Document:

<PAGE>   1
                                                                  Exhibit 10.22

                            FIRST AMENDMENT TO LEASE

THIS FIRST AMENDMENT TO LEASE (this "FIRST AMENDMENT") is made this 16th day of
February, 2000, by and between SPIEKER PROPERTIES, L.P., a California limited
partnership, ("LANDLORD"), and BROCADE COMMUNICATIONS SYSTEMS, INC., a Delaware
corporation ("TENANT").

        WHEREAS, Landlord and Tenant entered into a Lease dated December 17,
1999, (as amended, the "LEASE"), for those certain premises located at 1745
Technology Drive, San Jose, California (the "PERMANENT PREMISES"), and at 2055
Gateway Place, San Jose, California (the "PHASE I TEMPORARY PREMISES"), and 1741
Technology Drive, San Jose, California (the "PHASE II TEMPORARY PREMISES"), each
as more fully described in the Lease. Capitalized terms used but not otherwise
defined herein shall have the meanings given them in the Lease; and

        WHEREAS, Tenant desires to lease from Landlord, and Landlord desires to
lease to Tenant, additional space in Phase I Temporary Premises Building on a
temporary basis and under the terms and conditions as provided herein; and

        WHEREAS, Landlord and Tenant desire to convert the Phase II Temporary
Premises to become a portion of the Permanent Premises; and

        WHEREAS, Landlord and Tenant desire to modify the Lease as provided
herein.

        NOW, THEREFORE, in consideration of the covenants and agreements
contained herein, the parties hereby mutually agree as follows:

        1. The following shall be added to and made a part of the Lease as a new
Paragraph 39.F:

           "ADDITIONAL TEMPORARY PREMISES.

           a.         TERM; RENT. Landlord shall deliver to Tenant possession of
                      the premises depicted on ATTACHMENT A attached hereto,
                      which premises is comprised of approximately four thousand
                      one hundred ninety-five (4,195) rentable square feet (the
                      "PART A ADDITIONAL TEMPORARY PREMISES"), and the premises
                      depicted on ATTACHMENT B attached hereto, which premises
                      is comprised of approximately eight thousand two hundred
                      ten (8,210) rentable square feet (the "PART B ADDITIONAL
                      TEMPORARY PREMISES," the Part A Additional Temporary
                      Premises and the Part B Additional Temporary Premises
                      shall sometimes be referred to herein collectively as the
                      "ADDITIONAL TEMPORARY PREMISES"), which total Additional
                      Temporary Premises comprise in total approximately twelve
                      thousand four hundred five (12,405) rentable square feet
                      located in the Phase I Temporary Premises Building. The
                      terms and conditions of this Lease shall apply to Tenant's
                      possession and use of the Additional Temporary Premises;
                      provided, however, that Rent due and payable commencing on
                      each of the Part A Additional Temporary Premises Term
                      Commencement Date and the Part B Additional Temporary
                      Premises Term Commencement Date (each as defined herein)
                      through the date Tenant surrenders possession of the
                      entire Additional Temporary Premises to Landlord as
                      provided herein shall be as follows: with respect to the
                      Part A Additional Temporary Premises, an amount equal to
                      Twelve Thousand Five Hundred Eighty-Five Dollars and
                      No/100 ($12,585.00) per month, and with respect to the
                      Part B Additional Temporary Premises, an amount equal to
                      Twenty-Four Thousand Six Hundred Thirty and No/100
                      ($24,630.00) per month; The total amount Rent payable by
                      Tenant on a monthly basis after the Part B Additional
                      Temporary Premises shall be Thirty-Seven Thousand Two
                      Hundred Fifteen Dollars and No/100 ($37,215.00). If the
                      obligation for payment of Rent for either of the Part A
                      Additional Temporary Premises or the Part B Additional
                      Temporary Premises commences on a day other than the first
                      day of a month, then such Rent shall be prorated and the
                      prorated installment shall be paid on the first day of the
                      calendar month next succeeding the Part A Additional
                      Temporary Premises Term Commencement Date or the Part B
                      Additional Temporary Premises Term Commencement Date (each
                      as defined herein), as the case may be. The term
                      commencement date ("PART A ADDITIONAL TEMPORARY PREMISES
                      TERM COMMENCEMENT DATE") with respect to the Part A
                      Additional Temporary Premises shall be the date Landlord
                      delivers possession of the Part A Additional Temporary
                      Premises to Tenant. The term commencement date ("PART B
                      ADDITIONAL TEMPORARY PREMISES TERM COMMENCEMENT DATE")
                      with respect to the Part B Additional Temporary Premises
                      shall be the date Landlord delivers possession of the Part
                      B Additional Temporary Premises to Tenant.

           b.         TENANT IMPROVEMENTS.

                      (i) Landlord, at Landlord's sole cost and expense, hereby
                      agrees to perform or cause to be performed the following
                      improvements in the Additional Temporary Premises prior to
                      the Part B Additional Temporary Premises Term Commencement
                      Date: (1) restoration of the ceilings, lighting and HVAC
                      systems to a condition consistent with the building
                      standards and located in the Part B Additional Temporary
                      Premises, (2) shampoo of exiting carpets within the Part A
                      Additional Temporary Premises and replacing the carpeting
                      with building standard carpeting within the Part B
                      Additional Temporary Premises, and (3) repaint those walls
                      located within the entire Additional Temporary Premises
                      which are not currently covered with wallcoverings.

                      (ii) Tenant shall be liable for and shall contribute an
                      amount equal to fifty percent (50%) of the total cost of
                      the removal of the training and rear projection rooms
                      currently located in the Part B Additional Temporary
                      Premises. Within ten (10) days following the date of
                      execution of this First Amendment, Tenant shall deliver to
                      Landlord the amount equal to Sixteen Thousand Four Hundred
                      Fifty-Six Dollars and 50/100 ($16,456.50) ("TENANT'S
                      ESTIMATED CONTRIBUTION AMOUNT"). In the event Tenant's
                      Estimated Contribution Amount is less than fifty percent
                      (50%) of the costs actually incurred in connection with
                      the removal of the training and rear projection rooms,
                      Landlord shall deliver to Tenant a written request with
                      documentary evidence of the actual cost and Tenant shall,
                      within ten (10) days after delivery of such notice,
                      deliver to Landlord the remaining balance owed to Landlord
                      above Tenant's Estimated Contribution Amount. In the event
                      Tenant's Estimated Contribution Amount is more than fifty

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                      percent (50%) of the costs actually incurred in connection
                      with the removal of the training and rear projection
                      rooms, Landlord shall reimburse Tenant such excess amount
                      within ten (10) days after such actual costs is finally
                      determined by Landlord and all lien releases and other
                      items related to such removal have been received by
                      Landlord.

           c.         SURRENDER OF ADDITIONAL TEMPORARY PREMISES. Within thirty
                      (30) days following substantial completion of the Tenant
                      Improvements (as defined in EXHIBIT C hereto), Tenant
                      shall surrender possession of the Additional Temporary
                      Premises in accordance with Paragraph 36 hereof."

        2.      Delete Paragraph 39.D(2) in its entirety.

        3.      Delete Paragraph 39.A in its entirety and replace with the
                following:

        "A.     RENT.

        Subject to the provisions of Paragraphs 2.B, Base Rent, net of Operating
        Expenses per Paragraph 7 of this Lease, for the Premises shall be as
        follows:

<TABLE>
<S>                                                            <C>
        From the Term Commencement Date through the
        end of the twelfth (12th)                               $627,432.00 per month plus operating expenses per Paragraph 7 of
                                                                this Lease. Operating Expenses for calendar year 2000 are estimated
                                                                to be

        month following the Term Commencement Date:             $217,256.00 per month.

        Month 13 following the Term Commencement
        Date through Month 24:                                  $646,254.00 per month plus operating expenses per Paragraph 7 of
                                                                this Lease

        Month 25 following the Term Commencement
        Date through Month 36:                                  $665,642.00 per month plus operating expenses per Paragraph 7 of
                                                                this Lease.

        Month 37 following the Term Commencement
        Date through Month 48:                                  $685,611.00 per month plus operating expenses per Paragraph 7 of
                                                                this Lease.

        Month 49 following the Term Commencement
        Date through Month 60:                                  $706,179.00 per month plus operating expenses per Paragraph 7 of
                                                                this Lease.

        Month 61 following the Term Commencement
        Date through Month 72:                                  $727,364.00 per month plus operating expenses per Paragraph 7 of
                                                                this Lease.

        Month 73 following the Term Commencement
        Date through Month 84:                                  $749,185.00 per month plus operating expenses per Paragraph 7 of
                                                                this Lease.

        Month 85 following the Term Commencement
        Date through Month 96:                                  $771,661.00 per month plus operating expenses per Paragraph 7 of
                                                                this Lease.

        Month 97 following the Term Commencement
        Date through Month 108:                                 $794,811.00 per month plus operating expenses per Paragraph 7 of
                                                                this Lease

        Month 109 following the Term Commencement
        Date through Month 120:                                 $818,655.00 per month plus operating expenses per Paragraph 7 of
                                                                    this Lease."
</TABLE>

        4.      Insert as a new Paragraph 39.F the following:

        "F.     EXPANSION PREMISES. Prior to delivery by Landlord to Tenant of
        the Premises, Landlord shall deliver to Tenant possession of the
        premises depicted on ATTACHMENT C, attached hereto (the "EXPANSION
        PREMISES"), which Expansion Premises comprise approximately thirty-nine
        thousand forty-three (39,043) rentable square feet and is in the
        building located at 1741 Technology Drive, San Jose, California. The
        terms and conditions of this Lease shall apply to Tenant's possession
        and use of the Expansion Premises; provided, however, that Base Rent due
        and payable commencing on the Expansion Premises Term Commencement Date
        (as defined herein) through the Term Commencement Date shall be an
        amount equal to One Hundred Eleven Thousand Two Hundred Seventy-Three
        Dollars and No/100 ($111,273.00) per month. Tenant shall be liable for
        the payment of Operating Expenses with respect to the Expansion Premises
        as of the Expansion Premises Term Commencement Date (as defined below).
        If the obligation for payment of Base Rent for the Expansion Premises
        commences on a day other than the first day of a month, then such Base
        Rent shall be prorated and the prorated installment shall be paid on the
        first day of the calendar month next succeeding the Expansion Premises
        Term Commencement Date (as defined below). The term commencement date
        ("EXPANSION PREMISES TERM COMMENCEMENT DATE") with respect to the
        Expansion Premises shall be the date Landlord delivers possession of the
        Expansion Premises with the improvements, if any, substantially complete
        in accordance with the terms of ATTACHMENT D, attached hereto. By taking
        possession of the Expansion Premises, Tenant accepts them "as is," as
        being in good order, condition and repair and the condition in which
        Landlord is obligated to deliver them and suitable for the Permitted Use
        (with respect to the Expansion Premises) and Tenant's intended
        operations in the Expansion Premises, whether or not any notice of
        acceptance is given. Landlord shall make commercially reasonable efforts
        to deliver possession of the Expansion Premises to Tenant on or before
        May 1, 2000. Tenant's taking of possession of the Expansion Premises or
        any part thereof shall constitute Tenant's confirmation of substantial
        completion thereof for all purposes hereof, whether or not substantial
        completion of the Expansion Premises Building or Project shall have
        occurred. If for any reason Landlord cannot deliver possession of the
        Expansion Premises to Tenant on the scheduled

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        Expansion Premises Term Commencement Date, Landlord shall not be subject
        to any liability therefor, nor shall Landlord be in default hereunder
        nor shall such failure affect the validity of this Lease, and unless the
        Expansion Premises have been delivered to Tenant, Tenant agrees to
        accept possession of the Expansion Premises at such time as such
        improvements have been substantially completed, which date shall then be
        deemed the Expansion Premises Term Commencement Date. In the event of
        any dispute as to substantial completion of work performed or required
        to be performed by Landlord with respect to the Expansion Premises, the
        certificate of Landlord's architect or general contractor shall be
        conclusive. Upon the Term Commencement Date, the Expansion Premises
        shall be a part of the Premises under this Lease and the terms and
        conditions of the Lease shall apply to the Expansion Premises as a part
        of the Premises, except as expressly stated herein."

        5.      The following shall be added to and made a part of the Lease as
                a new Paragraph 39.G:

        "G.     ADDITIONAL LETTER OF CREDIT.

        (1)     DELIVERY OF ADDITIONAL LETTER OF CREDIT. In lieu of depositing a
                cash security deposit with Landlord and in addition to the LOC,
                Tenant shall, on execution of this Lease, deliver to Landlord
                and cause to be in effect during the Lease Term an
                unconditional, irrevocable letter of credit ("ADDITIONAL LOC")
                in the amount of One Million Three Hundred Thirty-Five Thousand
                Two Hundred Seventy-One and No/100 Dollars ($1,335,271.00), as
                it may be increased as provided in this Lease (the "ADDITIONAL
                LOC AMOUNT") for an initial term of the Additional LOC of three
                (3) years and thereafter shall renew automatically from year to
                year through 30 days beyond the expiration date of this Lease or
                any extension thereto. The Additional LOC shall be in a form
                acceptable to Landlord and shall be issued by an "LOC bank"
                selected by Tenant and acceptable to Landlord. The Additional
                LOC shall survive the termination of this Lease. An "LOC bank"
                is a bank that accepts deposits, maintains accounts, has a local
                office that will negotiate a letter of credit, and the deposits
                of which are insured by the Federal Deposit Insurance
                Corporation. Tenant shall pay all expenses, points, or fees
                incurred by Tenant in obtaining the Additional LOC. The
                Additional LOC shall not be mortgaged, assigned or encumbered in
                any manner whatsoever by Tenant without the prior written
                consent of Landlord. Tenant acknowledges that Landlord has the
                right to transfer or mortgage its interest in the Project, the
                Building and in this Lease and Tenant agrees that in the event
                of any such transfer or mortgage, Landlord shall have the right
                to transfer or assign the Additional LOC and/or the Additional
                LOC Security Deposit (as defined below) to the transferee or
                mortgagee, and in the event of such transfer, Tenant shall look
                solely to such transferee or mortgagee for the return of the
                Additional LOC and/or the Additional LOC Security Deposit. The
                maximum amount of any transfer fee associated with such transfer
                shall not be in excess of reasonable transfer fees customarily
                required by issuing banks, which about shall be expressly stated
                in the terms of the Additional LOC, and shall be payable by
                Landlord.

        (2)     REPLACEMENT OF ADDITIONAL LETTER OF CREDIT. Tenant may, from
                time to time, replace any existing Additional LOC with a new
                Additional LOC if the new Additional LOC (a) becomes effective
                at least thirty (30) days before expiration of the Additional
                LOC that it replaces; (b) is in the required Additional LOC
                amount; (c) is issued by an LOC bank acceptable to Landlord; and
                (d) otherwise complies with the requirements of this Paragraph
                39.G.

        (3)     LANDLORD'S RIGHT TO DRAW ON ADDITIONAL LOC. Landlord shall hold
                the Additional LOC as security for the performance of Tenant's
                obligations under this Lease. If, after notice and failure to
                cure within any applicable period provided in this Lease, Tenant
                is in default pursuant to this Lease, Landlord may, without
                prejudice to any other remedy it has, draw on that portion of
                the Additional LOC necessary to (a) pay Rent or other sum in
                default; (b) pay or reimburse Landlord for any amount that
                Landlord may spend or become obligated to spend in exercising
                Landlord's rights under Paragraph 30 (Right of Landlord to
                Perform Tenant's Covenant); and/or (c) compensate Landlord for
                any expense, loss, or damage that Landlord may suffer because of
                Tenant's default. If Tenant fails to renew or replace the
                Additional LOC at least thirty (30) days before its expiration,
                Landlord may, without prejudice to any other remedy it has, draw
                on the entire amount of the Additional LOC.

        (4)     ADDITIONAL LOC SECURITY DEPOSIT. Any amount of the Additional
                LOC that is drawn on by Landlord but not applied by Landlord
                shall be held by Landlord as a security deposit (the "ADDITIONAL
                LOC SECURITY DEPOSIT") in accordance with Paragraph 19 of this
                Lease.

        (5)     RESTORATION OF ADDITIONAL LOC AND ADDITIONAL LOC SECURITY
                DEPOSIT. If Landlord draws on any portion of the Additional LOC
                and/or applies all or any portion of such draw, Tenant shall,
                within five (5) business days after demand by Landlord, either
                (a) deposit cash with Landlord in an amount that, when added to
                the amount remaining under the Additional LOC and the amount of
                any Additional LOC Security Deposit, shall equal the Additional
                LOC Amount then required under this Paragraph 39.G; or (b)
                reinstate the Additional LOC to the full Additional LOC Amount.

        (6)     REDUCTION OF ADDITIONAL LOC AMOUNT. At least fifteen (15)
                business days prior to the dates specified in each of clauses a.
                through d. below, Tenant shall deliver to Landlord for review
                Tenant's financial statements prepared in accordance with
                generally accepted accounting principles and audited by a
                nationally recognized public accounting firm acceptable to
                Landlord, and any other financial information requested by
                Landlord ("TENANT'S FINANCIAL INFORMATION") If: (i) Tenant has a
                tangible net worth, which "tangible net worth" shall be
                determined by Landlord in its sole discretion and shall mean
                assets less intangible assets and total liabilities, with
                intangible asserts including nonmaterial benefits such as
                goodwill, patents, copyrights, and trademarks, in excess of One
                Hundred Seventy Five Million and No/100 Dollars
                ($175,000,000.00) as reflected in Tenant's Financial
                Information, which amount shall be determined by Landlord to its
                satisfaction prior to any reduction in the Additional LOC
                Amount; and (ii) Tenant's Financial Information reflects four
                (4) consecutive calendar quarters of profitability, as
                determined by Landlord, during the time period immediately
                preceding Tenant's request for reduction in the Additional LOC
                Amount described in this subparagraph during the time period
                immediately preceding Tenant's request for reduction in the
                Additional LOC Amount, as such profitability is determined by
                Landlord, then the following reductions in the Additional LOC
                Amount may be made in accordance with the terms of this
                Paragraph 39.G(6):

<PAGE>   4

                a.      At any time after the end of the thirty-sixth (36th)
                        month following the Term Commencement Date, the
                        Additional LOC Amount may be reduced to an amount equal
                        to One Million One Thousand Four Hundred Fifty-Three and
                        No/100 Dollars ($1,001,453.00);

                b.      At any time after the end of the forty-eighth (48th)
                        month following the Term Commencement Date, the
                        Additional LOC Amount may be reduced to an amount equal
                        to Six Hundred Sixty-Five Thousand Nine Hundred
                        Sixty-Six and No/100 Dollars ($665,966.00);

                c.      At any time after the end of the sixtieth (60th) month
                        following the Term Commencement Date, the Additional LOC
                        Amount may be reduced to an amount equal to Three
                        Hundred Thirty Thousand Nine Hundred Eighty-Five and
                        No/100 Dollars ($330,985.00); and

                d.      At any time after the end of the seventy-second (72nd)
                        month following the Term Commencement Date, the
                        Additional LOC may be returned by Landlord to the
                        issuing bank for cancellation provided that Tenant has,
                        prior to such delivery by Landlord, delivered a cash
                        security Deposit (to be held by Landlord in accordance
                        with the terms of Paragraph 19 of this Lease) an amount
                        equal to One Hundred Seventy-Nine Thousand Two Hundred
                        Seven and No/100 Dollars ($179,207.00).

        In the event that any of the above described reductions to the
        Additional LOC Amount is made and, subsequently, Tenant fails to meet
        the corresponding profitability and tangible net worth condition
        precedent for a period of thirty (30) days following delivery by
        Landlord of written notice of any such failure, Tenant shall within two
        (2) business days, increase the face amount of the Additional LOC to an
        amount equal to the Additional LOC Amount existing prior to such
        reduction (including the reduction described in clause d. above). If
        Tenant fails to increase the Additional LOC Amount as provided above,
        such failure shall constitute a default hereunder (which default shall
        not be subject to any cure rights afforded anywhere in this Lease and
        Landlord shall be entitled to draw on the Additional LOC for the full
        Additional LOC Amount and hold such Additional LOC Amount as a Security
        Deposit in accordance with the terms of this Lease, and enforce all
        other rights available to Landlord pursuant to the terms of this Lease
        or under applicable law."

        6.      Paragraph 4.1 of Exhibit C attached to the Lease shall be
                modified as follows: Delete the reference to "One Hundred
                Eighty-Five and No/100 Dollars ($185,000.00)" and insert
                therefor the following: "One Hundred Seventy Thousand and No/100
                ($170,000.00)".

        7.      The definition of Security Deposit in the Basic lease
                Information shall be deleted and replaced by the following:

                "Seven Million Five Hundred Twenty-Nine Thousand One Hundred
                Seventy-Five Dollars and No/100 ($7,529,175.00) Letter of Credit
                delivered in accordance with the terms of Paragraph 39.E
                (subject to adjustment as provided in Paragraphs 39.E, 39.G (as
                applicable) and 19 hereof)."

        8.      "Tenant's Proportionate Share" with respect to the Expansion
                Premises in the Phase II Temporary Premises Building shall be
                29.35%.

        9.      "Occupancy Density" with respect to the Expansion Premises in
                the Phase II Temporary Premises Building shall be 4.5 people per
                one thousand rentable square feet.

        10.     Provided Tenant is not, and has not been, in default of any
                terms and conditions of this Lease, during the initial Term of
                the Lease only, Tenant shall have a one-time right of first
                offer to lease space in the Phase II Temporary Premises Building
                at such time as such additional space is vacated by the prior
                tenant. Upon notification by Landlord in writing of the
                availability of space and the terms and conditions on which
                Landlord is willing to lease such additional space to Tenant,
                Tenant shall have five (5) days to notify Landlord in writing of
                Tenant's desire to exercise Tenant's right of first offer on the
                terms and conditions. In the event Tenant fails to give Landlord
                notice of Tenant's election to lease such additional space
                within such time period, or if Tenant elects not to lease such
                space, Tenant shall have no further right, title or interest in
                such additional space (except as expressly provided in this
                Lease) and this right of first offer shall terminate with
                respect to the portion of the available space so offered to
                Tenant. If, on the other hand, Tenant exercises its right of
                first offer in the manner prescribed, Tenant shall immediately
                deliver to Landlord payment for the first month's rent for such
                additional space (in the same manner as provided for in this
                Lease), and the lease for such additional space shall be
                consummated without delay in accordance with the terms and
                conditions set forth in Landlord's notice Such additional space
                shall be leased to Tenant on an "as is" basis and Landlord shall
                have no obligation to improve such additional space or grant
                Tenant any improvement allowance thereon. Notwithstanding
                anything to the contrary herein contained, Tenant's right to the
                expansion premises shall be conditioned upon the following: (i)
                at the time Tenant agrees to accept the expansion premises and
                at the time of the commencement of the term for the expansion
                premises, Tenant shall be in possession of and occupying the
                primary premises for the conduct of its business therein and the
                same shall not be occupied by any assignee, subtenant or
                licensee and, provided further, that the option for additional
                space shall be applicable hereunder only if the expansion
                premises will actually be occupied by Tenant and (ii) the
                agreement of acceptance shall constitute a representation by
                Tenant to Landlord, effective as of the date of the agreement of
                acceptance and as of the date of commencement of the lease for
                the expansion premises, that Tenant does not intend to assign
                the lease for the expansion premises, in whole or in part or
                sublet all or any portion of the Premises, the election to
                expand being for the purpose of utilizing the expansion premises
                for Tenant's purposes in the conduct of Tenant's business
                therein.

<PAGE>   5

        11.     The following phrase from last sentence of Paragraph 7.C of the
                Lease shall be deleted: "up to an amount not to exceed Fifteen
                Thousand Dollars ($15,000)".

Except as expressly modified above, all terms and conditions of the Lease remain
in full force and effect and are hereby ratified and confirmed.

        IN WITNESS WHEREOF, the parties hereto have entered into this First
Amendment as of the date first written above.

LANDLORD:                                 TENANT:
Spieker Properties, L.P.,                 Brocade Communications Systems, Inc.,
A California limited partnership          a Delaware corporation

By: Spieker Properties, Inc.,            By:
    a Maryland corporation                  --------------------------------
    its General Partner                     Michael J. Byrd
                                            Its: Vice President, Finance
                                                 Chief Financial Officer

By:                                      By:
    --------------------------------        --------------------------------
    Joseph D. Russell, Jr.                  Victor Rinkle
    Its: President,                         Its: Vice President, Operations
         Silicon Valley Region

<PAGE>   6

                                  ATTACHMENT A

<PAGE>   7

                                  ATTACHMENT B

<PAGE>   8

                                  ATTACHMENT C

<PAGE>   9

                                  ATTACHMENT D

                 LEASE EXPANSION PREMISES IMPROVEMENT AGREEMENT

        This Lease Expansion Premises Improvement Agreement ("EXPANSION PREMISES
IMPROVEMENT AGREEMENT") sets forth the terms and conditions relating to
construction of the initial Expansion Premises Tenant Improvements described in
the Plans referred to below (the "EXPANSION PREMISES TENANT IMPROVEMENTS") in
the Expansion Premises. Capitalized terms used but not otherwise defined herein
shall have the meanings set forth in the Lease (the "LEASE") to which this
Expansion Premises Improvement Agreement is attached and forms a part.

1.      Plans and Specifications.

           1.1. Landlord shall construct the Expansion Premises Tenant
Improvements in the Expansion Premises pursuant to the plans and drawings as
provided to Landlord by Devcon (collectively, the "PLANS"). Tenant shall make no
changes or modifications to the Plans or submit any change orders without the
prior written approval of Landlord.

           1.2. Notwithstanding Landlord's review and approval of the Plans,
Landlord shall have no responsibility or liability whatsoever for any errors or
omissions contained in the Plans, or to verify dimensions or conditions, or for
the quality, design or compliance with applicable Regulations of any
improvements described therein or constructed in the Expansion Premises.
Landlord shall assign to Tenant all warranties and guarantees by the contractor
who constructs the Expansion Premises Tenant Improvements relating to the
Expansion Premises Tenant Improvements, and Tenant hereby waives all claims
against Landlord relating to, or arising out of the construction of, the
Expansion Premises Tenant Improvements.

2.      Specifications for Standard Expansion Premises Tenant Improvements.

           2.1. Specifications and quantities of standard building components
which will comprise and be used in the construction of the Expansion Premises
Tenant Improvements ("STANDARDS") are set forth in SCHEDULE 1 to this ATTACHMENT
D. As used herein, "STANDARDS" or "BUILDING STANDARDS" shall mean the standards
for a particular item selected from time to time by Landlord for the Building,
including those set forth on SCHEDULE 1 of this ATTACHMENT D, or such other
standards of equal or better quality as may be mutually agreed between Landlord
and Tenant in writing.

           2.2. No deviations from the Standards are permitted.

3.      Construction of Expansion Premises Tenant Improvements.

           3.1. Promptly upon the execution of this Expansion Premises
Improvement Agreement, Landlord shall secure a building permit and commence
construction of the Expansion Premises Tenant Improvements provided that Tenant
shall cooperate with Landlord in executing permit applications and performing
other actions reasonably necessary to enable Landlord to obtain any required
permits or certificates of occupancy. Without limiting the provisions of
Paragraph 35 of the Lease, Landlord shall not be liable for any direct or
indirect damages suffered by Tenant as a result of delays in construction beyond
Landlord's reasonable control, including, but not limited to, delays due to
strikes or unavailability of materials or labor, or delays caused by Tenant
(including delays by the contractor or anyone else performing services on behalf
of Landlord or Tenant).

           3.2. If any work is to be performed on the Expansion Premises by
Tenant or Tenant's contractor or agents:

               (a) Such work shall proceed upon Landlord's written approval of
Tenant's contractor, public liability and property damage insurance carried by
Tenant's contractor, and detailed plans and specifications for such work shall
be at Tenant's sole cost and expense, and shall further be subject to the
provisions of Paragraphs 12 and 27 of the Lease.

               (b) All work shall be done in conformity with a valid building
permit when required, a copy of which shall be furnished to Landlord before such
work is commenced, and in any case, all such work shall be performed in
accordance with all applicable Regulations. Notwithstanding any failure by
Landlord to object to any such work, Landlord shall have no responsibility for
Tenant's failure to comply with all applicable Regulations.

               (c) If required by Landlord or any lender of Landlord, all work
by Tenant or Tenant's contractor or agents shall be done with union labor in
accordance with all union labor agreements applicable to the trades being
employed.

               (d) All work by Tenant or Tenant's contractor or agents shall be
scheduled through Landlord.

               (e) Tenant or Tenant's contractor or agents shall arrange for
necessary utility, hoisting and elevator service with Landlord's contractor and
shall pay such reasonable charges for such services as may be charged by
Tenant's or Landlord's contractor.

               (f) Tenant's entry to the Expansion Premises for any purpose,
including, without limitation, inspection or performance of Tenant construction
by Tenant's agents, prior to the date Tenant's obligation to pay rent commences
shall be subject to all the terms and conditions of the Lease except the payment
of Rent. Tenant's entry shall mean entry by Tenant, its officers, contractors,
licensees, agents, servants, employees, guests, invitees, or visitors.

               (g) Tenant shall promptly reimburse Landlord upon demand for any
reasonable expense actually incurred by the Landlord by reason of faulty work
done by Tenant or its contractors or by reason of any delays caused by such
work, or by reason of inadequate clean-up.

4.      Completion and Rental Commencement Date.

           4.1. Tenant's obligation to pay Rent under the Lease shall commence
on the applicable date described in Paragraph 2 of the Lease. However:

               (a) If Tenant delays in approving any matter requiring Tenant's
approval within the time limits specified herein; or

<PAGE>   10

               (b) If the construction period is extended because Tenant
requests any changes in construction or modifies the Plans or if the same do not
comply with applicable Regulations; or

               (c) If Landlord is otherwise delayed in the construction of the
Expansion Premises Tenant Improvements for any act or omission of or breach by
Tenant or anyone performing services on behalf of Tenant or on account of any
work performed on the Expansion Premises by Tenant or Tenant's contractors or
agents, then the date described in Paragraph 2 of the Lease shall be deemed to
be accelerated by the total number of days of Tenant delays described in (a)
through (c) above (each, a "TENANT DELAY"), calculated in accordance with the
provisions of Paragraph 4.2 below.

           4.2. If the Term of the Lease has not already commenced pursuant to
the provisions of Paragraph 2 of the Lease and substantial completion of the
Expansion Premises Tenant Improvements has been delayed on account of any Tenant
Delays, then upon actual substantial completion of the Expansion Premises Tenant
Improvements (as defined in Paragraph 2 of the Lease), Landlord shall notify
Tenant in writing of the date substantial completion of the Expansion Premises
Tenant Improvements would have occurred but for such Tenant Delays, and such
date shall thereafter be deemed to be the Term Commencement Date for all
purposes under the Lease. Tenant shall pay to Landlord, within three (3)
business days after receipt of such written notice (which notice shall include a
summary of Tenant Delays), the per diem Base Rent times the number of days
between the date the Term Commencement Date would have otherwise occurred but
for the Tenant Delays (as determined by Landlord's contractor), and the date of
actual substantial completion of the Expansion Premises Tenant Improvements.

           4.3. Promptly after substantial completion of the Expansion Premises
Tenant Improvements, Landlord shall give notice to Tenant and Tenant shall
conduct an inspection of the Expansion Premises with a representative of
Landlord and develop with such representative of Landlord a punchlist of items,
if any, of the Expansion Premises Tenant Improvements that are not complete or
that require correction. Upon receipt of such punchlist, Landlord shall proceed
diligently to remedy such items at Landlord's cost and expense provided such
items are part of the Expansion Premises Tenant Improvements to be constructed
by Landlord hereunder and are otherwise consistent with Landlord's obligations
under this Expansion Premises Improvement Agreement (with any dispute between
Landlord and Tenant pertaining thereto to be resolved by Landlord's architect or
general contractor). Substantial completion shall occur notwithstanding delivery
of any such punchlist.

           4.4. A default under this Expansion Premises Improvement Agreement
shall constitute a default under the Lease, and the parties shall be entitled to
all rights and remedies under the Lease in the event of a default hereunder by
the other party (notwithstanding that the Term thereof has not commenced).

           4.5. Without limiting the "as-is" provisions of the Lease, except for
the Expansion Premises Tenant Improvements to be constructed by Landlord
pursuant to this Expansion Premises Improvement Agreement, Tenant accepts the
Expansion Premises in its "as-is" condition and acknowledges that it has had an
opportunity to inspect the Expansion Premises prior to signing the Lease.

5.      Expansion Premises Tenant Improvement Costs.

           5.1. The cost of the Expansion Premises Tenant Improvements shall be
paid for by Tenant (provided, however, that Landlord shall allocate the
Expansion Premises Tenant Improvement Allowance (as herein defined) to such
costs), including, without limitation, the cost of: Standards; space plans and
studies; architectural and engineering fees; permits, approvals and other
governmental fees; labor, material, equipment and supplies; construction fees
and other amounts payable to contractors or subcontractors; taxes; off-site
improvements; remediation and preparation of the Premises for construction of
the Expansion Premises Tenant Improvements; taxes; filing and recording fees;
premiums for insurance and bonds; attorneys' fees; financing costs; and all
other costs expended or to be expended in the construction of the Expansion
Premises Tenant Improvements, including those costs incurred for construction of
elements of the Tenant Improvements in the Premises, which construction was
performed by Landlord prior to the execution of the Lease or for materials
comprising the Expansion Premises Tenant Improvements which were purchased by
Landlord prior to the execution of the Lease; and an administration fee of three
percent (3%) of the amount of the Expansion Premises Tenant Improvements.

           5.2. Provided Tenant is not in default under the Lease, including
this Expansion Premises Improvement Agreement, Landlord shall contribute a
one-time tenant improvement allowance not to exceed Thirty and No/100 Dollars
($30.00) per rentable square foot of the Expansion Premises ("EXPANSION PREMISES
TENANT IMPROVEMENT ALLOWANCE") toward the cost of the initial Expansion Premises
Tenant Improvements. If the cost of the Expansion Premises Tenant Improvements
exceeds the Expansion Premises Tenant Improvement Allowance, Tenant shall pay
Landlord such excess cost within ten (10) days after Landlord's notice to Tenant
of such excess cost. No credit shall be given to Tenant if the cost of the
Expansion Premises Tenant Improvements is less than the Expansion Premises
Tenant Improvement Allowance.

           5.3. If the cost of the Expansion Premises Tenant Improvements
increases after the Tenant's approval of the Plans due to the requirements of
any governmental agency or applicable Regulation or any other reason, Tenant
shall pay Landlord the amount of such increase within ten (10) days after notice
from Landlord of such increase.

           5.4. If Tenant requests any change(s) in the Plans after approval of
the estimate of the cost of the Expansion Premises Tenant Improvements and any
such requested changes are approved by Landlord in writing in Landlord's sole
discretion, Landlord shall advise Tenant promptly of any cost increases and/or
delays such approved change(s) will cause in the construction of the Expansion
Premises Tenant Improvements. Tenant shall approve or disapprove any or all such
change(s) within three (3) business days after notice from Landlord of such cost
increases and/or delays. To the extent Tenant disapproves any such cost increase
and/or delay attributable thereto, Landlord shall have the right, in its sole
discretion, to disapprove Tenant's request for any changes to the approved
Plans. If the cost of the Expansion Premises Tenant Improvements increases due
to any changes in the Plan(s) requested by Tenant, Tenant shall pay Landlord the
amount of such increase within ten (10) days after notice from Landlord of such
increase and Tenant's approval thereof in accordance with this Paragraph 5.4.

           5.5. Notwithstanding anything to the contrary in this Expansion
Premises Improvement Agreement, in the event that the cost of the Expansion
Premises Tenant Improvements exceeds the Expansion Premises Tenant Improvement
Allowance, upon Tenant's written request, Landlord shall provide an additional
amount not to exceed Four Dollars ($4.00) per rentable square foot (the
"EXPANSION PREMISES BASE RENT INCREASE FACTOR") toward the excess cost of the
Expansion Premises Tenant Improvements. Tenant must provide such written request
to Landlord prior to the Expansion Premises Term

<PAGE>   11

Commencement Date defined in the Lease. In the event Tenant fails to so provide
such written notice to Landlord, Tenant shall be deemed to waive its right to
receive the Expansion Premises Base Rent Increase Factor. The Expansion Premises
Base Rent Increase Factor shall be amortized over the initial Term of the Lease
commencing upon disbursement of monies, at an interest rate of ten percent (10%)
per annum, payable in monthly installments as Base Rent, in accordance with the
terms of the Lease. If the costs of the Expansion Premises Tenant Improvements
does exceed the Expansion Premises Tenant Improvement Allowance, and Tenant
elects to receive the Expansion Premises Base Increase Rent Factor pursuant to
this Paragraph 5.3, Landlord and Tenant shall each execute a written amendment
to the Lease, prepared by Landlord, to reflect the appropriate increase in the
amount of Base Rent.

           5.6. Within forty-five (45) days following Landlord's receipt of the
approved Plans, Landlord shall provide to Tenant a cost estimate for the
Expansion Premises Tenant Improvements which cost estimate shall be prepared in
reasonable detail and in good faith. IN the event that the cost of the Expansion
Premises Tenant Improvements is greater than the Expansion Premises Tenant
Improvement Allowance, Tenant shall either (i) deliver such excess amounts to
Landlord in accordance with this Expansion Premises Improvement Agreement, or
(ii) for the excess amount equal to or less than Four Dollars ($4.00) per
rentable square foot, inform Landlord in writing whether Tenant elects to
exercise its rights pursuant to Paragraph 5.5 above with respect to the
Expansion Premises Base Rent Increase Factor. In the event that Tenant elects
clause (ii) above and the excess amount is greater than the Expansion Premises
Base Rent Increase Factor, Tenant shall pay such excess amount above the
Expansion Premises Base Rent Increase Factor to Landlord in accordance with this
Expansion Premises Improvement Agreement.

<PAGE>   12

                                   SCHEDULE 1
                                 TO ATTACHMENT D

                               BUILDING STANDARDS

        The following constitutes the Building Standard Expansion Premises
Tenant Improvements ("STANDARDS") in the quantities specified:

                                (to be provided)<PAGE>   1

                                                                  Exhibit 10.23

                           SECOND AMENDMENT TO LEASE

THIS SECOND AMENDMENT TO LEASE (this "SECOND AMENDMENT") is made this 11th day
of August, 2000, by and between SPIEKER PROPERTIES, L.P., a California limited
partnership ("LANDLORD"), and BROCADE COMMUNICATIONS SYSTEMS, INC., a Delaware
corporation ("TENANT").

        WHEREAS, Landlord and Tenant entered into a Lease dated December 17,
1999 (the "Original Lease"), as modified by that certain First Amendment to
Lease dated as of February 16, 2000 (the "First Amendment"), for those certain
premises located at 1745 Technology Drive (approximately 210,677 rentable square
feet) and 1741 Technology Drive (approximately 39,043 rentable square feet), San
Jose, California (the "ORIGINAL PREMISES"), each as more fully described in the
Lease. Capitalized terms used but not otherwise defined herein shall have the
meanings given them in the Lease; and

        WHEREAS, Tenant desires to lease from Landlord, and Landlord desires to
lease to Tenant, additional space at 1741 Technology Drive (approximately 21,667
rentable square feet) to become part of the Original Premises under the terms
and conditions as provided herein; and

        WHEREAS, Landlord and Tenant desire to modify the Lease as provided
herein.

        NOW, THEREFORE, in consideration of the covenants and agreements
contained herein, the parties hereby mutually agree as follows:

        1.      The following shall be added to and made a part of the Lease as
                a new Paragraph 39.F:

        "A. RENT. Subject to the provisions of Paragraphs 2.B of the Lease, Base
        Rent, net of Operating Expenses per Paragraph 7 of this Lease, for the
        Original Premises and the Second Expansion Premises shall be as follows:

<TABLE>
<CAPTION>
                                                                     SECOND
                                              FIRST                 AMENDMENT
                                            AMENDMENT                (SECOND               NEW TOTAL BASE RENT FOR ORIGINAL
                                            (ORIGINAL                EXPANSION              PREMISES AND SECOND EXPANSION
    RENTAL MONTHS                           PREMISES)                PREMISES)                        PREMISES
---------------------------------          -----------              ----------           ----------------------------------------
<S>                                       <C>                       <C>                 <C>
From the Term Commencement Date            $627,432.00               $0.00 per           $627,432.00 per month plus Operating
through December 31, 2000:                  per month                 month              Expenses per Paragraph 7 of this Lease.
                                                                                         Operating Expenses for the calendar year
                                                                                         2000 are estimated to be $217,256.00 per
                                                                                         month.

January 1, 2001 through Month 12:          $627,432.00             $104,002.00           $731,434.00 per month plus Operating
                                            per month               per month            Expenses per Paragraph 7 of this Lease.

Month 13 following the Term                $646,254.00             $107,122.00           $753,376.00 per month plus Operating
Commencement Date through Month 24:         per month               per month            Expenses per Paragraph 7 of this Lease.

Month 25 following the Term                $665,642.00             $110,335.00           $775,977.00 per month plus Operating
Commencement Date through Month 36:         per month               per month            Expenses per Paragraph 7 of this Lease.

Month 37 following the Term                $685,611.00             $113,645.00           $799,256.00 per month plus Operating
Commencement Date through Month 48:         per month               per month            Expenses per Paragraph 7 of this Lease.

Month 49 following the Term                $706,179.00             $117,055.00           $823,234.00 per month plus Operating
Commencement Date through Month 60:         per month               per month            Expenses per Paragraph 7 of this Lease.

Month 61 following the Term                $727,364.00             $120,566.00           $847,930.00 per month plus Operating
Commencement Date through Month 72:         per month               per month            Expenses per Paragraph 7 of this Lease.

Month 73 following the Term                $749,185.00             $124,183.00           $873,368.00 per month plus Operating
Commencement Date through Month 84:         per month               per month            Expenses per Paragraph 7 of this Lease.

Month 85 following the Term                $771,661.00             $127,909.00           $899,570.00 per month plus Operating
Commencement Date through Month 96:         per month               per month            Expenses per Paragraph 7 of this Lease.

Month 97 following the Term                $794,811.00             $131,746.00           $926,557.00 per month plus Operating
Commencement Date through Month 108:        per month               per month            Expenses per Paragraph 7 of this Lease.

Month 109 following the Term               $818,655.00             $135,698.00           $954,353.00 per month plus Operating
Commencement Date through Month 120:        per month               per month            Expenses per Paragraph 7 of this Lease.
</TABLE>

        2.      Insert as a new Paragraph 39.G. the following:

        "G. SECOND EXPANSION PREMISES. Landlord shall deliver to Tenant
        possession of the premises depicted on ATTACHMENT A, attached hereto
        (the "SECOND EXPANSION PREMISES"), which Second Expansion Premises
        comprise approximately twenty-one thousand six hundred sixty-seven
        (21,667) rentable square feet and is in

<PAGE>   2

        the building located at 1741 Technology Drive, San Jose, California. The
        terms and conditions of this Lease shall apply to Tenant's possession
        and use of the Second Expansion Premises. Tenant shall be liable for the
        payment of Base Rent and Operating Expenses with respect to the Second
        Expansion Premises as of the Second Expansion Premises Term Commencement
        Date (as defined below). The term commencement date ("SECOND EXPANSION
        PREMISES TERM COMMENCEMENT DATE") with respect to the Second Expansion
        Premises shall be January 1, 2001. By taking possession of the Second
        Expansion Premises, Tenant accepts them "as is", as being in good order,
        condition and repair and the condition in which Landlord is obligated to
        deliver them and suitable for the Permitted Use and Tenant's intended
        operations in the Second Expansion Premises, whether or not any notice
        of acceptance is given. Landlord shall make commercially reasonable
        efforts to deliver possession of the Second Expansion Premises to Tenant
        on January 1, 2001. If for any reason Landlord cannot deliver possession
        of the Second Expansion Premises to Tenant on the scheduled Second
        Expansion Premises Term Commencement Date, Landlord shall not be subject
        to any liability therefor, nor shall Landlord be in default hereunder
        nor shall such failure affect the validity of this Lease, and unless the
        Second Expansion Premises have been delivered to Tenant, Tenant agrees
        to accept possession of the Second Expansion Premises at such time that
        Landlord delivers possession, which date shall then be deemed the Second
        Expansion Premises Term Commencement Date. Upon the Second Expansion
        Premises Term Commencement Date, the Second Expansion Premises shall be
        a part of the Premises under this Lease and the terms and conditions of
        the Lease shall apply to the Second Expansion Premises as a part of the
        Premises, except as expressly stated herein."

        3.      "Tenant's Proportionate Share" with respect to the Original
        Premises at 1741 Technology Drive and the Second Expansion Premises
        (collectively) shall be 45.64%.

        4.      The effectiveness of this Second Amendment shall be contingent
        upon Landlord obtaining a fully executed and binding termination of the
        lease agreement with the current tenant of the Second Expansion Premises
        and such current tenant surrenders possession of the Second Expansion
        Premises to Landlord. In the event that Landlord fails to obtain such
        termination of lease agreement on or before the Second Expansion
        Premises Term Commencement Date, this Second Amendment shall be null and
        void and of no further force and effect.

        5.      Provided this Second Amendment is not rendered ineffective
        pursuant to Paragraph 4 above, Tenant's one-time right of first offer as
        provided in Paragraph 10 of the First Amendment shall be null and void
        with respect to the Second Expansion Premises.

        6.      Landlord and Tenant each represent and warrant to the other that
        they have had no other dealings with any real estate broker or agent in
        connection with the negotiation of this Second Amendment to Lease,
        excepting only Bailes & Associates, Inc. ("Broker") who represents
        Tenant, and that Landlord shall not pay any commissions or fees to
        Broker in connection with this Second Amendment to Lease. Each party
        agrees to indemnify and defend the other party against and hold the
        other party harmless from any and all claims, demands, losses,
        liabilities, lawsuits, judgments, costs and expenses with respect to any
        leasing commission or equivalent compensation alleged to be owing on
        account of any dealings with any real estate broker or agent, occurring
        by, through, or under the indemnifying party.

        Except as expressly modified above, all terms and conditions of the
Lease remain in full force and effect and are hereby ratified and confirmed.

        IN WITNESS WHEREOF, the parties hereto have entered into this Second
Amendment as of the date first written above.

LANDLORD:                                  TENANT:

Spieker Properties, L.P.,                  Brocade Communications Systems, Inc.,
A California limited partnership           a Delaware corporation

By: Spieker Properties, Inc.,              By:
    a Maryland corporation                    --------------------------------
    its General Partner                       Michael J. Byrd
                                              Its: Vice President, Finance
                                                   Chief Financial Officer

  By:                                      By:
    --------------------------------          --------------------------------
         John W. Petersen                          Victor Rinkle
    Its: Senior Vice President                Its: Vice President, Operations

<PAGE>   3

                                  ATTACHMENT A

                       1741 TECHNOLOGY DRIVE, SUITE #300

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00019-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00019-of-00352.parquet"}]]