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                                                                     EXHIBIT 4.2

                      BROCADE COMMUNICATIONS SYSTEMS, INC.

                        1999 EMPLOYEE STOCK PURCHASE PLAN



        1. Purpose. The purpose of the Plan is to provide employees of the
Company and its Designated Subsidiaries with an opportunity to purchase Common
Stock of the Company through accumulated payroll deductions. It is the intention
of the Company to have the Plan qualify as an "Employee Stock Purchase Plan"
under Section 423 of the Internal Revenue Code of 1986, as amended. The
provisions of the Plan, accordingly, shall be construed so as to extend and
limit participation in a manner consistent with the requirements of that section
of the Code.

        2. Definitions.

               (a) "Board" shall mean the Board of Directors of the Company.

               (b) "Code" shall mean the Internal Revenue Code of 1986, as
amended.

               (c) "Common Stock" shall mean the Common Stock of the Company.

               (d) "Company" shall mean Brocade Communications Systems, Inc., a
Delaware corporation, and any Designated Subsidiary of the Company.

               (e) "Compensation" shall mean all base straight time gross
earnings and commissions, exclusive of payments for overtime, shift premium,
incentive compensation, incentive payments, cash bonuses, non-cash bonuses and
other compensation. Commencing on the first Trading Day for the Offering Period
beginning on December 1, 1999, Compensation shall also mean cash bonuses.

               (f) "Designated Subsidiary" shall mean any Subsidiary which has
been designated by the Board from time to time in its sole discretion as
eligible to participate in the Plan.

               (g) "Employee" shall mean any individual who is an Employee of
the Company for tax purposes whose customary employment with the Company is at
least twenty (20) hours per week and more than five (5) months in any calendar
year. For purposes of the Plan, the employment relationship shall be treated as
continuing intact while the individual is on sick leave or other leave of
absence approved by the Company. Where the period of leave exceeds 90 days and
the individual's right to reemployment is not guaranteed either by statute or by
contract, the employment relationship shall be deemed to have terminated on the
91st day of such leave.

               (h) "Enrollment Date" shall mean the first day of each Offering
Period.

               (i) "Exercise Date" shall mean the last day of each Offering
Period.

               (j) "Fair Market Value" shall mean, as of any date, the value of
Common Stock determined as follows:


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                      (i) If the Common Stock is listed on any established stock
exchange or a national market system, including without limitation the Nasdaq
National Market or The Nasdaq SmallCap Market of The Nasdaq Stock Market, its
Fair Market Value shall be the closing sales price for such stock (or the
closing bid, if no sales were reported) as quoted on such exchange or system for
the last market trading day on the date of such determination, as reported in
The Wall Street Journal or such other source as the Board deems reliable, or;

                      (ii) If the Common Stock is regularly quoted by a
recognized securities dealer but selling prices are not reported, its Fair
Market Value shall be the mean of the closing bid and asked prices for the
Common Stock on the date of such determination, as reported in The Wall Street
Journal or such other source as the Board deems reliable, or;

                      (iii) In the absence of an established market for the
Common Stock, the Fair Market Value thereof shall be determined in good faith by
the Board.

                      (iv) For purposes of the Enrollment Date of the first
Offering Period under the Plan, the Fair Market Value shall be the initial price
to the public as set forth in the final prospectus included within the
registration statement in Form S-1 filed with the Securities and Exchange
Commission for the initial public offering of the Company's Common Stock (the
"Registration Statement").

               (k) "Offering Period" shall mean a period of approximately six
(6) months during which an option granted pursuant to the Plan may be exercised,
commencing on the first Trading Day on or after June 1 and terminating on the
last Trading Day in the period ending the following November 30, or commencing
on the first Trading Day on or after December 1 and terminating on the last
Trading Day in the period ending the following May 31; provided, however, that
the first Offering Period under the Plan shall commence with the first Trading
Day on or after the date on which the Securities and Exchange Commission
declares the Company's Registration Statement effective and ending on the last
Trading Day on or before November 30, 1999. The duration of Offering Periods may
be changed pursuant to Section 4 of this Plan.

               (l) "Plan" shall mean this Employee Stock Purchase Plan.

               (m) "Purchase Price" shall mean an amount equal to 85% of the
Fair Market Value of a share of Common Stock on the Enrollment Date or on the
Exercise Date, whichever is lower; provided, however, that the Purchase Price
may be adjusted by the Board pursuant to Section 20.

               (n) "Reserves" shall mean the number of shares of Common Stock
covered by each option under the Plan which have not yet been exercised and the
number of shares of Common Stock which have been authorized for issuance under
the Plan but not yet placed under option.


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               (o) "Subsidiary" shall mean a corporation, domestic or foreign,
of which not less than 50% of the voting shares are held by the Company or a
Subsidiary, whether or not such corporation now exists or is hereafter organized
or acquired by the Company or a Subsidiary.

               (p) "Trading Day" shall mean a day on which national stock
exchanges and the Nasdaq System are open for trading.

        3. Eligibility.

               (a) Any Employee who shall be employed by the Company on a given
Enrollment Date shall be eligible to participate in the Plan.

               (b) Any provisions of the Plan to the contrary notwithstanding,
no Employee shall be granted an option under the Plan (i) to the extent that,
immediately after the grant, such Employee (or any other person whose stock
would be attributed to such Employee pursuant to Section 424(d) of the Code)
would own capital stock of the Company and/or hold outstanding options to
purchase such stock possessing five percent (5%) or more of the total combined
voting power or value of all classes of the capital stock of the Company or of
any Subsidiary, or (ii) to the extent that his or her rights to purchase stock
under all employee stock purchase plans of the Company and its subsidiaries
accrues at a rate which exceeds Twenty-Five Thousand Dollars ($25,000) worth of
stock (determined at the fair market value of the shares at the time such option
is granted) for each calendar year in which such option is outstanding at any
time.

        4. Offering Periods. The Plan shall be implemented by consecutive
Offering Periods with a new Offering Period commencing on the first Trading Day
on or after June 1 and December 1 each year, or on such other date as the Board
shall determine, and continuing thereafter until terminated in accordance with
Section 20 hereof; provided, however, that the first Offering Period under the
Plan shall commence with the first Trading Day on or after the date on which the
Securities and Exchange Commission declares the Company's Registration Statement
effective and ending on the last Trading Day on or before November 30, 1999. The
Board shall have the power to change the duration of Offering Periods (including
the commencement dates thereof) with respect to future offerings without
stockholder approval if such change is announced at least five (5) days prior to
the scheduled beginning of the first Offering Period to be affected thereafter.

        5. Participation.

               (a) An eligible Employee may become a participant in the Plan by
completing a subscription agreement authorizing payroll deductions in the form
of Exhibit A to this Plan and filing it with the Company's payroll office prior
to the applicable Enrollment Date.

               (b) Payroll deductions for a participant shall commence on the
first payroll following the Enrollment Date and shall end on the last payroll in
the Offering Period to which such authorization is applicable, unless sooner
terminated by the participant as provided in Section 10 hereof.


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        6. Payroll Deductions.

               (a) At the time a participant files his or her subscription
agreement, he or she shall elect to have payroll deductions made on each pay day
during the Offering Period in an amount not exceeding fifteen percent (15%) of
the Compensation which he or she receives on each pay day during the Offering
Period.

               (b) All payroll deductions made for a participant shall be
credited to his or her account under the Plan and shall be withheld in whole
percentages only. A participant may not make any additional payments into such
account.

               (c) A participant may discontinue his or her participation in the
Plan as provided in Section 10 hereof, or may increase or decrease the rate of
his or her payroll deductions during the Offering Period by completing or filing
with the Company a new subscription agreement authorizing a change in payroll
deduction rate. The Board may, in its discretion, limit the number of
participation rate changes during any Offering Period. The change in rate shall
be effective with the first full payroll period following five (5) business days
after the Company's receipt of the new subscription agreement unless the Company
elects to process a given change in participation more quickly. A participant's
subscription agreement shall remain in effect for successive Offering Periods
unless terminated as provided in Section 10 hereof.

               (d) Notwithstanding the foregoing, to the extent necessary to
comply with Section 423(b)(8) of the Code and Section 3(b) hereof, a
participant's payroll deductions may be decreased to zero percent (0%) at any
time during an Offering Period. Payroll deductions shall recommence at the rate
provided in such participant's subscription agreement at the beginning of the
first Offering Period which is scheduled to end in the following calendar year,
unless terminated by the participant as provided in Section 10 hereof.

               (e) At the time the option is exercised, in whole or in part, or
at the time some or all of the Company's Common Stock issued under the Plan is
disposed of, the participant must make adequate provision for the Company's
federal, state, or other tax withholding obligations, if any, which arise upon
the exercise of the option or the disposition of the Common Stock. At any time,
the Company may, but shall not be obligated to, withhold from the participant's
compensation the amount necessary for the Company to meet applicable withholding
obligations, including any withholding required to make available to the Company
any tax deductions or benefits attributable to sale or early disposition of
Common Stock by the Employee.

        7. Grant of Option. On the Enrollment Date of each Offering Period, each
eligible Employee participating in such Offering Period shall be granted an
option to purchase on the Exercise Date of such Offering Period (at the
applicable Purchase Price) up to a number of shares of the Company's Common
Stock determined by dividing such Employee's payroll deductions accumulated
prior to such Exercise Date and retained in the Participant's account as of the
Exercise Date by the applicable Purchase Price; provided that in no event shall
an Employee be permitted to purchase during each Offering Period more than 3000
shares (subject to any adjustment pursuant to Section 19), and provided further
that such purchase shall be subject to the limitations set forth in


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Sections 3(b) and 12 hereof. Exercise of the option shall occur as provided in
Section 8 hereof, unless the participant has withdrawn pursuant to Section 10
hereof. The Option shall expire on the last day of the Offering Period.

        8. Exercise of Option. Unless a participant withdraws from the Plan as
provided in Section 10 hereof, his or her option for the purchase of shares
shall be exercised automatically on the Exercise Date, and the maximum number of
full shares subject to option shall be purchased for such participant at the
applicable Purchase Price with the accumulated payroll deductions in his or her
account. No fractional shares shall be purchased; any payroll deductions
accumulated in a participant's account which are not sufficient to purchase a
full share shall be retained in the participant's account for the subsequent
Offering Period, subject to earlier withdrawal by the participant as provided in
Section 10 hereof. Any other monies left over in a participant's account after
the Exercise Date shall be returned to the participant. During a participant's
lifetime, a participant's option to purchase shares hereunder is exercisable
only by him or her.

        9. Delivery. As promptly as practicable after each Exercise Date on
which a purchase of shares occurs, the Company shall arrange the delivery to
each participant, as appropriate, the shares purchased upon exercise of his or
her option.

        10. Withdrawal.

               (a) A participant may withdraw all but not less than all the
payroll deductions credited to his or her account and not yet used to exercise
his or her option under the Plan at any time by giving written notice to the
Company in the form of Exhibit B to this Plan. All of the participant's payroll
deductions credited to his or her account shall be paid to such participant
promptly after receipt of notice of withdrawal and such participant's option for
the Offering Period shall be automatically terminated, and no further payroll
deductions for the purchase of shares shall be made for such Offering Period. If
a participant withdraws from an Offering Period, payroll deductions shall not
resume at the beginning of the succeeding Offering Period unless the participant
delivers to the Company a new subscription agreement.

               (b) A participant's withdrawal from an Offering Period shall not
have any effect upon his or her eligibility to participate in any similar plan
which may hereafter be adopted by the Company or in succeeding Offering Periods
which commence after the termination of the Offering Period from which the
participant withdraws.

        11. Termination of Employment. Upon a participant's ceasing to be an
Employee for any reason, he or she shall be deemed to have elected to withdraw
from the Plan and the payroll deductions credited to such participant's account
during the Offering Period but not yet used to exercise the option shall be
returned to such participant or, in the case of his or her death, to the person
or persons entitled thereto under Section 15 hereof, and such participant's
option shall be automatically terminated. The preceding sentence
notwithstanding, a participant who receives payment in lieu of notice of
termination of employment shall be treated as continuing to be an Employee for
the participant's customary number of hours per week of employment during the
period in which the participant is subject to such payment in lieu of notice.


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        12. Interest. No interest shall accrue on the payroll deductions of a
participant in the Plan.

        13. Stock.

               (a) Subject to adjustment upon changes in capitalization of the
Company as provided in Section 19 hereof, the maximum number of shares of the
Company's Common Stock which shall be made available for sale under the Plan
shall be 200,000 shares, plus an annual increase to be added on the first day of
the Company's fiscal year beginning in 2000 equal to the lesser of (i) 2,500,000
shares, (ii) 2.5% of the outstanding shares on such date or (iii) a lesser
amount determined by the Board. If, on a given Exercise Date, the number of
shares with respect to which options are to be exercised exceeds the number of
shares then available under the Plan, the Company shall make a pro rata
allocation of the shares remaining available for purchase in as uniform a manner
as shall be practicable and as it shall determine to be equitable.

               (b) The participant shall have no interest or voting right in
shares covered by his option until such option has been exercised.

               (c) Shares to be delivered to a participant under the Plan shall
be registered in the name of the participant or in the name of the participant
and his or her spouse.

        14. Administration. The Plan shall be administered by the Board or a
committee of members of the Board appointed by the Board. The Board or its
committee shall have full and exclusive discretionary authority to construe,
interpret and apply the terms of the Plan, to determine eligibility and to
adjudicate all disputed claims filed under the Plan. Every finding, decision and
determination made by the Board or its committee shall, to the full extent
permitted by law, be final and binding upon all parties.

        15. Designation of Beneficiary.

               (a) A participant may file a written designation of a beneficiary
who is to receive any shares and cash, if any, from the participant's account
under the Plan in the event of such participant's death subsequent to an
Exercise Date on which the option is exercised but prior to delivery to such
participant of such shares and cash. In addition, a participant may file a
written designation of a beneficiary who is to receive any cash from the
participant's account under the Plan in the event of such participant's death
prior to exercise of the option. If a participant is married and the designated
beneficiary is not the spouse, spousal consent shall be required for such
designation to be effective.

               (b) Such designation of beneficiary may be changed by the
participant at any time by written notice. In the event of the death of a
participant and in the absence of a beneficiary validly designated under the
Plan who is living at the time of such participant's death, the Company shall
deliver such shares and/or cash to the executor or administrator of the estate
of the participant, or if no such executor or administrator has been appointed
(to the knowledge of the Company), the Company, in its discretion, may deliver
such shares and/or cash to the spouse or to any one or more


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dependents or relatives of the participant, or if no spouse, dependent or
relative is known to the Company, then to such other person as the Company may
designate.

        16. Transferability. Neither payroll deductions credited to a
participant's account nor any rights with regard to the exercise of an option or
to receive shares under the Plan may be assigned, transferred, pledged or
otherwise disposed of in any way (other than by will, the laws of descent and
distribution or as provided in Section 15 hereof) by the participant. Any such
attempt at assignment, transfer, pledge or other disposition shall be without
effect, except that the Company may treat such act as an election to withdraw
funds from an Offering Period in accordance with Section 10 hereof.

        17. Use of Funds. All payroll deductions received or held by the Company
under the Plan may be used by the Company for any corporate purpose, and the
Company shall not be obligated to segregate such payroll deductions.

        18. Reports. Individual accounts shall be maintained for each
participant in the Plan. Statements of account shall be given to participating
Employees at least annually, which statements shall set forth the amounts of
payroll deductions, the Purchase Price, the number of shares purchased and the
remaining cash balance, if any.

        19. Adjustments Upon Changes in Capitalization, Dissolution,
            Liquidation, Merger or Asset Sale.

               (a) Changes in Capitalization. Subject to any required action by
the stockholders of the Company, the Reserves, the maximum number of shares each
participant may purchase per Offering Period (pursuant to Section 7), as well as
the price per share and the number of shares of Common Stock covered by each
option under the Plan which has not yet been exercised shall be proportionately
adjusted for any increase or decrease in the number of issued shares of Common
Stock resulting from a stock split, reverse stock split, stock dividend,
combination or reclassification of the Common Stock, or any other increase or
decrease in the number of shares of Common Stock effected without receipt of
consideration by the Company; provided, however, that conversion of any
convertible securities of the Company shall not be deemed to have been "effected
without receipt of consideration". Such adjustment shall be made by the Board,
whose determination in that respect shall be final, binding and conclusive.
Except as expressly provided herein, no issuance by the Company of shares of
stock of any class, or securities convertible into shares of stock of any class,
shall affect, and no adjustment by reason thereof shall be made with respect to,
the number or price of shares of Common Stock subject to an option.

               (b) Dissolution or Liquidation. In the event of the proposed
dissolution or liquidation of the Company, the Offering Period then in progress
shall be shortened by setting a new Exercise Date (the "New Exercise Date"), and
shall terminate immediately prior to the consummation of such proposed
dissolution or liquidation, unless provided otherwise by the Board. The New
Exercise Date shall be before the date of the Company's proposed dissolution or
liquidation. The Board shall notify each participant in writing, at least ten
(10) business days prior to the New Exercise Date, that the Exercise Date for
the participant's option has been changed to the


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New Exercise Date and that the participant's option shall be exercised
automatically on the New Exercise Date, unless prior to such date the
participant has withdrawn from the Offering Period as provided in Section 10
hereof.

               (c) Merger or Asset Sale. In the event of a proposed sale of all
or substantially all of the assets of the Company, or the merger of the Company
with or into another corporation, each outstanding option shall be assumed or an
equivalent option substituted by the successor corporation or a Parent or
Subsidiary of the successor corporation. In the event that the successor
corporation refuses to assume or substitute for the option, the Offering Period
then in progress shall be shortened by setting a new Exercise Date (the "New
Exercise Date"). The New Exercise Date shall be before the date of the Company's
proposed sale or merger. The Board shall notify each participant in writing, at
least ten (10) business days prior to the New Exercise Date, that the Exercise
Date for the participant's option has been changed to the New Exercise Date and
that the participant's option shall be exercised automatically on the New
Exercise Date, unless prior to such date the participant has withdrawn from the
Offering Period as provided in Section 10 hereof.

        20. Amendment or Termination.

               (a) The Board of Directors of the Company may at any time and for
any reason terminate or amend the Plan. Except as provided in Section 19 hereof,
no such termination can affect options previously granted, provided that an
Offering Period may be terminated by the Board of Directors on any Exercise Date
if the Board determines that the termination of the Offering Period or the Plan
is in the best interests of the Company and its stockholders. Except as provided
in Section 19 and Section 20 hereof, no amendment may make any change in any
option theretofore granted which adversely affects the rights of any
participant. To the extent necessary to comply with Section 423 of the Code (or
any other applicable law, regulation or stock exchange rule), the Company shall
obtain shareholder approval in such a manner and to such a degree as required.

               (b) Without stockholder consent and without regard to whether any
participant rights may be considered to have been "adversely affected," the
Board (or its committee) shall be entitled to change the Offering Periods, limit
the frequency and/or number of changes in the amount withheld during an Offering
Period, establish the exchange ratio applicable to amounts withheld in a
currency other than U.S. dollars, permit payroll withholding in excess of the
amount designated by a participant in order to adjust for delays or mistakes in
the Company's processing of properly completed withholding elections, establish
reasonable waiting and adjustment periods and/or accounting and crediting
procedures to ensure that amounts applied toward the purchase of Common Stock
for each participant properly correspond with amounts withheld from the
participant's Compensation, and establish such other limitations or procedures
as the Board (or its committee) determines in its sole discretion advisable
which are consistent with the Plan.

               (c) In the event the Board determines that the ongoing operation
of the Plan may result in unfavorable financial accounting consequences, the
Board may, in its discretion and, to the extent necessary or desirable, modify
or amend the Plan to reduce or eliminate such accounting consequence including,
but not limited to:


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<PAGE>   9
                      (i) altering the Purchase Price for any Offering Period
including an Offering Period underway at the time of the change in Purchase
Price;

                      (ii) shortening any Offering Period so that Offering
Period ends on a new Exercise Date, including an Offering Period underway at the
time of the Board action; and

                      (iii) allocating shares.

        Such modifications or amendments shall not require stockholder approval
or the consent of any Plan participants.

        21. Notices. All notices or other communications by a participant to the
Company under or in connection with the Plan shall be deemed to have been duly
given when received in the form specified by the Company at the location, or by
the person, designated by the Company for the receipt thereof.

        22. Conditions Upon Issuance of Shares. Shares shall not be issued with
respect to an option unless the exercise of such option and the issuance and
delivery of such shares pursuant thereto shall comply with all applicable
provisions of law, domestic or foreign, including, without limitation, the
Securities Act of 1933, as amended, the Securities Exchange Act of 1934, as
amended, the rules and regulations promulgated thereunder, and the requirements
of any stock exchange upon which the shares may then be listed, and shall be
further subject to the approval of counsel for the Company with respect to such
compliance.

        As a condition to the exercise of an option, the Company may require the
person exercising such option to represent and warrant at the time of any such
exercise that the shares are being purchased only for investment and without any
present intention to sell or distribute such shares if, in the opinion of
counsel for the Company, such a representation is required by any of the
aforementioned applicable provisions of law.

        23. Term of Plan. The Plan shall become effective upon the earlier to
occur of its adoption by the Board of Directors or its approval by the
stockholders of the Company. It shall continue in effect for a term of ten (10)
years unless sooner terminated under Section 20 hereof.


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<PAGE>   10
                                    EXHIBIT A



                      BROCADE COMMUNICATIONS SYSTEMS, INC.

                        1999 EMPLOYEE STOCK PURCHASE PLAN

                             SUBSCRIPTION AGREEMENT



        _____ Original Application                     Enrollment Date: _______

        _____ Change in Payroll Deduction Rate

        _____ Change of Beneficiary(ies)

        1. _____________________________________ hereby elects to participate in
the Brocade Communications Systems, Inc. 1999 Employee Stock Purchase Plan (the
"Employee Stock Purchase Plan") and subscribes to purchase shares of the
Company's Common Stock in accordance with this Subscription Agreement and the
Employee Stock Purchase Plan.

        2. I hereby authorize payroll deductions from each paycheck in the
amount of ____% of my Compensation on each payday (from 1 to 15%) during the
Offering Period in accordance with the Employee Stock Purchase Plan. (Please
note that no fractional percentages are permitted.)

        3. I understand that said payroll deductions shall be accumulated for
the purchase of shares of Common Stock at the applicable Purchase Price
determined in accordance with the Employee Stock Purchase Plan. I understand
that if I do not withdraw from an Offering Period, any accumulated payroll
deductions will be used to automatically exercise my option.

        4. I have received a copy of the complete Employee Stock Purchase Plan.
I understand that my participation in the Employee Stock Purchase Plan is in all
respects subject to the terms of the Plan. I understand that my ability to
exercise the option under this Subscription Agreement is subject to stockholder
approval of the Employee Stock Purchase Plan.

        5. Shares purchased for me under the Employee Stock Purchase Plan should
be issued in the name(s) of (Employee or Employee and Spouse only):.

        6. I understand that if I dispose of any shares received by me pursuant
to the Plan within 2 years after the Enrollment Date (the first day of the
Offering Period during which I purchased such shares), I will be treated for
federal income tax purposes as having received ordinary income at the


<PAGE>   11
time of such disposition in an amount equal to the excess of the fair market
value of the shares at the time such shares were purchased by me over the price
which I paid for the shares. I hereby agree to notify the Company in writing
within 30 days after the date of any disposition of shares and I will make
adequate provision for Federal, state or other tax withholding obligations, if
any, which arise upon the disposition of the Common Stock. The Company may, but
will not be obligated to, withhold from my compensation the amount necessary to
meet any applicable withholding obligation including any withholding necessary
to make available to the Company any tax deductions or benefits attributable to
sale or early disposition of Common Stock by me. If I dispose of such shares at
any time after the expiration of the 2-year holding period, I understand that I
will be treated for federal income tax purposes as having received income only
at the time of such disposition, and that such income will be taxed as ordinary
income only to the extent of an amount equal to the lesser of (1) the excess of
the fair market value of the shares at the time of such disposition over the
purchase price which I paid for the shares, or (2) 15% of the fair market value
of the shares on the first day of the Offering Period. The remainder of the
gain, if any, recognized on such disposition will be taxed as capital gain.

        7. I hereby agree to be bound by the terms of the Employee Stock
Purchase Plan. The effectiveness of this Subscription Agreement is dependent
upon my eligibility to participate in the Employee Stock Purchase Plan.

        8. In the event of my death, I hereby designate the following as my
beneficiary(ies) to receive all payments and shares due me under the Employee
Stock Purchase Plan




NAME:  (Please print)
                      ---------------------------------------------------------
                        (First)          (Middle)                 (Last)


--------------------------------------------------
Relationship


--------------------------------------------------
(Address)


Employee's Social Security Number:
                                   -------------------------------

Employee's Address:
                      -------------------------------------------------

                      -------------------------------------------------

                      -----------------------------------------------


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<PAGE>   12
        I UNDERSTAND THAT THIS SUBSCRIPTION AGREEMENT SHALL REMAIN IN EFFECT
THROUGHOUT SUCCESSIVE OFFERING PERIODS UNLESS TERMINATED BY ME.


Dated:
       ------------------------             ----------------------------------
                                            Signature of Employee


                                            ----------------------------------
                                            Spouse's Signature
                                            (If beneficiary other than spouse)


<PAGE>   13
                                    EXHIBIT B



                      BROCADE COMMUNICATIONS SYSTEMS, INC.

                        1999 EMPLOYEE STOCK PURCHASE PLAN

                              NOTICE OF WITHDRAWAL



        The undersigned participant in the Offering Period of the Brocade
Communications Systems, Inc. 1999 Employee Stock Purchase Plan which began on
___________, ______ (the "Enrollment Date") hereby notifies the Company that he
or she hereby withdraws from the Offering Period. He or she hereby directs the
Company to pay to the undersigned as promptly as practicable all the payroll
deductions credited to his or her account with respect to such Offering Period.
The undersigned understands and agrees that his or her option for such Offering
Period will be automatically terminated. The undersigned understands further
that no further payroll deductions will be made for the purchase of shares in
the current Offering Period and the undersigned shall be eligible to participate
in succeeding Offering Periods only by delivering to the Company a new
Subscription Agreement.



Name and Address of Participant:

------------------------------------

------------------------------------

------------------------------------

Signature:

------------------------------------

Date:
      -------------------------------