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                                                                   EXHIBIT 10.15

                       CATAPULT COMMUNICATIONS CORPORATION

                                 1998 STOCK PLAN

                  (As Amended and Restated October 30, 2001 and
                        further amended January 21, 2003)

         1.       Purposes of the Plan. The purposes of this Stock Plan are:

                  -        to attract and retain the best available personnel
                           for positions of substantial responsibility,

                  -        to provide additional incentive to Employees,
                           Directors and Consultants, and

                  -        to promote the success of the Company's business.

         Options granted under the Plan may be Incentive Stock Options or
Nonstatutory Stock Options, as determined by the Administrator at the time of
grant. Stock Purchase Rights may also be granted under the Plan.

         2.       Definitions. As used herein, the following definitions shall
apply:

                  (a)      "Administrator" means the Board or any of its
Committees as shall be administering the Plan, in accordance with Section 4 of
the Plan.

                  (b)      "Applicable Laws" means the requirements relating to
the administration of stock option plans under U.S. state corporate laws, U.S.
federal and state securities laws, the Code, any stock exchange or quotation
system on which the Common Stock is listed or quoted and the applicable laws of
any foreign country or jurisdiction where Options or Stock Purchase Rights are,
or will be, granted under the Plan.

                  (c)      "Board" means the Board of Directors of the Company.

                  (d)      "Change in Control" means the occurrence of any of
the following events:

                           (i)      Any "person" (as such term is used in
Sections 13(d) and 14(d) of the Exchange Act), other than (A) a trustee or other
fiduciary holding securities under an employee benefit plan of the Company
acting in such capacity, (B) a corporation owned directly or indirectly by the
stockholders of the Company in substantially the same proportions as their
ownership of stock of the Company or (C) Richard A. or Nancy H. Karp, becomes
the "beneficial owner" (as defined in Rule 13d-3 of the Exchange Act), directly
or indirectly, of securities of the Company representing

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fifty percent (50%) or more of the total voting power represented by the
Company's then outstanding voting securities; or

                           (ii)     The consummation of the sale or disposition
by the Company of all or substantially all of the Company's assets; or

                           (iii)    The consummation of a merger or
consolidation of the Company with any other corporation, other than a merger or
consolidation which would result in the voting securities of the Company
outstanding immediately prior thereto continuing to represent (either by
remaining outstanding or by being converted into voting securities of the
surviving entity or its parent) at least fifty percent (50%) of the total voting
power represented by the voting securities of the Company or such surviving
entity or its parent outstanding immediately after such merger or consolidation.

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

                  (f)      "Committee" means a committee of Directors appointed
by the Board in accordance with Section 4 of the Plan.

                  (g)      "Common Stock" means the common stock of the Company.

                  (h)      "Company" means Catapult Communication Corporation, a
Nevada corporation.

                  (i)      "Consultant" means any person, including an advisor,
engaged by the Company or a Parent or Subsidiary to render services to such
entity.

                  (j)      "Director" means a member of the Board.

                  (k)      "Disability" means total and permanent disability as
defined in Section 22(e)(3) of the Code.

                  (l)      "Employee" means any person, including Officers and
Directors, employed by the Company or any Parent or Subsidiary of the Company. A
Service Provider shall not cease to be an Employee in the case of (i) any leave
of absence approved by the Company or (ii) transfers between locations of the
Company or between the Company, its Parent, any Subsidiary, or any successor.
For purposes of Incentive Stock Options, no such leave may exceed ninety days,
unless reemployment upon expiration of such leave is guaranteed by statute or
contract. If reemployment upon expiration of a leave of absence approved by the
Company is not so guaranteed, on the 181st day of such leave any Incentive Stock
Option held by the Optionee shall cease to be treated as an Incentive Stock
Option and shall be treated for tax purposes as a Nonstatutory Stock Option.
Neither service as a Director nor payment of a director's fee by the Company
shall be sufficient to constitute "employment" by the Company.

                  (m)      "Exchange Act" means the Securities Exchange Act of
1934, as amended.

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                  (n)      "Fair Market Value" means, as of any date, the value
of Common Stock determined as follows:

                           (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 prior to the time of
determination, as reported in The Wall Street Journal or such other source as
the Administrator deems reliable;

                           (ii)     If the Common Stock is regularly quoted by a
recognized securities dealer but selling prices are not reported, the Fair
Market Value of a Share of Common Stock shall be the mean between the high bid
and low asked prices for the 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 Administrator deems reliable; or

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

                  (o)      "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.

                  (p)      "Nonstatutory Stock Option" means an Option not
intended to qualify as an Incentive Stock Option.

                  (q)      "Notice of Grant" means a written or electronic
notice evidencing certain terms and conditions of an individual Option or Stock
Purchase Right grant. The Notice of Grant is part of the Option Agreement.

                  (r)      "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.

                  (s)      "Option" means a stock option granted pursuant to the
Plan.

                  (t)      "Option Agreement" means an agreement between the
Company and an Optionee evidencing the terms and conditions of an individual
Option grant. The Option Agreement is subject to the terms and conditions of the
Plan.

                  (u)      "Option Exchange Program" means a program whereby
outstanding Options are surrendered in exchange for Options with a lower
exercise price.

                  (v)      "Optioned Stock" means the Common Stock subject to an
Option or Stock Purchase Right.

                  (w)      "Optionee" means the holder of an outstanding Option
or Stock Purchase Right granted under the Plan.

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                  (x)      "Parent" means a "parent corporation," whether now or
hereafter existing, as defined in Section 424(e) of the Code.

                  (y)      "Plan" means this 1998 Stock Plan.

                  (z)      "Restricted Stock" means shares of Common Stock
acquired pursuant to a grant of Stock Purchase Rights under Section 11 of the
Plan.

                  (aa)     "Restricted Stock Purchase Agreement" means a written
agreement between the Company and the Optionee evidencing the terms and
restrictions applying to stock purchased under a Stock Purchase Right. The
Restricted Stock Purchase Agreement is subject to the terms and conditions of
the Plan and the Notice of Grant.

                  (bb)     "Rule 16b-3" means Rule 16b-3 of the Exchange Act or
any successor to Rule 16b-3, as in effect when discretion is being
exercised with respect to the Plan.

                  (cc)     "Section 16(b) " means Section 16(b) of the Exchange
Act.

                  (dd)     "Service Provider" means an Employee, Director or
Consultant.

                  (ee)     "Share" means a share of the Common Stock, as
adjusted in accordance with Section 13 of the Plan.

                  (ff)     "Stock Purchase Right" means the right to purchase
Common Stock pursuant to Section 11 of the Plan, as evidenced by a Notice of
Grant.

                  (gg)     "Subsidiary" means a "subsidiary corporation",
whether now or hereafter existing, as defined in Section 424(f) of the Code.

         3.       Stock Subject to the Plan. Subject to the provisions of
Section 13 of the Plan, the maximum aggregate number of Shares which may be
optioned and sold under the Plan is 2,800,000 Shares. The Shares may be
authorized, but unissued, or reacquired Common Stock.

         If an Option or Stock Purchase Right expires or becomes unexercisable
without having been exercised in full, or is surrendered pursuant to an Option
Exchange Program, the unpurchased Shares which were subject thereto shall become
available for future grant or sale under the Plan (unless the Plan has
terminated); provided, however, that Shares that have actually been issued under
the Plan, whether upon exercise of an Option or Right, shall not be returned to
the Plan and shall not become available for future distribution under the Plan,
except that if Shares of Restricted Stock are repurchased by the Company at
their original purchase price, such Shares shall become available for future
grant under the Plan.

         4.       Administration of the Plan.

                  (a)      Procedure.

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                           (i)      Multiple Administrative Bodies. The Plan may
be administered by different Committees with respect to different groups of
Service Providers.

                           (ii)     Section 162(m). To the extent that the
Administrator determines it to be desirable to qualify Options granted hereunder
as "performance-based compensation" within the meaning of Section 162(m) of the
Code, the Plan shall be administered by a Committee of two or more "outside
directors" within the meaning of Section 162(m) of the Code.

                           (iii)    Rule 16b-3. To the extent desirable to
qualify transactions hereunder as exempt under Rule 16b-3, the transactions
contemplated hereunder shall be structured to satisfy the requirements for
exemption under Rule 16b-3.

                           (iv) Other Administration. Other than as provided
above, the Plan shall be administered by (A) the Board or (B) a Committee, which
committee shall be constituted to satisfy Applicable Laws.

                  (b)      Powers of the Administrator. Subject to the
provisions of the Plan, and in the case of a Committee, subject to the specific
duties delegated by the Board to such Committee, the Administrator shall have
the authority, in its discretion:

                           (i)      to determine the Fair Market Value;

                           (ii)     to select the ServiceProviders to whom
Options and Stock Purchase Rights may be granted hereunder;

                           (iii)    to determine the number of shares of Common
Stock to be covered by each Option and Stock Purchase Right granted hereunder;

                           (iv)     to approve forms of agreement for use under
the Plan;

                           (v)      to determine the terms and conditions, not
inconsistent with the terms of the Plan, of any Option or Stock Purchase Right
granted hereunder. Such terms and conditions include, but are not limited to,
the exercise price, the time or times when Options or Stock Purchase Rights may
be exercised (which may be based on performance criteria), any vesting
acceleration or waiver of forfeiture restrictions, and any restriction or
limitation regarding any Option or Stock Purchase Right or the shares of Common
Stock relating thereto, based in each case on such factors as the Administrator,
in its sole discretion, shall determine;

                           (vi)     to reduce the exercise price of any Option
or Stock Purchase Right to the then current Fair Market Value if the Fair Market
Value of the Common Stock covered by such Option or Stock Purchase Right shall
have declined since the date the Option or Stock Purchase Right was granted;

                           (vii)    to institute an Option Exchange Program;

                           (viii)   to construe and interpret the terms of the
Plan and awards granted pursuant to the Plan;

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                           (ix)     to prescribe, amend and rescind rules and
regulations relating to the Plan, including rules and regulations relating to
sub-plans established for the purpose of qualifying for preferred tax treatment
under foreign tax laws;

                           (x)      to modify or amend each Option or Stock
Purchase Right (subject to Section 15(c) of the Plan), including the
discretionary authority to extend the post-termination exercisability period of
Options longer than is otherwise provided for in the Plan;

                           (xi)     to allow Optionees to satisfy withholding
tax obligations by electing to have the Company withhold from the Shares to be
issued upon exercise of an Option or Stock Purchase Right that number of Shares
having a Fair Market Value equal to the amount required to be withheld. The Fair
Market Value of the Shares to be withheld shall be determined on the date that
the amount of tax to be withheld is to be determined. All elections by an
Optionee to have Shares withheld for this purpose shall be made in such form and
under such conditions as the Administrator may deem necessary or advisable;

                           (xii)    to authorize any person to execute on behalf
of the Company any instrument required to effect the grant of an Option or Stock
Purchase Right previously granted by the Administrator;

                           (xiii)   to make all other determinations deemed
necessary or advisable for administering the Plan.

                  (c)      Effect of Administrator's Decision. The
Administrator's decisions, determinations and interpretations shall be final and
binding on all Optionees and any other holders of Options or Stock Purchase
Rights.

         5.       Eligibility. Nonstatutory Stock Options and Stock Purchase
Rights may be granted to Service Providers. Incentive Stock Options may be
granted only to Employees.

         6.       Limitations.

                  (a)      Each Option shall be designated in the Option
Agreement as either an Incentive Stock Option or a Nonstatutory Stock Option.
However, notwithstanding such designation, to the extent that the aggregate Fair
Market Value of the Shares with respect to which Incentive Stock Options are
exercisable for the first time by the Optionee during any calendar year (under
all plans of the Company and any Parent or Subsidiary) exceeds $100,000, such
Options shall be treated as Nonstatutory Stock Options. For purposes of this
Section 6(a), Incentive Stock Options shall be taken into account in the order
in which they were granted. The Fair Market Value of the Shares shall be
determined as of the time the Option with respect to such Shares is granted.

                  (b)      Neither the Plan nor any Option or Stock Purchase
Right shall confer upon an Optionee any right with respect to continuing the
Optionee's relationship as a Service Provider with the Company, nor shall they
interfere in any way with the Optionee's right or the Company's right to
terminate such relationship at any time, with or without cause.

                                                                             -6-

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                  (c)      On the date grants of Options under the Plan are
required to comply with Section 162(m) of the Code, the following limitations
shall apply to grants of Options:

                           (i)      No Service Provider shall be granted, in any
fiscal year of the Company, Options to purchase more than 225,000 Shares.

                           (ii)     In connection with his or her initial
service, a Service Provider may be granted Options to purchase up to an
additional 225,000 Shares which shall not count against the limit set forth in
subsection (i) above.

                           (iii)    The foregoing limitations shall be adjusted
proportionately in connection with any change in the Company's capitalization as
described in Section 13.

                           (iv)     If an Option is canceled in the same fiscal
year of the Company in which it was granted (other than in connection with a
transaction described in Section 13), the canceled Option will be counted
against the limits set forth in subsections (i) and (ii) above. For this
purpose, if the exercise price of an Option is reduced, the transaction will be
treated as a cancellation of the Option and the grant of a new Option.

         7.       Term of Plan. Subject to Section 19 of the Plan, the Plan
shall become effective upon its adoption by the Board. It shall continue in
effect for a term of ten (10) years unless terminated earlier under Section 15
of the Plan.

         8.       Term of Option. The term of each Option shall be stated in the
Option Agreement, provided, however, that prior to the date the Common Stock is
listed on a national securities exchange or a national market system which
qualifies under Section 25100(o) of the Corporations Code of California, the
term of each Option shall be no more than ten (10) years from the date of grant.
In the case of an Incentive Stock Option, the term shall be ten (10) years from
the date of grant or such shorter term as may be provided in the Option
Agreement. Moreover, in the case of an Incentive Stock Option granted to an
Optionee who, at the time the Incentive Stock Option is granted, owns stock
representing more than ten percent (10%) of the total combined voting power of
all classes of stock of the Company or any Parent or Subsidiary, the term of the
Incentive Stock Option shall be five (5) years from the date of grant or such
shorter term as may be provided in the Option Agreement.

         9.       Option Exercise Price and Consideration.

                  (a)      Exercise Price. The per share exercise price for the
Shares to be issued pursuant to exercise of an Option shall be determined by the
Administrator, subject to the following:

                           (i)      In the case of an Incentive Stock Option

                                    (A)      granted to an Employee who, at the
time the Incentive Stock Option is granted, owns stock representing more than
ten percent (10%) of the voting power of all classes of stock of the Company or
any Parent or Subsidiary, the per Share exercise price shall be no less than
110% of the Fair Market Value per Share on the date of grant.

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                                    (B)      granted to any Employee other than
an Employee described in paragraph (A) immediately above, the per Share exercise
price shall be no less than 100% of the Fair Market Value per Share on the date
of grant.

                           (ii)     In the case of a Nonstatutory Stock Option
granted:

                                    (A)      prior to the date the Common Stock
is listed on a national securities exchange or a national market system which
qualifies under Section 25100(o) of the Corporations Code of California:

                                            (1)      to a Service Provider who,
at the time the Nonstatutory Stock Option is granted, owns stock representing
more than ten percent (10%) of the voting power of all classes of stock of the
Company or any Parent or Subsidiary, the per Share exercise price shall be no
less than 110% of the Fair Market Value per Share on the date of grant.

                                            (2)      granted to any other
Service Provider the per Share exercise price shall be no less than 85% of the
Fair Market Value per Share on the date of grant.

                                    (B)      on or after the date the Common
Stock is listed on a national securities exchange or a national market system
which qualifies under Section 25100(o) of the Corporations Code of California to
any Service Provider, the per Share exercise price shall be determined by the
Administrator. In the case of a Nonstatutory Stock Option intended to qualify as
"performance-based compensation" within the meaning of Section 162(m) of the
Code, the per Share exercise price shall be no less than 100% of the Fair Market
Value per Share on the date of grant.

                           (iii)    Notwithstanding the foregoing, Options may
be granted with a per Share exercise price of less than 100% of the Fair Market
Value per Share on the date of grant pursuant to a merger or other corporate
transaction.

                  (b)      Waiting Period and Exercise Dates. At the time an
Option is granted, the Administrator shall fix the period within which the
Option may be exercised and shall determine any conditions which must be
satisfied before the Option may be exercised; provided, however, that prior to
the date the Common Stock is listed on a national securities exchange or a
national market system which qualifies under Section 25100(o) of the
Corporations Code of California, except in the case of Options granted to
Officers, Directors, and Consultants, Options shall become exercisable at a rate
of no less than 20% per year over five (5) years from the date the Options are
granted.

                  (c)      Form of Consideration. The Administrator shall
determine the acceptable form of consideration for exercising an Option,
including the method of payment. In the case of an Incentive Stock Option, the
Administrator shall determine the acceptable form of consideration at the time
of grant. Such consideration may consist entirely of:

                           (i)      cash;

                           (ii)     check;

                           (iii)    promissory note;

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                           (iv)     other Shares which (A) in the case of Shares
acquired upon exercise of an option, have been owned by the Optionee for more
than six months on the date of surrender, and (B) have a Fair Market Value on
the date of surrender equal to the aggregate exercise price of the Shares as to
which said Option shall be exercised;

                           (v)      consideration received by the Company under
a cashless exercise program implemented by the Company in connection with the
Plan;

                           (vi)     a reduction in the amount of any Company
liability to the Optionee, including any liability attributable to the
Optionee's participation in any Company-sponsored deferred compensation program
or arrangement;

                           (vii)    any combination of the foregoing methods of
payment; or

                           (viii)   such other consideration and method of
payment for the issuance of Shares to the extent permitted by Applicable Laws.

         10.       Exercise of Option.

                           (a)      Procedure for Exercise; Rights as a
Shareholder. Any Option granted hereunder shall be exercisable according to the
terms of the Plan and at such times and under such conditions as determined by
the Administrator and set forth in the Option Agreement. Unless the
Administrator provides otherwise, vesting of Options granted to Officers and
Directors hereunder shall be tolled during any unpaid leave of absence. An
Option may not be exercised for a fraction of a Share.

         An Option shall be deemed exercised when the Company receives: (i)
written or electronic notice of exercise (in accordance with the Option
Agreement) from the person entitled to exercise the Option, and (ii) full
payment for the Shares with respect to which the Option is exercised. Full
payment may consist of any consideration and method of payment authorized by the
Administrator and permitted by the Option Agreement and the Plan. Shares issued
upon exercise of an Option shall be issued in the name of the Optionee or, if
requested by the Optionee, in the name of the Optionee and his or her spouse.
Until the Shares are issued (as evidenced by the appropriate entry on the books
of the Company or of a duly authorized transfer agent of the Company), no right
to vote or receive dividends or any other rights as a shareholder shall exist
with respect to the Optioned Stock, notwithstanding the exercise of the Option.
The Company shall issue (or cause to be issued) such Shares promptly after the
Option is exercised. No adjustment will be made for a dividend or other right
for which the record date is prior to the date the Shares are issued, except as
provided in Section 13 of the Plan.

         Exercising an Option in any manner shall decrease the number of Shares
thereafter available, both for purposes of the Plan and for sale under the
Option, by the number of Shares as to which the Option is exercised.

                  (b)      Termination of Relationship as a Service Provider. If
an Optionee ceases to be a Service Provider, other than upon the Optionee's
death or Disability, the Optionee may exercise his or her Option within such
period of time as is specified in the Option Agreement to the extent

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that the Option is vested on the date of termination (but in no event later than
the expiration of the term of such Option as set forth in the Option Agreement).
In the absence of a specified time in the Option Agreement, the Option shall
remain exercisable for thirty (30) days following the Optionee's termination.
Prior to the date the Common Stock is listed on a national securities exchange
or a national market system which qualifies under Section 25100(o) of the
Corporations Code of California, such Option must remain exercisable for a
period of at least thirty (30) days after the Optionee ceases to be a Service
Provider. If, on the date of termination, the Optionee is not vested as to his
or her entire Option, the Shares covered by the unvested portion of the Option
shall revert to the Plan. If, after termination, the Optionee does not exercise
his or her Option within the time specified by the Administrator, the Option
shall terminate, and the Shares covered by such Option shall revert to the Plan.

                  (c)      Disability of Optionee. If an Optionee ceases to be a
Service Provider as a result of the Optionee's Disability, the Optionee may
exercise his or her Option within such period of time as is specified in the
Option Agreement to the extent the Option is vested on the date of termination
(but in no event later than the expiration of the term of such Option as set
forth in the Option Agreement). In the absence of a specified time in the Option
Agreement, the Option shall remain exercisable for twelve (12) months following
the Optionee's termination. Prior to the date the Common Stock is listed on a
national securities exchange or a national market system which qualifies under
Section 25100(o) of the Corporations Code of California, such Option must remain
exercisable for a period of at least six (6) months after the Optionee ceases to
be a Service Provider due to Optionee's disability. If, on the date of
termination, the Optionee is not vested as to his or her entire Option, the
Shares covered by the unvested portion of the Option shall revert to 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 the Plan.

                  (d)      Death of Optionee. If an Optionee dies while a
Service Provider, the Option may be exercised within such period of time as is
specified in the Option Agreement (but in no event later than the expiration of
the term of such Option as set forth in the Notice of Grant), by the Optionee's
estate or by a person who acquires the right to exercise the Option by bequest
or inheritance, but only to the extent that the Option is vested on the date of
death. In the absence of a specified time in the Option Agreement, the Option
shall remain exercisable for twelve (12) months following the Optionee's
termination. Prior to the date the Common Stock is listed on a national
securities exchange or a national market system which qualifies under Section
25100(o) of the Corporations Code of California, such Option must remain
exercisable for a period of at least six (6) months after the Optionee ceases to
be a Service Provider. If, at the time of death, the Optionee is not vested as
to his or her entire Option, the Shares covered by the unvested portion of the
Option shall immediately revert to the Plan. The Option may be exercised by the
executor or administrator of the Optionee's estate or, if none, by the person(s)
entitled to exercise the Option under the Optionee's will or the laws of descent
or distribution. If the Option is not so exercised within the time specified
herein, the Option shall terminate, and the Shares covered by such Option shall
revert to the Plan.

                  (e)      Buyout Provisions. The Administrator may at any time
offer to buy out for a payment in cash or Shares an Option previously granted
based on such terms and conditions as the Administrator shall establish and
communicate to the Optionee at the time that such offer is made.

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         11.      Stock Purchase Rights.

                  (a)      Rights to Purchase. Stock Purchase Rights may be
issued either alone, in addition to, or in tandem with other awards granted
under the Plan and/or cash awards made outside of the Plan. After the
Administrator determines that it will offer Stock Purchase Rights under the
Plan, it shall advise the offeree in writing or electronically, by means of a
Notice of Grant, of the terms, conditions and restrictions related to the offer,
including the number of Shares that the offeree shall be entitled to purchase,
the price to be paid, and the time within which the offeree must accept such
offer. The offer shall be accepted by execution of a Restricted Stock Purchase
Agreement in the form determined by the Administrator. Prior to the date the
Common Stock is listed on a national securities exchange or a national market
system which qualifies under Section 25100(o) of the Corporations Code of
California, the terms of the offer of Stock Purchase Rights under the Plan shall
comply in all respects with Section 260.140.42 of Title 10 of the California
Code of Regulations.

                  (b)      Repurchase Option. Unless the Administrator
determines otherwise, the Restricted Stock Purchase Agreement shall grant the
Company a repurchase option exercisable upon the voluntary or involuntary
termination of the purchaser's service with the Company for any reason
(including death or Disability). The purchase price for Shares repurchased
pursuant to the Restricted Stock Purchase Agreement shall be the original price
paid by the purchaser and may be paid by cancellation of any indebtedness of the
purchaser to the Company. The repurchase option shall lapse at a rate determined
by the Administrator; provided, however, that prior to the date the Common Stock
is listed on a national securities exchange or a national market system which
qualifies under Section 25100(o) of the Corporations Code of California, that
except with respect to Shares purchased by Officers, Directors and Consultants,
the repurchase option shall in no case lapse at a rate of less than 20% per year
over five (5) years from the date of purchase.

                  (c)      Other Provisions. The Restricted Stock Purchase
Agreement shall contain such other terms, provisions and conditions not
inconsistent with the Plan as may be determined by the Administrator in its sole
discretion.

                  (d)      Rights as a Shareholder. Once the Stock Purchase
Right is exercised, the purchaser shall have the rights equivalent to those of a
shareholder, and shall be a shareholder when his or her purchase is entered upon
the records of the duly authorized transfer agent of the Company. No adjustment
will be made for a dividend or other right for which the record date is prior to
the date the Stock Purchase Right is exercised, except as provided in Section 13
of the Plan.

         12.      Non-Transferability of Options and Stock Purchase Rights.
Unless determined otherwise by the Administrator, an Option or Stock Purchase
Right may not be sold, pledged, assigned, hypothecated, transferred, or disposed
of in any manner other than by will or by the laws of descent or distribution
and may be exercised, during the lifetime of the Optionee, only by the Optionee.
If the Administrator makes an Option or Stock Purchase Right transferable, such
Option or Stock Purchase Right shall contain such additional terms and
conditions as the Administrator deems appropriate.

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<PAGE>

         13.      Adjustments Upon Changes in Capitalization, Dissolution,
Merger or Asset Sale, or Change in Control

                  (a)      Changes in Capitalization. Subject to any required
action by the shareholders of the Company, the number of shares of Common Stock
covered by each outstanding Option and Stock Purchase Right, and the number of
shares of Common Stock which have been authorized for issuance under the Plan
but as to which no Options or Stock Purchase Rights have yet been granted or
which have been returned to the Plan upon cancellation or expiration of an
Option or Stock Purchase Right, as well as the price per share of Common Stock
covered by each such outstanding Option or Stock Purchase Right, 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 issued 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 or Stock Purchase Right.

                  (b)      Dissolution or Liquidation. In the event of the
proposed dissolution or liquidation of the Company, the Administrator shall
notify each Optionee as soon as practicable prior to the effective date of such
proposed transaction. The Administrator in its discretion may provide for an
Optionee to have the right to exercise his or her Option until ten (10) days
prior to such transaction as to all of the Optioned Stock covered thereby,
including Shares as to which the Option would not otherwise be exercisable. In
addition, the Administrator may provide that any Company repurchase option
applicable to any Shares purchased upon exercise of an Option or Stock Purchase
Right shall lapse as to all such Shares, provided the proposed dissolution or
liquidation takes place at the time and in the manner contemplated. To the
extent it has not been previously exercised, an Option or Stock Purchase Right
will terminate immediately prior to the consummation of such proposed action.

                  (c)      Merger or Asset Sale. In the event of a merger of the
Company with or into another corporation, or the sale of substantially all of
the assets of the Company, each outstanding Option and Stock Purchase Right
shall be assumed or an equivalent option or right 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 or
Stock Purchase Right, the Optionee shall fully vest in and have the right to
exercise the Option or Stock Purchase Right as to all of the Optioned Stock,
including Shares as to which it would not otherwise be vested or exercisable. If
an Option or Stock Purchase Right becomes fully vested and exercisable in lieu
of assumption or substitution in the event of a merger or sale of assets, the
Administrator shall notify the Optionee in writing or electronically that the
Option or Stock Purchase Right shall be fully vested and exercisable for a
period of fifteen (15) days from the date of such notice, and the Option or
Stock Purchase Right shall terminate upon the expiration of such period. For the
purposes of this paragraph, the Option or Stock Purchase Right shall be
considered assumed if, following the merger

                                                                            -12-

<PAGE>

or sale of assets, the option or right confers the right to purchase or receive,
for each Share of Optioned Stock subject to the Option or Stock Purchase Right
immediately prior to the merger or sale of assets, the consideration (whether
stock, cash, or other securities or property) received in the merger or sale of
assets by holders of Common Stock for each Share held on the effective date of
the transaction (and if holders were offered a choice of consideration, the type
of consideration chosen by the holders of a majority of the outstanding Shares);
provided, however, that if such consideration received in the merger or sale of
assets is not solely common stock of the successor corporation or its Parent,
the Administrator may, with the consent of the successor corporation, provide
for the consideration to be received upon the exercise of the Option or Stock
Purchase Right, for each Share of Optioned Stock subject to the Option or Stock
Purchase Right, to be solely common stock of the successor corporation or its
Parent equal in fair market value to the per share consideration received by
holders of Common Stock in the merger or sale of assets.

                  (d)      Additional Vesting for Certain Directors Upon Change
in Control. Unless the Option shall have become fully exercisable pursuant to
Sections 13(b) or 13(c) of the Plan, in the event of a Change in Control each
outstanding option granted to a Director who is not an Employee shall become
vested and exercisable as to an additional number of Shares equal to the number
of Shares which had become vested and exercisable immediately prior to the
Change in Control; provided, however, that in no event shall the Option become
vested and exercisable pursuant to this provision for a number of Shares greater
in the aggregate than the number of Shares subject to the Option. The
Administrator shall notify the Director in writing or electronically not less
than fifteen (15) days prior to the Change in Control that the vesting of the
Option shall accelerate and the Director shall be entitled to exercise the
Option as to the additional Shares concurrently with the Change in Control.

         14.      Date of Grant. The date of grant of an Option or Stock
Purchase Right shall be, for all purposes, the date on which the Administrator
makes the determination granting such Option or Stock Purchase Right, or such
other later date as is determined by the Administrator. Notice of the
determination shall be provided to each Optionee within a reasonable time after
the date of such grant.

         15.      Amendment and Termination of the Plan.

                  (a)      Amendment and Termination. The Board may at any time
amend, alter, suspend or terminate the Plan.

                  (b)      Shareholder Approval. The Company shall obtain
shareholder approval of any Plan amendment to the extent necessary and
desirable to comply with Applicable Laws.

                  (c)      Effect of Amendment or Termination. No amendment,
alteration, suspension or termination of the Plan shall impair the rights of any
Optionee, unless mutually agreed otherwise between the Optionee and the
Administrator, which agreement must be in writing and signed by the Optionee and
the Company. Termination of the Plan shall not affect the Administrator's
ability to exercise the powers granted to it hereunder with respect to Options
granted under the Plan prior to the date of such termination.

                                                                            -13-

<PAGE>

         16.      Conditions Upon Issuance of Shares.

                  (a)      Legal Compliance. Shares shall not be issued pursuant
to the exercise of an Option or Stock Purchase Right unless the exercise of such
Option or Stock Purchase Right and the issuance and delivery of such Shares
shall comply with Applicable Laws and shall be further subject to the approval
of counsel for the Company with respect to such compliance.

                  (b)      Investment Representations. As a condition to the
exercise of an Option or Stock Purchase Right, the Company may require the
person exercising such Option or Stock Purchase Right 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.

         17.      Inability to Obtain Authority. The inability of the Company to
obtain authority from any regulatory body having jurisdiction, which authority
is deemed by the Company's counsel to be necessary to the lawful issuance and
sale of any Shares hereunder, shall relieve the Company of any liability in
respect of the failure to issue or sell such Shares as to which such requisite
authority shall not have been obtained.

         18.      Reservation of Shares. The Company, during the term of this
Plan, will at all times reserve and keep available such number of Shares as
shall be sufficient to satisfy the requirements of the Plan.

         19.      Shareholder Approval. The Plan shall be subject to approval by
the shareholders of the Company within twelve (12) months after the date the
Plan is adopted. Such shareholder approval shall be obtained in the manner and
to the degree required under Applicable Laws.

         20.      Information to Optionees and Purchasers. Prior to the date the
Common Stock is listed on a national securities exchange or a national market
system which qualifies under Section 25100(o) of the Corporations Code of
California, the Company shall provide to each Optionee and to each individual
who acquires Shares pursuant to the Plan, not less frequently than annually
during the period such Optionee or purchaser has one or more Options or Stock
Purchase Rights outstanding, and, in the case of an individual who acquires
Shares pursuant to the Plan, during the period such individual owns such Shares,
copies of annual financial statements. The Company shall not be required to
provide such statements to key employees whose duties in connection with the
Company assure their access to equivalent information.

                                                                            -14-

<PAGE>

                              [PUBLIC COMPANY FORM]

                       CATAPULT COMMUNICATIONS CORPORATION

                                 1998 STOCK PLAN

                             STOCK OPTION AGREEMENT

         Unless otherwise defined herein, the terms defined in the Plan shall
have the same defined meanings in this Option Agreement.

I.       NOTICE OF STOCK OPTION GRANT

[Optionee's Name and Address]

         You have been granted an option to purchase Common Stock of the
Company, subject to the terms and conditions of the Plan and this Option
Agreement, as follows:

         Grant Number                   ________________________________________

         Date of Grant                  ________________________________________

         Vesting Commencement Date      ________________________________________

         Exercise Price per Share      $________________________________________

         Total Number of Shares Granted ________________________________________

         Total Exercise Price          $________________________________________

         Type of Option:               ___  Incentive Stock Option

                                       ___ Nonstatutory Stock Option

         Term/Expiration Date:         _________________________________________

Vesting Schedule:

         This Option may be exercised, in whole or in part, in accordance with
the following schedule:

         20% of the Shares subject to the Option shall vest twelve months after
the Vesting Commencement Date, and 1/60 of the Shares subject to the Option
shall vest each month thereafter, subject to the Optionee continuing to be a
Service Provider on such dates.

<PAGE>

Termination Period:

         This Option may be exercised for thirty (30) days after Optionee ceases
to be a Service Provider. Upon the death or Disability of the Optionee, this
Option may be exercised for one year after Optionee ceases to be a Service
Provider. In no event shall this Option be exercised later than the
Term/Expiration Date as provided above.

II.      AGREEMENT

         1.       Grant of Option. The Plan Administrator of the Company hereby
grants to the Optionee named in the Notice of Grant attached as Part I of this
Agreement (the "Optionee") an option (the "Option") to purchase the number of
Shares, as set forth in the Notice of Grant, at the exercise price per share set
forth in the Notice of Grant (the "Exercise Price"), subject to the terms and
conditions of the Plan, which is incorporated herein by reference. Subject to
Section 15(c) of the Plan, in the event of a conflict between the terms and
conditions of the Plan and the terms and conditions of this Option Agreement,
the terms and conditions of the Plan shall prevail.

         If designated in the Notice of Grant as an Incentive Stock Option
("ISO"), this Option is intended to qualify as an Incentive Stock Option under
Section 422 of the Code. However, if this Option is intended to be an Incentive
Stock Option, to the extent that it exceeds the $100,000 rule of Code Section
422(d) it shall be treated as a Nonstatutory Stock Option ("NSO").

         2.       Exercise of Option.

                  (a)      Right to Exercise. This Option is exercisable during
its term in accordance with the Vesting Schedule set out in the Notice of Grant
and the applicable provisions of the Plan and this Option Agreement.

                  (b)      Method of Exercise. This Option is exercisable by
delivery of an exercise notice, in the form attached as Exhibit A (the "Exercise
Notice"), which shall state the election to exercise the Option, the number of
Shares in respect of which the Option is being exercised (the "Exercised
Shares"), and such other representations and agreements as may be required by
the Company pursuant to the provisions of the Plan. The Exercise Notice shall be
completed by the Optionee and delivered to [Title] of the Company. The Exercise
Notice shall be accompanied by payment of the aggregate Exercise Price as to all
Exercised Shares. This Option shall be deemed to be exercised upon receipt by
the Company of such fully executed Exercise Notice accompanied by such aggregate
Exercise Price.

         No Shares shall be issued pursuant to the exercise of this Option
unless such issuance and exercise complies with Applicable Laws. Assuming such
compliance, for income tax purposes the Exercised Shares shall be considered
transferred to the Optionee on the date the Option is exercised with respect to
such Exercised Shares.

         3.       Method of Payment. Payment of the aggregate Exercise Price
shall be by any of the following, or a combination thereof, at the election of
the Optionee:

                  (a)      cash; or

                                                                             -2-

<PAGE>

                  (b)      check; or

                  (c)      consideration received by the Company under a
cashless exercise program implemented by the Company in connection with the
Plan; or

                  (d)      surrender of other Shares which (i) in the case of
Shares acquired upon exercise of an option, have been owned by the Optionee for
more than six (6) months on the date of surrender, AND (ii) have a Fair Market
Value on the date of surrender equal to the aggregate Exercise Price of the
Exercised Shares; or

                  (e)      with the Administrator's consent, delivery of
Optionee's promissory note (the "Note") in the form attached hereto as Exhibit
C, in the amount of the aggregate Exercise Price of the Exercised Shares
together with the execution and delivery by the Optionee of the Security
Agreement attached hereto as Exhibit B. The Note shall bear interest at the
"applicable federal rate" prescribed under the Code and its regulations at time
of purchase, and shall be secured by a pledge of the Shares purchased by the
Note pursuant to the Security Agreement.

         4.       Non-Transferability of Option. This Option may not be
transferred in any manner otherwise than by will or by the laws of descent or
distribution and may be exercised during the lifetime of Optionee only by the
Optionee. The terms of the Plan and this Option Agreement shall be binding upon
the executors, administrators, heirs, successors and assigns of the Optionee.

         5.       Term of Option. This Option may be exercised only within the
term set out in the Notice of Grant, and may be exercised during such term only
in accordance with the Plan and the terms of this Option Agreement.

         6.       Tax Consequences. Some of the federal tax consequences
relating to this Option, as of the date of this Option, are set forth below.
THIS SUMMARY IS NECESSARILY INCOMPLETE, AND THE TAX LAWS AND REGULATIONS ARE
SUBJECT TO CHANGE. THE OPTIONEE SHOULD CONSULT A TAX ADVISER BEFORE EXERCISING
THIS OPTION OR DISPOSING OF THE SHARES.

                  (a)      Exercising the Option.

                           (i)      Nonstatutory Stock Option. The Optionee may
incur regular federal income tax liability upon exercise of a NSO. The Optionee
will be treated as having received compensation income (taxable at ordinary
income tax rates) equal to the excess, if any, of the Fair Market Value of the
Exercised Shares on the date of exercise over their aggregate Exercise Price. If
the Optionee is an Employee or a former Employee, the Company will be required
to withhold from his or her compensation or collect from Optionee and pay to the
applicable taxing authorities an amount in cash equal to a percentage of this
compensation income at the time of exercise, and may refuse to honor the
exercise and refuse to deliver Shares if such withholding amounts are not
delivered at the time of exercise.

                           (ii)     Incentive Stock Option. If this Option
qualifies as an ISO, the Optionee will have no regular federal income tax
liability upon its exercise, although the excess, if any, of the Fair Market
Value of the Exercised Shares on the date of exercise over their aggregate

                                                                             -3-

<PAGE>

Exercise Price will be treated as an adjustment to alternative minimum taxable
income for federal tax purposes and may subject the Optionee to alternative
minimum tax in the year of exercise. In the event that the Optionee ceases to be
an Employee but remains a Service Provider, any Incentive Stock Option of the
Optionee that remains unexercised shall cease to qualify as an Incentive Stock
Option and will be treated for tax purposes as a Nonstatutory Stock Option on
the date three (3) months and one (1) day following such change of status.

                  (b)      Disposition of Shares.

                           (i)      NSO. If the Optionee holds NSO Shares for at
least one year, any gain realized on disposition of the Shares will be treated
as long-term capital gain for federal income tax purposes.

                           (ii)     ISO. If the Optionee holds ISO Shares for at
least one year after exercise and two years after the grant date, any gain
realized on disposition of the Shares will be treated as long-term capital gain
for federal income tax purposes. If the Optionee disposes of ISO Shares within
one year after exercise or two years after the grant date, any gain realized on
such disposition will be treated as compensation income (taxable at ordinary
income rates) to the extent of the excess, if any, of the lesser of (A) the
difference between the Fair Market Value of the Shares acquired on the date of
exercise and the aggregate Exercise Price, or (B) the difference between the
sale price of such Shares and the aggregate Exercise Price. Any additional gain
will be taxed as capital gain, short-term or long-term depending on the period
that the ISO Shares were held.

                  (c)      Notice of Disqualifying Disposition of ISO Shares. If
the Optionee sells or otherwise disposes of any of the Shares acquired pursuant
to an ISO on or before the later of (i) two years after the grant date, or (ii)
one year after the exercise date, the Optionee shall immediately notify the
Company in writing of such disposition. The Optionee agrees that he or she may
be subject to income tax withholding by the Company on the compensation income
recognized from such early disposition of ISO Shares by payment in cash or out
of the current earnings paid to the Optionee.

         7.       Entire Agreement; Governing Law. The Plan is incorporated
herein by reference. The Plan and this Option Agreement constitute the entire
agreement of the parties with respect to the subject matter hereof and supersede
in their entirety all prior undertakings and agreements of the Company and
Optionee with respect to the subject matter hereof, and may not be modified
adversely to the Optionee's interest except by means of a writing signed by the
Company and Optionee. This agreement is governed by the internal substantive
laws, but not the choice of law rules, of California.

         8.       NO GUARANTEE OF CONTINUED SERVICE. OPTIONEE ACKNOWLEDGES AND
AGREES THAT THE VESTING OF SHARES PURSUANT TO THE VESTING SCHEDULE HEREOF IS
EARNED ONLY BY CONTINUING AS A SERVICE PROVIDER AT THE WILL OF THE COMPANY (AND
NOT THROUGH THE ACT OF BEING HIRED, BEING GRANTED AN OPTION OR PURCHASING SHARES
HEREUNDER). OPTIONEE FURTHER ACKNOWLEDGES AND AGREES THAT THIS AGREEMENT, THE
TRANSACTIONS CONTEMPLATED HEREUNDER AND THE VESTING SCHEDULE SET FORTH HEREIN DO
NOT CONSTITUTE AN EXPRESS OR IMPLIED PROMISE OF CONTINUED ENGAGEMENT

                                                                             -4-

<PAGE>

AS A SERVICE PROVIDER FOR THE VESTING PERIOD, FOR ANY PERIOD, OR AT ALL, AND
SHALL NOT INTERFERE WITH OPTIONEE'S RIGHT OR THE COMPANY'S RIGHT TO TERMINATE
OPTIONEE'S RELATIONSHIP AS A SERVICE PROVIDER AT ANY TIME, WITH OR WITHOUT
CAUSE.

         By your signature and the signature of the Company's representative
below, you and the Company agree that this Option is granted under and governed
by the terms and conditions of the Plan and this Option Agreement. Optionee has
reviewed the Plan and this Option Agreement in their entirety, has had an
opportunity to obtain the advice of counsel prior to executing this Option
Agreement and fully understands all provisions of the Plan and Option Agreement.
Optionee hereby agrees to accept as binding, conclusive and final all decisions
or interpretations of the Administrator upon any questions relating to the Plan
and Option Agreement. Optionee further agrees to notify the Company upon any
change in the residence address indicated below.

OPTIONEE:                                              CATAPULT COMMUNICATIONS
                                                       CORPORATION

___________________________                            _________________________
Signature                                              By

_________________________                              _________________________
Print Name                                             Title

___________________________
Residence Address

___________________________

                                                                             -5-

<PAGE>

                       CATAPULT COMMUNICATIONS CORPORATION

                                CONSENT OF SPOUSE

         The undersigned spouse of __________, ("Optionee") has read and hereby
approves the terms and conditions of the Plan and this Option Agreement. In
consideration of the Company's granting his or her spouse the right to purchase
Shares as set forth in the Plan and this Option Agreement, the undersigned
hereby agrees to be irrevocably bound by the terms and conditions of the Plan
and this Option Agreement and further agrees that any community property
interest shall be similarly bound. The undersigned hereby appoints the
undersigned's spouse as attorney-in-fact for the undersigned with respect to any
amendment or exercise of rights under the Plan or this Option Agreement.

                                                ________________________________
                                                Spouse of Optionee

<PAGE>

                                    EXHIBIT A

                                 1998 STOCK PLAN

                                 EXERCISE NOTICE

Catapult Communications Corporation
160 South Whisman Road
Mountain View, CA 94041

Attention:  [Title]

         1.       Exercise of Option. Effective as of today, ________________,
20__, the undersigned ("Purchaser") hereby elects to purchase ______________
shares (the "Shares") of the Common Stock of Catapult Communications Corporation
(the "Company") under and pursuant to the 1998 Stock Plan (the "Plan") and the
Stock Option Agreement dated, 20___ (the "Option Agreement"). The purchase price
for the Shares shall be $, as required by the Option Agreement.

         2.       Delivery of Payment. Purchaser herewith delivers to the
Company the full purchase price for the Shares.

         3.       Representations of Purchaser. Purchaser acknowledges that
Purchaser has received, read and understood the Plan and the Option Agreement
and agrees to abide by and be bound by their terms and conditions.

         4.       Rights as Shareholder. Until the issuance (as evidenced by the
appropriate entry on the books of the Company or of a duly authorized transfer
agent of the Company) of the Shares, no right to vote or receive dividends or
any other rights as a shareholder shall exist with respect to the Optioned
Stock, notwithstanding the exercise of the Option. The Shares so acquired shall
be issued to the Optionee as soon as practicable after exercise of the Option.
No adjustment will be made for a dividend or other right for which the record
date is prior to the date of issuance, except as provided in Section 13 of the
Plan.

         5.       Tax Consultation. Purchaser understands that Purchaser may
suffer adverse tax consequences as a result of Purchaser's purchase or
disposition of the Shares. Purchaser represents that Purchaser has consulted
with any tax consultants Purchaser deems advisable in connection with the
purchase or disposition of the Shares and that Purchaser is not relying on the
Company for any tax advice.

         6.       Entire Agreement; Governing Law. The Plan and Option Agreement
are incorporated herein by reference. This Agreement, the Plan and the Option
Agreement constitute the entire agreement of the parties with respect to the
subject matter hereof and supersede in their entirety all prior undertakings and
agreements of the Company and Purchaser with respect to the subject matter
hereof, and may not be modified adversely to the Purchaser's interest except by
means of a writing

<PAGE>

signed by the Company and Purchaser. This agreement is governed by the internal
substantive laws, but not the choice of law rules, of California.

Submitted by:                                Accepted by:

PURCHASER:                                   CATAPULT COMMUNICATIONS
                                             CORPORATION:
___________________________                  ___________________________________
Signature                                    By

___________________________                  ___________________________________
Print Name                                   Its

Address:                                     Address:

___________________________                  Catapult Communications Corporation
                                             160 South Whisman Road
___________________________                  Mountain View, CA 94041

                                             ___________________________________
                                             Date Received

                                                                             -2-

<PAGE>

                                    EXHIBIT B

                               SECURITY AGREEMENT

         This Security Agreement is made as of __________, 20___ between
Catapult Communications Corporation, a Nevada corporation ("Pledgee"), and
_________________________ ("Pledgor").

                                    Recitals

         Pursuant to Pledgor's election to purchase Shares under the Option
Agreement dated ________ (the "Option"), between Pledgor and Pledgee under
Pledgee's 1998 Stock Plan, and Pledgor's election under the terms of the Option
to pay for such shares with his promissory note (the "Note"), Pledgor has
purchased _________ shares of Pledgee's Common Stock (the "Shares") at a price
of $________ per share, for a total purchase price of $__________. The Note and
the obligations thereunder are as set forth in Exhibit C to the Option.

         NOW, THEREFORE, it is agreed as follows:

         1.       Creation and Description of Security Interest. In
consideration of the transfer of the Shares to Pledgor under the Option
Agreement, Pledgor, pursuant to the California Commercial Code, hereby pledges
all of such Shares (herein sometimes referred to as the "Collateral")
represented by certificate number ______, duly endorsed in blank or with
executed stock powers, and herewith delivers said certificate to the Secretary
of Pledgee ("Pledgeholder"), who shall hold said certificate subject to the
terms and conditions of this Security Agreement.

         The pledged stock (together with an executed blank stock assignment for
use in transferring all or a portion of the Shares to Pledgee if, as and when
required pursuant to this Security Agreement) shall be held by the Pledgeholder
as security for the repayment of the Note, and any extensions or renewals
thereof, to be executed by Pledgor pursuant to the terms of the Option, and the
Pledgeholder shall not encumber or dispose of such Shares except in accordance
with the provisions of this Security Agreement.

         2.       Pledgor's Representations and Covenants. To induce Pledgee to
enter into this Security Agreement, Pledgor represents and covenants to Pledgee,
its successors and assigns, as follows:

                  a.       Payment of Indebtedness. Pledgor will pay the
principal sum of the Note secured hereby, together with interest thereon, at the
time and in the manner provided in the Note.

                  b.       Encumbrances. The Shares are free of all other
encumbrances, defenses and liens, and Pledgor will not further encumber the
Shares without the prior written consent of Pledgee.

                  c.       Margin Regulations. In the event that Pledgee's
Common Stock is now or later becomes margin-listed by the Federal Reserve Board
and Pledgee is classified as a "lender" within the meaning of the regulations
under Part 207 of Title 12 of the Code of Federal Regulations

<PAGE>

("Regulation G"), Pledgor agrees to cooperate with Pledgee in making any
amendments to the Note or providing any additional collateral as may be
necessary to comply with such regulations.

         3.       Voting Rights. During the term of this pledge and so long as
all payments of principal and interest are made as they become due under the
terms of the Note, Pledgor shall have the right to vote all of the Shares
pledged hereunder.

         4.       Stock Adjustments. In the event that during the term of the
pledge any stock dividend, reclassification, readjustment or other changes are
declared or made in the capital structure of Pledgee, all new, substituted and
additional shares or other securities issued by reason of any such change shall
be delivered to and held by the Pledgee under the terms of this Security
Agreement in the same manner as the Shares originally pledged hereunder. In the
event of substitution of such securities, Pledgor, Pledgee and Pledgeholder
shall cooperate and execute such documents as are reasonable so as to provide
for the substitution of such Collateral and, upon such substitution, references
to "Shares" in this Security Agreement shall include the substituted shares of
capital stock of Pledgor as a result thereof.

         5.       Options and Rights. In the event that, during the term of this
pledge, subscription Options or other rights or options shall be issued in
connection with the pledged Shares, such rights, Options and options shall be
the property of Pledgor and, if exercised by Pledgor, all new stock or other
securities so acquired by Pledgor as it relates to the pledged Shares then held
by Pledgeholder shall be immediately delivered to Pledgeholder, to be held under
the terms of this Security Agreement in the same manner as the Shares pledged.

         6.       Default. Pledgor shall be deemed to be in default of the Note
and of this Security Agreement in the event:

                  a.       Payment of principal or interest on the Note shall be
delinquent for a period of 10 days or more; or

                  b.       Pledgor fails to perform any of the covenants set
forth in the Option or contained in this Security Agreement for a period of 10
days after written notice thereof from Pledgee.

         In the case of an event of Default, as set forth above, Pledgee shall
have the right to accelerate payment of the Note upon notice to Pledgor, and
Pledgee shall thereafter be entitled to pursue its remedies under the California
Commercial Code.

         7.       Release of Collateral. Subject to any applicable contrary
rules under Regulation G, there shall be released from this pledge a portion of
the pledged Shares held by Pledgeholder hereunder upon payments of the principal
of the Note. The number of the pledged Shares which shall be released shall be
that number of full Shares which bears the same proportion to the initial number
of Shares pledged hereunder as the payment of principal bears to the initial
full principal amount of the Note.

                                                                             -2-

<PAGE>

         8.       Withdrawal or Substitution of Collateral. Pledgor shall not
sell, withdraw, pledge, substitute or otherwise dispose of all or any part of
the Collateral without the prior written consent of Pledgee.

         9.       Term. The within pledge of Shares shall continue until the
payment of all indebtedness secured hereby, at which time the remaining pledged
stock shall be promptly delivered to Pledgor, subject to the provisions for
prior release of a portion of the Collateral as provided in paragraph 7 above.

         10.      Insolvency. Pledgor agrees that if a bankruptcy or insolvency
proceeding is instituted by or against it, or if a receiver is appointed for the
property of Pledgor, or if Pledgor makes an assignment for the benefit of
creditors, the entire amount unpaid on the Note shall become immediately due and
payable, and Pledgee may proceed as provided in the case of default.

         11.      Pledgeholder Liability. In the absence of willful or gross
negligence, Pledgeholder shall not be liable to any party for any of his acts,
or omissions to act, as Pledgeholder.

         12.      Invalidity of Particular Provisions. Pledgor and Pledgee agree
that the enforceability or invalidity of any provision or provisions of this
Security Agreement shall not render any other provision or provisions herein
contained unenforceable or invalid.

         13.      Successors or Assigns. Pledgor and Pledgee agree that all of
the terms of this Security Agreement shall be binding on their respective
successors and assigns, and that the term "Pledgor" and the term "Pledgee" as
used herein shall be deemed to include, for all purposes, the respective
designees, successors, assigns, heirs, executors and administrators.

         14.      Governing Law. This Security Agreement shall be interpreted
and governed under the internal substantive laws, but not the choice of law
rules, of California.

                                                                             -3-

<PAGE>

         IN WITNESS WHEREOF, the parties hereto have executed this Agreement as
of the day and year first above written.

"PLEDGOR"                                   ____________________________________
                                            Signature

                                            ____________________________________
                                            Print Name

                                    Address:____________________________________

                                            ____________________________________

"PLEDGEE"                                   CATAPULT COMMUNICATIONS CORPORATION,
                                            a Nevada corporation

                                            ____________________________________
                                            Signature

                                            ____________________________________
                                            Print Name

                                            ____________________________________
                                            Title

"PLEDGEHOLDER"                              ____________________________________
                                            Secretary of Catapult Communications
                                            Corporation

                                                                             -4-

<PAGE>

                                    EXHIBIT C

                                      NOTE

$_______________                                             Mountain View, CA

                                                           ______________, 20___

         FOR VALUE RECEIVED, _______________ promises to pay to Catapult
Communications Corporation, a Nevada corporation (the "Company"), or order, the
principal sum of _______________________ ($_____________), together with
interest on the unpaid principal hereof from the date hereof at the rate of
_______________ percent (____%) per annum, compounded semiannually.

         Principal and interest shall be due and payable on __________, 20___.
Payment of principal and interest shall be made in lawful money of the United
States of America.

         The undersigned may at any time prepay all or any portion of the
principal or interest owing hereunder.

         This Note is subject to the terms of the Option, dated as of
________________. This Note is secured in part by a pledge of the Company's
Common Stock under the terms of a Security Agreement of even date herewith and
is subject to all the provisions thereof.

         The holder of this Note shall have full recourse against the
undersigned, and shall not be required to proceed against the collateral
securing this Note in the event of default.

         In the event the undersigned shall cease to be an employee, director or
consultant of the Company for any reason, this Note shall, at the option of the
Company, be accelerated, and the whole unpaid balance on this Note of principal
and accrued interest shall be immediately due and payable.

         Should any action be instituted for the collection of this Note, the
reasonable costs and attorneys' fees therein of the holder shall be paid by the
undersigned.

                                   _____________________________________________
                                   Signature

                                   _____________________________________________
                                   Print Name

<PAGE>

                       CATAPULT COMMUNICATIONS CORPORATION

                                 1998 STOCK PLAN

                     NOTICE OF GRANT OF STOCK PURCHASE RIGHT

         Unless otherwise defined herein, the terms defined in the Plan shall
have the same defined meanings in this Notice of Grant.

[Grantee's Name and Address]

         You have been granted the right to purchase Common Stock of the
Company, subject to the Company's Repurchase Option and your ongoing status as a
Service Provider (as described in the Plan and the attached Restricted Stock
Purchase Agreement), as follows:

         Grant Number                       ____________________________________

         Date of Grant                      ____________________________________

         Price Per Share                    $___________________________________

         Total Number of Shares Subject     ____________________________________

         to This Stock Purchase Right       ____________________________________

         Expiration Date:                   ____________________________________

         YOU MUST EXERCISE THIS STOCK PURCHASE RIGHT BEFORE THE EXPIRATION DATE
OR IT WILL TERMINATE AND YOU WILL HAVE NO FURTHER RIGHT TO PURCHASE THE SHARES.
By your signature and the signature of the Company's representative below, you
and the Company agree that this Stock Purchase Right is granted under and
governed by the terms and conditions of the 1998 Stock Plan and the Restricted
Stock Purchase Agreement, attached hereto as Exhibit A-1, both of which are made
a part of this document. You further agree to execute the attached Restricted
Stock Purchase Agreement as a condition to purchasing any shares under this
Stock Purchase Right.

GRANTEE:                                             CATAPULT COMMUNICATIONS
                                                     CORPORATION
___________________________                          ___________________________
Signature                                            By

___________________________                          ___________________________
Print Name                                           Title

<PAGE>

                                   EXHIBIT A-1

                       CATAPULT COMMUNICATIONS CORPORATION

                                 1998 STOCK PLAN

                       RESTRICTED STOCK PURCHASE AGREEMENT

         Unless otherwise defined herein, the terms defined in the Plan shall
have the same defined meanings in this Restricted Stock Purchase Agreement.

         WHEREAS the Purchaser named in the Notice of Grant, (the "Purchaser")
is an Service Provider, and the Purchaser's continued participation is
considered by the Company to be important for the Company's continued growth;
and

         WHEREAS in order to give the Purchaser an opportunity to acquire an
equity interest in the Company as an incentive for the Purchaser to participate
in the affairs of the Company, the Administrator has granted to the Purchaser a
Stock Purchase Right subject to the terms and conditions of the Plan and the
Notice of Grant, which are incorporated herein by reference, and pursuant to
this Restricted Stock Purchase Agreement (the "Agreement").

         NOW THEREFORE, the parties agree as follows:

         1.       Sale of Stock. The Company hereby agrees to sell to the
Purchaser and the Purchaser hereby agrees to purchase shares of the Company's
Common Stock (the "Shares"), at the per Share purchase price and as otherwise
described in the Notice of Grant.

         2.       Payment of Purchase Price. The purchase price for the Shares
may be paid by delivery to the Company at the time of execution of this
Agreement of cash, a check, or some combination thereof.

         3.       Repurchase Option.

                  (a)      In the event the Purchaser ceases to be a Service
Provider for any or no reason (including death or disability) before all of the
Shares are released from the Company's Repurchase Option (see Section 4), the
Company shall, upon the date of such termination (as reasonably fixed and
determined by the Company) have an irrevocable, exclusive option (the
"Repurchase Option") for a period of sixty (60) days from such date to
repurchase up to that number of shares which constitute the Unreleased Shares
(as defined in Section 4) at the original purchase price per share (the
"Repurchase Price"). The Repurchase Option shall be exercised by the Company by
delivering written notice to the Purchaser or the Purchaser's executor (with a
copy to the Escrow Holder) AND, at the Company's option, (i) by delivering to
the Purchaser or the Purchaser's executor a check in the amount of the aggregate
Repurchase Price, or (ii) by canceling an amount of the Purchaser's indebtedness
to the Company equal to the aggregate Repurchase Price, or (iii) by a
combination of (i) and (ii) so that the combined payment and cancellation of
indebtedness equals the aggregate Repurchase Price. Upon delivery of such notice
and the payment of the aggregate Repurchase Price,

<PAGE>

the Company shall become the legal and beneficial owner of the Shares being
repurchased and all rights and interests therein or relating thereto, and the
Company shall have the right to retain and transfer to its own name the number
of Shares being repurchased by the Company.

                  (b)      Whenever the Company shall have the right to
repurchase Shares hereunder, the Company may designate and assign one or more
employees, officers, directors or shareholders of the Company or other persons
or organizations to exercise all or a part of the Company's purchase rights
under this Agreement and purchase all or a part of such Shares. If the Fair
Market Value of the Shares to be repurchased on the date of such designation or
assignment (the "Repurchase FMV") exceeds the aggregate Repurchase Price of such
Shares, then each such designee or assignee shall pay the Company cash equal to
the difference between the Repurchase FMV and the aggregate Repurchase Price of
such Shares.

         4.       Release of Shares From Repurchase Option.

                  (a)      _______________________ percent (______%) of the
Shares shall be released from the Company's Repurchase Option [one year] after
the Date of Grant and __________________ percent (______%) of the Shares [at the
end of each month thereafter], provided that the Purchaser does not cease to be
a Service Provider prior to the date of any such release.

                  (b)      Any of the Shares that have not yet been released
from the Repurchase Option are referred to herein as "Unreleased Shares."

                  (c)      The Shares that have been released from the
Repurchase Option shall be delivered to the Purchaser at the Purchaser's request
(see Section 6).

         5.       Restriction on Transfer. Except for the escrow described in
Section 6 or the transfer of the Shares to the Company or its assignees
contemplated by this Agreement, none of the Shares or any beneficial interest
therein shall be transferred, encumbered or otherwise disposed of in any way
until such Shares are released from the Company's Repurchase Option in
accordance with the provisions of this Agreement, other than by will or the laws
of descent and distribution.

         6.       Escrow of Shares.

                  (a)      To ensure the availability for delivery of the
Purchaser's Unreleased Shares upon repurchase by the Company pursuant to the
Repurchase Option, the Purchaser shall, upon execution of this Agreement,
deliver and deposit with an escrow holder designated by the Company (the "Escrow
Holder") the share certificates representing the Unreleased Shares, together
with the stock assignment duly endorsed in blank, attached hereto as Exhibit
A-2. The Unreleased Shares and stock assignment shall be held by the Escrow
Holder, pursuant to the Joint Escrow Instructions of the Company and Purchaser
attached hereto as Exhibit A-3, until such time as the Company's Repurchase
Option expires. As a further condition to the Company's obligations under this
Agreement, the Company may require the spouse of Purchaser, if any, to execute
and deliver to the Company the Consent of Spouse attached hereto as Exhibit A-4.

                                                                             -2-

<PAGE>

                  (b)      The Escrow Holder shall not be liable for any act it
may do or omit to do with respect to holding the Unreleased Shares in escrow
while acting in good faith and in the exercise of its judgment.

                  (c)      If the Company or any assignee exercises the
Repurchase Option hereunder, the Escrow Holder, upon receipt of written notice
of such exercise from the proposed transferee, shall take all steps necessary to
accomplish such transfer.

                  (d)      When the Repurchase Option has been exercised or
expires unexercised or a portion of the Shares has been released from the
Repurchase Option, upon request the Escrow Holder shall promptly cause a new
certificate to be issued for the released Shares and shall deliver the
certificate to the Company or the Purchaser, as the case may be.

                  (e)      Subject to the terms hereof, the Purchaser shall have
all the rights of a shareholder with respect to the Shares while they are held
in escrow, including without limitation, the right to vote the Shares and to
receive any cash dividends declared thereon. If, from time to time during the
term of the Repurchase Option, there is (i) any stock dividend, stock split or
other change in the Shares, or (ii) any merger or sale of all or substantially
all of the assets or other acquisition of the Company, any and all new,
substituted or additional securities to which the Purchaser is entitled by
reason of the Purchaser's ownership of the Shares shall be immediately subject
to this escrow, deposited with the Escrow Holder and included thereafter as
"Shares" for purposes of this Agreement and the Repurchase Option.

         7.       Legends. The share certificate evidencing the Shares, if any,
issued hereunder shall be endorsed with the following legend (in addition to any
legend required under applicable state securities laws):

         THE SHARES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO CERTAIN
RESTRICTIONS UPON TRANSFER AND RIGHTS OF REPURCHASE AS SET FORTH IN AN AGREEMENT
BETWEEN THE COMPANY AND THE SHAREHOLDER, A COPY OF WHICH IS ON FILE WITH THE
SECRETARY OF THE COMPANY.

         8.       Adjustment for Stock Split. All references to the number of
Shares and the purchase price of the Shares in this Agreement shall be
appropriately adjusted to reflect any stock split, stock dividend or other
change in the Shares which may be made by the Company after the date of this
Agreement.

         9.       Tax Consequences. The Purchaser has reviewed with the
Purchaser's own tax advisors the federal, state, local and foreign tax
consequences of this investment and the transactions contemplated by this
Agreement. The Purchaser is relying solely on such advisors and not on any
statements or representations of the Company or any of its agents. The Purchaser
understands that the Purchaser (and not the Company) shall be responsible for
the Purchaser's own tax liability that may arise as a result of the transactions
contemplated by this Agreement. The Purchaser understands that Section 83 of the
Internal Revenue Code of 1986, as amended (the "Code"), taxes as ordinary income
the difference between the purchase price for the Shares and the Fair Market
Value of the Shares as of the date any restrictions on the Shares lapse. In this
context, "restriction" includes the

                                                                             -3-

<PAGE>

right of the Company to buy back the Shares pursuant to the Repurchase Option.
The Purchaser understands that the Purchaser may elect to be taxed at the time
the Shares are purchased rather than when and as the Repurchase Option expires
by filing an election under Section 83(b) of the Code with the IRS within 30
days from the date of purchase. The form for making this election is attached as
Exhibit A-5 hereto.

         THE PURCHASER ACKNOWLEDGES THAT IT IS THE PURCHASER'S SOLE
RESPONSIBILITY AND NOT THE COMPANY'S TO FILE TIMELY THE ELECTION UNDER SECTION
83(b), EVEN IF THE PURCHASER REQUESTS THE COMPANY OR ITS REPRESENTATIVES TO MAKE
THIS FILING ON THE PURCHASER'S BEHALF.

         10.      General Provisions.

                  (a)      This Agreement shall be governed by the internal
substantive laws, but not the choice of law rules of California. This Agreement,
subject to the terms and conditions of the Plan and the Notice of Grant,
represents the entire agreement between the parties with respect to the purchase
of the Shares by the Purchaser. Subject to Section 15(c) of the Plan, in the
event of a conflict between the terms and conditions of the Plan and the terms
and conditions of this Agreement, the terms and conditions of the Plan shall
prevail. Unless otherwise defined herein, the terms defined in the Plan shall
have the same defined meanings in this Agreement.

                  (b)      Any notice, demand or request required or permitted
to be given by either the Company or the Purchaser pursuant to the terms of this
Agreement shall be in writing and shall be deemed given when delivered
personally or deposited in the U.S. mail, First Class with postage prepaid, and
addressed to the parties at the addresses of the parties set forth at the end of
this Agreement or such other address as a party may request by notifying the
other in writing.

         Any notice to the Escrow Holder shall be sent to the Company's address
with a copy to the other party hereto.

                  (c)      The rights of the Company under this Agreement shall
be transferable to any one or more persons or entities, and all covenants and
agreements hereunder shall inure to the benefit of, and be enforceable by the
Company's successors and assigns. The rights and obligations of the Purchaser
under this Agreement may only be assigned with the prior written consent of the
Company.

                  (d)      Either party's failure to enforce any provision of
this Agreement shall not in any way be construed as a waiver of any such
provision, nor prevent that party from thereafter enforcing any other provision
of this Agreement. The rights granted both parties hereunder are cumulative and
shall not constitute a waiver of either party's right to assert any other legal
remedy available to it.

                  (e)      The Purchaser agrees upon request to execute any
further documents or instruments necessary or desirable to carry out the
purposes or intent of this Agreement.

                  (f)      PURCHASER ACKNOWLEDGES AND AGREES THAT THE VESTING OF
SHARES PURSUANT TO SECTION 4 HEREOF IS EARNED ONLY BY CONTINUING

                                                                             -4-

<PAGE>

SERVICE AS A SERVICE PROVIDER AT THE WILL OF THE COMPANY (AND NOT THROUGH THE
ACT OF BEING HIRED OR PURCHASING SHARES HEREUNDER). PURCHASER FURTHER
ACKNOWLEDGES AND AGREES THAT THIS AGREEMENT, THE TRANSACTIONS CONTEMPLATED
HEREUNDER AND THE VESTING SCHEDULE SET FORTH HEREIN DO NOT CONSTITUTE AN EXPRESS
OR IMPLIED PROMISE OF CONTINUED ENGAGEMENT AS A SERVICE PROVIDER FOR THE VESTING
PERIOD, FOR ANY PERIOD, OR AT ALL, AND SHALL NOT INTERFERE WITH PURCHASER'S
RIGHT OR THE COMPANY'S RIGHT TO TERMINATE PURCHASER'S RELATIONSHIP AS A SERVICE
PROVIDER AT ANY TIME, WITH OR WITHOUT CAUSE.

         By Purchaser's signature below, Purchaser represents that he or she is
familiar with the terms and provisions of the Plan, and hereby accepts this
Agreement subject to all of the terms and provisions thereof. Purchaser has
reviewed the Plan and this Agreement in their entirety, has had an opportunity
to obtain the advice of counsel prior to executing this Agreement and fully
understands all provisions of this Agreement. Purchaser agrees to accept as
binding, conclusive and final all decisions or interpretations of the
Administrator upon any questions arising under the Plan or this Agreement.
Purchaser further agrees to notify the Company upon any change in the residence
indicated in the Notice of Grant.

DATED:  _________________________

PURCHASER:                                       CATAPULT COMMUNICATIONS
                                                 CORPORATION:

_________________________________                _______________________________
Signature                                        By

_________________________________                _______________________________
Print Name                                       Title

                                                                             -5-

<PAGE>

                                   EXHIBIT A-2

                      ASSIGNMENT SEPARATE FROM CERTIFICATE

         FOR VALUE RECEIVED I, __________________________, hereby sell, assign
and transfer unto __________________________________________ (__________) shares
of the Common Stock of Catapult Communications Corporation standing in my name
of the books of said corporation represented by Certificate No. _____ herewith
and do hereby irrevocably constitute and appoint _____________________________
to transfer the said stock on the books of the within named corporation with
full power of substitution in the premises.

         This Stock Assignment may be used only in accordance with the
Restricted Stock Purchase Agreement (the "Agreement") between___________________
and the undersigned dated ______________, 20__.

Dated:  _______________, 20__

                                            Signature: _________________________

INSTRUCTIONS: Please do not fill in any blanks other than the signature line.
The purpose of this assignment is to enable the Company to exercise the
Repurchase Option, as set forth in the Agreement, without requiring additional
signatures on the part of the Purchaser.

<PAGE>

                                   EXHIBIT A-3

                            JOINT ESCROW INSTRUCTIONS

                                                               ___________, 20__

Corporate Secretary
Catapult Communications Corporation
160 South Whisman Road
Mountain View, CA 94041

Dear  ________________:

         As Escrow Agent for both Catapult Communications Corporation, a Nevada
corporation (the "Company"), and the undersigned purchaser of stock of the
Company (the "Purchaser"), you are hereby authorized and directed to hold the
documents delivered to you pursuant to the terms of that certain Restricted
Stock Purchase Agreement ("Agreement") between the Company and the undersigned,
in accordance with the following instructions:

         1.       In the event the Company and/or any assignee of the Company
(referred to collectively as the "Company") exercises the Company's Repurchase
Option set forth in the Agreement, the Company shall give to Purchaser and you a
written notice specifying the number of shares of stock to be purchased, the
purchase price, and the time for a closing hereunder at the principal office of
the Company. Purchaser and the Company hereby irrevocably authorize and direct
you to close the transaction contemplated by such notice in accordance with the
terms of said notice.

         2.       At the closing, you are directed (a) to date the stock
assignments necessary for the transfer in question, (b) to fill in the number of
shares being transferred, and (c) to deliver same, together with the certificate
evidencing the shares of stock to be transferred, to the Company or its
assignee, against the simultaneous delivery to you of the purchase price (by
cash, a check, or some combination thereof) for the number of shares of stock
being purchased pursuant to the exercise of the Company's Repurchase Option.

         3.       Purchaser irrevocably authorizes the Company to deposit with
you any certificates evidencing shares of stock to be held by you hereunder and
any additions and substitutions to said shares as defined in the Agreement.
Purchaser does hereby irrevocably constitute and appoint you as Purchaser's
attorney-in-fact and agent for the term of this escrow to execute with respect
to such securities all documents necessary or appropriate to make such
securities negotiable and to complete any transaction herein contemplated,
including but not limited to the filing with any applicable state blue sky
authority of any required applications for consent to, or notice of transfer of,
the securities. Subject to the provisions of this paragraph 3, Purchaser shall
exercise all rights and privileges of a shareholder of the Company while the
stock is held by you.

<PAGE>

         4.       Upon written request of the Purchaser, but no more than once
per calendar year, unless the Company's Repurchase Option has been exercised,
you shall deliver to Purchaser a certificate or certificates representing so
many shares of stock as are not then subject to the Company's Repurchase Option.
Within 90 days after Purchaser ceases to be a Service Provider, you shall
deliver to Purchaser a certificate or certificates representing the aggregate
number of shares held or issued pursuant to the Agreement and not purchased by
the Company or its assignees pursuant to exercise of the Company's Repurchase
Option.

         5.       If at the time of termination of this escrow you should have
in your possession any documents, securities, or other property belonging to
Purchaser, you shall deliver all of the same to Purchaser and shall be
discharged of all further obligations hereunder.

         6.       Your duties hereunder may be altered, amended, modified or
revoked only by a writing signed by all of the parties hereto.

         7.       You shall be obligated only for the performance of such duties
as are specifically set forth herein and may rely and shall be protected in
relying or refraining from acting on any instrument reasonably believed by you
to be genuine and to have been signed or presented by the proper party or
parties. You shall not be personally liable for any act you may do or omit to do
hereunder as Escrow Agent or as attorney-in-fact for Purchaser while acting in
good faith, and any act done or omitted by you pursuant to the advice of your
own attorneys shall be conclusive evidence of such good faith.

         8.       You are hereby expressly authorized to disregard any and all
warnings given by any of the parties hereto or by any other person or
corporation, excepting only orders or process of courts of law, and are hereby
expressly authorized to comply with and obey orders, judgments or decrees of any
court. In case you obey or comply with any such order, judgment or decree, you
shall not be liable to any of the parties hereto or to any other person, firm or
corporation by reason of such compliance, notwithstanding any such order,
judgment or decree being subsequently reversed, modified, annulled, set aside,
vacated or found to have been entered without jurisdiction.

         9.       You shall not be liable in any respect on account of the
identity, authorities or rights of the parties executing or delivering or
purporting to execute or deliver the Agreement or any documents or papers
deposited or called for hereunder.

         10.      You shall not be liable for the outlawing of any rights under
the statute of limitations with respect to these Joint Escrow Instructions or
any documents deposited with you.

         11.      You shall be entitled to employ such legal counsel and other
experts as you may deem necessary properly to advise you in connection with your
obligations hereunder, may rely upon the advice of such counsel, and may pay
such counsel reasonable compensation therefor.

         12.      Your responsibilities as Escrow Agent hereunder shall
terminate if you shall cease to be an officer or agent of the Company or if you
shall resign by written notice to each party. In the event of any such
termination, the Company shall appoint a successor Escrow Agent.

                                                                             -2-

<PAGE>

         13.      If you reasonably require other or further instruments in
connection with these Joint Escrow Instructions or obligations in respect
hereto, the necessary parties hereto shall join in furnishing such instruments.

         14.      It is understood and agreed that should any dispute arise with
respect to the delivery and/or ownership or right of possession of the
securities held by you hereunder, you are authorized and directed to retain in
your possession without liability to anyone all or any part of said securities
until such disputes shall have been settled either by mutual written agreement
of the parties concerned or by a final order, decree or judgment of a court of
competent jurisdiction after the time for appeal has expired and no appeal has
been perfected, but you shall be under no duty whatsoever to institute or defend
any such proceedings.

         15.      Any notice required or permitted hereunder shall be given in
writing and shall be deemed effectively given upon personal delivery or upon
deposit in the United States Post Office, by registered or certified mail with
postage and fees prepaid, addressed to each of the other parties thereunto
entitled at the following addresses or at such other addresses as a party may
designate by ten days' advance written notice to each of the other parties
hereto.

                  COMPANY:                   Catapult Communications Corporation
                                             160 South Whisman Road
                                             Mountain View, CA 94041

                  PURCHASER:                 ___________________________________

                                             ___________________________________

                                             ___________________________________

                  ESCROW AGENT:              Corporate Secretary
                                             Catapult Communications Corporation
                                             160 South Whisman Road
                                             Mountain View, CA 94041

         16.      By signing these Joint Escrow Instructions, you become a party
hereto only for the purpose of said Joint Escrow Instructions; you do not become
a party to the Agreement.

         17.      This instrument shall be binding upon and inure to the benefit
of the parties hereto, and their respective successors and permitted assigns.

         18.      These Joint Escrow Instructions shall be governed by, and
construed and enforced in accordance with, the internal substantive laws, but
not the choice of law rules, of California.

                                            Very truly yours,

                                            CATAPULT COMMUNICATIONS
                                            CORPORATION

                                                                             -3-

<PAGE>

                                            ____________________________________
                                            By

                                            ____________________________________
                                            Title

                                            PURCHASER:

                                            ____________________________________
                                            Signature

                                            ____________________________________
                                            Print Name

ESCROW AGENT:

________________________________
Corporate Secretary

                                                                             -4-

<PAGE>

                                   EXHIBIT A-4

                                CONSENT OF SPOUSE

         I, ____________________, spouse of ___________________, have read and
approve the foregoing Restricted Stock Purchase Agreement (the "Agreement"). In
consideration of the Company's grant to my spouse of the right to purchase
shares of Catapult Communications Corporation, as set forth in the Agreement, I
hereby appoint my spouse as my attorney-in-fact in respect to the exercise of
any rights under the Agreement and agree to be bound by the provisions of the
Agreement insofar as I may have any rights in said Agreement or any shares
issued pursuant thereto under the community property laws or similar laws
relating to marital property in effect in the state of our residence as of the
date of the signing of the foregoing Agreement.

Dated:  _______________, 20__

                                            ____________________________________
                                            Signature of Spouse

<PAGE>

                                   EXHIBIT A-5

                          ELECTION UNDER SECTION 83(b)
                      OF THE INTERNAL REVENUE CODE OF 1986

The undersigned taxpayer hereby elects, pursuant to Section 83(b) of the
Internal Revenue Code of 1986, as amended, to include in taxpayer's gross income
for the current taxable year the amount of any compensation taxable to taxpayer
in connection with his or her receipt of the property described below:

1.       The name, address, taxpayer identification number and taxable year of
         the undersigned are as follows:

         NAME:                      TAXPAYER:                SPOUSE:

         ADDRESS:

         IDENTIFICATION NO.:        TAXPAYER:                SPOUSE:

         TAXABLE YEAR:

2.       The property with respect to which the election is made is described as
         follows:________shares (the "Shares") of the Common Stock of Catapult
         Communications Corporation (the "Company").

3.       The date on which the property was transferred is:__________, 20__.

4.       The property is subject to the following restrictions:

         The Shares may be repurchased by the Company, or its assignee, upon
         certain events. This right lapses with regard to a portion of the
         Shares based on the continued performance of services by the taxpayer
         over time.

5.       The fair market value at the time of transfer, determined without
         regard to any restriction other than a restriction which by its terms
         will never lapse, of such property is:

         $_________________.

6.       The amount (if any) paid for such property is:

         $_________________.

The undersigned has submitted a copy of this statement to the person for whom
the services were performed in connection with the undersigned's receipt of the
above-described property. The transferee of such property is the person
performing the services in connection with the transfer of said property.

<PAGE>

The undersigned understands that the foregoing election may not be revoked
except with the consent of the Commissioner.

Dated:___________________, 20_________________________________________________
                             Taxpayer

The undersigned spouse of taxpayer joins in this election.

Dated:___________________, 20___________________________________________________
                             Spouse of Taxpayer

                                                                             -2-