.

ARTICLE 14.  PRODUCT CHANGES.

          14.1  Prior to shipment, Corvis may at any time make changes in
     Products or modify the drawings and specifications relating thereto or
     substitute Products of later design, provided the changes, modifications or
     substitutions under normal and proper use do not impact upon form, fit or
     function of the ordered Equipment or materially adversely affect the use,
     function, or performance of the ordered Software, as provided in the
     Technical Requirements. Unless otherwise agreed, such Software substitution
     will not result in any additional charges to Customer with respect to
     licenses for which Corvis has quoted fees to Customer. With respect to
     changes, modifications, and substitutions which affect the form, fit,
     function, use or performance of an ordered Product, Corvis will notify
     Customer in writing [*] prior to their effective dates. In the event any
     such change is not desired by Customer, Customer will notify Corvis within
     [*] from the date of notice and Corvis will not furnish any such changed
     Products to Customer on any orders in process at the time Corvis is so
     notified. In no event will Corvis change the form, fit, function, use or
     performance of any Product if such change causes the Product not to conform
     to the Technical Requirements, except to the extent such change conforms to
     changes in network telecommunications standards generally accepted in the
     industry.

          Corvis may discontinue any Product or Software version if Corvis gives
     Customer at least [*] notice thereof. In such event, Corvis will provide
     Customer with a suggested product replacement at the same time for the
     remainder of the term of this Agreement. Customer will have the right to
     substitute the replacement product for the Product under this Agreement, at
     a price to be negotiated by the parties. [*] Customer may give a last order
     ("One Time Buy Order") immediately prior to the end of the [*] period. The
     One Time Buy Order is non-cancelable, non-reschedulable and non-returnable;
     except as otherwise provided in this Agreement. Products ordered with the
     One Time Buy Order will be delivered to Customer as requested by Customer
     but no later than [*] after the notice of discontinuance.

     14.2  Class Changes.

           (a)  After Corvis Equipment has been shipped to Customer, if Corvis
           issues a Class A Change or Class B Change, or where modification to
           correct an error in

                                       11
<PAGE>

 Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

           Documentation is to be introduced, Corvis will promptly notify
           Customer of such change through Corvis' designated notification
           procedure ("Change Notification"). Corvis will promptly provide, or
           cause the respective manufacturer to provide, to Customer any changes
           comparable to Class A and Class B Changes to the extent they are made
           available by manufacturers with respect to Vendor Items sold to
           Customer by Corvis; it being understood that the respective
           manufacturers of the Vendor Items may not provide such changes for
           the same period of time for which Corvis is obligated to provide
           Class A and Class B changes.

           (b)  Corvis will, [*], furnish the parts and documentation necessary
           for Customer to implement such Class A Change if it is issued within
           the Product Life for the applicable Product.

           (c)  In any of the instances above, if Corvis determines that the
           Equipment or part thereof subject to such change is readily
           returnable (e.g. plug-in items), Customer, at its expense, will
           remove and will return such Equipment or part to Corvis' facility and
           Corvis, [*], will implement such change at its facility and return
           such changed Equipment or part to Customer's designated location.
           Reinstallation will be performed by Customer at its expense.

           (d)  Corvis' undertaking under this Section 14 with respect to Vendor
           Items is limited to the extent changes comparable to Class A Changes
           are provided by the respective manufacturers of Vendor Items.

           (e)  If Customer does not make or permit Corvis to make a Class A
           Change Notification within [*] after the date of the related Change
           Notification, or a Class B Change within [*] after the date of the
           related Change Notification, subsequent changes, repairs, or
           replacements affected by the failure to make such change may, at
           Corvis' option, be billed to Customer whether or not such subsequent
           change, repair, or replacement is covered under warranty.

           (f)  If Corvis or any applicable manufacturer of a Vendor Item issues
           a Class B Change (or comparable change in the case of such
           manufacturer) after Equipment has been shipped to Customer, Corvis
           will promptly notify Customer of such change if it is being generally
           offered to Corvis' customers. When a Class B Change is requested by
           Customer, billing will be at Corvis' applicable prices or the
           respective manufacturer's then current prices to Corvis, as the case
           may be. Notwithstanding the above, there will be [*] for any Class B
           Change (or, in the case of a Vendor Item, a comparable change) if
           such change is included in the Maintenance or Support Services then
           in effect pursuant to the terms of this Agreement.

                                       12
<PAGE>

 Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

     14.3  Corvis reserves the right to discontinue any product that is a
     Product under this Agreement if Customer has not ordered any of that
     Product for [*]. Corvis will provide [*] notice for Products being
     discontinued.

     14.4  Corvis reserves the right to develop, manufacture and market Products
     incorporating new features, functionality, or performance characteristics
     identified as a result of its relationship with Customer. Customer
     acknowledges that such Products will be the sole and exclusive property of
     Corvis.

ARTICLE 15.  PROPRIETARY INFORMATION.

     15.1  Each party acknowledges the other party's ownership of trade secrets,
     proprietary or confidential information, including but not limited to
     products, planned products, services or planned services, the identity of
     or information concerning customers or prospective customers, data,
     financial information, computer software, processes, methods, knowledge,
     inventions, ideas, marketing promotions, discoveries, current or planned
     activities, research development or other information relating to the other
     party's business activities or operations and those of its customers or
     subcontractors, as well as the pricing and other terms and conditions of
     this Agreement (collectively referred to hereinafter as the "Proprietary
     Information").

     15.2  (a)  This Agreement creates a confidential relationship between
           Customer and the Corvis and, in the course of, negotiating or
           performing this Agreement, including providing Products pursuant to
           this Agreement, the disclosing party may disclose Proprietary
           Information to the receiving party. The receiving party will keep
           Proprietary Information confidential and, except as directed or
           authorized in writing, will use Proprietary Information only to
           provide the Products and services pursuant to this Agreement and will
           not disclose to any person or entity, directly or indirectly, in
           whole or in part, any Proprietary Information, information prepared
           from Proprietary Information, or information that comes into
           possession by reason of services hereunder. Dissemination of
           Proprietary Information will be limited to the personnel within the
           receiving party's organization with a need to know and solely for the
           purpose of the performance of duties hereunder. Upon cessation of
           work hereunder, the receiving party will return or destroy and
           certify to the disclosing party such destruction of all documents,
           papers and other materials in its control that contain or relate to
           Proprietary Information. To the extent practicable all proprietary
           information disclosed to the receiving party will be promptly
           identified as such [*].

           (b)  The receiving party will protect the Proprietary Information
           from unauthorized use or disclosure by exercising the same degree of
           care that it uses with respect to information of its own of a similar
           nature, but in no event less than reasonable care.

                                       13
<PAGE>

 Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

     15.3  Customer acknowledges and agrees that the Products constitute and
     embody the valuable trade secrets and intellectual property of Corvis
     developed at great expense to Corvis. Customer may not sell, assign or
     otherwise transfer any of the Products to a third party other than a
     telecommunications carrier for its own internal use in providing
     telecommunication services, without the prior written consent of Corvis,
     which consent will not be unreasonably withheld. Customer agrees that it
     would be reasonable for Corvis to withhold its consent to any such sale,
     assignment or transfer of any Product to a company involved in the
     development, marketing, distribution or sale of any products that are
     competitive with the Products.

     15.4  Notwithstanding anything to the contrary contained herein, no
     information will be deemed Proprietary Information if the party receiving
     such information hereunder or any of its Affiliates ("Receiving Party") can
     demonstrate that such information: (a) is generally known to the public on
     the date of disclosure of same or becomes generally known to the public
     after such date through no breach of this Agreement or any other obligation
     of confidentiality; (b) was known by the Receiving Party without any
     obligation to hold it in confidence at the time of disclosure; (c) is
     received by the Receiving Party after the date of disclosure by the other
     party or any of its affiliates ("Disclosing Party") from a third party
     without breach of any obligation of confidentiality and without any
     obligation of confidentiality binding upon the Receiving Party; (d) is
     independently developed by the Receiving Party after the date of disclosure
     by employees without access to Proprietary Information of the Disclosing
     Party; (e) is approved for release by written authorization of the
     Disclosing Party, but only to the extent of and subject to such conditions
     as may be imposed in such written authorization; (f) is required by law,
     rule or regulation, including requirements of the applicable securities
     exchanges, to be disclosed, but only to the extent and for the purposes of
     such required disclosure and subject to Section 15.5; or (g) is disclosed
     in response to a valid order of a court or other governmental body, but
     only to the extent of and for the purposes of such order and subject to
     Section 15.5.

     15.5  If a Receiving Party is or may be required by law or court order to
     disclose any Proprietary Information of a Disclosing Party, such Receiving
     Party: (a) will provide to such Disclosing Party immediate notice of such
     possible disclosure; and (b) will permit such Disclosing Party, at its
     expense, to take all reasonable actions to eliminate such requirement of
     such disclosure, to limit the scope of same and to obtain protective orders
     to protect the confidentiality of such Proprietary Information, including,
     without limitation, filing motions and otherwise making appearances before
     the court.

     15.6  The provisions of this Article 15 will survive any termination or
     expiration of this Agreement.

                                       14
<PAGE>

 Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

ARTICLE 16.   WARRANTIES, AND WARRANTY EXCLUSIONS AND LIMITATIONS.

     16.1  Corvis warrants, to Customer only, that (i) for the applicable
     warranty period set forth in Attachment 16.1 ("Warranty Period") and
     subject to the support limitations set forth in Attachment 19, the Corvis
     Equipment and Software (as applicable) will be free from defects in
     material and workmanship, will conform in all material respects to its
     Technical Requirements, (ii) upon delivery, the Equipment will be free from
     all liens and encumbrances, and (iii) Corvis' Services will be performed in
     a workmanlike manner and in accordance with good usage and accepted
     practices in the community in which services are provided. With respect to
     any Third Party Software or any Equipment furnished by Corvis but neither
     manufactured by Corvis nor purchased by Corvis pursuant to its procurement
     specifications (e.g., items such as personal computers and products offered
     as accessories to the Corvis Products) ("Vendor Items"), Corvis does hereby
     assign to Customer the warranties given to Corvis by its vendor(s) of such
     Vendor Items to the fullest extent permitted by such warranties.

     16.2  With respect to Products repaired or replaced during the applicable
     Warranty Period, Corvis warrants, for a period equal to the greater of (i)
     the remaining unexpired portion of such Warranty Period, or (ii) [*] from
     the date the repair is effected, in the case of Products repaired at the
     installation site, and from the date a replacement is shipped to Customer,
     in the case of defective Products that are replaced, that such Products
     will satisfy and perform in accordance with the warranty set forth in
     clause (i) in Section 16.1, throughout such time period.

     16.3  Corvis will continue to make available for purchase by Customer
     repair parts for Corvis' Products furnished pursuant to this Agreement so
     long as Corvis is manufacturing or stocking such equipment or repair parts,
     but in no event less than the Product Life for the Product.

     16.4  Corvis may use either new or remanufactured, reconditioned or
     refurbished Equipment or parts if in like-new condition, or functionally
     equivalent Equipment or parts (at equivalent or comparable prices) in the
     furnishing of repairs or replacements under this Agreement. Corvis will
     have appropriate safeguards and systems in place to assure that parts
     previously determined to be defective are not reused unless they have been
     proven to be in compliance with applicable specifications.

     16.5  Corvis warrants that it has good marketable title to the Equipment,
     that it has the full power and authority to grant the license granted
     Customer under this Agreement with respect to the Licensed Software, and to
     Corvis' knowledge, neither the license to nor use by Customer of the
     Licensed Software or Equipment, as permitted under this Agreement, will
     constitute an infringement or other violation of any copyright, patent,
     trade secret, trademark, non-disclosure, or any other intellectual property
     right of any third party.

                                       15
<PAGE>

 Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

     16.6  THE FOREGOING WARRANTIES IN THIS ARTICLE 16 ARE THE EXCLUSIVE
     WARRANTIES WITH RESPECT TO ANY OF THE PRODUCTS OR SERVICES PROVIDED
     HEREUNDER, AND ARE IN LIEU OF ALL OTHER EXPRESS AND IMPLIED WARRANTIES,
     INCLUDING BUT NOT LIMITED TO WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     A PARTICULAR PURPOSE. CUSTOMER'S SOLE AND EXCLUSIVE REMEDY WILL BE CORVIS'
     OBLIGATION TO REPAIR OR REPLACE OR, SUBJECT TO THE CONDITIONS STATED IN
     THIS ARTICLE 16 AND IN ARTICLE 18, TO CREDIT OR REFUND AS SET FORTH SECTION
     18.1.

     16.7  In the event that Customer (i) makes any unauthorized modifications
     to the Equipment or Software, or (ii) uses the Equipment or Software in the
     core optical network in connection with any other equipment or software not
     approved by Corvis, the Equipment and Software warranty will be voided with
     respect to the Equipment or Software modified or used with unapproved
     equipment or software. Corvis and Customer agree to cooperate to plan the
     configuration of Customer's network to optimize its efficiency.

     16.8  Corvis makes no warranty with respect to defective conditions or non-
     conformities resulting from the following: Customer (including third
     parties contracted by Customer) modifications, misuse, neglect, accident or
     abuse; improper wiring, repairing, splicing, alteration, installation,
     storage or maintenance by Customer (or third parties contracted by
     Customer); use in a manner not in accordance with the applicable
     specifications, or operating instructions or failure of Customer to apply
     previously applicable Corvis' modifications or corrections. In addition,
     Corvis makes no warranty with respect to Products which have had their
     serial numbers or month and year of manufacture removed, altered and with
     respect to expendable items. Corvis makes no warranty with respect to
     defects related to Customer's database errors. Moreover, no warranty is
     made that Software will run uninterrupted or error free.

     16.9  Customer agrees not to use any third party equipment or software in
     connection with the Corvis Equipment and Software other than to the [*]
     interfaces of the Corvis [*] and [*] modules, the [*] and order wire
     interfaces, or to the network management interfaces provided on the Corvis
     Equipment and Software. Customer shall pay Corvis a right to use annual
     license fee equal to [*] of the current price of the Corvis products
     equivalent to any third party equipment or software used in connection with
     Corvis Equipment and Software other than in a manner set forth above.
     Customer represents and warrants that the Products are being acquired
     hereunder for Customer's internal use and not for resale to any third
     party.

ARTICLE 17.  REPRESENTATIONS AND OTHER WARRANTIES.

                                       16
<PAGE>

 Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

     17.1  Each party represents and warrants that it is duly organized,
     existing and in good standing under the laws of its State of organization,
     and is duly qualified as a foreign corporation and in good standing in all
     jurisdictions in which the failure to so qualify would have a materially
     adverse impact upon its business and assets.

     17.2  Each party represents and warrants that it has the corporate power
     and requisite authority to execute, deliver and perform this Agreement, any
     Escrow Agreement entered into pursuant to this Agreement, and all Purchase
     Orders to be executed pursuant to or in connection with this Agreement, and
     that it is duly authorized to, and has taken all corporate action necessary
     to authorize, the execution, delivery and performance of this Agreement and
     such other agreements and documents.

     17.3  Each party represents and warrants that neither the execution and
     delivery of this Agreement and the agreements or documents stated in
     Section 17.2 above executed by it pursuant to or in connection with this
     Agreement, nor the consummation of any of the transactions herein or
     therein contemplated, nor compliance by it with the terms and provisions
     hereof or with the terms and provisions thereof will (i) contravene or
     materially conflict with any provision of applicable law to which it is
     subject or any judgment, license, order or permit applicable to it, or any
     indenture, mortgage, deed of trust, or other agreement or instrument to
     which it is a party or by which it or its property may be bound, or to
     which it or its property may be subject, (ii) violate any provision of its
     articles of incorporation or bylaws or partnership agreement, if any or
     (iii) require the consent or approval of, the giving of notice to, or the
     registration, recording or filing of any document with, or the taking of
     any other action in respect of, any person, entity or governmental agency.

     17.4  Each party represents and warrants that this Agreement and the
     agreements or documents stated in Section 17.2 above executed by it
     pursuant to or in connection with this Agreement will constitute when
     executed in full the legal, valid and binding obligations of said party,
     enforceable in accordance with their respective terms, subject to
     applicable bankruptcy, insolvency, reorganization, fraudulent transfer,
     moratorium or similar laws affecting the enforcement of creditors rights
     generally and to general principles of equity.

ARTICLE 18.  REMEDIES AND LIMITATIONS.

     18.1  If, under normal and proper use (i.e., as approved by Corvis or as
     provided in the applicable Technical Requirements) any Product fails to
     conform to the warranty specified in Article 16 during the applicable
     Warranty Period, Corvis will promptly repair or replace, at its option and
     expense, all such defective or nonconforming Product so as to cause it to
     satisfy, and perform in accordance with, its applicable Technical
     Requirements. If Corvis cannot repair or replace such Product, it will
     provide a refund or credit for the original purchase price or license fee
     paid by Customer for such Product. If Corvis' installation

                                       17
<PAGE>

 Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

     services prove not to be performed as warranted, within a [*] period
     commencing on the date of Acceptance of the Services, Corvis, at its
     option, either will correct the defect or non-conforming Services or render
     a full or pro-rated refund or credit based on the original charges for the
     Services. No Product will be accepted for repair or replacement without the
     written authorization of and in accordance with reasonable instructions of
     Corvis. Removal and reinstallation expenses as well as transportation
     expenses associated with returning such Product to Corvis for readily
     returnable Products (e.g., plug-in items) will be borne by Corvis only if
     Corvis performed improper installation services necessitating such removal
     and reinstallation. Corvis will [*] of the repaired or replaced Product to
     the destination designated by Customer. In repairing or replacing any
     Equipment or Software medium under this warranty, Corvis may use either new
     Products or parts or remanufactured, reconditioned or refurbished Products
     or parts if in like-new condition or functionally equivalent Products or
     parts. Replaced Products or parts will be retained by Corvis and become
     Corvis' property. Replacement Products or parts become the property of
     Customer.

     18.2  In the event Customer returns Products for repair that are not
     defective, Corvis may require that Customer pay with respect to any
     subsequently returned Products which prove not to be defective a fee which
     reflects Corvis' cost of handling, inspecting and testing and, if
     applicable, travel and related expenses by Corvis' employees.

     18.3  The parties acknowledge that disclosure of any Proprietary
     Information other than as allowed by Articles 12 or 15 may give rise to
     irreparable injury and may be inadequately compensable in monetary damages
     and therefore the non-disclosing party will be entitled to seek and to
     obtain injunctive or other equitable relief against the breach or
     threatened breach of the obligations of said Articles 12 or 15, in addition
     to any other remedies which may be available.

     18.4  The remedies available to either party under this Agreement are
     cumulative. The exercise of any one remedy will not be deemed an election
     of such remedy to the exclusion of other remedies; and the rights and
     remedies of the parties as set forth in this Agreement are not exclusive
     and are in addition to any other rights and remedies available to it at law
     or in equity.

     18.5  EXCEPT FOR CORVIS' INDEMNITY OBLIGATIONS SET FORTH IN ARTICLES 21 AND
     22, ANYTHING IN THIS AGREEMENT TO THE CONTRARY NOTWITHSTANDING, (I) THE
     MAXIMUM AGGREGATE AMOUNT THAT CUSTOMER WILL BE PERMITTED TO RECOVER BECAUSE
     OF A DEFECTIVE PRODUCT OR DEFICIENT SERVICE WILL NOT EXCEED THE NET PRICE
     OF SUCH PRODUCT OR SERVICE INVOICED TO CUSTOMER, AND (II) CORVIS' LIABILITY
     TO CUSTOMER UNDER THIS AGREEMENT OR IN CONNECTION WITH ANY OTHER MATTERS
     WILL NOT EXCEED IN THE AGGREGATE NET PRICE PAID TO CORVIS UNDER THIS
     AGREEMENT DURING THE [*] PRECEDING THE EVENT GIVING RISE TO SUCH LIABILITY.

                                       18
<PAGE>

 Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

     18.6  NOTWITHSTANDING ANY OTHER PROVISION OF THIS AGREEMENT, CORVIS AND ITS
     AFFILIATES, AND THEIR DIRECTORS, EMPLOYEES AND AGENTS WILL NOT BE LIABLE
     FOR ANY INCIDENTAL, INDIRECT, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
     OR LOST PROFITS, REVENUES OR SAVINGS ARISING OUT OF THIS AGREEMENT, OR THE
     USE OR PERFORMANCE OF ANY PRODUCT OR SERVICES, WHETHER IN AN ACTION FOR OR
     ARISING OUT OF BREACH OF CONTRACT, TORT, INCLUDING NEGLIGENCE, INDEMNITY OR
     STRICT LIABILITY. THIS PARAGRAPH WILL SURVIVE FAILURE OF AN EXCLUSIVE OR
     LIMITED REMEDY. THE FOREGOING WILL NOT BE DEEMED TO LIMIT CORVIS' INDEMNITY
     OBLIGATIONS UNDER SECTION 22.

     18.7  ANY ACTION OR PROCEEDING BY EITHER PARTY UNDER THIS AGREEMENT MUST BE
     BROUGHT WITHIN [*] AFTER THE DATE SUCH PARTY KNOWS OR SHOULD HAVE KNOWN
     THAT SUCH CAUSE OF ACTION HAS ACCRUED.

ARTICLE 19.  SUPPORT AND OTHER SERVICES.

     19.1  Customer will purchase the maintenance and support services
     ("Maintenance and Support Services") identified in Attachment 19 for the
     Products. Customer may purchase additional maintenance and support services
     at Corvis prevailing time and materials rates, upon mutually agreeable
     terms.

ARTICLE 20.  INSURANCE.

     20.1  Corvis will procure and maintain, during the Term of this Agreement
     insurance in not less than the following amounts:

           (a)  Worker's Compensation insurance in accordance with the
           provisions of the applicable Workers' Compensation or similar law of
           the state with jurisdiction applicable to Corvis' personnel.

           (b)  Commercial General Liability, including Contractual Liability
           insurance with a coverage limit of not less than [*] dollars ($[*])
           combined single limit per occurrence for bodily injury or property
           damage liability

           (c)  If the use of any automobile is required by the Corvis or any
           third party acting on behalf of Corvis in the performance of this
           Agreement, Corvis will also obtain and maintain business auto
           liability insurance for the operation of all owned, non-owned and
           hired automobiles with a coverage limit of not less than [*] dollars

                                       19
<PAGE>

 Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

           ($[*]) combined single limit per accident for bodily injury or
           property damage liability.

     20.2  Corvis will deliver to Customer certificates of insurance
     satisfactory in form and content to Customer evidencing that all of the
     insurance required by this Agreement is in force, and that no policy may be
     canceled or materially altered without first giving Customer at least [*]
     days prior written notice.

ARTICLE 21.  INDEMNIFICATION.

     21.1  Corvis will be responsible for and agree to indemnify and hold
     harmless Customer from and against all losses, liabilities, demands,
     claims, actions, proceedings, suits and damages (including reasonable legal
     fees) for injury to persons or damage to tangible property to the extent it
     results directly from the intentional or negligent acts or omissions, or
     strict liability, of Corvis, its officers, agents, employees, or
     contractors.

     21.2  Customer will be responsible for and agrees to indemnify and hold
     harmless Corvis from and against all losses, liabilities, demands, claims,
     actions, proceedings, suits and damages (including reasonable legal fees)
     for injury, including death, to persons or damage to tangible property to
     the extent it results directly from the intentional or negligent acts or
     omissions, or strict liability, of Customer, its officers, agents,
     employees or contractors.

     21.3  With respect to each of Sections 21.1 and 21.2 above, the indemnified
     party will give the indemnifying party prompt written notice of all such
     claims, actions, proceedings or suits and the indemnifying party will have
     the sole defense thereof, including appeals, and the sole right to settle
     the same; provided, however, that the indemnifying party will not agree to
     any settlement which imposes liability or obligation on the indemnified for
     which the indemnified party is not fully indemnified without first
     obtaining the indemnified party's consent. The indemnified party will, upon
     the indemnifying party's request and at the indemnifying party's expense,
     furnish all relevant information available to the indemnifying party and
     cooperate and assist the indemnifying party in every reasonable way to
     facilitate the defense and/or settlement of any such claim, action,
     proceeding or suit.

ARTICLE 22.  PATENT, COPYRIGHT AND TRADE SECRET.

     22.1.  In the event of any claim, action, proceeding or suit by a third
     party against Customer alleging an infringement of any patent, copyright,
     or trademark, or a violation or misappropriation of any trade secret or
     other proprietary rights by reason of the purchase, license or use, in
     accordance with Corvis' specifications, of any Product (other than Third

                                       20
<PAGE>

 Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

     Party Software) furnished by Corvis to Customer under this Agreement,
     Corvis, at its expense, will defend Customer, subject to the conditions and
     exceptions stated below. Corvis will reimburse Customer for any reasonable
     cost, expense or attorneys' fees, which Customer is required to incur
     cooperating with Corvis at Corvis' request in the defense or settlement of
     such action. Corvis will indemnify Customer against any liability assessed
     against Customer by final judgment on account of such action, proceeding or
     suit. The foregoing indemnity with respect to patent, trademark and
     copyright infringement arising from Products sold or licensed for use in
     the United States or another designated country is limited to the patents,
     trademarks, and copyrights enforced under the laws of the United States or
     such other designated country, as applicable.

     22.2.  Corvis' obligation to indemnify Customer pursuant to this Article 22
     is contingent upon (i) Customer giving Corvis prompt written notice of all
     such claims, actions, proceedings or suits alleging infringement or
     violation, (ii) Customer tendering to Corvis full and complete authority to
     assume the sole defense thereof, including appeals, and the sole right to
     settle same, and (iii) Customer furnishing to Corvis all relevant
     information available to Customer and cooperating with and assisting Corvis
     in every reasonable way to facilitate the defense and/or settlement of any
     such claim, action, proceeding or suit.

     22.3.  If Customer's use is enjoined or in Corvis' opinion is likely to be
     enjoined, Corvis will, at its expense and at its option, either (1) replace
     the enjoined Product furnished pursuant to this Agreement with a suitable
     substitute free of any infringement, provided such substitute has
     comparable functionality and performance characteristics; (2) modify it so
     that it will be free of the infringement, provided such modification does
     not result in a material degradation in performance or functionality; or
     (3) procure for Customer a license or other right to use it. If none of the
     foregoing options are available to Corvis on a commercially reasonable
     basis, Corvis will remove the enjoined Product, and refund to Customer any
     amounts paid to Corvis therefor less the amortized value of the Product(s)
     based on the applicable Product Life.

     22.4.  No undertaking of Corvis under this Article will extend to any such
     alleged infringement or violation to the extent that it: (1) arises from
     adherence to design modifications, specifications, drawings, or written
     instructions which Corvis is directed by Customer to follow; or (2) arises
     from adherence to instructions to apply Customer's trademark, trade name or
     other company identification; or (3) arises from a third party products,
     including any Third Party Software, furnished by Customer to Corvis for use
     under this Agreement; or (4) relates to uses of a Product provided by
     Corvis in combinations with other products furnished either by Corvis or
     Customer. In the foregoing cases numbered (1) through (4), Customer will
     defend and save Corvis harmless, subject to the same terms and conditions
     and exceptions stated above, with respect to the Corvis' rights and
     obligations under this Article. Corvis hereby assigns to Customer any
     rights which Corvis may have to indemnity from the original manufacturer
     with respect to any Vendor Item provided under this Agreement.

                                       21
<PAGE>

 Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

     22.5.  The liability of Corvis with respect to any and all claims, actions,
     proceedings or suits by third parties alleging infringement of patents,
     trademarks or copyrights or violation of trade secrets or other proprietary
     rights because of, or in connection with, any Products furnished pursuant
     to this Agreement will be limited to the specific undertakings contained in
     this Article.

ARTICLE 23.  TERMINATION.

     23.1   Either party may terminate this Agreement and any outstanding
     Purchase Order, in whole or in part, in the event of a default by the
     other, provided that the non-defaulting party so advises the defaulting
     party in writing of the event of alleged default and affords the defaulting
     party [*] within which to cure the default. Default is defined to include:

            (a)  Either party becomes insolvent, makes a general assignment for
            the benefit of creditors, files a voluntary petition in bankruptcy
            or an involuntary petition in bankruptcy is filed against such party
            which is not dismissed within [*] after the date such petition is
            filed, or suffers or permits the appointment of a receiver for its
            business, or its assets become subject to any proceeding under a
            bankruptcy or insolvency law, domestic or foreign, or has liquidated
            its business;

            (b)  Either party's material breach of any of the terms or
            conditions hereof;

            (c)  The execution by either party of an Assignment for the benefit
            of creditors or any other transfer or assignment of similar nature;
            or

            (d)  Termination by either party of the Transport Field Trial
            pursuant to Section 2.1(c).

     23.2   Neither the expiration of this Agreement according to its terms nor
     its termination under the provisions of Section 23.1 will prejudice any
     claim for any outstanding amount owed Corvis and Customer to each other,
     damages or any other rights or remedies that any party may have under this
     Agreement or at law or in equity or relieve any party from the duty to hold
     in confidence proprietary information and otherwise comply with, and
     exercise the rights set forth in, Articles or Sections 5.3, 6.1 (Right to
     Use Fee), 14.1, 15, 16, 18, 19, 20, 21, 22, 23, 24, 25, 26, and 28 hereof,
     each of which will survive such termination.

ARTICLE 24.  DISPUTE RESOLUTION.

                                       22
<PAGE>

 Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

     24.1   The parties will attempt in good faith to resolve promptly any
     controversy or claim arising out of or relating to this Agreement or any
     subsequent performance by the parties before resorting to other remedies
     available to them. Any such dispute will be referred to appropriate
     executives of each party who will have the authority to resolve the matter.
     If the executives are unable to resolve the dispute, the parties may by
     agreement refer the matter to an appropriate form of alternative dispute
     resolution such as mediation. If the parties cannot resolve the matter or
     if they cannot agree upon an alternative form of dispute resolution, then
     either party may pursue resolution of the matter through arbitration in
     accordance with the rules of the American Arbitration Association (the
     "AAA") applying the substantive law of the State of Delaware without regard
     to any conflict of laws provisions. The arbitration will be conducted by a
     panel of three (3) arbitrators selected in accordance with the rules of the
     AAA. Each arbitrator will be an attorney familiar with telecommunications
     technology and the telecommunications industry. The arbitration will be
     governed by the United States Arbitration Act, 9, U.S.C. Section 1, et.
     seq. and judgment upon the award rendered by the arbitrators may be entered
     by any court with jurisdiction. The arbitrators are not empowered to award
     damages in excess of compensatory damages, and each party waives any
     damages in excess of compensatory damages.

     24.2   Notwithstanding the foregoing, either party may bring a claim [*] as
     provided in Section 18.3 in any court of competent jurisdiction without
     first submitting the claim to arbitration.

ARTICLE 25.  NOTICE AND REPRESENTATIVES OF THE PARTIES.

     Any notice ("Notice") required or permitted under this Agreement must be
     given in writing to the address or facsimile number provided for a party
     below (or such other address or number as any party may provide to the
     other in writing in the manner contemplated hereby) and will be deemed
     effective as follows:

            (a)  if delivered in person or by courier, on the date it is
            delivered;

            (b)  if sent by facsimile transmission, on the date that the
            transmission is received by the recipient party in legible form;

            (c)  if sent by certified or registered mail or the equivalent
            (return receipt requested), on the date that mail is delivered or
            its delivery is attempted but acceptance is refused; unless the date
            and time of any delivery or receipt, as applicable, is not during
            normal working hours on a local business day, in which case Notice
            will be deemed given and effective on the first following day that
            is a local business day. For purposes hereof, a "local business day"
            is a business day in the city specified in the address for notice
            provided by the recipient.

     The Notices provided for by this Article 25 will be given to the following:

                                       23
<PAGE>

 Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

            If to Customer:

            Broadwing Communications Services Inc.
            ATTN:  Mike Guess, Vice President of Engineering
            1835-B Kramer Lane
            Austin, Texas 78758

            If to Customer:

            Broadwing Communications Services Inc.
            Attn:  Contract Administration
            Rm 102-260
            201 E. Fourth Street
            Cincinnati, OH 45202

            With a copy to:

            Broadwing Communications Services, Inc.
            Office of General Counsel
            1122 Capital Texas Highway South
            Austin, Texas 78746

            If to Corvis:

            Corvis Corporation
            ATTN:  General Counsel
            7015 Albert Einstein Drive
            PO Box 9400
            Columbia, Maryland 21046-9400
            Telephone:  443.259.4110

ARTICLE 26.  GENERAL

     26.1   Assignment.  Neither party to this Agreement may assign, transfer,
     pledge, encumber or hypothecate its interest in this Agreement or any of
     its rights hereunder or delegate its obligations hereunder without the
     prior written consent of the other party to this Agreement, which consent
     will not be unreasonably withheld, and any attempted assignment which does
     not comply fully with this Article 26.1 will be null and void.
     Notwithstanding the foregoing, (i) Customer may assign or sublicense its
     rights and obligations under Article 12 as provided in Section 12.1; and
     (ii) either Customer or Corvis may, upon prompt written notice, assign
     their respective rights and obligations pursuant to this Agreement to any
     Affiliate, as appropriate, or to their respective successors

                                       24
<PAGE>

 Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

     by consolidation or merger, or the transferee of substantially all of the
     assets of either, so long as Customer or Corvis, as appropriate, remains
     liable under this Agreement and in such event this Agreement will be
     binding upon and inure to the benefit of each such successor or transferee.

     26.2  Governing Law.  This Agreement will be construed in accordance with
     and governed by the law of the State of Delaware without regard to the
     conflict of law provisions of such state or any other jurisdiction.

     26.3  Laws and Regulations.  The parties hereby agree to comply with all
     local, municipal, state, federal, foreign, governmental and regulatory
     laws, orders, codes, rules and regulations that are applicable to their
     respective performance of this Agreement.

     26.4  Amendment.  Any provision of this Agreement, or any schedule, exhibit
     or rider hereto, may be amended only if such amendment is in writing and
     signed by all the parties hereto. Additions to the Corvis Products in
     Attachment 6 may be made by each party signing an additional Attachment 6
     page containing the following information: Corvis Product, Equipment
     Description, and Price.

     26.5  Waiver.  Any waiver or delay in the exercise by either party of any
     of its rights under this Agreement will not be deemed to prejudice such
     party's right of termination or enforcement for any further, continuing or
     other breach by the other party.

     26.6  Successors and Assigns.  The provisions of this Agreement will be
     binding upon and inure to the benefit of the parties hereto and their
     respective permitted successors and permitted assigns.

     26.7  Public Disclosures.  Neither party will issue or release for
     publication any materials relating to the existence of this Agreement, the
     Products or any services to be performed pursuant to this Agreement without
     the prior written consent of the other party, which consent will not be
     unreasonably withheld.

     26.8  Severability.  Whenever possible, each provision of this Agreement,
     as well as any schedule, exhibit or rider attached hereto, will be
     interpreted in such manner as to be effective and valid under applicable
     law, order, code, rule or regulation, but if any provision of this
     Agreement, as well as any schedule, exhibit or rider hereto, is held to be
     invalid, illegal or unenforceable in any respect under any applicable law,
     order, code, rule or regulation, such invalidity, illegality or
     unenforceability will not affect any other provision, schedule, exhibit or
     rider of this Agreement, but this Agreement, schedule, exhibit or rider
     will be reformed, construed and enforced in such jurisdiction as if such
     invalid, illegal or unenforceable provision, schedule, exhibit or rider had
     never been contained herein or attached hereto.

                                       25
<PAGE>

 Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

     26.9    Descriptive Headings.  The descriptive headings of this Agreement
     are inserted for convenience only and do not constitute a part of this
     Agreement.

     26.10   Counterparts. This Agreement may be executed in separate
     counterparts each of which will be an original and all of which taken
     together will constitute one and the same Agreement.

     26.11   Relationship of Parties.  Neither Corvis, its subcontractors,
     employees or agents will be deemed to be employees or agents of Customer,
     it being understood that Corvis, its subcontractors, employees or agents
     are independent contractors with respect to Customer for all purposes and
     at all times. This Agreement will not be construed as establishing a
     partnership or joint venture between Customer and Corvis.

     26.12   Supersession of PO.  The terms and conditions of this Agreement
     supersede any pre-printed terms and conditions on any Purchase Order, both
     front and back, unless otherwise agreed by the parties in writing. Any pre-
     printed terms or conditions on any Purchase Order, other than the ordering
     information required by this Agreement, will be of no force or effect
     whatsoever.

     26.13   Customer will comply with the export control laws and regulations
     of the United States with respect to the Products purchased under this
     Agreement

ARTICLE 27.  INCORPORATION OF DOCUMENTS.

             This Agreement hereby incorporates by reference the Attachments
     referred to herein. In the event of an inconsistency or conflict between or
     among the provisions of this Agreement, the inconsistency will be resolved
     by giving precedence in the following order:

             (1)  Agreement
             (2)  Attachments
             (3)  Purchase Orders (excluding any preprinted terms and
             conditions)

ARTICLE 28.  DEFINITIONS.

     "Affiliate" means, with respect to any entity, any other entity which
     controls, is controlled by, or under common control with, such entity; and
     "control" means ownership of a majority of the voting equity or similar
     rights of an entity.

                                       26
<PAGE>

 Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

     "Catastrophic Failure" means any event where/when a large amount of
     Customer equipment fails at a site or multiple sites thus rendering Corvis'
     Equipment to be inoperable due to Acts of God or acts not within Customer's
     control, and such repair of Equipment is beyond the normal repair and
     return or sparing capabilities established for routine maintenance. Such
     events will include but not be limited to floods, fires, malicious acts,
     vandalism and sabotage.

     "Change Notification" is defined in Section 14.2

     "Class A Change" means a modification of existing Corvis manufactured
     Equipment to remedy a non-conformance to Technical Requirements required to
     correct design defects of a type that results in electrical or mechanical
     inoperative conditions or unsatisfactory operating conditions, or which is
     recommended to enhance safety. Corvis will use standards consistent with
     its practices for all its customers in determining which modifications
     constitute Class A changes.

     "Class B Change" means an optional change, available to Customer at an
     additional cost, that provides Equipment enhancements resulting in new
     features or improved service capabilities to Corvis Equipment.

     "Committed Amounts" is defined in Section  4.3.

     "Designated Equipment" is defined in Article 12.

     "Documentation" with respect to any Product means Corvis' technical
     documentation and operating manuals for such Product.

     "Effective Date" is defined in the Preamble.

     "Equipment" or "Corvis Equipment" means the equipment that may be purchased
     from Corvis pursuant to this Agreement.

     "Final Deployment Date" is defined in Section 4.1.

     "Initial Deployment Shortfall" is defined in Section 4.2.

     "Initial Term" is defined in Section 7.

     "Licensed Software" means the Corvis software and third party software,
     each of which in machine-readable form, and subsequent Software upgrades,
     necessary to install, operate, and maintain the Products purchased or
     licensed by Customer pursuant to this Agreement.

     "Maintenance and Support Services" is defined in Section 19.

                                       27
<PAGE>

 Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

     "Net Price" means the final price paid by any Customer after all sales
     discounts, price reductions, sales rebates, volume discounts or similar
     adjustments of any kind are applied, whether under the original contract of
     purchase or any supplemental, separate, or complimentary transaction.

     "Network Element" means a material component of Corvis' fiber optic
     transmission system, including, but not limited to, optical amplifiers,
     optical routers, optical add-drop multiplexers or end nodes at given sites
     or nodes in the network.

     "Product Life" for each Product is as set out in Attachment 5.3.

     "Products" means Equipment and Software.

     "Proprietary Information" is defined in Section 15.1.

     "Purchase Order" means the document issued by Customer which identifies the
     Products and specifies the scope of work, quantities and dates for
     delivery, billing instructions, and any other necessary information.

     "Rolling Forecast" is defined in Section 4.3.

     "Services" means the services provided by Corvis to Customer as specified
     in a Purchase Order to the extent such Services are not included in the
     supply of other Products.

     "Software" refers to all the programs, computer languages, and operations
     used to make Equipment perform a useful function or used to enable human
     access to the Equipment for the purposes of installing, operating, or
     maintaining such Equipment

     "SONET" means a Synchronous Optical Network which adheres to the interface
     standard of the same name created by the Exchange Carriers Standards
     Association for the American National Standards Institute ("ANSI"), and
     promulgated by Bellcore on behalf of the Regional Bell Operating Companies.

     "Source Code" means all intellectual information including but not limited
     to Documentation, Software in human-readable form, flow charts, schematics
     and annotations which comprise the pre-coding detailed design
     specifications for Licensed Software (excluding Third Party Software).

     "Specified Site" is defined in Section 4.4.

     "System" means a configuration of Equipment with two (2) end terminals, any
     intermediate line amplifiers connected by fiber to the end terminals, all
     associated Software, which has the ability to communicate to an element
     management system such that traffic can be

                                       28
<PAGE>

 Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

     transmitted from end terminal to end terminal and operation can be
     monitored by the element management system.

     "Technical Requirements" means (i) the specifications set forth in
     appropriate industry standard telecommunications technical requirements
     where applicable or as such specifications may be most currently modified
     or amended pursuant to mutual agreement of the parties.

     "Third Party Software" means Software which is independently developed by a
     third party, sub-licensed to Customer under this Agreement or otherwise
     provided with the Products hereunder.

     "Transport Field Trial" is defined is Section 2.1.

     "Transport Field Trial Test Criteria" is defined in Section 2.1

     "Vendor Items" is defined in Section 16.1.

     "Warranty Period" is defined in Section 16.1.

ARTICLE 29.   ENTIRE AGREEMENT.

     This Agreement together with all Exhibits and Attachments constitutes the
     entire Agreement between Customer and Corvis with respect to the subject
     matter hereof and supersedes all prior agreements and understandings, both
     written and oral, between the parties with respect to such subject matter,
     and is not intended to confer upon any person other than the parties hereto
     any rights or remedies hereunder.

     IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be
executed by their duly authorized representatives as of the day and year below
written.

CORVIS CORPORATION                 BROADWING COMMUNICATIONS SERVICES INC.

/s/David R.  Huber

BY:  David R. Huber                BY:  /s/ Richard G. Ellenberger

TITLE:  President and CEO          TITLE: President, COO

                                       29
<PAGE>

 Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

DATE: March 20, 2000               DATE: March 17, 2000

                                   /s/ Michael R.  Jones
                                   Michael R.  Jones
                                   Sr.  Vice President
                                   Engineering

                                       30
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission.  Asterisks denote omissions.

                              LIST OF ATTACHMENTS
                              -------------------

Attachment 1.1   -   Laboratory System

Attachment 1.3   -   Estimated Project Schedule

Attachment 2     -   Transport Field Trial Equipment, Software, and Services
                     Pricing

Attachment 2.1   -   Transport Field Trial Configuration and Test Criteria

Attachment 5.3   -   Product Life

Attachment 6     -   Prices for Products and Services

Attachment 11.1  -   Corvis Training

Attachment 12.1  -   Third Party Software Licenses

Attachment 12.7  -   Escrow Agreement

Attachment 16.1  -   Warranty Period

Attachment 19    -   Maintenance and Support Services and Other Services

Attachment 28    -   Product Specifications
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
                Exchange Commission. Asterisks denote omissions.

                                  ATTACHMENT 1

                               LABORATORY SYSTEM
                               -----------------

<TABLE>
<CAPTION>
-----------------------------------------------------------------------------------------
Corvis Products & Services                                  Net    Units   Extended
                                                           Price            Price     [*]
-----------------------------------------------------------------------------------------
<S>                                                        <C>     <C>     <C>        <C>
Network Elements
   ONG-160 [*]                                               [*]     [*]        [*]   [*]
   OADM-160 [*]                                              [*]     [*]        [*]   [*]
   OA3200                                                    [*]     [*]        [*]   [*]
   OC [*] Tx/Rx Interfaces                                   [*]     [*]        [*]   [*]
   ONG-160 [*] RTUs                                          [*]     [*]        [*]   [*]
   OADM [*] RTUs                                             [*]     [*]        [*]   [*]
   OA3200  RTUs                                              [*]     [*]        [*]   [*]

NOC
   CorManager NOC Equipment SUN 450                          [*]     [*]        [*]   [*]
   CorManager Applications Software                          [*]     [*]        [*]   [*]
   CorManager Annual Maintenance                             [*]     [*]        [*]   [*]
   CorManager Installation                                   [*]     [*]        [*]   [*]

Corvis CorManager Services
   Engineering, Installation, System Turn-Up and Test        [*]     [*]        [*]   [*]
   Training (per [*] Day Course)                             [*]     [*]        [*]   [*]
   Remote TAC (per Hour)                                     [*]     [*]        [*]   [*]
   On-Site Technical Support (per Day)                       [*]     [*]        [*]   [*]
   Documentation                                             [*]     [*]        [*]   [*]

-----------------------------------------------------------------------------------------
Total Extended Price                                                            [*]
-----------------------------------------------------------------------------------------
Total                                                                                 [*]
-----------------------------------------------------------------------------------------
</TABLE>
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission.  Asterisks denote omissions.

                                ATTACHMENT 1.3

                          ESTIMATED PROJECT SCHEDULE
                          --------------------------

<TABLE>
<CAPTION>
---------------------------------------------------------------------------------------------------------
          Event                       Date            Location                  Objective
---------------------------------------------------------------------------------------------------------
<S>                          <C>                      <C>        <C>
CUSTOMER                     Installation complete:   CUSTOMER   Install, test and turn-up trial system.
Laboratory System            [*]
Installed, Tested And        Test and Turn-up: [*]
Turned-Up
---------------------------------------------------------------------------------------------------------
CUSTOMER Field Trial         Commence shipment:       CUSTOMER   Install field trial system.  Delivery of
System Installation          [*]                                 equipment for field trial installation.
                             Test and Turn-up
                             Complete: [*]
---------------------------------------------------------------------------------------------------------
Formal CUSTOMER              Commencing [*]           CUSTOMER   Evaluate the Corvis system.
Field Trial Evaluation
---------------------------------------------------------------------------------------------------------
</TABLE>
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission.  Asterisks denote omissions.

                                 ATTACHMENT 2

        TRANSPORT FIELD TRIAL EQUIPMENT, SOFTWARE, AND SERVICES PRICING
        ---------------------------------------------------------------

<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission.  Asterisks denote omissions.

[*] to [*] Transport Field Trial Pricing

The Corvis CorWave(TM) Transport Field Trial system configuration is activated
with [*] circuits. All required Network Elements, , NOC network management,
engineering & installation, and documentation prices and configurations for the
Transport Field Trial system is outlined in the following table.

<TABLE>
<CAPTION>
-----------------------------------------------------------------------------------------
Corvis Products & Services                                  Net    Units   Extended
                                                           Price            Price     [*]
-----------------------------------------------------------------------------------------
<S>                                                        <C>     <C>     <C>        <C>
Network Elements
   ONG-160 [*]                                               [*]    [*]         [*]   [*]
   OADM-160 [*] (previously OADM-E)                          [*]    [*]         [*]   [*]
   OA3200                                                    [*]    [*]         [*]   [*]
   OC [*] Tx/Rx Interfaces                                   [*]    [*]         [*]   [*]
   ONG-160 [*] 6 RTUs                                        [*]    [*]         [*]   [*]
   OADM [*] RTUs                                             [*]    [*]         [*]   [*]
   OA3200  RTUs                                              [*]    [*]         [*]   [*]

NOC
   CorManager NOC Equipment SUN 450                          [*]    [*]         [*]   [*]
   CorManager Applications Software                          [*]    [*]         [*]   [*]
   CorManager Annual Maintenance                             [*]    [*]         [*]   [*]
   CorManager Installation                                   [*]    [*]         [*]   [*]

Corvis CorManager Services
   Engineering, Installation, System Turn-Up and Test        [*]    [*]         [*]   [*]
   Training (per [*] Day Course)                             [*]    [*]         [*]   [*]
   Remote TAC (per Hour)                                     [*]    [*]         [*]   [*]
   On-Site Technical Support (per Day)                       [*]    [*]         [*]   [*]
   Documentation                                             [*]    [*]         [*]   [*]

-----------------------------------------------------------------------------------------
Total Extended Price                                                            [*]
-----------------------------------------------------------------------------------------
Total                                                                                 [*]
-----------------------------------------------------------------------------------------
</TABLE>
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission.  Asterisks denote omissions.

                                  ATTACHMENT 2

             TRANSPORT FIELD TRIAL CONFIGURATION AND TEST CRITERIA
             -----------------------------------------------------

[*] to [*] Field Trial Summary

The Corvis CorWave(TM) product is used to establish a Field Trial system that
spans from [*] to [*]. The Field Trial system is configured in a [*]
configuration, shown in the following figure. Optical Network Gateways (ONGs)
are located in [*] and [*]. These ONGs are connected through [*] Optical Line
Amplifiers (OLAs) and an Optical Add/Drop Multiplexer (OADM), located in [*].
The initial configuration supports [*].

                   [Diagram of [*] to [*] field trial system
                   overlayed on a map of the United States]
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission.  Asterisks denote omissions.

Transport Field Trial Responsibilities

Corvis will conduct site surveys, fiber plant qualification, equipment
installation, equipment testing and turn-up, fiber splicing within the Broadwing
equipment rooms and limited on-site training at no charge.  Corvis is planning
to provide the appropriate number of installation and testing teams to support
the system. Corvis will deliver, install, test and turn-up the system as
outlined in the Master Project Schedule.

Broadwing agrees to a joint press release announcing the strategic partnership
with Corvis starting with the Corvis CorWave(TM) Field Trial.

Transport Field Trial Test Criteria

   Network Operations

 .  Gain Flatness/Gain Profile
   Demonstrates the spectral profile at points throughout the system. Signal
   amplitudes remain level after passing through many amplifiers for normal
   operating mode.

 .  End-to-End Jitter Test
   Demonstrates system meets Telcordia Jitter specs. (Transfer, Tolerance and
   Generation) at [*] reach interfaces.

 .  Eye Mask Test
   Verify Eye mask at Corvis Rx module (customer [*] Tributary  Side).

 .  Adjacent Channel Crosstalk ([*])
   [*] Monitor BER [*]. Drop and restore traffic [*] and verify no change in BER
   [*].

 .  FEC Error Correction Verification Test
   Demonstrates FEC circuitry functionality at the System level.

 .  Wavelength Accuracy & Control of Tx Channels
   Verifies the wavelength control of the laser diodes in the Tx module.
   Verifies the control loop [*] that maintains wavelength accuracy.

   Dynamic Performance

 .  [*] OSNR
   Demonstrates minimum system OSNR where system can maintain [*]. Also
   demonstrates system margin by measuring difference between nominal OSNR and
   minimum OSNR [*].

 .  [*] Gain Flattening
   [*] Input power is adjusted (increased or decreased) for a particular span on
   the network with the [*] or through other internal means. The [*] operator
   monitors the [*] and [*] data throughout the span to view increases and
   decreases in parameter values.

 .  [*]([*] Interface) Sensitivity Test
   Demonstrates the rapid response and settling time of the system as [*] data
   channels are [*] at the [*]. [*] Also measure BER during test to verify that
   no bit errors occur [*].
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission.  Asterisks denote omissions.

 .  [*] Dynamic Range Characterization
   Typically, channel assignments are performed using the Corvis Wave Planner
   (CWP) and the Corvis Provisioning tool (CPT). The CEI application also
   provides technicians with the ability to [*]. This test verifies the CEI
   application and the CPT application can be used to [*]. The test sequence
   will include first [*] at the receiver ONG and then [*] at the transmitter
   ONG to avoid unnecessary [*] alarms generated by the receiver. The test will
   also verify that CEI and CPT users with the appropriate privileges may [*].

   Network Provisioning

 .  ONG Channel [*]
   This test verifies the CEI application and the CPT application can be used to
   [*].

   Fault Management

 .  Fiber Cut/Eye Safety Test
   Fiber cuts may occur between Line Amplifiers and a GNE (Gateway Node Element)
   or between Line Amplifiers. This test verifies that when a fiber cut occurs,
   different alarms are generated by different NEs. All affected network
   elements generate the appropriate alarms and go into eye safety shutdown
   mode.

 .  Failed Data Communication Network
   The CEM monitors the status of the DCN. If a failure is detected, then an
   alarm is generated by the CEM. This test verifies that an alarm is generated
   when a DCN failure occurs

 .  Failed CPM
   Each rack contains a [*] CPM [*]. When the [*] CPM fails,[*] and [*] has the
   Ethernet connection to be able to take over that communication. Therefore,
   the CEM [*]. If a [*] fails, the CEM detects the failure alarm, but the NE is
   still able to communicate with the CEM. Based on the type of failure, either
   a technician replaces it with a new CPM card or a new software module is
   downloaded.
   Under both conditions the other modules in the shelf should continue to work
   properly.

 .  Pump Failure
   Demonstrates the system's ability to [*] for various Amplifier pump failures
   in a span. Also demonstrates the capability of the firmware/software to
   report the appropriate alarms to the CEM operator in the event of a
   catastrophic pump module failure.

 .  Tx Failure
   Failure of a Transmitter (Tx) Module causes the next [*] down the span [*] to
   generate a loss of input alarm. The CEM receives the alarm and notifies the
   operator. The CEM will also receive the alarm from the module's [*]
   indicating that the module has failed. This test verifies that the
   appropriate alarms are generated when a Transmitter Module fails.
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission.  Asterisks denote omissions.

   Operations
   ----------

 .  Environmental Control Unit
This test case verifies the functionality of the Environmental Control Unit
(ECU), which includes fan control, electrical power and breaker monitoring, and
the output relays.  The test will also demonstrate the Corvis Rack can operate
with [*] disabled for at least [*] at normal operating temps.

 .  [*]
Demonstrate functional orderwire and [*] link of the [*].

 .  Module Hot Swap Tests
Demonstrates the systems ability to hot swap various modules [*] without
interrupting service or system performance.
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

                                ATTACHMENT 5.3

                                 PRODUCT LIFE
                                 ------------

                The Product Life for each Product is [*] years.
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

                                 ATTACHMENT 6

                       PRICES FOR PRODUCTS AND SERVICES
                       --------------------------------

<TABLE>
<CAPTION>
---------------------------------------------------------------------------------------------------------------------
     CORVIS Product                                    Equipment Description                               Unit Price
---------------------------------------------------------------------------------------------------------------------
<S>                         <C>                                                                            <C>
ONG160/[*]                  Optical Network Gateway with support for up to [*] Gbps of capacity (any              [*]
                            combination of OC-48/192) Channels. Includes:  ONG, Racks, Tx/Rx Shelves,
                            NE Firmware, Power Supplies
---------------------------------------------------------------------------------------------------------------------
ONG160/[*]                  Optical Network Gateway with support for up to [*] Gbps of capacity (any              [*]
                            combination of OC-48/192).  Includes:  ONG, Racks, Tx/Rx Shelves, NE
                            Firmware, Power Supplies
---------------------------------------------------------------------------------------------------------------------
ONG160/[*]                  Optical Network Gateway with support for up to [*] Gbps of capacity (any              [*]
                            combination of OC-48/192).  Includes:  ONG, Racks, Tx/Rx Shelves, NE
                            Firmware, Power Supplies
---------------------------------------------------------------------------------------------------------------------
ONG160/[*]                  Optical Network Gateway with support for up to [*] Gbps of capacity (any              [*]
                            combination of OC-48/192). Includes:  ONG, Racks, Tx/Rx Shelves, NE
                            Firmware, Power Supplies
---------------------------------------------------------------------------------------------------------------------
ONG160/[*]                  Optical Network Gateway with support for up to [*] Gbps of capacity (any              [*]
                            combination of OC-48/192). Includes:  ONG, Racks, Tx/Rx Shelves, NE
                            Firmware, Power Supplies
---------------------------------------------------------------------------------------------------------------------
ONG160/[*]                  Optical Network Gateway with support for up to [*] Gbps of capacity (any              [*]
                            combination of OC-48/192). Includes:  ONG, Racks, Tx/Rx Shelves, NE
                            Firmware, Power Supplies
---------------------------------------------------------------------------------------------------------------------
ONG RTUs                    Optical Network Gateway Right to Use:  Corvis CorManager ONG-160 Node                 [*]
                            Software
---------------------------------------------------------------------------------------------------------------------
OADM-[*]                    Optical Add/Drop Mux with [*] capacity support for OC48.  Includes:                   [*]
                            Optical Amplifier, OADM, Racks, NE Firmware, Power Supplies
---------------------------------------------------------------------------------------------------------------------
OADM-[*]                    Optical Add/Drop Mux with [*] capacity support up to [*] Gbps of capacity             [*]
                            (any combination of OC-48/192). Includes:  Optical Amplifier, OADM, Racks,
                            Tx/Rx Shelves, NE Firmware, Power Supplies
---------------------------------------------------------------------------------------------------------------------
OADM-[*]                    Optical Add/Drop Mux with [*] capacity support up to [*] Gbps of capacity             [*]
                            (any combination of OC-48/192). Includes:  Optical Amplifier, OADM, Racks,
                            Tx/Rx Shelves, NE Firmware, Power Supplies
---------------------------------------------------------------------------------------------------------------------
OADM-[*]                    Optical Add/Drop Mux with [*] capacity support up to [*] Gbps of capacity             [*]
                            (any combination of OC-48/192). Includes:  Optical Amplifier, OADM, Racks,
                            Tx/Rx Shelves, NE Firmware, Power Supplies
---------------------------------------------------------------------------------------------------------------------
OADM-[*]                    Optical Add/Drop Mux with [*] capacity support up to [*] Gbps of capacity             [*]
                            (any combination of OC-48/192). Includes:  Optical Amplifier, OADM, Racks,
                            Tx/Rx Shelves, NE Firmware, Power Supplies
---------------------------------------------------------------------------------------------------------------------
OADM-[*]                    Optical Add/Drop Mux with [*] capacity support up to [*] Gbps of capacity             [*]
                            (any combination of OC-48/192). Includes:  Optical Amplifier, OADM, Racks,
                            Tx/Rx Shelves, NE Firmware, Power Supplies
---------------------------------------------------------------------------------------------------------------------
OADM-[*] RTUs               Optical Add/Drop Mux Right to Use:  Corvis CorManager OADM-[*] Node Software          [*]
---------------------------------------------------------------------------------------------------------------------
OA3200                      Optical Line Amplifier. Equipment Includes:  Optical Amplifier, NE                    [*]
                            Firmware, Power Supplies
---------------------------------------------------------------------------------------------------------------------
OA3200 RTUs                 Optical Line Amplifier Right to Use:  Corvis CorManager OA3200 Node Software          [*]
---------------------------------------------------------------------------------------------------------------------
OC-192                      OC-192 Interface                                                                      [*]
---------------------------------------------------------------------------------------------------------------------
OC-48                       OC-48 Interface                                                                       [*]
---------------------------------------------------------------------------------------------------------------------
CORWave NOC 3rd Party       CorWave TM NOC Equipment (NMS 3rd party Hardware & software).
H/W + S/W
---------------------------------------------------------------------------------------------------------------------
     SUN Server E450                                                                                              [*]
     Class
---------------------------------------------------------------------------------------------------------------------
     SUN Server E3500                                                                                             [*]
     Class
---------------------------------------------------------------------------------------------------------------------
     SUN Server E3500                                                                                             [*]
     High Availability
     Class
---------------------------------------------------------------------------------------------------------------------
</TABLE>
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

<TABLE>
<S>                         <C>                                                                                   <C>
---------------------------------------------------------------------------------------------------------------------
CorWave TM NOC              CorWave TM NOC Application Software (required for each NOC work station)              [*]
Application Software
---------------------------------------------------------------------------------------------------------------------
     License Fee            Required for each seat [*] per licensed copy of the NOC Application Software          [*]
---------------------------------------------------------------------------------------------------------------------
</TABLE>

<TABLE>
<S>                         <C>                                                                                   <C>
---------------------------------------------------------------------------------------------------------------------
Annual Software             Annual Maintenance Fee for Corvis CorWave software.                                   [*]
Maintenance Fee for
CorWave NOC
---------------------------------------------------------------------------------------------------------------------
Engineering, Installation,  Engineering, Installation, System Turn-Up and Test for Network Management             [*]
System Turn-Up and          (per NOC install).
Test
---------------------------------------------------------------------------------------------------------------------
Engineering, Installation,  Engineering, Installation, System Turn-Up and Test for Network Elements               [*]
System Turn-Up and          (percentage of all NE costs).
Test
--------------------------------------------------------------------------------------------------------------------
Remote TAS Non-             Remote TAS Non-Emergency Assistance @ [*]/hour.                                      [*]
Emergency Assistance
--------------------------------------------------------------------------------------------------------------------
On site Technical           On site Technical Support @ [*]/day.                                                 [*]
Support
--------------------------------------------------------------------------------------------------------------------
Training                    Training:  [*] per seat (a seat is a [*] day course).                                [*]
--------------------------------------------------------------------------------------------------------------------
Documentation               Per additional copy beyond what Corvis is obligated to provide pursuant              [*]
                            to Section 8.1 and per hard copy supplied
--------------------------------------------------------------------------------------------------------------------
</TABLE>

(A)  [*]

[*]

In consideration of Customer's commitment to purchase from Corvis and deploy
during the Term a total dollar value of Products equal to the Minimum Deployment
Commitment and Customer's agreement to make a jointly approved press
announcement of this Agreement, Corvis agrees as follows:

(a)  [*]

(b)  [*]

(c)  If, during Calendar Year 2000, Customer purchases from Corvis a total
     dollar value of Products equal to or greater U.S. [*], then Customer may
     apply the Product Credits against orders placed on and after [*] up to [*]
     of the purchase price of Products ordered by Customer [*].

(d)  Definitions.
---  -----------

     (i)   "Calendar Year 2000" means the period commencing on and including
            ------------------
           January 1, 2000 and ending on and including December 31, 2000.

     (ii)  "Calendar Year 2001" means the period commencing on and including
            ------------------
           January 1, 2001 and ending on and including December 31, 2001.

     (iii) "[*] Expiration Date" means either:
            -------------------

            i.   December 31, 2001; or
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

            ii.  if the total aggregate dollar value of Products purchased by
                 Customer from Corvis during Calendar Year 2000 and Calendar
                 Year 2001 exceeds the Minimum Revenue Commitment, [*].

     (iv)   "Extended Pricing" means the prices and license fees for the
             ----------------
            Products set forth in this Attachment 6, as such prices and license
            fees may, from time to time, be adjusted in accordance with
            subsection (a) above.

     (v)    "Qualifying Products" means Products purchased from Corvis for
             -------------------
            commercial deployment in North America, but not for laboratory
            testing, field trials or other similar purposes.

     (vi)   [*]
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

                                ATTACHMENT 11.1

                       CORVIS EQUIPMENT TRAINING CLASSES
                       ---------------------------------

<TABLE>
<CAPTION>
------------------------------------------------------------------------------------------------------------
Code      Class                                       Target Audience           Duration   Pre-requisites
------------------------------------------------------------------------------------------------------------
<S>       <C>                                          <C>                      <C>        <C>
          Corvis Transport Introduction and Basic
T-1       ---------------------------------------
          Operation (HW and SW):                       All operations           [*] days
          ---------------------                        personnel
              .  Overview
              .  Operation
              .  Safety
              .  Turn-up, Provisioning and
                 Maintenance
              .  Interpretation of alarm conditions
------------------------------------------------------------------------------------------------------------
          Corvis Switching Introduction and
T-2       ---------------------------------
          Basic Operation (HW and SW):
          ---------------------------                  All operations           [*] days   Course T-1
                 Overview                              personnel
                 Operation
                 Safety
                 Turn-up, Provisioning and
                 Maintenance
                 Interpretation of alarm
                 conditions
------------------------------------------------------------------------------------------------------------
          Transport Installation, Turn-up and
T-3       -----------------------------------
          Test:
          ----                                         Installation personnel   [*] days   Course T-1
                 Safety
                 Installation, turn-up and test of
                 Corvis transport Network
                 Elements (ONG, OA, OADM)
------------------------------------------------------------------------------------------------------------
          Switching Installation, Turn-up and
T-4       -----------------------------------
          Test:
          ----                                         Installation personnel   [*] days   Courses T-1,
                 Safety                                                                    T-2, T-3
                 Installation, turn-up and test of
                 Corvis switching Network
                 Elements (OR)
------------------------------------------------------------------------------------------------------------
          Network Operations:
T-5       ------------------                           Network Management       [*] days   Courses T-1 and
                 Network Management System             Center personnel                    T-2
                 overview
                 Installation
                 Configuration
                 Performance monitoring
                 Surveillance
                 Fault management
------------------------------------------------------------------------------------------------------------
          Network Planning and Equipment
T-6       ------------------------------
          Engineering:
          -----------                                  Network Planning and     [*] days   Courses T-1, T-2
                 HW and SW configurations and          Engineering personnel               and T-5
                 deployment
                 Route and capacity planning
                 Protection schemes
------------------------------------------------------------------------------------------------------------
</TABLE>
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

<TABLE>
<S>       <C>                                          <C>                   <C>          <C>
------------------------------------------------------------------------------------------------------------
                 Wavelength planning
                 Capacity Upgrade strategies
------------------------------------------------------------------------------------------------------------
          Field Operations:
T-7       ----------------                             Field Technical       [*] days     Courses T-1, T-2
                 Safety                                personnel                          and T-5
                 Fault interpretation and
                 troubleshooting
                 Capacity upgrade implementation
-------------------------------------------------------------------------------------------------------------
</TABLE>
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

                                ATTACHMENT 12.1

                         THIRD PARTY SOFTWARE LICENSES
                         -----------------------------

<TABLE>
<CAPTION>
-------------------------------------------------------------------------------
                Item                                           Version
-------------------------------------------------------------------------------
<S>                                                    <C>
SNMP (v1)  (AdventNet)                                 2.0
-------------------------------------------------------------------------------
Solstice Enterprise Manager                            3.0
-------------------------------------------------------------------------------
Solstice OSI 8.1.1 Comm. Platform                      8.1.1
-------------------------------------------------------------------------------
JRE/JVM                                                1.1.7b and 1.1.8
-------------------------------------------------------------------------------
</TABLE>
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

                                ATTACHMENT 12.6

                               ESCROW AGREEMENT
                               ----------------

                     Account Number ______________________

This Agreement is effective _________________, ______ ("Effective Date") among
_____________________________________ ("Escrow Agent"), Corvis Corporation
("Depositor") and Broadwing Communications Services, Inc. ("Preferred
Beneficiary"), who collectively may be referred to in this Agreement as "the
parties."

A.   Depositor and Preferred Beneficiary have entered into a Procurement
Agreement dated ________________, ______ regarding certain proprietary
technology of Depositor (referred to in this Agreement as the "Procurement
Agreement").

B.   Depositor desires to avoid disclosure of its proprietary technology except
under certain limited circumstances.

C.   The availability of the proprietary technology of Depositor is critical to
Preferred Beneficiary in the conduct of its business and, therefore, Preferred
Beneficiary needs access to the proprietary technology under certain limited
circumstances.

D.   Depositor and Preferred Beneficiary desire to establish an escrow with
Escrow Agent to provide for the retention, administration and controlled access
of the proprietary technology materials of Depositor.

E.   The parties desire this Agreement to be supplementary to the Procurement
Agreement pursuant to 11 United States Bankruptcy Code, Section 365(n).

ARTICLE 1  --  DEPOSITS

1.1  Obligation to Make Deposit.  Within thirty (30) days following successful
     --------------------------
completion of the Transport Field Trial (as defined in the Procurement
Agreement), Depositor will deliver to Escrow Agent the proprietary technology
and other materials ("Deposit Materials") identified on Exhibit A attached
hereto. Exhibit A will be prepared and signed by Depositor and Preferred
Beneficiary.  Escrow Agent will have no obligation with respect to the
preparation, signing or delivery of Exhibit A.  (Exhibit A will be defined after
the Field Trial.)

1.2  Identification of Tangible Media.  Prior to the delivery of the Deposit
     --------------------------------
Materials to Escrow Agent, Depositor will conspicuously label for identification
each document, magnetic tape, disk, or other tangible media upon which the
Deposit Materials are written or stored. Additionally, Depositor will complete
Exhibit B to this Agreement by listing each such tangible media by the item
label description, the type of media and the quantity. The Exhibit B (to be
defined after the field trial) must be signed by Depositor and delivered to
Escrow Agent with the Deposit Materials. Unless and until Depositor makes the
initial deposit with
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

Escrow Agent, Escrow Agent will have no obligation with respect to this
Agreement, except the obligation to notify the parties regarding the status of
the deposit account as required in Section 2.2 below.

1.3  Deposit Inspection.  When Escrow Agent receives the Deposit Materials and
     ------------------
the Exhibit B, Escrow Agent will conduct a deposit inspection by visually
matching the labeling of the tangible media containing the Deposit Materials to
the item descriptions and quantity listed on the Exhibit B.  In addition to the
deposit inspection, Preferred Beneficiary may elect to cause a verification of
the Deposit Materials in accordance with Section 1.6 below.

1.4  Acceptance of Deposit.   At completion of the deposit inspection, if Escrow
     ---------------------
Agent determines that the labeling of the tangible media matches the item
descriptions and quantity on Exhibit B, Escrow Agent will date and sign the
Exhibit B and mail a copy thereof to Depositor and Preferred Beneficiary.  If
Escrow Agent determines that the labeling does not match the item descriptions
or quantity on the Exhibit B, Escrow Agent will (a) note the discrepancies in
writing on the Exhibit B; (b) date and sign the Exhibit B with the exceptions
noted; and (c) mail a copy of the Exhibit B to Depositor and Preferred
Beneficiary.  Escrow Agent's acceptance of the deposit occurs upon the signing
of the Exhibit B by Escrow Agent.  Delivery of the signed Exhibit B to Preferred
Beneficiary is Preferred Beneficiary's  notice that the Deposit Materials have
been received and accepted by Escrow Agent.

1.5  Depositor's Representations.  Depositor represents as follows:
     ---------------------------

     a.   Depositor lawfully possesses all of the Deposit Materials deposited
          with Escrow Agent;

     b.   With respect to all of the Deposit Materials, Depositor has the right
          and authority to grant to Escrow Agent and Preferred Beneficiary the
          rights as provided in this Agreement;

     c.   The Deposit Materials are not subject to any lien or other
          encumbrance;

     d.   The Deposit Materials consist of the proprietary technology and other
          materials identified in Exhibit A; and

     e.   The Deposit Materials are readable and useable in their current form
          or, if the Deposit Materials are encrypted, the decryption tools and
          decryption keys have also been deposited.

1.6  Verification.  Preferred Beneficiary will have the right, at Preferred
     ------------
Beneficiary's expense, to cause a verification of any Deposit Materials. A
verification determines, in different levels of detail, the accuracy,
completeness, sufficiency and quality of the Deposit Materials. If a
verification is elected after the Deposit Materials have been delivered to
Escrow Agent, then only Escrow Agent, or at Escrow Agent's election an
independent person or company selected and supervised by Escrow Agent , may
perform the verification.

1.7  Deposit Updates.  Unless otherwise provided by the Procurement Agreement,
     ---------------
Depositor will update the Deposit Materials within 60 days after each release of
a new version of the product that is subject to the Procurement Agreement. Such
updates will be added to the existing deposit. All deposit updates will be
listed on a new Exhibit B and the new Exhibit B will be signed by Depositor.
Each Exhibit B will be held and maintained separately within the escrow account.
An independent record will be created which will document the activity for each
Exhibit B. The processing of all deposit updates will be in accordance with
Sections 1.2 through 1.6 above. All references in this Agreement to the Deposit
Materials will include the initial Deposit Materials and any updates.
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

1.8  Removal of Deposit Materials.  The Deposit Materials may be removed and/or
     ----------------------------
exchanged only on written instructions signed by Depositor and Preferred
Beneficiary, or as otherwise provided in this Agreement.

ARTICLE 2  -- CONFIDENTIALITY AND RECORD KEEPING

2.1  Confidentiality.  Escrow Agent will maintain the Deposit Materials in a
     ---------------
secure, environmentally safe, locked facility which is accessible only to
authorized representatives of Escrow Agent. Escrow Agent will have the
obligation to reasonably protect the confidentiality of the Deposit Materials.
Except as provided in this Agreement, Escrow Agent will not disclose, transfer,
make available, or use the Deposit Materials. Escrow Agent will not disclose the
content of this Agreement to any third party. If Escrow Agent receives a
subpoena or other order of a court or other judicial tribunal pertaining to the
disclosure or release of the Deposit Materials, Escrow Agent will immediately
notify the parties to this Agreement. It will be the responsibility of Depositor
and/or Preferred Beneficiary to challenge any such order; provided, however,
that Escrow Agent does not waive its rights to present its position with respect
to any such order. Escrow Agent will not be required to disobey any court or
other judicial tribunal order. (See Section 7.5 below for notices of requested
orders.) Notwithstanding the foregoing, in the event that Escrow Agent receives
any subpoena or order that is not issued pursuant to the procedure detailed in
Section 7.3, Escrow Agent will not comply with such order without first
notifying the parties and permitting the Depositor the opportunity to challenge
such order or to seek to have such order narrowed in a manner acceptable to the
Depositor, as owner of the proprietary information embodied on the Deposit
Materials.

2.2  Status Reports.  Escrow Agent  will issue to Depositor and Preferred
     --------------
Beneficiary a report profiling the account history at least semi-annually.
Escrow Agent  may provide copies of the account history pertaining to this
Agreement upon the request of any party to this Agreement.

2.3  Audit Rights.  During the term of this Agreement, Depositor and Preferred
     ------------
Beneficiary will each have the right to inspect the written records of Escrow
Agent  pertaining to this Agreement.  Any inspection will be held during normal
business hours and following reasonable prior notice.

ARTICLE 3  --  GRANT OF RIGHTS TO ESCROW AGENT

3.1  Title to Media.  Depositor hereby transfers to Escrow Agent  the title to
     --------------
the media upon which the proprietary technology and materials are written or
stored.  However, this transfer does not include the ownership of the
proprietary technology and materials contained on the media including any
copyright, trade secret, patent or other intellectual property rights.  Title to
all such intellectual property will at all times remain vested in Depositor.

3.2  Right to Make Copies.  Escrow Agent  will have the right to make copies of
     --------------------
the Deposit Materials as reasonably necessary to perform its obligations under
this Agreement. Escrow Agent will copy all copyright, nondisclosure, and other
proprietary notices and titles contained on the Deposit Materials onto any
copies made by Escrow Agent. With all Deposit Materials submitted to Escrow
Agent, Depositor will provide any and all instructions as may be necessary to
duplicate the Deposit Materials including but not limited to the hardware and/or
software needed.
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

3.3  Right to Transfer Upon Release. Depositor hereby grants to Escrow Agent a
     ------------------------------
non-exclusive, non-transferable, perpetual and royalty-free license to
sublicense the Deposit Materials to Preferred Beneficiary upon any release of
the Deposit Materials for use by Preferred Beneficiary in accordance with
Section 4.5. Except upon such a release or as otherwise provided in this
Agreement, Escrow Agent will not sublicense or otherwise transfer the Deposit
Materials or permit Preferred Beneficiary to make use of the Deposit Materials.
It is expressly understood and agreed that Escrow Agent is not authorized to
enter into any sublicense or similar agreement with Preferred Beneficiary that
alters the terms of this Section 3.3. In case of any conflict between the
provisions of this Section 3.3 (or Section 4.5) and the provisions of the
Procurement Agreement relating to the scope of the Preferred Beneficiary's
license upon release from escrow, the provisions of the Procurement Agreement
will control.

ARTICLE 4  -- RELEASE OF DEPOSIT

4.1  Release Conditions.  As used in this Agreement, "Release Condition" will
     ------------------
mean the following:

     a.  Depositor is in material breach of its support obligations, as
         described in the Maintenance and Support Services and Other Services
         pursuant to Article 19 of the Procurement Agreement, that is not cured
         within a reasonable period of time and that has a material adverse
         impact on Preferred Beneficiary's ability to conduct its business with
         the Depositor's Products; or

     b.  Depositor is the subject of a voluntary or involuntary bankruptcy or
         dissolution proceedings (that are not discharged within 60 days after
         they are filed, in the case of involuntary proceedings).

4.2  Request for Release.   If Preferred Beneficiary believes in good faith that
     -------------------
a release condition has occurred, Preferred Beneficiary may provide Escrow Agent
written notice that a Release Condition and a request for release of the Deposit
Materials.  The request will include instructions to Escrow Agent for
accomplishing the release, and a description in full detail of the release
condition that Preferred Beneficiary believes occurred.  Escrow Agent will
immediately send the notice to Depositor by overnight carrier.

4.3  Release by Escrow Agent.  Escrow Agent  will 10 days after Depositor's
     -----------------------
receipt of the notice of request for release, release the Deposit Materials to
Preferred Beneficiary pursuant to the instructions included in the request for
release, unless Depositor disputes that a release condition has occurred.
Subject to section 5.2, Escrow Agent will continue to store the Deposit
Materials without release pending (a) joint instructions from Depositor and
Preferred Beneficiary, (b) resolution pursuant to the Dispute Resolution
provisions or (c) order of a court.

4.4  Release of Deposit. If Escrow Agent does not receive notice that Depositor
     ------------------
disputes the condition of release and demand for submission to arbitration then
Escrow Agent is authorized to release the Deposit materials to the Preferred
Beneficiary or if more than one beneficiary is registered to the deposit, to
release a copy of the Deposit Materials to the Preferred Beneficiary. However,
Escrow Agent is entitled to receive any fees due Escrow Agent before making the
release. Any copying expense in excess of $300 will be chargeable to the
Preferred Beneficiary. This Agreement will terminate upon the release of the
Deposit Materials held by Escrow Agent. In the event that Escrow Agent does
receive notice that Depositor disputes the release condition and demands
arbitration and subsequently receives (a) joint instructions from Depositor and
Preferred Beneficiary; (b) resolution pursuant to the Dispute Resolution
provisions; or (c) order of a
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

court, Escrow Agent will release a copy of the Deposit Materials to the
Preferred Beneficiary in accordance with such joint instructions from Depositor
and Preferred Beneficiary; resolution pursuant to the Dispute Resolution
provisions; or court order. The provisions of the second, third and fourth
sentences of this Section 4.4 will apply to any such release.

4.5  Right to Use Following Release.  Unless otherwise provided in the
     ------------------------------
Procurement Agreement, upon release of the Deposit Materials in accordance with
this Article 4, Preferred Beneficiary will have the non-exclusive, non-
transferable, right to use the Deposit Materials for the sole purpose of
continuing the benefits afforded to Preferred Beneficiary by the Procurement
Agreement.  Preferred Beneficiary will be obligated to maintain the strict
confidentiality of the released Deposit Materials, including maintaining such
Deposit Materials in a single, access restricted, and locked location.
Preferred Beneficiary will provide access to the released Deposit Materials to
only those of its personnel who require such access for supporting Customer's
use of the Products sold or licensed to Customer under the Procurement Agreement
and Customer will maintain a written list of such personnel.  Without limiting
the foregoing, the Deposit Materials will also be protected as Corvis'
Proprietary Materials under Article 15 of the Procurement Agreement.  Receipt by
Preferred Beneficiary of the Deposit Materials pursuant to this Article 4 does
not in any way convey title or ownership of the Depositor products or the
intellectual property rights embodied in the products.  Preferred Beneficiary
may subcontract to third parties maintenance and support work permitted under
this Section 4.5; provided all such third parties enter into a written agreement
containing terms equivalent to those contained in the Procurement Agreement
regarding Depositor's confidential information and preservation of Depositor's
proprietary rights.  Preferred Beneficiary will provide signed copies of all
such agreements to Depositor before providing any such party with access to the
Deposit Materials.

4.6  Preferred Beneficiary will place all Deposit Materials (including all
copies and extracts thereof) in another escrow under terms similar to this
Agreement if and when Depositor is able to demonstrate to Preferred
Beneficiary's reasonable satisfaction that Depositor is able and willing to
resume performance of its support obligations, as described in the Maintenance
and Support Services pursuant to Article 19 of the Procurement Agreement.

ARTICLE 5  --  TERM AND TERMINATION

5.1  Term of Agreement.  The initial term of this Agreement is for a period of
     -----------------
one year.  Thereafter, this Agreement will automatically renew from year-to-year
unless  (a) Depositor  and Preferred Beneficiary jointly instruct Escrow Agent
in writing that the Agreement is terminated; or (b) the Agreement is terminated
by Escrow Agent  for nonpayment in accordance with Section 5.2.  If the Deposit
Materials are subject to another escrow agreement with Escrow Agent, Escrow
Agent  reserves the right, after the initial one year term, to adjust the
anniversary date of this Agreement to match the then prevailing anniversary date
of such other escrow arrangements.

5.2  Termination for Nonpayment.  In the event of the nonpayment of fees owed to
     --------------------------
Escrow Agent, Escrow Agent will provide written notice of delinquency to all
parties to this Agreement. Any party to this Agreement will have the right to
make the payment to Escrow Agent to cure the default. If the past due payment is
not received in full by Escrow Agent within one month of the date of such
notice, then Escrow Agent will have the right to terminate this Agreement at any
time thereafter by sending written notice of termination to all parties. Escrow
Agent will have no obligation to take any action under this Agreement so long as
any payment due to Escrow Agent remains unpaid.
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

5.3  Disposition of Deposit Materials Upon Termination. Upon termination of this
     -------------------------------------------------
Agreement, Escrow Agent  will destroy, return, or otherwise deliver the Deposit
Materials in accordance with Depositor's instructions.  If there are no
instructions, Escrow Agent  may, at its sole discretion, destroy the Deposit
Materials or return them to Depositor.  Escrow Agent  will have no obligation to
return or destroy the Deposit Materials if the Deposit Materials are subject to
another escrow agreement with Escrow Agent.

5.4  Survival of Terms Following Termination.  Upon termination of this
     ---------------------------------------
Agreement, the following provisions of this Agreement will survive:

     a.   Depositor's Representations (Section 1.5);

     b.   The obligations of Escrow Agent and Preferred Beneficiary to maintain
          confidentiality with respect to the Deposit Materials;

     c.   The rights granted in the sections entitled Right to Transfer Upon
          Release (Section 3.3) and Right to Use Following Release (Section
          4.5), if a release of the Deposit Materials has been made using the
          procedure described in Article 4 prior to termination;

     d.   The obligation to pay Escrow Agent  any fees and expenses due; and

     e.   The provisions of Sections 7.1 and 7.2.

ARTICLE 6  --  ESCROW'S FEES

6.1  Fee Schedule.  Escrow Agent is entitled to be paid its standard fees and
     ------------
expenses applicable to the services provided. Escrow Agent will notify the party
responsible for payment of Escrow Agent's fees at least 90 days prior to any
increase in fees. For any service not listed on Escrow Agent 's standard fee
schedule, Escrow Agent will provide a quote prior to rendering the service, if
requested.

6.2  Payment Terms. Escrow Agent will not be required to perform any service
     -------------
unless the payment for such service and any outstanding balances owed to Escrow
Agent are paid in full. Fees are due upon receipt of a signed contract or
receipt of the Deposit Materials whichever is earliest. If invoiced fees are not
paid, Escrow Agent may terminate this Agreement in accordance with Section 5.2.
Late fees on past due amounts will accrue interest at the rate of one and one-
half percent per month (18% per annum) from the date of the invoice.

ARTICLE 7  --  LIABILITY AND DISPUTES

7.1  Right to Rely on Instructions. Escrow Agent may act in reliance upon any
     -----------------------------
instruction, instrument, or signature reasonably believed by Escrow Agent to be
genuine.  Escrow Agent may assume that any employee of a party to this Agreement
who gives any written notice, request, or instruction has the authority to do
so. Escrow Agent will not be responsible for failure to act as a result of
causes beyond the reasonable control of Escrow Agent.

7.2  Indemnification. Escrow Agent will be responsible to perform its
     ---------------
obligations under this Agreement and to act in a reasonable and prudent manner
with regard to this escrow arrangement.  Provided Escrow
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

Agent has acted in the manner stated in the preceding sentence, Depositor and
Preferred Beneficiary each agree to indemnify, defend and hold harmless Escrow
Agent from any and all claims, actions, damages, arbitration fees and expenses,
costs, attorney's fees and other liabilities incurred by Escrow Agent relating
in any way to this escrow arrangement.

7.3  Dispute Resolution.  (a) Any dispute relating to or arising from this
     ------------------
Agreement will be resolved by arbitration under the Commercial Arbitration Rules
of the American Arbitration Association. Unless otherwise agreed by Depositor
and Preferred Beneficiary, arbitration will take place in Boston, Massachusetts,
U.S.A. Service of a petition to confirm the arbitration award may be made by
First Class mail or by commercial express mail, to the attorney for the party
or, if unrepresented, to the party at the last known business address. Depositor
and Preferred Beneficiary will submit any dispute relating to the release of
Deposit Materials to the jurisdiction of a board of arbitrators (the "Board")
sitting in Boston, Massachusetts for resolution and will so notify Escrow Agent.
The Board will be selected within thirty (30) days from the date of the filing
of the notice of a dispute by Escrow Agent under Section 4.3 (or other location
or time mutually agreeable to Depositor and Preferred Beneficiary). The Board
will comprise three (3) members, one selected by Depositor, one selected by
Preferred Beneficiary and the third chosen by the two members so selected, or if
they cannot agree, by the American Arbitration Association. The sole question
before the Board will be whether or not Depositor or Preferred Beneficiary is
entitled to have the Deposit Materials released from escrow. The Board will have
no authority to order a modification or amendment of this Agreement or the
Procurement Agreement. The decision of the Board will be forthwith delivered to
Escrow Agent, Depositor and Preferred Beneficiary, will be final and binding on
Depositor and Preferred Beneficiary, and judgment thereon may be entered in any
court of competent jurisdiction. Service of a petition to confirm the
arbitration award may be made by First Class mail or by commercial express mail,
to the attorney for the party or, if unrepresented, to the party at the last
known business address. The dispute resolution procedures outlined above may be
followed for any other dispute arising out of this Agreement, but the timetables
established above will be adjusted by agreement of the effected parties to
account for the event that triggers the desire of any party to seek arbitration.
The limitations on the authority of the Board enumerated above will apply to any
arbitration pursued under this Agreement.

     (b)  All fees charged by the Board will be paid by the nonprevailing party
to the arbitration. Each of Depositor and Preferred Beneficiary, however, will
be responsible for payment of all fees and expenses connected with the
presentation of its respective case, except that the Board may award such
reasonable fees and expenses of presentation, including counsel fees, to the
prevailing party in the event that the Board determines that the contentions of
the nonprevailing party were made in bad faith or without reasonable
justification.

7.4  Controlling Law.  This Agreement is to be governed and construed in
     ---------------
accordance with the laws of the State of New York, without regard to its
conflict of law provisions.

7.5  Notice of Requested Order.  If any party intends to obtain an order from
     -------------------------
the arbitrator or any court of competent jurisdiction that may direct Escrow
Agent  to take, or refrain from taking any action, that party will:

     a.   Give Escrow Agent at least two business days' prior notice of the
          hearing;

     b.   Include in any such order that, as a precondition to Escrow Agent's
          obligation, Escrow Agent be paid in full for any past due fees and be
          paid for the reasonable value of the services to be rendered pursuant
          to such order; and
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

     c.   Ensure that Escrow Agent not be required to deliver the original (as
          opposed to a copy) of the Deposit Materials if Escrow Agent may need
          to retain the original in its possession to fulfill any of its other
          duties.

ARTICLE 8  --  GENERAL PROVISIONS

8.1  Entire Agreement.  This Agreement, which includes the Exhibits described
     ----------------
herein, embodies the entire understanding among the parties with respect to its
subject matter and supersedes all previous communications, representations or
understandings, either oral or written. Escrow Agent is not a party to the
Procurement Agreement between Depositor and Preferred Beneficiary and has no
knowledge of any of the terms or provisions of any such Procurement Agreement.
Escrow Agent's only obligations to Depositor or Preferred Beneficiary are as set
forth in this Agreement. No amendment or modification of this Agreement will be
valid or binding unless signed by all the parties hereto, except that Exhibit A
need not be signed by Escrow Agent, Exhibit B need not be signed by Preferred
Beneficiary and Exhibit C need not be signed.

8.2  Notices.  All notices, invoices, payments, deposits and other documents and
     -------
communications will be given to the parties at the addresses specified in the
attached Exhibit C.  It will be the responsibility of the parties to notify each
other as provided in this Section in the event of a change of address. The
parties will have the right to rely on the last known address of the other
parties.  Unless otherwise provided in this Agreement, all documents and
communications may be delivered by First Class mail.

8.3  Severability.  In the event any provision of this Agreement is found to be
     ------------
invalid, voidable or unenforceable, the parties agree that unless it materially
affects the entire intent and purpose of this Agreement, such invalidity,
voidability or unenforceability will affect neither the validity of this
Agreement nor the remaining provisions herein, and the provision in question
will be deemed to be replaced with a valid and enforceable provision most
closely reflecting the intent and purpose of the original provision.

8.4  Successors.  This Agreement will be binding upon and will inure to the
     ----------
benefit of the successors and assigns of the parties.  However, Escrow Agent
will have no obligation in performing this Agreement to recognize any successor
or assign of Depositor or Preferred Beneficiary unless Escrow Agent receives
clear, authoritative and conclusive written evidence of the change of parties.

8.5  Regulations. Depositor and Preferred Beneficiary are responsible for and
     -----------
warrant compliance with all applicable laws, rules and regulations, including
but not limited to customs laws, import, export, and re-export laws and
government regulations of any country from or to which the Deposit Materials may
be delivered in accordance with the provisions of this Agreement.

8.6  Conflict of Interest.  Escrow Agent will not pay any commissions, fees or
     --------------------
rebates of significant value to any employees of Depositor or Preferred
Beneficiary, nor favor any employee of Depositor or Preferred Beneficiary with
gifts or entertainment of significant value.  If Depositor or Preferred
Beneficiary has reasonable cause to believe that this provision has been
violated, Escrow Agent agrees to cooperate with Depositor or Preferred
Beneficiary in its investigation.
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

Corvis Corporation                       Broadwing Communications Services, Inc.
Depositor                                Preferred Beneficiary

By:_________________________________     By:___________________________________

Name:_______________________________     Name:_________________________________

Title:______________________________     Title:________________________________

Date:_______________________________     Date:_________________________________

[*]
Escrow Agent

By:

Name:

Title:

Date:
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

ATTACHMENT 16.1

                                WARRANTY PERIOD
                                ---------------

     The Warranty Period shall be [*] years.
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission.  Asterisks denote omissions.

                                 ATTACHMENT 19

              MAINTENANCE AND SUPPORT SERVICES AND OTHER SERVICES
              ---------------------------------------------------

The Corvis Support Program includes the following maintenance services:

 .  24 X 7 Corvis Networks Technical Assistance Center (TAC)
 .  Emergency priority access to TAC
 .  Non-emergency Technical Assistance Center (TAC)
 .  Basic software maintenance (patches and maintenance releases)
 .  Repair and Return - Basic
 .  Repair and Return - Advanced Replacement

     The price for the Corvis Support Program is as follows:

<TABLE>
<CAPTION>
                                                  Standard Services               Optional
           Maintenance Services                   Annual Fee as a %              Fee as of %
                                              of Network Element Price    of Network Element Price
--------------------------------------------------------------------------------------------------
<S>                                           <C>                         <C>
  Repair and Return - Basic                             [*]%
  Emergency TAC Telephone Support                       [*]%
  Basic software maintenance support                    [*]%                    $[*] per hour
  Non-emergency TAC Telephone Support                   [*]%                        [*]%
  Repair and Return - Advanced Replacement                -
--------------------------------------------------------------------------------------------------
</TABLE>

Customer must include all Corvis Products under the Standard Corvis Support
Program in order to be eligible for maintenance of any Products or the Repair
and Return - Advanced Replacement program. The Annual Fees for the Corvis
Support Program and the Repair and Return - Advanced Replacement Program are due
upon shipment of the associated Network Element (pro rated for the portion of
the calendar year remaining). The term of the Corvis Support Program for
individual shipments made during a calendar year shall end on December 31 of
each applicable year, and shall be renewed for the ensuing 12-month period
effective January 1 of each year.  Corvis shall invoice Customer for the Corvis
Support Program at the commencement of each calendar year for such calendar
year.

Maintenance Services descriptions are provided below:

1.0  Corvis Emergency Technical Assistance Center (TAC)

     .1  Staffing and Availability  The Corvis Support Program provides priority
         Customer telephonic access to the Corvis Technical Assistance Center
         (TAC) 7 days per week and 24 hours per day. Corvis will provide
         Customer with the proper telephone number and procedures for contacting
         the TAC. TAC personnel provide problem status information to Customer
         for serious problems and are the interface to Corvis Management and
         Development Engineering.
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission.  Asterisks denote omissions.

     .2  Scope of Activities  In addition to support on problem determination
         and resolution, the following information and services are available
         through the TAC: technical tips, hardware information, software release
         notes, information on pending software updates, problem status report
         updates, and documentation updates.

     .3  Problem Handling Procedures All problems reported to the TAC will be
         assigned a Severity Classification.  The Severity Level will be agreed
         upon between Corvis and Customer according to the table below.

<TABLE>
<CAPTION>

----------------------------------------------------------------------------------------------------------------------------------
Severity                   Description                                          Escalation Procedure/Response Time
----------------------------------------------------------------------------------------------------------------------------------
<C>      <S>                                                       <C>
1        Critical - Customer is experiencing a network outage      Corvis [*] and Customer Service will be immediately notified.
         that prevents its customers from accessing service and    Corvis personnel will update Customer at least hourly and will
         for which there is no workaround or recovery action       work on the problem until resolution.
         possible.
----------------------------------------------------------------------------------------------------------------------------------
2        Major - Customer is experiencing a problem that           Corvis Level 3 personnel will resolve the problem within four
         affects service but for which there is a work-around      hours or escalate to Development Engineering.  Corvis personnel
         or recovery action.  Business can continue although       will update Customer at least every two hours.
         performance may be degraded.
----------------------------------------------------------------------------------------------------------------------------------
3        Minor - Customer is experiencing problems and requires    Severity 3 problems will be resolved by Corvis in a reasonable
         technical advice or a recommendation for the best         period of time or will be escalated to Development Engineering.
         solution.  Severity 3 problems have a reliable
         workaround and have, at most, a slight impact on the
         operational environment.
----------------------------------------------------------------------------------------------------------------------------------
4        Questions (Non Emergency)                                 Questions received by the TAC will be logged and answered in a
                                                                     timely manner.
----------------------------------------------------------------------------------------------------------------------------------
</TABLE>

   Corvis will meet its priority response goal as provided herein at a [*]
effectiveness level for any calendar month.  Should Corvis fail to meet its
response goal at least [*] in any calendar month, Customer maintenance Service
credits of [*] will be credited back and may be applied towards renewals/future
service contracts.

   The effectiveness level shall be calculated for any given month in
accordance with the following formula with Total Missed Calls being the number
of Severity 1 and Severity 2 Support calls for which priority support was not
delivered within [*] (Missed Calls) of the initial call.

   Effectiveness Calculation equals:  Total Calls per Month - Total Missed Calls
                                      ------------------------------------------
                                                Total Calls per Month

2.0  Software Maintenance Support.   Software Maintenance Support is also
provided through the TAC.  Software Maintenance includes patch releases of
software to correct reported problems, maintenance releases, upgrades to system
base software in new releases and other software updates that are made generally
available at no additional charge from time to time.  Software maintenance
releases will be made available via magnetic media or remote download, as
appropriate.  Major releases are anticipated to be made by Corvis [*].  New
software features and functionality offered in major new releases, if priced
separately, are not included in Software Maintenance Support. Additionally, any
incremental hardware required to support additional software is priced
separately.
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission.  Asterisks denote omissions.

   In addition to software patches and maintenance releases, Corvis will provide
Customer with revision releases, including installation, verification, and
uninstall procedures, and other documentation, pertaining to problem status,
code corrections, work-around procedures and known limitations of Corvis
products.

   In addition to the individual software releases referred to above, Corvis
will from time to time make available to Customer, subject to the applicable
license fees, "Baseline Package Releases" consisting of groups of Corvis'
software Products.  Notwithstanding anything to the contrary in the Agreement,
Corvis will only be obligated to provide support for the current and [*]
Baseline Package Releases made available by Corvis.  Corvis' obligation to
support any version of Third Party Software will be subject to the continuing
availability of support from the third party vendor for such version. Corvis
will not be obligated to provide services to correct any error or defect in any
Corvis Product that can be corrected by Customer's installation of a more recent
software release available from Corvis.

3.0 Repair and Return.  Basic

   Corvis will supply replacement components for Products that have failed. The
customer is responsible for first calling Corvis Customer Repair and getting a
Return Material Authorization number. The customer is responsible for sending
the faulty component to the Corvis designated location along with the assigned
RMA# for that module/component. Customer is responsible for packing material,
shipping enclosure and all necessary documentation to facilitate the return of
the defective component to Corvis. Requests for Basic Repair and Return on
replacement module/components received by Corvis by 3:00 p.m. Eastern Time will
generally be processed and sent back to customer within [*] of receiving the
faulty module/component. Requests made after 3:00 p.m. Eastern Time or on
weekends or Corvis holidays will be processed the next business day.

4.0 Repair and Return.   Advanced Replacement

   Corvis will supply replacement components for products that have failed. As a
prerequisite to advance replacement service, Customer must establish a sparing
depot.  Depot inventory must be maintained at the Corvis recommended minimum
sparing levels.

   Should Corvis determine that the failure is due to faulty hardware, Corvis
will send replacement component(s) to the designated depot location.  Included
with such component(s) will be packing material, a prepaid shipping enclosure
and all necessary documentation to facilitate the return of the defective
component to Corvis by Customer or Customer personnel.  Corvis will assume all
costs associated with the shipment of the replacement component(s) and the
return of the failed component(s). Customer shall return the malfunctioning
hardware product to Corvis within [*] of the receipt of the replacement product.

   Should Corvis determine that the cards are fully functional and are "no fault
found" in accordance with Corvis fault diagnostic and testing procedures, Corvis
will invoice customer for the replacement component, associated testing and all
shipping and shipping related costs.
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission.  Asterisks denote omissions.

   Advance replacement requests received at the Corvis TAC by 3:00 p.m. Eastern
Time will be processed [*].  Corvis will make all reasonable commercial efforts
to effect delivery of the replacement hardware component into the designated
sparing depot(s) by [*] for those locations where international customs need not
be cleared.  Requests made after 3:00 p.m. Eastern Time or on weekends or Corvis
holidays will be processed on the [*].

   It is Corvis' intention to use Customer's preferred carrier for shipments to
Customer contingent upon availability, quality, pricing, and terms and
conditions of service that such carrier makes available to Corvis. In all cases,
Corvis will use an internationally recognized carrier.  Should Corvis elect not
to use Customer's preferred carrier, Corvis will notify Customer and will, at
Customer's option, assume responsibility for package tracking.
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission.  Asterisks denote omissions.

                                 ATTACHMENT 28

                            PRODUCT SPECIFICATIONS
                            ----------------------

    Corvis System Specifications

The Corvis system comprises a number of network elements, which can be
configured to form point to point and mesh network connections.  The maximum
span distance that any of the [*] channels can traverse before electronic
regeneration depends on the individual fiber types and span losses between
optical amplifier sites.  The Corvis Wave Planner automatically determines
appropriate locations for each of the network elements and regeneration sites
based on the actual span losses and fiber types in the system.

Tables 2 and 3 specify the system performance under the following assumptions:
     1.  all span losses in the system are identical;
     2.  absolute value of fiber dispersion is greater than [*] for all
         channels;
     3.  all spans consist of Corning-LS or Lucent TrueWave-Classic, Plus, or RS
         fiber and have an average [*];
     4.  the maximum transmission distance is 3200 km; and,
     5.  the system is operated using the parameters listed in Table 1.

                           Table 1: System Parameters
<TABLE>
<CAPTION>

--------------------------------------------------------------------------
       Parameter                                 Value         Units
--------------------------------------------------------------------------
<S>                                           <C>            <C>

Amplifier Input Connector Loss                    0.2            dB
--------------------------------------------------------------------------
Amplifier Output Connector Loss                   0.2            dB
--------------------------------------------------------------------------
Operating Range                                1530-1564         nm
--------------------------------------------------------------------------
Maximum System Gain Flatness Variation            [*]            dB
--------------------------------------------------------------------------
Maximum Amplifier Gain [*]                        [*]            dB
--------------------------------------------------------------------------
[*] (See note 1)                                  [*]            dB
--------------------------------------------------------------------------
Nominal Fiber Launch Power / Channel              [*]           dBm
--------------------------------------------------------------------------
Equivalent OSNR at Fiber Launch                   [*]          dB.nm
--------------------------------------------------------------------------
Maximum accumulated dispersion (See note 2)       [*]          ps/nm
--------------------------------------------------------------------------
Receiver Sensitivity [*]                          [*]          dB.nm
--------------------------------------------------------------------------
Minimum EOL System Margin (See Note 3)            [*]            dB
--------------------------------------------------------------------------
Additional EOL System Margin Connector Penalty    [*]            dB
--------------------------------------------------------------------------
</TABLE>

Note 1: Total loss = span loss + amplifier module loss.
Note 2: [*]
Note 3: The Minimum EOL margin includes the following:
        [*]dB [*]
        [*]dB [*] variation across all [*] Channels
        [*]dB Unallocated margin
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission.  Asterisks denote omissions.

                   Table 2: System Performance using [*]/4-6/
<TABLE>
<CAPTION>

---------------------------------------------------------------
                      [*]               [*]              [*]
     [*]        Number of Spans   Number of Spans
  EOL Span          w/[*]             w/[*]
  Loss (dB)
---------------------------------------------------------------
<S>             <C>               <C>                  <C>
     [*]              [*]               [*]              [*]
---------------------------------------------------------------
     [*]              [*]               [*]              [*]
---------------------------------------------------------------
     [*]              [*]               [*]              [*]
---------------------------------------------------------------
</TABLE>

                   Table 3: System Performance using [*]/4-6/
<TABLE>
<CAPTION>

         [*]                  [*]                  [*]                [*]
 EOL Span Loss (dB)     Number of Spans   Number of Spans w/[*]
                             w/[*]
----------------------------------------------------------------------------
<S>                     <C>               <C>                         <C>
         [*]                  [*]                  [*]                [*]
----------------------------------------------------------------------------
         [*]                  [*]                  [*]                [*]
---------------------------------------------------------------------------
         [*]                  [*]                  [*]                [*]
---------------------------------------------------------------------------
         [*]                  [*]                  [*]                [*]
---------------------------------------------------------------------------
         [*]                  [*]                  [*]                [*]
---------------------------------------------------------------------------
         [*]                  [*]                  [*]                [*]
---------------------------------------------------------------------------
         [*]                  [*]                  [*]                [*]
---------------------------------------------------------------------------
         [*]                  [*]                  [*]                [*]
---------------------------------------------------------------------------
         [*]                  [*]                  [*]                [*]
---------------------------------------------------------------------------
         [*]                  [*]                  [*]                [*]
---------------------------------------------------------------------------
</TABLE>

Note 4: [*]
Note 5: [*]
Note 6: Based on an Amplifier Module Loss for [*] of [*] dB and a [*] dB
        respectively.

The transmission distance can be calculated based on the average loss per km
(dB/km) for a span using the equation:

[*] transmission distance (km) = Minimum (3200,([*] EOL Span Loss)x(# of
spans)/(Average Loss/km).
A sample calculation is shown below for a system with an average loss per km of
0.245 dB/km and a 17 dB EOL span loss using [*].
<TABLE>
<CAPTION>

-------------------------------------------------------------------------------------------------------------------------------
 Amp     System w/[*]                                               System w/[*]
-------------------------------------------------------------------------------------------------------------------------------
<S>      <C>                                                        <C>
 [*]     Max Distance = (17 dB/span)*([*] spans)/(0.0245 dB/km)     Max Distance = (17 dB/span)*([*] spans)/(0.0245 dB/km)
                      = Min(3200, [*] km) = 3200 km                              = Min(3200, [*] km) = 3200 km
-------------------------------------------------------------------------------------------------------------------------------
 [*]     Max Distance = (17 dB/span)*([*] spans)/(0.0245 dB/km)     Max Distance = (17 dB/span)*([*] spans)/(0.0245 dB/km)
                      = Min(3200, [*] km) = 3200 km                              = Min(3200, [*] km) = [*] km
-------------------------------------------------------------------------------------------------------------------------------
</TABLE>
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission.  Asterisks denote omissions.

   Corvis Optical Amplifier

The Corvis Optical Amplifier provides optical amplification of up to [*]
channels that allows for transmission distances up to 3,200 km without
electrical regeneration using Corvis transmitters and receivers.  Two Corvis
Optical Amplifiers are provided on a single [*] amplifier shelf for use in two
fiber systems.  A single rack can house up to [*] amplifier shelves.  The Corvis
Optical Amplifier can be provided in [*] to amplify spans with losses up to [*].
A [*] can be added to either [*] as required to [*] for [*] and the [*] loss is
added to the span loss.  The Corvis Optical Amplifier is equipped to transmit
and receive [*] carrying [*] channels, Corvis system supervisory information,
and [*] order wires.  A Craft Interface and Environmental Control Unit (ECU) are
provided for local control of the amplifier.

<TABLE>
<CAPTION>
                                       [*] Amplifier
-----------------------------------------------------------------------------------------------
Parameter                         Nominal Value   Units                 Notes
-----------------------------------------------------------------------------------------------
<S>                               <C>             <C>     <C>
Max. Amplifier Gain                    [*]         dB     Based on LS, TW-C, TW-P and TW-RS
                                                          fiber spans having an average [*]
-----------------------------------------------------------------------------------------------
Operating Range                     1530-1564      nm
-----------------------------------------------------------------------------------------------
Gain Flatness over Operating           [*]         dB
Range
-----------------------------------------------------------------------------------------------
</TABLE>

<TABLE>
<CAPTION>
                                       [*] Amplifier
-----------------------------------------------------------------------------------------------
Parameter                         Nominal Value   Units                 Notes
--------------------------------------------------------------------------------------------
<S>                               <C>             <C>     <C>
Max. Amplifier Gain                    [*]         dB     Based on LS, TW-C, TW-P and TW-
  [*]                                  [*]         dB     RS fiber spans having an average [*]
--------------------------------------------------------------------------------------------
Operating Range                     1530-1564      nm
--------------------------------------------------------------------------------------------
Gain Flatness over Operating           [*]         dB
Range
--------------------------------------------------------------------------------------------
</TABLE>

<TABLE>
<CAPTION>

              -----------------------------------------------
               Size and Weight             Specification
              -----------------------------------------------
               <S>                      <C>
               Power                    -48 volts @ [*] Amps
              -----------------------------------------------
               Heat Dissipation         [*] Watts /Shelf
              -----------------------------------------------
               Size                     84"x24"x24"
              -----------------------------------------------
               Weight (OA3200L[*])      [*]
              -----------------------------------------------
</TABLE>
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission.  Asterisks denote omissions.

  Corvis Optical Network Gateway

The Corvis Optical Network Gateway (ONG) can be configured to transmit and
receive up to [*] optical signal channels for up to 3,200 km without electrical
regeneration when used with Corvis Optical Amplifiers.  [*] racks are required
to house equipment for [*] transmit channels and [*] receive channels according
to the channel plan provided below.  [*] ONG rack includes [*] transmit channels
and [*] receive channels along with multiplexing, demultiplexing, and monitoring
equipment.  In addition, [*] rack is equipped to transmit and receive [*] and
provides a Craft Interface for local access to the ONG.

<TABLE>
<CAPTION>

------------------------------------------------------------------------------
       Parameter                    Min   Typ   Max    Units     Comments
------------------------------------------------------------------------------
<S>                                 <C>   <C>   <C>    <C>       <C>
Number of channels                              160
------------------------------------------------------------------------------
[*]                                 [*]   [*]   [*]
------------------------------------------------------------------------------
Data Rate per channel                     [*]           Gb/s       [*]
------------------------------------------------------------------------------

------------------------------------------------------------------------------
Tx Output Power per channel               [*]           dBm
------------------------------------------------------------------------------
Fiber Launch power per channel            [*]           dBm
------------------------------------------------------------------------------

------------------------------------------------------------------------------
Rx Input Power per channel                [*]           dBm
------------------------------------------------------------------------------
Receiver Sensitivity at [*]         [*]   [*]          dB.nm
------------------------------------------------------------------------------
</TABLE>

<TABLE>
<CAPTION>

---------------------------------------------------------------------------------------
              Parameter                          Value     Units        Comments
---------------------------------------------------------------------------------------
<S>                                              <C>       <C>       <C>
Number of Racks - up to [*] Tx/Rx Channels        [*]
---------------------------------------------------------------------------------------
Number of Racks - up to [*] Tx/Rx Channels        [*]
---------------------------------------------------------------------------------------
Number of Racks - up to [*] Tx/Rx Channels        [*]
---------------------------------------------------------------------------------------
Number of Racks - up to [*] Tx/Rx Channels        [*]
---------------------------------------------------------------------------------------
Number of Racks - up to [*] Tx/Rx Channels        [*]
---------------------------------------------------------------------------------------
Number of Racks - up to [*] Tx/Rx Channels        [*]
---------------------------------------------------------------------------------------
Voltage requirements                              -48        V       Standard Voltage
---------------------------------------------------------------------------------------
Power requirements/Rack                           [*]        W
---------------------------------------------------------------------------------------
Dimensions per Rack (WxDxH)                     19x24x84   Inches
---------------------------------------------------------------------------------------
</TABLE>
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission.  Asterisks denote omissions.

 CORVIS Optical Add/Drop Multiplexer [*] (OADM [*])

The OADM [*] allows up to 160 channels of Add Drop access, [*], and [*] of
channels.  The OADM [*] is partitioned into [*] section that provides for [*]
and [*], which can be upgraded to provide add/drop functionality by addition of
ONGs.  The rack configuration and space requirements depend on the number of
channels accessed in each direction.

<TABLE>
<CAPTION>

-------------------------------------------------------------------------------
              Parameter                  Min    Typ   Max    Units   Comments
-------------------------------------------------------------------------------
<S>                                      <C>    <C>   <C>    <C>     <C>

Number of channels                       [*]           160
-------------------------------------------------------------------------------
Wavelength range                         1530         1564    nm
-------------------------------------------------------------------------------
[*]                                      [*]          [*]
-------------------------------------------------------------------------------
[*]                                      [*]          [*]
-------------------------------------------------------------------------------
Output optical power per channel         [*]    [*]   [*]     dBm
-------------------------------------------------------------------------------
Output optical power (160 channels)      [*]    [*]   [*]     dBm
-------------------------------------------------------------------------------
[*]                                      [*]          [*]     [*]
-------------------------------------------------------------------------------
[*]                                      [*]                  [*]
-------------------------------------------------------------------------------
</TABLE>

<TABLE>
<CAPTION>

--------------------------------------------------------------------------------------
          Parameter               Value     Units               Comments
--------------------------------------------------------------------------------------
<S>                               <C>       <C>       <C>
Number of Racks: [*]               [*]                            [*]
--------------------------------------------------------------------------------------
Number of Racks: OADM [*]          [*]                Up to [*] channels Add/Drop in
                                                            each direction
--------------------------------------------------------------------------------------
Number of Racks: OADM [*]          [*]                Up to [*] channels Add/Drop in
                                                            each direction
--------------------------------------------------------------------------------------
Number of Racks: OADM [*]          [*]                Up to [*] channels Add/Drop in
                                                            each direction
--------------------------------------------------------------------------------------
Voltage requirements               -48        V             Standard Voltage
--------------------------------------------------------------------------------------
Power requirements/Rack            [*]        W
--------------------------------------------------------------------------------------
Dimensions per Rack (WxDxH)      19x24x84   Inches
--------------------------------------------------------------------------------------
</TABLE>
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission.  Asterisks denote omissions.

Channel Plan:

The Corvis system transmits and receives [*] channels [*] as shown in the table
below.  [*] resulting in total system capacity of 400 Gb/s.  [*] are allocated
in the channel plan [*].

<TABLE>
<CAPTION>
--------------------------------------------------
 WavelengthNumber     Frequency    Wavelength(nm)
                       (THz)
--------------------------------------------------
<S>                   <C>         <C>
        [*]              [*]           [*]
--------------------------------------------------
</TABLE>
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

                             [BROADWING LETTERHEAD]

                                                                   April 7, 2000

Kim Larsen
General Counsel
Corvis Corporation
7015 Albert Einstein Drive
PO Box 9400
Columbia, Maryland 21046-9400

Dear Kim,

     As we discussed, please note the following items which should revised in
the Procurement Agreement between Broadwing Communications Services Inc.  and
Corvis Corporation, dated March 17, 2000.

     Article 4 "Volume Deployment; Quantities and Delivery Schedules" shall be
amended to read as follows:

     4.1  Initial Deployment.  Upon successful completion of the Transport Field
     Trial, Customer will purchase from Corvis and deploy the Corvis Transport
     Equipment and Software in quantities and in configurations priced at U.S.
     $200,000,000.00 (the "Minimum Deployment Commitment"), U.S. $100,000,000.00
     of which (the "First Year Deployment Commitment") must be ordered within 12
     months after the successful completion of the Field Trial with delivery no
     later than [*] after such 12 month period, in each case based on the prices
     and license fees set forth in Attachment 6. The Minimum Deployment
     Commitment and the First Year Deployment Commitment shall be adjusted for
     late delivery by Corvis as provided in Section 4.2. Customer will be [*] in
     accordance with the terms and conditions of Attachment 6.

     4.2  Initial Deployment Schedule; Late Deliveries.  Within [*] after
     successful completion of the Transport Field Trial, Customer and Corvis
     shall agree upon a [*] estimated deployment schedule (the "Estimated
     Deployment Schedule") for the Corvis Transport Equipment and Software
     constituting the Minimum Deployment Commitment.
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

If Customer submits Purchase Orders for Corvis Transport Equipment and Software
in accordance with applicable lead times and the amount ordered and previously
shipped does not exceed the Estimated Deployment Schedule, the Minimum
Deployment Commitment and the First Year Deployment Commitment shall each be [*]
the Corvis Transport Equipment and Software Corvis [*] after the agreed delivery
date.

     4.3  Non-binding Forecasts.  Quantity Forecast.  By the [*] business day of
     each [*] (the [*] hereafter being "[*]"), Customer will provide to Corvis
     a [*] month rolling forecast (the "Rolling Forecast") of deliveries for the
     [*] commencing at the beginning of the [*] after the [*] in which the
     forecast is made. The Rolling Forecast ([*] through [*]) will show the
     quantity of each Product by product code which Customer anticipates it will
     need to be delivered during the specified month.

     4.4  During the Term of this Agreement, Customer will issue Purchase Orders
     specifying the Products ordered, the quantities necessary, the delivery
     site or sites (hereinafter the "Specified Site[s]") for the Products and
     its proposed delivery schedule.

     4.5  All deliveries of Products will be made [*].  Customer agrees to pay
     [*] charges. The preceding provisions of this clause are valid for
     deliveries in the United States, its possessions and territories only.  All
     deliveries outside the aforementioned areas will be mutually agreed upon on
     a case by case basis.

     4.6  Customer will have the right to alter the destination site at least
     [*] days prior to Corvis' scheduled shipment date for Products, without
     cost or expense to Customer, by timely transmitting Notice to Corvis of the
     new Specified Site(s).

     4.7  Corvis will execute and deliver to Custumer an order acknowledgment
     within [*] after Corvis' receipt of each Purchase Order or, if Corvis
     cannot meet the proposed delivery times, the parties shall mutually agree
     to appropriate delivery times. If Corvis and Customer cannot agree upon
     delivery times, Corvis shall have the right to reject a Purchase Order.
     Product order lead times shall be [*] unless otherwise specified by Corvis.

     4.8  Customer will purchase on-site installation spares, parts and
     components of the Equipment ("Spares Kits" or "Kits") reasonably designated
     by Corvis and agreed upon by Corvis and Customer from time to time as the
     quantity necessary to enable Corvis to provide the warranty and support
     services required by this Agreement.  The quantity and locations of the
     Kits may change with installation requirements and changes in the topology
     of Customer's network.
<PAGE>

  Confidential materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

     4.9   [*]

     4.10  [*]

               Article 28 "Definitions" shall be amended as follows:

     "Committed Amounts" shall be deleted.
     "Final Deployment Date" shall be deleted.
     "Initial Deployment Shortfall" shall be deleted.
     "Specified Site" shall reference the definition contained in Section 4.4.

     All other definitions shall remain in full force and effect.

     Please execute your concurrence by counter-execution below and return at
your earliest convenience.

                                         Sincerely,

                                         /s/ Angela L. Jones
                                         Angela L. Jones

_________________________________

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00010-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00010-of-00352.parquet"}]]