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                                                                   EXHIBIT 10.20

                               MCDATA CORPORATION

                             1997 STOCK OPTION PLAN

                             ADOPTED OCTOBER 1, 1997

1.   PURPOSE.

     (a)  The purpose of the Plan is to provide a means by which selected
Employees and Directors of the Company, and its Affiliates, may be given an
opportunity to purchase stock of the Company.

     (b)  The Company, by means of the Plan, seeks to retain the services of
persons who are now Employees or Directors of the Company or its Affiliates, to
secure and retain the services of new Employees and Directors, and to provide
incentives for such persons to exert maximum efforts for the success of the
Company and its Affiliates.

     (c)  The Company intends that the Options issued under the Plan shall, in
the discretion of the Board or any Committee to which responsibility for
administration of the Plan has been delegated pursuant to subsection 3(c), be
either Incentive Stock Options or Nonstatutory Stock Options. All Options shall
be separately designated Incentive Stock Options or Nonstatutory Stock Options
at the time of grant, and in such form as issued pursuant to Section 6, and a
separate certificate or certificates will be issued for shares purchased on
exercise of each type of Option.

2.   DEFINITIONS.

     (a)  "AFFILIATE" means any parent corporation or subsidiary corporation,
whether now or hereafter existing, as those terms are defined in Sections 424(e)
and (f) respectively, of the Code.

     (b)  "BOARD" means the Board of Directors of the Company.

     (c)  "CODE" means the Internal Revenue Code of 1986, as amended.

     (d)  "COMMITTEE" means a Committee appointed by the Board in accordance
with subsection 3(c) of the Plan.

                                       1.

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     (e)  "COMPANY" means McDATA Corporation, a Delaware corporation.

     (f)  "CONTINUOUS STATUS AS AN EMPLOYEE OR DIRECTOR" means that the service
of an individual to the Company, whether as an Employee or Director, is not
interrupted or terminated. The Board or the chief executive officer of the
Company may determine, in that party's sole discretion, whether Continuous
Status as an Employee or Director shall be considered interrupted in the case
of: (i) any leave of absence approved by the Board or the chief executive
officer of the Company, including sick leave, military leave, or any other
personal leave; or (ii) transfers between the Company, Affiliates or their
successors.

     (g)  "COVERED EMPLOYEE" means the chief executive officer and the four (4)
other highest compensated officers of the Company for whom total compensation is
required to be reported to stockholders under the Exchange Act, as determined
for purposes of Section 162(m) of the Code.

     (h)  "DIRECTOR" means a member of the Board.

     (i)  "EMPLOYEE" means any person, including Officers and Directors,
employed by the Company or any Affiliate of the Company. Neither service as a
Director nor payment of a director's fee by the Company shall be sufficient to
constitute "employment" by the Company.

     (j)  "EXCHANGE ACT" means the Securities Exchange Act of 1934, as amended.

     (k)  "FAIR MARKET VALUE" means, as of any date, the value of the Class B
Common Stock of the Company determined as follows:

          (1)  If the Class B Common Stock is listed on any established stock
exchange or traded on the Nasdaq National Market or the Nasdaq SmallCap Market,
the Fair Market Value of a share of Class B Common Stock shall be the closing
sales price for such stock (or the closing bid, if no sales were reported) as
quoted on such exchange or market (or the exchange or market with the greatest
volume of trading in the Company's Class B Common Stock) on the last market
trading day prior to the day of determination, as reported in The Wall Street
Journal or such other source as the Board deems reliable.

          (2)  In the absence of such markets for the Class B Common Stock, the
Fair Market Value shall be determined in good faith by the Board.

                                       2.

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     (l)  "INCENTIVE STOCK OPTION" means an Option intended to qualify as an
incentive stock option within the meaning of Section 422 of the Code and the
regulations promulgated thereunder.

     (m)  "LISTING DATE" means the first date upon which any security of the
Company is listed (or approved for listing) upon notice of issuance on any
securities exchange, or designated (or approved for designation) upon notice of
issuance as a national market security on an interdealer quotation system.

     (n)  "NON-EMPLOYEE DIRECTOR" means a Director who either (i) is not a
current Employee or Officer of the Company or its parent or subsidiary, does not
receive compensation (directly or indirectly) from the Company or its parent or
subsidiary for services rendered as a consultant or in any capacity other than
as a Director (except for an amount as to which disclosure would not be required
under Item 404(a) of Regulation S-K promulgated pursuant to the Securities Act
("Regulation S-K")), does not possess an interest in any other transaction as to
which disclosure would be required under Item 404(a) of Regulation S-K, and is
not engaged in a business relationship as to which disclosure would be required
under Item 404(b) of Regulation S-K; or (ii) is otherwise considered a
"non-employee director" for purposes of Rule 16b-3.

     (o)  "NONSTATUTORY STOCK OPTION" means an Option not intended to qualify as
an Incentive Stock Option.

     (p)  "OFFICER" means a person who is an officer of the Company within the
meaning of Section 16 of the Exchange Act and the rules and regulations
promulgated thereunder.

     (q)  "OPTION" means a stock option granted pursuant to the Plan.

     (r)  "OPTION AGREEMENT" means a written agreement between the Company and
an Optionee evidencing the terms and conditions of an individual Option grant.
Each Option Agreement shall be subject to the terms and conditions of the Plan.

     (s)  "OPTIONEE" means a person to whom an Option is granted pursuant to the
Plan or, if applicable, such other person who holds an outstanding Option.

     (t)  "OUTSIDE DIRECTOR" means a Director who either (i) is not a current
employee of the Company or an "affiliated corporation" (within the meaning of
the Treasury regulations promulgated under Section 162(m) of the Code), is not a
former employee of the Company or an

                                       3.
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"affiliated corporation" receiving compensation for prior services (other than
benefits under a tax qualified pension plan), was not an officer of the Company
or an "affiliated corporation" at any time, and is not currently receiving
direct or indirect remuneration from the Company or an "affiliated corporation"
for services in any capacity other than as a Director, or (ii) is otherwise
considered an "outside director" for purposes of Section 162(m) of the Code.

     (u)  "PLAN" means this 1997 Stock Option Plan.

     (v)  "RULE 16b-3" means Rule 16b-3 of the Exchange Act or any successor to
Rule 16b-3, as in effect with respect to the Company at the time discretion is
being exercised regarding the Plan.

     (w)  "SECURITIES ACT" means the Securities Act of 1933, as amended.

3.   ADMINISTRATION.

     (a)  The Plan shall be administered by the Board unless and until the Board
delegates administration to a Committee, as provided in subsection 3(c).

     (b)  The Board shall have the power, subject to, and within the limitations
of, the express provisions of the Plan:

          (1)  To determine from time to time which of the persons eligible
under the Plan shall be granted Options; when and how each Option shall be
granted; whether an Option will be an Incentive Stock Option or a Nonstatutory
Stock Option; the provisions of each Option granted (which need not be
identical), including the time or times such Option may be exercised in whole or
in part; and the number of shares for which an Option shall be granted to each
such person.

          (2)  To construe and interpret the Plan and Options granted under it,
and to establish, amend and revoke rules and regulations for its administration.
The Board, in the exercise of this power, may correct any defect, omission or
inconsistency in the Plan or in any Option Agreement, in a manner and to the
extent it shall deem necessary or expedient to make the Plan fully effective.

          (3)  To amend the Plan or an Option as provided in Section 12.

          (4)  Generally, to exercise such powers and to perform such acts as
the Board deems necessary or expedient to promote the best interests of the
Company.

                                       4.

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     (c)  The Board may delegate administration of the Plan to a committee of
the Board composed of not fewer than two (2) members (the "Committee"), all of
the members of which Committee may be, in the discretion of the Board,
Non-Employee Directors and/or Outside Directors. If administration is delegated
to a Committee, the Committee shall have, in connection with the administration
of the Plan, the powers theretofore possessed by the Board, including the power
to delegate to a subcommittee of two (2) or more Outside Directors any of the
administrative powers the Committee is authorized to exercise (and references in
this Plan to the Board shall thereafter be to the Committee or such a
subcommittee), subject, however, to such resolutions, not inconsistent with the
provisions of the Plan, as may be adopted from time to time by the Board. The
Board may abolish the Committee at any time and revest in the Board the
administration of the Plan. Additionally, prior to the Listing Date, and
notwithstanding anything to the contrary contained herein, the Board may
delegate administration of the Plan to a committee of one or more members of the
Board and the term "Committee" shall apply to any person or persons to whom such
authority has been delegated. Notwithstanding anything in this Section 3 to the
contrary, the Board or the Committee may delegate to a committee of one or more
members of the Board the authority to grant Options to eligible persons who (1)
are not then subject to Section 16 of the Exchange Act and/or (2) are either (i)
not then Covered Employees and are not expected to be Covered Employees at the
time of recognition of income resulting from such Option, or (ii) not persons
with respect to whom the Company wishes to comply with Section 162(m) of the
Code.

4.   SHARES SUBJECT TO THE PLAN.

     (a)  Subject to the provisions of Section 10 relating to adjustments upon
changes in stock, the stock that may be sold pursuant to Options shall not
exceed in the aggregate nine million five hundred thousand (9,500,000) shares of
the Company's Class B Common Stock. If any Option shall for any reason expire or
otherwise terminate, in whole or in part, without having been exercised in full,
the stock not purchased under such Option shall revert to and again become
available for issuance under the Plan.

     (b)  The stock subject to the Plan may be unissued shares or reacquired
shares, bought on the market or otherwise.

                                       5.

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5.   ELIGIBILITY.

     (a)  Incentive Stock Options may be granted only to Employees. Nonstatutory
Stock Options may be granted only to Employees or Directors.

     (b)  No person shall be eligible for the grant of an Incentive Stock Option
if, at the time of grant, such person owns (or is deemed to own pursuant to
Section 424(d) of the Code) stock possessing more than ten percent (10%) of the
total combined voting power of all classes of stock of the Company or of any of
its Affiliates unless the exercise price of such Incentive Stock Option is at
least one hundred ten percent (110%) of the Fair Market Value of such stock at
the date of grant and the Incentive Stock Option is not exercisable after the
expiration of five (5) years from the date of grant.

     (c)  Subject to the provisions of Section 10 relating to adjustments upon
changes in stock, no person shall be eligible to be granted Options covering
more than two million (2,000,000) shares of the Company's Class B Common Stock
in any calendar year. This subsection 5(c) shall not apply prior to the Listing
Date and, following the Listing Date, shall not apply until (i) the earliest of:
(A) the first material modification of the Plan (including any increase to the
number of shares reserved for issuance under the Plan in accordance with Section
4); (B) the issuance of all of the shares of Class B Common Stock reserved for
issuance under the Plan; (C) the expiration of the Plan; or (D) the first
meeting of stockholders at which directors are to be elected that occurs after
the close of the third calendar year following the calendar year in which
occurred the first registration of an equity security under Section 12 of the
Exchange Act; or (ii) such other date required by Section 162(m) of the Code and
the rules and regulations promulgated thereunder.

6.   OPTION PROVISIONS.

     Each Option shall be in such form and shall contain such terms and
conditions as the Board shall deem appropriate. The provisions of separate
Options need not be identical, but each Option shall include (through
incorporation of provisions hereof by reference in the Option or otherwise) the
substance of each of the following provisions:

     (a)  TERM. No Option shall be exercisable after the expiration of ten (10)
years from the date it was granted.

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     (b)  PRICE. The exercise price of each Incentive Stock Option shall be not
less than one hundred percent (100%) of the Fair Market Value of the stock
subject to the Option on the date the Option is granted; the exercise price of
each Nonstatutory Stock Option shall be not less than eighty-five percent (85%)
percent of the Fair Market Value of the stock subject to the Option on the date
the Option is granted. Notwithstanding the foregoing, an Option (whether an
Incentive Stock Option or a Nonstatutory Stock Option) may be granted with an
exercise price lower than that set forth in the preceding sentence if such
Option is granted pursuant to an assumption or substitution for another option
in a manner satisfying the provisions of Section 424(a) of the Code.

     (c)  CONSIDERATION. The purchase price of stock acquired pursuant to an
Option shall be paid, to the extent permitted by applicable statutes and
regulations, either (i) in cash at the time the Option is exercised, or (ii) at
the discretion of the Board or the Committee, at the time of the grant of the
Option, (A) by delivery to the Company of other Class B Common Stock of the
Company or (B) in any other form of legal consideration that may be acceptable
to the Board.

     (d)  TRANSFERABILITY. An Incentive Stock Option shall not be transferable
except by will or by the laws of descent and distribution, and shall be
exercisable during the lifetime of the person to whom the Incentive Stock Option
is granted only by such person. A Nonstatutory Stock Option shall only be
transferable with the Optionee upon such terms and conditions as are set forth
in the Option Agreement for such Nonstatutory Stock Option, as the Board or the
Committee shall determine in its discretion, except that each Nonstatutory Stock
Option may be transferred to the spouse, children, lineal ancestors and lineal
descendants of the Optionee (or to a trust created solely for the benefit of the
Optionee and the foregoing persons) or to an organization exempt from taxation
pursuant to Section 501(c)(3) of the Code or to which tax deductible charitable
contributions may be made under Section 170 of the Code (excluding such
organizations classified as private foundations under applicable regulations and
rulings). The person to whom the Option is granted may, by delivering written
notice to the Company, in a form satisfactory to the Company, designate a third
party who, in the event of the death of the Optionee, shall thereafter be
entitled to exercise the Option.

     (e)  VESTING. The total number of shares of stock subject to an Option
shall be allotted in periodic installments (which may, but need not, be equal).
The Option Agreement

                                       7.

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may provide that from time to time during each of such installment periods, the
Option may become exercisable ("vest") with respect to some or all of the shares
allotted to that period, and may be exercised with respect to some or all of the
shares allotted to such period and/or any prior period as to which the Option
became vested but was not fully exercised. The Option may be subject to such
other terms and conditions on the time or times when it may be exercised (which
may be based on performance or other criteria) as the Board may deem
appropriate. The provisions of this subsection 6(e) are subject to any Option
provisions governing the minimum number of shares as to which an Option may be
exercised.

     (f)  SECURITIES LAW COMPLIANCE. The Company may require any Optionee, or
any person to whom an Option is transferred under subsection 6(d), as a
condition of exercising any such Option, (1) to give written assurances
satisfactory to the Company as to the Optionee's knowledge and experience in
financial and business matters and/or to employ a purchaser representative
reasonably satisfactory to the Company who is knowledgeable and experienced in
financial and business matters, and that he or she is capable of evaluating,
alone or together with the purchaser representative, the merits and risks of
exercising the Option; and (2) to give written assurances satisfactory to the
Company stating that such person is acquiring the stock subject to the Option
for such person's own account and not with any present intention of selling or
otherwise distributing the stock. The foregoing requirements, and any assurances
given pursuant to such requirements, shall be inoperative if (i) the issuance of
the shares upon the exercise of the Option has been registered under a then
currently effective registration statement under the Securities Act, or (ii) as
to any particular requirement, a determination is made by counsel for the
Company that such requirement need not be met in the circumstances under the
then applicable securities laws. The Company may require the Optionee to provide
such other representations, written assurances or information which the Company
shall determine is necessary, desirable or appropriate to comply with applicable
securities and other laws as a condition of granting an Option to such Optionee
or permitting the Optionee to exercise such Option. The Company may, upon advice
of counsel to the Company, place legends on stock certificates issued under the
Plan as such counsel deems necessary or appropriate in order to comply with
applicable securities laws, including, but not limited to, legends restricting
the transfer of the stock.

                                       8.

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     (g)  TERMINATION OF EMPLOYMENT OR RELATIONSHIP AS A DIRECTOR. In the event
an Optionee's Continuous Status as an Employee or Director terminates (other
than upon the Optionee's death or disability), the Optionee may exercise his or
her Option (to the extent that the Optionee was entitled to exercise it as of
the date of termination) but only within such period of time ending on the
earlier of (i) the date three (3) months following the termination of the
Optionee's Continuous Status as an Employee or Director, or such longer or
shorter period specified in the Option Agreement, or (ii) the expiration of the
term of the Option as set forth in the Option Agreement. If, at the date of
termination, the Optionee is not entitled to exercise his or her entire Option,
the shares covered by the unexercisable portion of the Option shall revert to
and again become available for issuance under the Plan. If, after termination,
the Optionee does not exercise his or her Option within the time specified in
the Option Agreement, the Option shall terminate, and the shares covered by such
Option shall revert to and again become available for issuance under the Plan.

     (h)  DISABILITY OF OPTIONEE. In the event an Optionee's Continuous Status
as an Employee or Director terminates as a result of the Optionee's disability,
the Optionee may exercise his or her Option (to the extent that the Optionee was
entitled to exercise it as of the date of termination), but only within such
period of time ending on the earlier of (i) the date twelve (12) months
following such termination (or such longer or shorter period specified in the
Option Agreement), or (ii) the expiration of the term of the Option as set forth
in the Option Agreement. If, at the date of termination, the Optionee is not
entitled to exercise his or her entire Option, the shares covered by the
unexercisable portion of the Option shall revert to and again become available
for issuance under the Plan. If, after termination, the Optionee does not
exercise his or her Option within the time specified herein, the Option shall
terminate, and the shares covered by such Option shall revert to and again
become available for issuance under the Plan.

     (i)  DEATH OF OPTIONEE. In the event of the death of an Optionee during, or
within a period specified in the Option Agreement after the termination of, the
Optionee's Continuous Status as an Employee or Director, the Option may be
exercised (to the extent the Optionee was entitled to exercise the Option as of
the date of death) by the Optionee's estate, by a person who acquired the right
to exercise the Option by bequest or inheritance or by a person designated to
exercise the option upon the Optionee's death pursuant to subsection 6(d), but
only within the

                                       9.

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period ending on the earlier of (i) the date eighteen (18) months following the
date of death (or such longer or shorter period specified in the Option
Agreement), or (ii) the expiration of the term of such Option as set forth in
the Option Agreement. If, at the time of death, the Optionee was not entitled to
exercise his or her entire Option, the shares covered by the unexercisable
portion of the Option shall revert to and again become available for issuance
under the Plan. If, after death, the Option is not exercised within the time
specified herein, the Option shall terminate, and the shares covered by such
Option shall revert to and again become available for issuance under the Plan.

     (j)  RIGHT OF REPURCHASE. The Option may, but need not, include a provision
whereby the Company may elect, prior to the Listing Date, to repurchase all or
any part of the vested shares exercised pursuant to the Option.

     (k)  RIGHT OF FIRST REFUSAL. The Option may, but need not, include a
provision whereby the Company may elect, prior to the Listing Date, to exercise
a right of first refusal following receipt of notice from the Optionee of the
intent to transfer all or any part of the shares exercised pursuant to the
Option.

     (l)  WITHHOLDING. To the extent provided by the terms of an Option
Agreement, the Optionee may satisfy any federal, state or local tax withholding
obligation relating to the exercise of such Option by any of the following means
or by a combination of such means: (1) tendering a cash payment; (2) authorizing
the Company to withhold shares from the shares of the Class B Common Stock
otherwise issuable to the Optionee as a result of the exercise of the Option; or
(3) delivering to the Company owned and unencumbered shares of the Class B
Common Stock of the Company.

     (m)  LOCK-UP. In connection with a public offering of the Company's Common
Stock resulting in gross proceeds to the Company and the selling stockholders,
if any, of not less than $30 million (prior to expenses and underwriting
commissions) and at an offering price per share representing a pre-offering
valuation of the Company of at least $500 million, the Company (or a
representative of the underwriters) may require that an Optionee sign a
"lock-up" agreement providing that the Optionee will not sell or otherwise
transfer or dispose of any shares of Class B Common Stock or other securities of
the Company during a period as may be specified by the representative of the
underwriters of Common Stock (or other securities) of the Company and

                                      10.

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agreed to by EMC Corporation and the Company, provided that all executive
officers and directors of the Company enter into similar agreements. The Company
may impose stop-transfer instructions with respect to securities subject to the
foregoing restrictions until the end of such period.

7.   COVENANTS OF THE COMPANY.

     (a)  During the terms of the Options, the Company shall keep available at
all times the number of shares of stock required to satisfy such Options.

     (b)  The Company shall seek to obtain from each regulatory commission or
agency having jurisdiction over the Plan such authority as may be required to
issue and sell shares of stock upon exercise of the Options; provided, however,
that this undertaking shall not require the Company to register under the
Securities Act either the Plan, any Option or any stock issued or issuable
pursuant to any such Option. If, after reasonable efforts, the Company is unable
to obtain from any such regulatory commission or agency the authority which
counsel for the Company deems necessary for the lawful issuance and sale of
stock under the Plan, the Company shall be relieved from any liability for
failure to issue and sell stock upon exercise of such Options unless and until
such authority is obtained.

8.   USE OF PROCEEDS FROM STOCK.

     Proceeds from the sale of stock pursuant to Options shall constitute
general funds of the Company.

9.   MISCELLANEOUS.

     (a)  The Board shall have the power to accelerate the time at which an
Option may first be exercised or the time during which an Option or any part
thereof will vest pursuant to subsection 6(e), notwithstanding the provisions in
the Option stating the time at which it may first be exercised or the time
during which it will vest.

     (b)  Neither an Optionee nor any person to whom an Option is transferred
under subsection 6(d) shall be deemed to be the holder of, or to have any of the
rights of a holder with respect to, any shares subject to such Option unless and
until such person has satisfied all requirements for exercise of the Option
pursuant to its terms.

     (c)  Nothing in the Plan or any instrument executed or Option granted
pursuant thereto shall confer upon any Employee, Director or Optionee any right
to continue in the employ of the

                                      11.

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Company or any Affiliate (or to continue acting as a Director) or shall affect
the right of the Company or any Affiliate to terminate the employment of any
Employee, with or without cause, or to remove any Director as provided in the
Company's By-Laws and the provisions of the General Corporation Law of the State
of Delaware.

     (d)  To the extent that the aggregate Fair Market Value (determined at the
time of grant) of stock with respect to which Incentive Stock Options are
exercisable for the first time by any Optionee during any calendar year under
all plans of the Company and its Affiliates exceeds one hundred thousand dollars
($100,000), the Options or portions thereof which exceed such limit (according
to the order in which they were granted) shall be treated as Nonstatutory Stock
Options.

     (e)  (1) The Board or the Committee shall have the authority to effect, at
any time and from time to time (i) the repricing of any outstanding Options
under the Plan and/or (ii) with the consent of the affected holders of Options,
the cancellation of any outstanding Options and the grant in substitution
therefor of new Options under the Plan covering the same or different numbers of
shares of Class B Common Stock, but having an exercise price per share not less
than eighty-five percent (85%) of the Fair Market Value (one hundred percent
(100%) of the Fair Market Value in the case of an Incentive Stock Option or, in
the case of a ten percent (10%) stockholder (as defined in subsection 5(b)), in
the case of an Incentive Stock Option, not less than one hundred and ten percent
(110%) of the Fair Market Value) per share of Class B Common Stock on the new
grant date.

          (2)  Shares subject to an Option canceled under this subsection 9(e)
shall continue to be counted, for the applicable period in which it was granted,
against the maximum award of Options permitted to be granted pursuant to
subsection 5(c) of the Plan. The repricing of an Option under this subsection
9(e), resulting in a reduction of the exercise price, shall be deemed to be a
cancellation of the original Option and the grant of a substitute Option; in the
event of such repricing, both the original and the substituted Options shall be
counted for the applicable period against the maximum awards of Options
permitted to be granted pursuant to subsection 5(c) of the Plan. The provisions
of this subsection 9(e)(2) shall be applicable only to the extent required by
Section 162(m) of the Code.

10.  ADJUSTMENTS UPON CHANGES IN STOCK.

                                      12.

<PAGE>   13

     (a)  If any change is made in the stock subject to the Plan, or subject to
any Option (through merger, consolidation, reorganization, recapitalization,
stock dividend, dividend in property other than cash, stock split, liquidating
dividend, combination of shares, exchange of shares, change in corporate
structure or other transaction not involving the receipt of consideration by the
Company), the Plan will be appropriately adjusted in the type(s) and maximum
number of securities subject to the Plan pursuant to subsection 4(a) and the
maximum number of securities subject to award to any person during any calendar
year period pursuant to subsection 5(c), and the outstanding Options will be
appropriately adjusted in the type(s) and number of securities and price per
share of stock subject to such outstanding Options. Such adjustments shall be
made by the Board or Committee, the determination of which shall be final,
binding and conclusive. (The conversion of any convertible securities of the
Company shall not be treated as a "transaction not involving the receipt of
consideration by the Company.")

     (b)  In the event of: (1) a dissolution, liquidation, or sale of all or
substantially all of the assets of the Company; (2) a merger or consolidation in
which the Company is not the surviving corporation; or (3) a reverse merger in
which the Company is the surviving corporation but the shares of the Company's
Class B Common Stock outstanding immediately preceding the merger are converted
by virtue of the merger into other property, whether in the form of securities,
cash or otherwise, then: (i) any surviving or acquiring corporation shall assume
any Options outstanding under the Plan or shall substitute similar options
(including an option to acquire the same consideration paid to the stockholders
in the transaction described in this subsection 10(b)) for those outstanding
under the Plan, or (ii) in the event any surviving or acquiring corporation
refuses to assume such Options or to substitute similar options for those
outstanding under the Plan, (A) with respect to Options held by persons then
performing services as Employees or Director, the vesting of such Options and
the time during which such Options may be exercised shall be accelerated prior
to such event and the Options terminated if not exercised after such
acceleration and at or prior to such event, and (B) with respect to any other
Options outstanding under the Plan, such Options shall be terminated if not
exercised prior to such event.

                                      13.

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11.  CONVERSION OF INCENTIVE STOCK OPTIONS INTO NONSTATUTORY OPTIONS.

     Notwithstanding the foregoing, in the case of an Incentive Stock Option, at
the written request or with the written consent of an Optionee (to the extent
such Optionee's option has not been exercised at such time) the Board may take
such actions as may be necessary to convert such Optionee's Incentive Stock
Option into a Nonstatutory Stock Option. Such actions may include, but shall not
be limited to, extending the exercise period or reducing the exercise price of
the appropriate installments of such Incentive Stock Option. At the time of such
conversion, the Board (with the consent of the Optionee) may impose such
conditions on the exercise of the resulting Nonstatutory Stock Option as the
Board in its discretion may determine, provided that such conditions shall not
be inconsistent with this Plan.

12.  AMENDMENT OF THE PLAN AND OPTIONS.

     (a)  The Board at any time, and from time to time, may amend the Plan.
However, except as provided in Section 10 relating to adjustments upon changes
in stock, no amendment shall be effective unless approved by the stockholders of
the Company within twelve (12) months before or after the adoption of the
amendment, where the amendment will:

          (1)  Increase the number of shares reserved for Options under the
Plan;

          (2)  Modify the requirements as to eligibility for participation in
the Plan (to the extent such modification requires stockholder approval in order
for the Plan to satisfy the requirements of Section 422 of the Code); or

          (3)  Modify the Plan in any other way if such modification requires
stockholder approval in order for the Plan to satisfy the requirements of
Section 422 of the Code or to comply with the requirements of Rule 16b-3.

     (b)  The Board may in its sole discretion submit any other amendment to the
Plan for stockholder approval, including, but not limited to, amendments to the
Plan intended to satisfy the requirements of Section 162(m) of the Code and the
regulations promulgated thereunder regarding the exclusion of performance-based
compensation from the limit on corporate deductibility of compensation paid to
certain executive officers.

     (c)  It is expressly contemplated that the Board may amend the Plan in any
respect the Board deems necessary or advisable to provide Optionees with the
maximum benefits provided or to be provided under the provisions of the Code and
the regulations promulgated thereunder

                                      14.

<PAGE>   15

relating to Incentive Stock Options and/or to bring the Plan and/or Incentive
Stock Options granted under it into compliance therewith.

     (d)  Rights and obligations under any Option granted before amendment of
the Plan shall not be impaired by any amendment of the Plan unless (i) the
Company requests the consent of the person to whom the Option was granted and
(ii) such person consents in writing.

     (e)  The Board at any time, and from time to time, may amend the terms of
any one or more Options; provided, however, that the rights and obligations
under any Option shall not be impaired by any such amendment unless (i) the
Company requests the consent of the person to whom the Option was granted and
(ii) such person consents in writing.

13.  TERMINATION OR SUSPENSION OF THE PLAN.

     (a)  The Board may suspend or terminate the Plan at any time. Unless sooner
terminated, the Plan shall terminate on September 30, 2007, which shall be
within ten (10) years from the date the Plan is adopted by the Board or approved
by the stockholders of the Company, whichever is earlier. No Options may be
granted under the Plan while the Plan is suspended or after it is terminated.

     (b)  Rights and obligations under any Option granted while the Plan is in
effect shall not be impaired by suspension or termination of the Plan, except
with the written consent of the person to whom the Option was granted.

14.  EFFECTIVE DATE OF PLAN.

     The Plan shall become effective as determined by the Board, but no Options
granted under the Plan shall be exercised unless and until the Plan has been
approved by the stockholders of the Company, which approval shall be within
twelve (12) months before or after the date the Plan is adopted by the Board.

                                      15.<PAGE>   1

                                                                   EXHIBIT 10.21

                         FORM OF STOCK OPTION AGREEMENT

     Pursuant to the Grant Notice and this Stock Option Agreement, the Company
has granted you an option to purchase the number of shares of the Company's
Class B Common Stock ("CLASS B COMMON STOCK") indicated in the Grant Notice at
the exercise price indicated in the Grant Notice.

     Your option is granted in connection with and in furtherance of the
Company's 1997 Stock Option Plan (the "PLAN") for the Company's employees
(including officers) or directors, and is intended to comply with the provisions
of Rule 701 promulgated by the Securities and Exchange Commission (the
"COMMISSION") under the Securities Act of 1933, as amended (the "SECURITIES
ACT"). Defined terms not explicitly defined in this Stock Option Agreement but
defined in the Plan shall have the same definitions as in the Plan.

     The details of your option are as follows:

     1.   VESTING. Subject to the limitations contained herein, your option will
vest as provided in the Grant Notice, provided that vesting will cease upon the
termination of your Continuous Status as an Employee or Director.

     2.   METHOD OF PAYMENT. Payment, in cash (including check), of the exercise
price per share is due in full upon exercise of all or any part of each
installment which has accrued to you.

     3.   WHOLE SHARES. Your option may only be exercised for whole shares.

     4.   SECURITIES LAW COMPLIANCE. Notwithstanding anything to the contrary
contained herein, your option may not be exercised unless the shares issuable
upon exercise of your option are then registered under the Securities Act or, if
such shares are not then so registered, the Company has determined that such
exercise and issuance would be exempt from the registration requirements of the
Securities Act.

     5.   TERM.

          (a)  The term of your option commences on the date of grant and
expires upon the earliest of:

               (i)  the Expiration Date indicated in the Grant Notice;

               (ii) ten (10) years after the Date of Grant;

<PAGE>   2

               (iii) eighteen (18) months after your death, if you die during,
or within three (3) months after the termination of your Continuous Status as
Employee or Director; or

               (iv) twelve (12) months after the termination of your Continuous
Status as Employee or Director due to disability; or

               (v)  three (3) months after the termination of your Continuous
Status as an Employee or Director for any other reason.

          (b)  Notwithstanding the foregoing, in the case of an incentive stock
option (to the extent such option has not been exercised at such time), at your
written request or with your written consent the Board of Directors may take
such actions as may be necessary to convert your incentive stock option into a
nonstatutory stock option pursuant to the provisions of Section 11 of the Plan.
To obtain the federal income tax advantages associated with an incentive stock
option, the Code requires that at all times beginning on the date of grant of
the option and ending on the day three (3) months before the date of the
option's exercise, you must be an employee of the Company, except in the event
of your death or permanent and total disability. The Company cannot guarantee
that your option will be treated as an incentive stock option if you exercise
your option more than three (3) months after the date your employment with the
Company terminates.

     6.   EXERCISE.

          (a)  You may exercise the vested portion of your option during its
term (and the unvested portion of your option if the Grant Notice so permits) by
delivering a notice of exercise (in a form designated by the Company) together
with the exercise price to the Secretary of the Company, or to such other person
as the Company may designate, during regular business hours, together with such
additional documents as the Company may then require.

          (b)  By exercising your option you agree that:

               (i)  as a condition to any exercise of your option, the Company
may require you to enter an arrangement providing for the payment by you to the
Company of any tax withholding obligation of the Company arising by reason of
(1) the exercise of your option; (2) the lapse of any substantial risk of
forfeiture to which the shares are subject at the time of exercise; or (3) the
disposition of shares acquired upon such exercise; and

               (ii) you will notify the Company in writing within fifteen (15)
days after the date of any disposition of any of the shares of the Class B
Common Stock issued upon exercise of an incentive stock option that occurs
within two (2) years after the date of your option grant or within one (1) year
after such shares of Class B Common Stock are acquired by you upon exercise of
your option.

     7.   TRANSFERABILITY. If your option is an incentive stock option, it is
not transferable, except by will or by the laws of descent and distribution, and
is exercisable during

                                       2.

<PAGE>   3

your life only by you. If your option is a nonstatutory stock option, it may be
transferred to your spouse, children, lineal ancestors and lineal descendants
(or to a trust created solely for your benefit and/or the benefit of the
foregoing persons) or to an organization exempt from taxation pursuant to
Section 501(c)(3) of the Code or to which tax deductible charitable
contributions may be made under Section 170 of the Code (excluding such
organizations classified as private foundations under applicable regulations and
rulings). Notwithstanding the foregoing, by delivering written notice to the
Company, in a form satisfactory to the Company, you may designate a third party
who, in the event of your death, shall thereafter be entitled to exercise your
option.

     8.   RIGHT OF FIRST REFUSAL. Before any Class B Common Stock issued to you
or any transferee of you (either being sometimes referred to herein as the
"HOLDER") may be sold or otherwise transferred (including transfer by gift or
operation of law), the Company shall have an assignable right of first refusal
to purchase such Class B Common Stock (the "SHARES") on the terms and conditions
set forth in this Section 8 (the "RIGHT OF FIRST REFUSAL").

          (a)  NOTICE OF PROPOSED TRANSFER. The Holder of the Shares shall
deliver to the Company a written notice (the "NOTICE") stating: (i) the Holder's
bona fide intention to sell or otherwise transfer the Shares; (ii) the name of
each proposed purchaser or other transferee (the "PROPOSED TRANSFEREE"); (iii)
the Shares to be transferred to each Proposed Transferee; and (iv) the bona fide
cash price or other consideration for which the Holder proposes to transfer the
Shares (the "OFFERED PRICE"); and the Holder shall offer to sell the Shares at
the Offered Price to the Company.

          (b)  EXERCISE OF RIGHT OF FIRST REFUSAL. At any time within thirty
(30) days after receipt of the Notice, the Company or its assignee may, by
giving written notice to the Holder, elect to purchase all (but not less than
all) of the Shares proposed to be transferred to any one or more of the Proposed
Transferees, at the Offered Price.

          (c)  PAYMENT. Payment of the purchase price shall be made, at the
option of the Company or its assignee, either (i) in cash (by check) or (ii) in
the manner and at the time(s) set forth in the Notice.

          (d)  HOLDER'S RIGHT TO TRANSFER. If all of the Shares proposed in the
Notice to be transferred to a given Proposed Transferee are not purchased by the
Company and/or its assignee as provided in this Section 8, then the Holder may
sell or otherwise transfer such Shares to that Proposed Transferee at the
Offered Price or at a higher price, provided that (i) such sale or other
transfer is consummated within one hundred twenty (120) days after the date of
the Notice; (ii) any such sale or other transfer is effected in accordance with
any applicable securities laws; and (iii) the transferee or other recipient
shall agree in writing to receive and hold the Shares so transferred subject to
the provisions of this Agreement, and to transfer such Shares no further except
in accordance with the terms of this Agreement. If the Shares described in the
Notice are not transferred to the Proposed Transferee within such period, a new
Notice shall be given to the Company, and the Company shall again be offered the
Right of First Refusal, before any Shares held by the Holder may be sold or
otherwise transferred.

                                       3.

<PAGE>   4

          (e)  EXCEPTION FOR CERTAIN FAMILY TRANSFERS AND EXERCISES OF EXCHANGE
RIGHT. Anything to the contrary contained in this Section 8 notwithstanding, the
transfer of any or all of the Shares during the Holder's lifetime or on the
Holder's death by will or intestacy to Holder's immediate family or to a trust
for the benefit of Holder or Holder's immediate family shall be exempt from the
provisions of this Section 8; provided that, as a condition to receiving the
Shares, the transferee or other recipient shall agree in writing to receive and
hold the Shares so transferred subject to the provisions of this Agreement, and
to transfer such Shares no further except in accordance with the terms of this
Agreement. As used herein, "immediate family" shall mean spouse, lineal
descendant or antecedent, father, mother, brother or sister. Anything to the
contrary contained in this Section 8 notwithstanding, the transfer of any or all
of the Shares pursuant to exercise of the Exchange Right pursuant to Section 10
below shall be exempt from the provisions of this Section 8.

          (f)  TERMINATION OF RIGHT OF FIRST REFUSAL. The Right of First Refusal
shall terminate as to any Shares upon the first sale of Common Stock of the
Company to the general public pursuant to a registration statement filed with
and declared effective by the Commission (other than a registration statement
solely covering an employee benefit plan or corporate reorganization).

     9.   VESTED PURCHASE OPTION.

          (a)  The Class B Common Stock to be purchased by you pursuant to this
Agreement shall be subject to the following additional option (the "VESTED
PURCHASE OPTION"): In the event that your service as an Employee or Director of
the Company ceases for any reason (including your death), or no reason, with or
without cause, the Vested Purchase Option may be exercised. The Company shall
have the right at any time within ninety (90) days after your cessation of
service with the Company or such longer period as may be agreed to by you and
the Company (for example, for purposes of satisfying the requirements of Section
1202(c)(3) of the Internal Revenue Code), to purchase from you or your personal
representative, as the case may be, up to but not exceeding the number of shares
(including fractional shares) in which you have vested pursuant to the terms set
forth in Section 1 of this Agreement as of the date of such cessation of service
at their Fair Market Value (as defined below). "FAIR MARKET VALUE" shall mean
the fair market value of shares of Class B Common Stock, as determined by a
Nationally Recognized Investment Bank (a defined in Section 10 below) selected
by the Board of Directors.

          (b)  The Company shall be entitled to pay for any Class B Common Stock
purchased pursuant to its Vested Purchase Option at the Company's option in
cash, by offset against any indebtedness owing to the Company by you, including
without limitation any Note given in payment for the Class B Common Stock, or by
a combination of both.

          (c)  The Vested Purchase Option may be exercised by giving written
notice of exercise delivered or mailed as provided in Section 14 hereof. Upon
provision of such notice and payment or tender of the purchase price, the
Company shall become the legal and beneficial owner of the Shares being
purchased and all rights and interests therein or related thereto.

                                       4.

<PAGE>   5

          (d)  The Vested Purchase Option shall terminate as to any Class B
Common Stock upon the first sale of Common Stock of the Company to the general
public pursuant to a registration statement filed with and declared effective by
the Commission (other than a registration statement solely covering an employee
benefit plan or corporate reorganization).

     10.  EXCHANGE RIGHT.

          (a)  If the Company obtains advice in writing from a Nationally
Recognized Investment Bank (as defined below) that in its reasonable judgment it
should be possible for the Company to successfully complete a public offering of
Common Stock resulting in gross proceeds to the Company and the selling
stockholders, if any, of not less than $30 million (prior to expenses and
underwriting commissions) and at an offering price per share representing a
pre-offering valuation of the Company of at least $500 million (a "QUALIFIED
PUBLIC Offering"), and EMC Corporation ("EMC") does not use its best efforts
(including giving any necessary consents or approvals) (i) to assist the Company
with preparing a registration statement for filing with the Commission within
six months thereafter and (ii) to cooperate with the Company in seeking to cause
such registration statement to become effective, then the holders of a majority
of the shares of the Company's Class B Common Stock then outstanding (the "CLASS
B ELECTING HOLDERS") may, by written election (the "ELECTION") delivered to EMC,
require EMC to exchange their shares of Class B Common Stock (the "ELECTING
SHARES") for shares of EMC Common Stock and to offer to holders of vested
options the right to exchange such options for cash (the options so electing
shall be referred to as the "ELECTING OPTIONS"). Upon receipt of the Election,
EMC agrees that it shall exchange the Electing Shares for shares of EMC Common
Stock with an EMC Market Value (as defined below) equal to the Class B Fair
Value (as defined below) of the Electing Shares and shall exchange the Electing
Options for cash in an amount equal to the Class B Fair Value minus the exercise
price of each Electing Option (all of the foregoing, hereinafter known as the
"EXCHANGE RIGHT"). Within a reasonable period of time after notice of the
Election from the Class B Electing Holders, EMC shall prepare and file a
registration statement with the SEC that will seek to register shares of EMC
Common Stock for the Electing Shares. EMC will exercise its reasonable best
efforts to have such registration statement declared effective by the SEC and
upon effectiveness, EMC shall distribute shares of EMC Common Stock to the Class
B Holders who exercised the Exchange Right (the "EXCHANGE SHARES") within a
reasonable period of time thereafter. Any cash payments to Electing Options will
be made simultaneously with the distribution of the Exchange Shares. The
foregoing sets forth the Class B Electing Holders' sole and exclusive remedy
against EMC and Holdings with respect to any claims under this Section 10. The
date for determining the EMC Market Value and Class B Fair Value shall be two
days before such exchange and payments are effected. Notwithstanding any of the
foregoing, a Qualified Public Offering may be delayed by EMC or McDATA Holdings
Corporation ("HOLDINGS") without liability to anyone as follows: (i) one time,
for as long as considered necessary in the reasonable judgment of EMC and its
accountants, to avoid loss of pooling of interests accounting treatment with
respect to a completed or pending acquisition by EMC, (ii) one time, until
thirty (30) days after the end of the then-current fiscal year, to enable the
Company to remain part of a consolidated group with EMC, (iii) for such period
of time deemed necessary in the reasonable judgment of EMC and its accountants
in connection with an acquisition by EMC of the business or assets of another
entity undertaken at

                                       5.

<PAGE>   6

the Company's request and on its behalf, and (iv) one time, for a period of six
(6) months, for any reason in EMC's sole discretion (collectively, the "DELAY
RIGHTS"). If the parties commence work on a public offering but the price and
terms proposed by the managing underwriter would not satisfy the $30 million
deal size and $500 million pre-offering valuation requirements, then EMC will
not be obligated to complete such offering and the failure to do so will not
trigger the Exchange Right.

          (b)  For purposes of this Agreement, the following definitions shall
apply:

               (i)  The "CLASS B FAIR VALUE" shall mean the fair market value as
determined by one or more Qualified Investment Banks. The Class B Fair Value
shall be determined by a single Qualified Investment Bank unless EMC and a
majority in interest of the Class B Electing Holders agree to select two
Qualified Investment Banks, in which case the Class B Fair Value shall be the
average of the values determined by each of such Qualified Investment Banks.

               (ii) The "EMC MARKET VALUE" shall mean the average of (i) the
closing price quoted on the New York Stock Exchange (NYSE) or, (ii) if EMC's
Common Stock is not then listed, the closing price on the principal exchange
upon which EMC's Common Stock is listed or the Nasdaq Stock Market (National
Market), whichever is applicable, as published in the Western Edition of The
Wall Street Journal, for the five (5) trading days prior to the date of
determination of the EMC Market Value.

               (iii) A "QUALIFIED INVESTMENT BANK" shall mean (i) a Nationally
Recognized Investment Bank selected by mutual consent of EMC and a majority in
interest of the Class B Electing Holders or (ii) if EMC and a majority in
interest of the Class B Electing Holders are unable to agree on the selection of
a Nationally Recognized Investment Bank, then a Nationally Recognized Investment
Bank chosen by the American Arbitration Association.

               (iv) A "NATIONALLY RECOGNIZED INVESTMENT BANK" shall mean one of
the top 15 U.S. investment banking firms in the previous calendar year ranked
according to underwritten equity offerings as published in the Securities Data
Corp. Annual Review.

          (c)  The foregoing Exchange Right may be amended or modified only with
the written consent of the Company and a majority in interest of the Class B
Holders (as defined in Section 11 below). The obligations of the Company and the
rights of the Class B Holders pursuant to the Exchange Right may be waived with
respect to the rights of an individual Class B Holder, with the written consent
of such Class B Holder, or with respect to all Class B Holders with the written
consent of a majority in interest of the Class B Holders.

     11.  CO-SALE RIGHT. You shall have a co-sale right as a Class B Holder as
set forth below.

          (a)  If Holdings proposes to transfer any shares of the Company's
Class A Common Stock held by it in one or more related transactions, then
Holdings shall promptly give written notice (the "NOTICE") to the Company and to
(i) holders of all shares of the Class B

                                       6.

<PAGE>   7

Common Stock issued to the Investors (as defined in the Investors' Rights
Agreement by and among the Company, EMC and the investors listed on Exhibit A
thereto) and (ii) holders of Class B Common Stock issued or issuable upon
exercise of options to purchase Class B Common Stock granted under the Plan (the
holders referred to in clauses (i) and (ii) above may be referred to hereinafter
as the "CLASS B HOLDERS") at least twenty (20) days prior to the closing of such
sale or transfer. The Notice shall describe in reasonable detail the proposed
sale or transfer including, without limitation, the number of shares of the
Company's Class A Common Stock held by it to be sold or transferred (the
"HOLDINGS SHARES"), the nature of such sale or transfer, the consideration to be
paid, and the name and address of each prospective purchaser or transferee. In
the event the transfer is being made pursuant to the provisions of subsection
(h)(i) or (h)(ii) hereof, the Notice shall state under which subsection the sale
or transfer is being made.

          (b)  Each Class B Holder shall have the right, exercisable upon
written notice to Holdings within twenty (20) days after receipt of the Notice,
to participate in such sale of Holdings Shares on the same terms and conditions
(as adjusted for any differential in the fair market value of the Class B Common
Stock compared with the Class A Common Stock). To the extent one or more of the
Class B Holders exercise such right of participation in accordance with the
terms and conditions set forth below, the number of Holdings Shares that
Holdings may sell in the transaction shall be correspondingly reduced.

          (c)  Each Class B Holder may sell all or any part of that number of
shares of Class B Common Stock equal to the product obtained by multiplying (i)
the number of shares of the Company's Class A Common Stock held by Holdings by
(ii) a fraction the numerator of which is the number of shares of Class B Common
Stock owned, or issuable upon exercise of vested options granted under the Plan
to purchase Common Stock held, by such Class B Holder at the time of the sale or
transfer and the denominator of which is the total number of shares of the
Company's Class A Common Stock owned by Holdings and the total number of shares
of Class B Common Stock owned, or issuable upon exercise of vested options
granted under the Plan to purchase Class B Common Stock held, by all Class B
Holders at the time of the sale or transfer.

          (d)  If a Class B Holder fails to elect to fully participate in
Holdings' sale pursuant to this Section 11, Holdings shall give notice of such
failure to the Class B Holders who did so elect (the "PARTICIPANTS"). Such
notice may be made by telephone if confirmed in writing within two (2) days. The
Participants shall have ten (10) days from the date such notice was given to
agree to sell their pro rata share of the unsold portion. For purposes of this
subsection, a Participant's pro rata share shall be the ratio of (x) the number
of shares of Class B Common Stock owned, or issuable upon exercise of vested
options granted under the Plan to purchase Class B Common Stock held, by such
Participant to (y) the total number of shares of Class B Common Stock owned, or
issuable upon exercise of vested options granted under the Plan to purchase
Class B Common Stock held, by all Participants and the total number of shares of
the Company's Class A Common Stock owned by Holdings.

          (e)  Each Participant shall effect its participation in the sale by
promptly delivering to Holdings for transfer to the prospective purchaser one or
more certificates, properly

                                       7.

<PAGE>   8

endorsed for transfer, which represent number of shares of Class B Common Stock
that such Participant elects to sell.

          (f)  The stock certificate or certificates that the Participant
delivers to Holdings pursuant to subsection (e) above shall be transferred to
the prospective purchaser in consummation of the sale of the stock pursuant to
the terms and conditions specified in the Notice (as adjusted for any
differential in the fair market value of the Class B Common Stock compared with
the Class A Common Stock), and Holdings shall concurrently therewith remit to
such Participant that portion of the sale proceeds to which such Participant is
entitled by reason of its participation in such sale. To the extent that any
prospective purchaser or purchasers prohibit such assignment or otherwise refuse
to purchase shares or other securities from a Participant exercising its rights
of co-sale hereunder, Holdings shall not sell to such prospective purchaser or
purchasers any Holdings Shares unless and until, simultaneously with such sale,
Holdings shall purchase such shares or other securities from such Participant.

          (g)  The exercise or non-exercise of the rights of the Participants
hereunder to participate in one or more sales of Holdings Shares shall not
adversely affect their rights to participate in subsequent sales of Holdings
Shares subject to this Section 11.

          (h)  EXEMPT TRANSFERS.

               (i)  Notwithstanding the foregoing, the co-sale rights of the
Class B Holders shall not apply to: (i) any pledge of the Company's Class A
Common Stock made pursuant to a bona fide loan transaction that creates a mere
security interest; (ii) any transfer to an affiliate of EMC or Holdings; or
(iii) any transfer to EMC's or Holdings' stockholders; provided that (A)
Holdings shall inform the Class B Holders of such pledge or transfer prior to
effecting it and (B) the pledgee or transferee shall furnish the Company with a
written agreement to be bound by and comply with all provisions of this Section
11. Such transferred stock will remain subject to the provisions of this Section
11 and the holder of such transferred stock will be treated as Holdings for
purposes of this Agreement.

               (ii) Notwithstanding the foregoing, the provisions of this
Section 11 shall not apply to the sale of any of the Company's Common Stock (i)
to the public pursuant to a registration statement filed with, and declared
effective by the Commission under the Securities Act, or (ii) to the Company.

     12.  MARKET STANDOFF. In connection with a Qualified Public Offering, you
hereby agree that you shall not sell or otherwise transfer or dispose of any
shares of Common Stock (or other securities) of the Company held by you (other
than those included in the registration) for a period as may be specified by the
representative of the underwriters of Common Stock (or other securities) of the
Company and agreed to by EMC and the Company, provided that all executive
officers and directors of the Company enter into similar agreements.

     You agree to execute and deliver such other agreements as may be reasonably
requested by the Company or the underwriter which are consistent with the
foregoing or which are necessary to

                                       8.

<PAGE>   9

give further effect thereto. The obligations described in this Section 12 shall
not apply to a registration relating solely to employee benefit plans on Form
S-1 or Form S-8 or similar forms that may be promulgated in the future, or a
registration relating solely to a Commission Rule 145 transaction on Form S-4 or
similar forms that may be promulgated in the future. The Company may impose
stop-transfer instructions with respect to the shares of Common Stock (or other
securities) subject to the foregoing restriction until the end of said period of
time.

     13.  OPTION NOT A SERVICE CONTRACT. Your option is not an employment
contract and nothing in your option shall be deemed to create in any way
whatsoever any obligation on your part to continue in the employ of the Company,
or of the Company to continue your employment with the Company. In addition,
nothing in your option shall obligate the Company, its stockholders, Board of
Directors, officers or employees to continue any relationship which you might
have as a director for the Company.

     14.  NOTICES. Any notice required or permitted hereunder shall be given in
writing addressed to the other party hereto at his address hereinafter shown
below his signature or at such other address as such party may designate by ten
(10) days' advance written notice to the other party hereto, and shall be deemed
effectively given upon personal delivery, upon facsimile transmission (the
receipt of which has been confirmed), one (1) day after deposit with a
commercial overnight courier, or five (5) days after deposit in any United
States Post Office Box, by first class mail, postage prepaid. Any notice to the
Company may be given through the means specified in the preceding sentence at
the following address: McDATA Corporation, Attn: President, 310 Interlocken
Parkway, Broomfield, CO 80021 or at such other address as the Company shall
designate by ten (10) days' advance written notice to you. Any notice to EMC may
be given through the means specified in this Section 14 at the following
address: EMC Corporation, Attn: General Counsel, 171 South Street, Hopkinton, MA
01748 or at such other address as EMC shall designate by ten (10) days' advance
written notice to you. Any notice to Holdings may be given through the means
specified in this Section 14 at the following address: c/o EMC Corporation,
Attn: General Counsel, 171 South Street, Hopkinton, MA 01748, with a copy to
McDATA Corporation, Attn: President, 310 Interlocken Parkway, Broomfield, CO
80021 or at such other address as Holdings shall designate by ten (10) days'
advance written notice to you.

     15.  GOVERNING PLAN DOCUMENT. Your option is subject to all the provisions
of the Plan, the provisions of which are hereby made a part of your option,
including without limitation the provisions of the Plan relating to option
provisions, and is further subject to all interpretations, amendments, rules and
regulations which may from time to time be promulgated and adopted pursuant to
the Plan. In the event of any conflict between the provisions of your option and
those of the Plan, the provisions of the Plan shall control.

     16.  TERMINATION OF CERTAIN RIGHTS. The rights set forth in Sections 8, 9,
10 and 11 of this Agreement shall terminate and be of no further force and
effect upon the consummation of a Qualified Public Offering of securities of the
Company.

                                       9.

<PAGE>   10

     IN WITNESS WHEREOF, the parties hereto have executed this Stock Option
Agreement as of the _____ day of _____________, _________.

MCDATA CORPORATION                       OPTIONEE

By:
   ----------------------------          -------------------------------------
Name:
Title:

                                         -------------------------------------
                                         [Print Name]

                                         Address:

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

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

The undersigned:

          (a)  Acknowledges receipt of the foregoing option and understands that
all rights and liabilities with respect to this option are set forth in the
option and the Plan; and

          (b)  Acknowledges that as of the date of grant of this option, it sets
forth the entire understanding between the undersigned optionee and the Company
and its Affiliates regarding the acquisition of stock in the Company and
supersedes all prior oral and written agreements on that subject with the
exception of (i) the options previously granted and delivered to the undersigned
under stock option plans of the Company, and (ii) the following agreements only:

      NONE    ___________________
              (Initial)

      OTHER
           -------------------------------------

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

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

                                    -------------------------------------------
                                    OPTIONEE

                                      10.

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