Document:

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                                                                    EXHIBIT 10.4

                              EMPLOYMENT AGREEMENT

               This EMPLOYMENT AGREEMENT ("Agreement") is effective as of the
16th day of June, 2000 by and between Unisphere Solutions, Inc. (the "Company"),
a Delaware Corporation with offices at One Executive Drive, Chelmsford, MA
01824, and John Connolly, an individual residing at 37 Country Club Road, N.
Reading, MA 01864 (the "Employee").

               WHEREAS, the Company desires to enter into this Agreement to
employ the services of the Employee on the terms and conditions set forth below;

               WHEREAS, the Employee desires to be employed by the Company and
is willing to do so on the terms and conditions set forth below;

               NOW, THEREFORE, in consideration of the above recitals and of the
mutual promises and conditions in this Agreement, it is agreed as follows:

1.             TERM OF EMPLOYMENT.

               The initial term of the Employee's employment under this
Agreement (the "Initial Term") shall be deemed to have commenced on July 6, 2000
and shall terminate on the second (2nd) anniversary thereof. The Initial Term
shall be automatically extended for additional terms of successive one (1) year
periods (the "Additional Employment Term") unless the Company or Employee gives
written notice to the other at least ninety (90) days prior to the expiration of
the then Initial Employment Term or Additional Employment Term of the
termination of Employee's employment hereunder at the end of such Employment
Term. The term of this Agreement, including the Initial Employment Term and the
Additional Employment Term, as from time to time is modified in writing by and
between the parties and in effect, is hereafter referred to as the "Employment
Term" or the "term of this Agreement" or "the term hereof." Upon termination of
the term hereof, this Agreement and all obligations of the parties hereunder
shall terminate, except as provided in Sections 5, 6, 7 and 8 hereof. If the
Employment Term ends at the option of the Company, the Employee shall be
considered to have been terminated "without cause" and shall be entitled to
those termination payments and benefits specified in Section 6(c). The Employee
and the Company have no other agreement, express or implied or written or oral,
regarding the term of their employment relationship other than the agreement set
forth in this paragraph.

2.             EMPLOYMENT AND DUTIES.

a. During the Term, the Company shall employ the Employee on a full-time basis
as Vice President & Chief Financial Officer of the Company with responsibility
for the day-to-day financial operations, books and records and accounting
practices of the Company in general and such other duties as may be assigned to
him from time-to-time by the Company's President and subject to the supervision
of the President. The Employee agrees to use his diligent efforts in and shall
devote at

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least forty (40) hours per week to the performance of his duties during the Term
and to the advancement of the interests of the Company and its affiliates.

b. The services of the Employee shall be performed at the Company's offices
located at One Executive Drive, Chelmsford, Massachusetts or at such other
facility designated by the Company. If the Company's offices are moved from the
above mentioned address to another location within the greater Boston,
Massachusetts metropolitan area, the Employee agrees to perform the employee's
services at such new address.

c. Employee will sign separate agreements, policies or certifications regarding
Confidentiality/Invention and Trade Secret Agreement and, in the future will
sign separate agreements, policies or certifications including, but not limited
to, Ethical Business Practices, Conflicts of Interest and Insider Trading, on
such forms as are or may be adopted by the Company from time to time for its
executives. Any such agreements, policies or certifications shall supplement the
terms and conditions of this Agreement, including, without limitation, the
provisions of Section 5 and 7 hereof.

3. EMPLOYEE'S OUTSIDE BUSINESS ACTIVITIES.

a. During the Term, the Employee shall devote such time, interest and effort as
shall be necessary to satisfactorily perform and discharge all duties and
responsibilities of the Employee's position and shall not, without the prior
written consent of the Company's President, render to others services of any
kind for compensation, or engage in any other business activity that would
materially interfere with the performance of the Employee's duties under this
Agreement.

b. During the Term, the Employee shall not take any action, without the prior
written consent of the Company's President, which consent he/she may grant or
withhold in his/her sole discretion, to establish, form or become employed upon
termination of employment with the Company by a competing business anywhere in
the United States or in any foreign country.

c. The Employee's failure to comply with the provisions of this Section shall
give the Company the right (in addition to any other remedies and rights the
Company may have) to terminate this Agreement.

4. COMPENSATION.

a. BASE SALARY. The Company shall pay the Employee, in arrears (payable no less
than on a monthly basis) in equal installments at such intervals as the Company
shall generally pay its senior executives, a base salary (the "Base Salary") at
a rate of Two Hundred Ten Thousand Dollars ($210,000.00) per year.

b. BONUS. In the event that the Company adopts and implements a bonus plan for
its executive employees, then Employee shall be eligible to participate in that
plan. The parties hereby acknowledge and agree that there is no bonus plan
currently in effect for the Company's fiscal year

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ending September 30, 2000 and whether or not the Company elects to adopt a bonus
plan in the future is in the Company's sole discretion. The parties hereby
acknowledge and agree that the Employee's entitlement to any bonus in respect of
the year of termination shall be governed by the terms of such bonus plan
provided, however, that the parties agree that if the Employee's employment
terminates during any bonus plan year, then the Employee shall be entitled to
receive a pro-rata portion of the bonus for that plan year through the date of
termination if the bonus plan objectives are actually achieved in that plan year
and the Company pays a bonus to the plan participants, which bonus shall be paid
to the Employee at the same time as bonuses are generally paid to the other
bonus plan participants.

c. STOCK OPTION AWARD. The Company shall submit to the Company's Board of
Directors a recommendation that the Employee be awarded two hundred twenty five
thousand (225,000) stock options under the Company's 1999 Stock Incentive Plan
(the "Stock Incentive Plan") at an exercise price to be determined by the Board
of Directors, which options shall be either incentive stock options (ISO's) or
non-qualified options, or a combination thereof, as determined by the Board of
Directors in its sole discretion, provided, however, that the exercise price of
said options shall be set at a price no greater than the fair market value of
the Company's common stock as of the grant date of the award to the Employee.
The vesting of such options shall be as follows: one-quarter (1/4) of the total
options granted shall vest on the first anniversary of the Employee's date of
hire and 6.25% of the remaining options shall vest following completion of each
quarterly anniversary thereafter, subject to the Employee's continued
employment, and the terms and conditions of the Company's Stock Incentive Plan.
The Employee shall receive a Stock Option Agreement following the Board of
Director's approval which shall set forth the number of options (both incentive
and non-qualified options), the exercise price thereof, the four year vesting
schedule and such other terms and conditions as set forth in and governed by the
Stock Incentive Plan. If the Board of Directors fail either to award the full
number of such stock options and or to approve the accelerated vesting
provisions of Section 6 within 30 days of Employee's commencement of employment,
the Employee may immediately terminate (without prior notice) his employment for
"Good Reason."

d. OTHER BENEFITS. During the Term, the Employee shall be entitled to
participate in such employee benefit programs as may be maintained from time to
time by the Company in its sole discretion for the purpose of covering salaried
employees of the Company. This Section 4(d) shall in no way create or be deemed
to create any obligation, express or implied, on the part of the Company with
respect to the continuation of any benefit or other plan or arrangement
maintained on or prior to the date of this Agreement or the creation and
maintenance of any particular benefit or other plan or arrangement at any time
during the Term. The Company shall provide the Employee with the same or similar
medical, dental, life and disability insurance benefits, if any, provided to
other salaried employees of the Company.

e. WITHHOLDING. All payments made to the Employee pursuant to this Section 4
shall be subject to withholding to the extent required under applicable law.

f. BUSINESS EXPENSES. The Company will reimburse the Employee for business
expenses in accordance with Company policy.

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5. CONFIDENTIAL INFORMATION, TRADE SECRETS, DESIGNS.

a. The Employee acknowledges and agrees that information concerning the work
conducted by the Company may constitute confidential information, trade secrets
or copyrightable or patentable works or expressions, including, but not limited
to, know-how, design information or concepts, advertising concepts, matters
which are subject to trademark, copyright or patent protection, manufacturing
information or concepts, marketing or sales information, price and cost
information, customer information, including points of contact at customers and
product requirements and buying habits of customers, financial information
regarding the Company, information regarding suppliers, and all personnel
information. The Employee further acknowledges that such information will be
entrusted to him by the Company and that the Employee will take all steps
necessary to protect the confidentiality of such information, including abiding
by all internal regulations, policies, procedures or safeguards to protect such
information from disclosure and to implement any necessary regulations,
procedures or safeguards to protect any such confidential information or trade
secret information from disclosure or to allow such information in any way to
lose its protection as intangible assets of the Company. The Employee agrees to
execute any documents necessary to protect the Company's rights or interests in
such inventions, patentable developments, copyrightable works, designs,
trademarks, advertising concepts or other confidential or trade secret
information.

b. During the Term hereof and during the entire course of his employment with
the Company and for a period of five (5) years following the termination of his
employment, the Employee promises and agrees not to disclose to any other person
or entity any trade secrets or confidential information, unless specifically
authorized in writing in advance by the Company's President to do so. If the
Company's President gives the Employee written authorization to make any such
disclosure, the Employee shall do so only within the limits and to the extent of
the authorization.

c. The Employee also agrees, during the Term of this Agreement and during the
entire course of his employment with the Company, to promptly divulge to the
Company all developments and information related to the Company's business, or
which relate to any actual or anticipated research and development of the
Company, and to assign any and all rights of any kind or character in such
patents, trademarks, copyrights, inventions and the like to the Company. The
Employee's duty to assign all such developments and information shall be
applicable to any invention or information the Employee develops which relates
at the time of conception or reduction to practice to the Company's business, or
actual or anticipated research or development, which results from any work
performed by the Employee for the Company, or any invention or information which
involves, in any way, the use of the Company's equipment, supplies, facilities,
trade secrets, or confidential information. The Employee agrees to execute all
documents necessary to the perfection and/or protection of the Company's
interest or rights in such intangible assets.

d. The Employee also acknowledges that by virtue of his employment with the
Company, he will have access to confidential information, trade secrets,
copyrightable works or expressions, design information or concepts,
manufacturing information or concepts, patentable information or concepts,
advertising concepts, and other confidential information and trade secrets of
the Company

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as set forth more fully above, which are the intangible assets of the Company.
The Employee agrees that his participation in the development of these
intangible assets or his knowledge of the existence of such information does not
give rise to any rights on the Employee's behalf to disclose or utilize these
intangible assets or information.

e. The Employee acknowledges that during the course of Employee's employment,
the Employee will obtain knowledge and skills pertaining to the Company's
industry, manufacturing processes, methods of production, methods of buying and
selling which are "know-how" acquired by virtue of the Employee's employment
relationship with the Company. This "know-how" is also an intangible asset of
the Company.

f. The Employee agrees during the entire course of his employment with the
Company to offer or otherwise make known or available to the Company and without
additional payment or other economic benefit to him, any business prospects,
contacts or other business opportunities which he may discover, find, develop or
otherwise have available to him in any field in which the Company is engaged,
and further agrees that any such business prospects, contacts or other business
opportunities shall be the property of the Company.

g. During the entire course of his employment with the Company and for a period
of one (1) year following his termination of employment, the Employee promises
and agrees not to: (i) hire, solicit or attempt to hire any employee of the
Company or any of its affiliates, or (ii) encourage, solicit or induce any such
employee to terminate his or her relationship or employment with the Company or
any affiliate.

6. TERMINATION.

               Prior to the expiration of the Employment Term as provided in
Section 1 hereof, this Agreement may be terminated as follows:

a. At any time by mutual written consent of the Employee and the Company. Upon
such termination as provided in this Section 6(a), the Employee shall be
entitled to receive any vacation pay and Base Salary pursuant to Section 4(a)
that is accrued and unpaid as of the termination date, with such amount payable
at the same intervals as Base Salary payments were made under Section 4 hereof,
subject to withholding. In addition, the Employee shall be entitled to exercise
any options which were vested on or before the termination date in accordance
with and subject to the terms of the Stock Incentive Plan, including, but not
limited, the time period for such exercise and any provisions regarding
forfeiture. Upon payment of such amount, the Company shall have no further
obligations hereunder, including, without limitation, the obligation to pay the
Employee any bonus in respect of the year of termination except as provided in
Section 4(b) hereof or any subsequent year, and the provisions of Sections 5, 7
and 8 shall remain in effect in accordance with their terms.

b. Upon the death or following the permanent disability (as defined below) of
the Employee. For purposes of this Agreement, the Employee shall have a
"permanent disability" if an independent medical doctor (selected by the
Company's health or disability insurer) certifies that the Employee

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has for four (4) months, consecutive or non-consecutive, in any twelve-month
period been physically or mentally disabled or incapacitated in a manner which
seriously interferes with his ability to perform his essential job
responsibilities under this Agreement despite reasonable accommodation. Upon
termination of the Employee's employment pursuant to this Section 6(b), (i) the
Company shall pay the Employee or his estate any vacation pay and Base Salary
pursuant to Section 4(a) that is accrued and unpaid as of the termination date,
and upon the making of such payment the Company shall have no further
obligations hereunder, including, without limitation, the obligation to pay the
Employee any bonus in respect of the year of termination except as otherwise
provided in Section 4(b) hereof or any subsequent year, and (ii) the provisions
of Sections 5, 7 and 8 to the extent relevant shall remain in effect in
accordance with their terms. In addition, the Employee shall be entitled to
exercise any options which were vested on or before the termination date in
accordance with and subject to the terms of the Stock Incentive Plan, including,
but not limited, the time period for such exercise and any provisions regarding
forfeiture.

c. At any time by the Company without cause upon written notice to the Employee.
In the event of termination of the Employee's employment by the Company pursuant
to this Section 6(c), the Company shall pay to the Employee any vacation and
Base Salary pursuant to Section 4(a) that is accrued and unpaid as of the
termination day. The Company also shall pay to the Employee severance pay,
provided that the Employee executes the Company's form of Termination Agreement
releasing his claims against the Company and its affiliates, consisting of an
amount equal to the Base Salary that would have been payable for six (6) months
from the date of termination had the Employee remained an employee of the
Company hereunder until that date, with such amount payable at the same
intervals as Base Salary payments were made under Section 4 hereof, subject to
withholding. In the alternative, at the Company's option, the Employee shall
receive a lump-sum payment equal to the salary continuation payments due under
the immediately preceding sentence. Upon payment of such amount, the Company
shall have no further obligations hereunder, including, without limitation, the
obligation to pay the Employee any bonus in respect of the year of termination
except as otherwise provided in Section 4(b) hereof or any subsequent year, and
the provisions of Sections 5, 7 and 8 shall remain in effect in accordance with
their terms. In addition, the Employee shall become immediately vested as of the
sixth month anniversary of the the termination date, for the lesser of: (i)
28,125 options of the 225,000 option award under the Company's Stock Incentive
Plan or (ii) the remaining balance (as of the termination date) of the unvested
options of the 225,000 option award under the Company's Stock Incentive Plan if
said amount is less than 28,125 options. The Employee may or may not be vested
in any options as of the termination date under the vesting schedule set forth
in his Stock Option Award but to the extent that the Employee is so vested in
any of said options, the accelerated vesting described in the foregoing sentence
shall be in addition to the shares which have vested in accordance with the
terms of the Stock Option Award. The Employee shall be entitled to exercise any
vested options which were vested or become vested as of the date of termination
in accordance with the terms of the Stock Incentive Plan, including, but not
limited to, the time period for such exercise and any provisions regarding
forfeiture. The parties hereby agree that the Employee shall act as a consultant
to the Company during the sixth month severance period without further
compensation to perform such services as may be mutually agreeable to the
parties provided, however, that nothing herein

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shall preclude Employee from obtaining alternative employment during this period
other than in accordance with the provisions of Section 7 hereof.

d. At any time by the Employee upon sixty (60) days prior written notice to the
Company. Upon termination by the Employee as provided in this Section 6(d), the
Employee shall be entitled to receive any vacation pay and Base Salary pursuant
to Section 4(a) that is accrued and unpaid as of the termination date, with such
amount payable at the same intervals as Base Salary payments were made under
Section 4 hereof, subject to withholding. Upon payment of such amount, the
Company shall have no further obligations hereunder, including, without
limitation, the obligation to pay the Employee any bonus in respect of the year
of termination except as otherwise provided in Section 4(b) hereof or any
subsequent year, and the provisions of Sections 5, 7 and 8 shall remain in
effect in accordance with their terms. In addition, the Employee shall be
entitled to exercise any options which were vested as of the termination date in
accordance with and subject to the terms of the Stock Incentive Plan, including,
but not limited, the time period for such exercise and any provisions regarding
forfeiture.

e. At any time for cause by the Company upon written notice to the Employee. For
purposes of this Agreement, a termination shall be for cause if:

               (i) the Employee shall commit an act of fraud, embezzlement,
               misappropriation, dishonesty or breach of fiduciary duty against
               the Company or any of its affiliates; or shall be convicted in a
               court of competent jurisdiction or shall plead guilty or nolo
               contendere to any felony or any other crime involving moral
               turpitude; or shall fail in the performance of his job
               responsibilities to comply with or violate a provision of
               federal, state or local law or regulation applicable to the
               Company or any of its affiliates; or upon the issuance of any
               order, whether civil, criminal or administrative, barring the
               Employee from continuing to carry on any assigned duties;

               (ii) the Employee shall commit a willful or material breach of
               any of the covenants, terms or provisions of Sections 3, 5 or 7
               hereof; or

               (iii) the Employee shall refuse to follow the written direction
               of a more senior officer of the Company or the Board of
               Directors,, provided that the foregoing refusal shall not be "for
               Cause" if the Employee in good faith reasonably believes that
               such direction is illegal, unethical or immoral and promptly so
               notifies in writing the Board or the more senior officer
               (whichever is applicable.) or the Employee shall substantially
               fail to perform the Employee's duties hereunder in a manner
               acceptable to the Company's President or Board of Directors,
               provided that the Company shall notify the Employee in writing of
               the basis for the termination pursuant to this Subsection (iii)
               and provide the Employee with thirty (30) days to cure the same,
               provided, however, that the Company shall not be required to
               provide the Employee with such notice and opportunity to cure (i)
               more than one (1) time during any consecutive three hundred sixty
               five (365) day period during the course of his employment and
               (ii) more than once with respect to any particular incident of an
               alleged failure to obey or perform

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Upon termination for cause as provided in Section 6(e), the Employee shall be
entitled to receive any vacation pay and Base Salary payments pursuant to
Section 4(a) that are accrued and unpaid as of the termination date (subject to
the further provisions of this Section 6). Upon payment of such amount, the
Company shall have no further obligations hereunder after the date of
termination, including, without limitation, the obligation to pay the Employee
any bonus, if any, in respect of the year of termination except as otherwise
provided under Section 4(b) hereof or any subsequent year, and the Company shall
be entitled to exercise any rights which the Company may have against the
Employee (including the rights of recovery by offset of any amounts due but not
yet paid to the Employee), and the provisions of Sections 5, 7 and 8 shall
remain in effect in accordance with their terms. In addition, the Employee may
be entitled to exercise any options which were vested as of the termination date
in accordance with and subject to the terms of the Stock Incentive Plan,
including, but not limited, the time period for such exercise and any provisions
regarding forfeiture.

f. The Employee may terminate his employment for Good Reason (as defined below).
For purposes of this Agreement, the Employee shall have "Good Reason" to
terminate his employment with the Company in the event of: (i) any material
breach by the Company of the provisions of this Agreement; (ii) any change of
control of the Company other than an internal reorganization; (iii) any
substantial reduction in the Employee's job responsibilities without the
Employee's consent. Notwithstanding the foregoing, the Employee shall not have
Good Reason to terminate his employment unless and until he has provided the
Company with written notice of such breach or event at least seven (7) days in
advance of his intended termination date and an opportunity and period to cure
such breach or event within the fourteen (14) day period following such notice;
provided further, however, if the Company cures such breach or event, the
Employee shall not have Good Reason to terminate this Agreement. In the event of
termination of the Employee's employment by the Company pursuant to this Section
6(f), the Company shall pay to the Employee any vacation pay and Base Salary
pursuant to Section 4(a) that is accrued and unpaid as of the termination date.
The Company also shall pay to the Employee severance pay, provided that the
Employee executes the Company's form of Termination Agreement releasing his
claims against the Company and its affiliates, consisting of an amount equal to
the Base Salary that would have been payable for the six (6) month period
following the date of termination had the Employee remained an employee of the
Company hereunder until that date, with such amount payable at the same
intervals as Base Salary payments were made under Section 4 hereof, subject to
withholding. In the alternative, at the Company's option, the Employee shall be
entitled to a lump-sum payment equal to the salary continuation payments due
under the immediately preceding sentence. Upon payment of such amounts, the
Company shall have no further obligations hereunder, including, without
limitation, the obligation to pay the Employee any bonus in respect of the year
of termination except as otherwise provided in Section 4(b) hereof or any
subsequent year, and the provisions of Sections 5, 7 and 8 shall remain in
effect in accordance with their terms. In addition, the Employee shall become
immediately vested as of the sixth month anniversary of the termination date,
for the lesser of: (i) 28,125 options of the 225,000 option award under the
Company's Stock Incentive Plan or (ii) the remaining balance (as of the
termination date) of the unvested options of the 225,000 option award under the
Company's Stock Incentive Plan if said amount is less than 28,125 options. The
Employee may or may not be vested in any options as of the termination date
under the vesting

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schedule set forth in his Stock Option Award but to the extent that the Employee
is so vested in any of said options, the accelerated vesting described in the
foregoing sentence shall be in addition to the shares which have vested in
accordance with the terms of the Stock Option Award. The Employee shall be
entitled to exercise any vested options which were vested or become vested as of
the date of termination in accordance with the terms of the Stock Incentive
Plan, including, but not limited to, the time period for such exercise and any
provisions regarding forfeiture. The parties hereby agree that the Employee
shall act as a consultant to the Company during the sixth month severance period
without further compensation to perform such services as may be mutually
agreeable to the parties provided, however, that nothing herein shall preclude
Employee from obtaining alternative employment during this period other than in
accordance with the provisions of Section 7 hereof.

7. NON-COMPETITION.

               As an inducement to the Company to enter into this Agreement with
Employee and to employ Employee as its Vice President & Chief Financial Officer,
during the Term of this Agreement and during the six month period that the
Employee receives severance post-termination (either in the form of salary
continuation payments or in a lump-sum payment), as provided under the terms and
provisions of Sections 6(c) or 6(f), the Employee agrees that he shall not,
anywhere in any county of any state in the United States and in any and all
foreign countries, without the express written advance consent of the President
of the Company, which consent he/she may grant or withhold in his/her sole
discretion, directly or indirectly, either as an employee, employer, trustee,
consultant, agent, principal, partner, corporate officer, director, creditor,
owner or shareholder or in any other individual or representative capacity,
promote, participate, invest or engage in any activity or other business
competitive with the Company's business in the design, manufacture, development,
distribution, marketing or sales of any products or services for the following
market: the internet infrastructure for carrier networks. The sole exception to
this restriction shall be that the Employee may make passive investments in a
competitive enterprise the shares of which are publicly traded if such
investment constitutes less than one percent of the outstanding capital stock or
other interests in the equity of such enterprise. Without implied limitation,
the foregoing covenant shall include: (i) the hiring or attempting to hire any
employee of the Company or any of its affiliates, (ii) encouraging or inducing
any such employee to terminate his or her relationship or employment with the
Company or any affiliate, (iii) soliciting for or on behalf of any competitor
any customer of the Company, and (iv) diverting to any competitor any customer
of the Company. As of the date of this Agreement, the Employee is not performing
any consulting or other duties for, and is not a party to any similar agreement
with, any business or venture competing in the relevant market described
hereinabove.

8. SPECIFIC PERFORMANCE; SEVERABILITY.

a. It is specifically understood and agreed that any breach of the provisions of
Sections 3, 5 or 7 of this Agreement by the Employee is likely to result in
irreparable injury to the Company, that the remedy at law alone will be an
inadequate remedy for such breach and that, in addition to any other remedy it
may have, the Company shall be entitled to enforce the specific performance of
this

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Agreement by the Employee and to seek both temporary and permanent injunctive
relief (to the extent permitted by law), without the necessity of proving actual
damages.

b. In case any of the provisions contained in this Agreement shall be for any
reason be held to be invalid, illegal or unenforceable in any respect by a court
of competent jurisdiction, any such invalidity, illegality or unenforceability
shall not affect any other provision of this Agreement, but this Agreement shall
be construed as if such invalid, illegal or unenforceable provision had been
limited or modified (consistent with its general intent) to the extent necessary
to make it valid, legal and enforceable, or if it shall not be possible to so
limit or modify such invalid, illegal or unenforceable provision or part of a
provision, this Agreement shall be construed as if such invalid, illegal or
unenforceable provision or part of a provision had never been contained in this
Agreement.

9. NOTICES.

               All notices permitted or required hereunder shall be deemed to
have been duly given if delivered personally or if sent by certified or
registered mail or overnight courier, postage prepaid, to the parties at their
respective addresses set forth below or to such other address as any party may
hereafter designate.

To the Company:                              With a copy to:
Unisphere Solutions, Inc.                    Unisphere Solutions, Inc.
One Executive Drive                          One Executive Drive
Chelmsford, MA 01824                         Chelmsford, MA 01824
Attention:  President                        Attention: General Counsel

To the Employee:
John Connolly
37 Country Club Road
N. Reading, MA 01864

10. WAIVER.

               Neither party's failure to enforce any provision or provisions of
this Agreement shall be deemed in any way to be or construed as a waiver of any
such provision or provisions, nor prevent that party thereafter from enforcing
each and every provision of this Agreement. The rights granted both parties
herein are cumulative and shall not constitute a waiver of either party's right
to assert all other legal remedies available to it under the circumstances.

11. MISCELLANEOUS.

               This Agreement shall be governed by and construed under the laws
of the Commonwealth of Massachusetts, and shall not be modified or discharged in
whole or in part except by an agreement in writing signed by the Company and the
Employee. The parties consent to personal

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jurisdiction, service of process and venue in the federal or state courts of
Massachusetts with respect to any and all claims or disputes between the parties
arising in connection with this Agreement. The parties hereby agree that the
prevailing party to any litigation commenced pursuant to this Agreement shall be
entitled to recover its or his reasonable attorney's fees incurred in connection
with that matter. This Agreement shall inure to the benefit of the successors
and assigns of the Company, including the successors of the Company by way of
merger, consolidation or transfer of substantially all the assets of the
Company, and may not be assigned by the Employee except as provided expressly
herein in Section 6(b).

12. ENTIRE AGREEMENT.

               This Agreement, and the agreement, policies and certifications
referenced in Section 2(c) hereof, contain the entire agreement of the parties
and supersedes and replaces any other agreements or understandings between them
with respect to the subject matter of this Agreement.

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

                                             UNISPHERE SOLUTIONS, INC.

                                             By:/s/ James A. Dolce
                                                ________________________________
                                                James A. Dolce, President

                                             /s/ John Connolly
                                             ___________________________________
                                             John Connolly

                                       11<PAGE>   1
                                                                    Exhibit 10.5

                              EMPLOYMENT AGREEMENT

         EMPLOYMENT AGREEMENT dated as of March 7, 1999, by and between Castle
Networks, Inc. with its principal place of business at 68 Tadmuck Road,
Westford, Massachusetts 01886 (the "Company"), and Thomas Burkardt, residing at
256 Abbott St., North Andover, MA 01845 (the "Executive").

         WHEREAS, pursuant to an Agreement and Plan of Merger dated as of March
7, 1999 (the "Merger Agreement") among Siemens Corporation, a Delaware
corporation ("Siemens"), Mediator Acquisition Corp., a Delaware corporation
("Acquisition"), and the Company, Acquisition has been merged with and into the
Company (the "Merger") and the Company is the surviving corporation in the
Merger.

         WHEREAS, the Executive's stock and other equity interests in the
Company have been acquired by Siemens in connection with the Merger.

         WHEREAS, the Executive has been employed by the Company, and the
Company wishes to offer continuing employment to the Executive in connection
with the Merger and the Executive wishes to accept such offer, on the terms set
forth below.

         Accordingly, the parties hereto agree as follows:

         1. TERM. The Company hereby employs the Executive, and the Executive
hereby accepts such employment, for an initial term commencing as of the Closing
date (as defined in the merger Agreement) and ending on the third anniversary of
such date, unless sooner terminated in accordance with the provisions of Section
4 or Section 5; with such employment to continue for successive one-year periods
in accordance with the terms of this Agreement (subject to termination as
aforesaid) unless either party notifies the other party in writing prior to 30
days
<PAGE>   2
before the expiration of the initial term and each annual renewal thereof (the
period during which the Executive is employed hereunder being hereinafter
referred to as the "Term"). Notwithstanding anything to the contrary contained
in this Agreement, in no event shall the Term commence, or any provision of this
Agreement be effective unless and until the Executive executes a Non-Competition
and Non-Solicitation Agreement and an Employee Patent and Secrecy Agreement
attached hereto as Exhibits A and B, respectively.

         2. DUTIES. During the Term, the Executive shall be employed by the
Company as Executive Vice President and Treasurer of the Company, and as such,
the Executive shall faithfully perform for the Company the duties of said office
and shall perform such other duties of an executive, managerial or
administrative nature consistent with such office as shall be specified and
designated from time to time by the Board of Directors of the Company. The
Executive shall devote substantially all of his business time and effort to the
performance of his duties hereunder.

         3.       COMPENSATION.

                  3.1 BASE SALARY. The Company shall pay the Executive during
the Term a base salary at the rate of $260,000 per annum (the "Annual Salary"),
in accordance with the customary payroll practices of the Company applicable to
senior executives. The Annual Salary shall be reviewed at least annually by the
Compensation Committee of the Board of Directors of the Company, but shall not
be decreased.

                  3.2 BONUS. During the Term, in addition to the Annual Salary,
the Executive shall participate in the Company's Milestone Incentive
Compensation Plan and shall have the opportunity to receive an annual bonus
based on the achievement of certain performance measures. Bonus at 40% as per
phone conversation with Marty Clague.

                                       2
<PAGE>   3
                  3.3 BENEFITS - IN GENERAL. The Executive shall be entitled
during the Term to participate in any group life, hospitalization or disability
insurance plans, health programs, retirement plans, fringe benefit programs and
similar benefits that may be available to other senior executives of the Company
generally, on the same terms as such other executives, in each case to the
extent that the Executive is eligible under the terms of such plans or programs,
which plans and programs shall generally provide a level of benefits that is at
least as favorable as the benefits provided by the Company on the date hereof.

                  3.4 EXPENSES. The Company shall pay or reimburse the Executive
for all ordinary and reasonable out-of-pocket expenses actually incurred (and,
in the case of reimbursement, paid) by the Executive during the Term in the
performance of the Executive's services under this Agreement in accordance with
the ordinary policies of the Company with respect to reimbursement of senior
executives for such expenses.

         4. TERMINATION UPON DEATH OR DISABILITY. If the Executive dies during
the Term, the Term shall terminate as of the date of death, and the obligations
of the Company to or with respect to the Executive shall terminate in their
entirety upon such date except as otherwise provided under this Section 4. If
the Executive becomes disabled for purposes of the long-term disability plan of
the Company for which the Executive is eligible, the Company shall have the
right, to the extent permitted by law, to terminate the employment of the
Executive upon notice in writing to the Executive. Upon termination of
employment due to death or disability, (i) the Executive (or the Executive's
estate or beneficiaries in the case of the death of the Executive) shall be
entitled to receive any Annual Salary and other benefits earned and accrued
under this Agreement prior to the date of termination (and reimbursement under
this Agreement for expenses incurred prior to the date of termination), (ii) the
Executive shall have a non-forfeitable

                                       3
<PAGE>   4
right to, and shall be entitled to receive, the consideration payable to the
Executive under the Merger Agreement with respect to which the Executive's
rights were not vested at Closing (as defined in the Merger Agreement) and which
has not yet been paid as of the date of termination, (iii) the Executive (or the
Executive's estate or beneficiaries in the case of the death of the Executive)
shall be entitled to receive all payments that he would have received under the
Company's Milestone Incentive Plan if he had remained employed through the
Performance Period (as defined in the Milestone Incentive Plan) and (iv) the
Executive (or, in the case of his death, his estate and beneficiaries) shall
have no further rights to any other compensation or benefits hereunder on or
after the termination of employment, or any other rights hereunder except as
required by law.

         5.       CERTAIN TERMINATIONS OF EMPLOYMENT.

                  5.1      TERMINATION BY THE COMPANY FOR CAUSE.

                           a.       For purposes of this Agreement, "Cause"
                                    shall mean the Executive's:

                                    (i)     commission  of a felony,  a crime of
moral turpitude, dishonesty, or any crime involving the Company;

                                    (ii) engagement in the performance of his
duties hereunder, or otherwise to the detriment of the Company, in willful
misconduct, willful or gross neglect, fraud, misappropriation or embezzlement;

                                    (iii) failure to follow directions of the
Board of Directors or to follow the Company's written policies and practices,
which failure is not cured within 30 days after written notice thereof is
provided to the Executive;

                                    (iv) breach of either of the agreements
attached hereto as Exhibits A and B, which breach is not cured within 30 days
after written notice thereof is provided to the Executive; or

                                       4
<PAGE>   5
                                    (v)     breach in any  material  respect  of
the terms and provisions of this Agreement, which breach is not cured within 30
days after written notice thereof is provided to the Executive; provided that
the Company shall not be permitted to terminate the Executive for Cause pursuant
to Section 5.1(b) except on written notice given to the Executive.

                           b.       The Company may terminate the  Executive's
employment hereunder for Cause. If the Company terminates the Executive for
Cause, (i) the Executive shall receive Annual Salary and other benefits (but, in
all events, and without increasing the Executive's rights under any other
provision hereof, excluding any bonuses not yet paid) earned and accrued under
this Agreement prior to the termination of employment (and reimbursement under
this Agreement for expenses incurred prior to the termination of employment);
and (ii) the Executive shall have no further rights to any other compensation or
benefits hereunder on or after the termination of employment, or any other
rights hereunder.

                  5.2 TERMINATION BY THE COMPANY WITHOUT CAUSE; TERMINATION BY
THE EXECUTIVE FOR GOOD REASON.

                           a.       The  Company  may  terminate  the
Executive's employment at any time for any reason or no reason. If the Company
terminates the Executive's employment and the termination is not covered by
Section 4 or 5.1 or the Executive terminates service for "Good Reason", (i) the
Executive shall receive Annual Salary and other benefits earned and accrued
under this Agreement and the Company's Milestone Incentive Compensation Plan to
the extent benefits are earned, accrued and payable under the terms of such plan
prior to the termination of employment (and reimbursement under this Agreement
for expenses incurred prior to the termination of employment); (ii) the
Executive shall receive (A) a cash payment equal to 100% of the Executive's
Annual Salary (as in effect immediately before such termination), payable no
later than 15 days after such termination and (B) for a period of 12 months
after termination of employment such continuing coverage under the group health
plan and the

                                       5
<PAGE>   6
basic life insurance plan as the Executive was receiving at the time of such
termination of employment at the same cost to the Executive as that paid by
active executive-level employees; (iii) the Executive shall have a
non-forfeitable right to, and shall be entitled to receive, the consideration
payable to the Executive under the Merger Agreement with respect to which the
Executive's rights were not vested at Closing (as defined in the Merger
Agreement) and which has not yet been paid as of the date of termination, (iv)
the Executive shall be entitled to receive all payments that he would have
received under the Company's Milestone Incentive Plan if he had remained
employed through the Performance Period (as defined in the Milestone Incentive
Plan), and (v) the Executive shall have no further rights to any other
compensation or benefits hereunder on or after the termination of employment, or
any other rights hereunder; provided that the Company's obligations with respect
to the payments and benefits provided for in this Section 5.2(a) are conditioned
upon the Executive's execution of a General Release in the standard form used by
the Company. It is expressly understood and agreed that any payment made
pursuant to this Section 5.2(a) shall be in lieu of any other payments that may
otherwise be due to the Executive under any severance or separation plan,
program or policy of the Company.

                           b. For purposes of this Agreement, "Good Reason"
shall mean (i) a breach by the Company in any material respect of the terms and
provisions of this Agreement, which breach is not cured within 30 days after
written notice thereof is provided by the Executive or (ii) the relocation of
the Company's principal place of business, without the consent of the Executive,
by more than 30 miles from such principal place of business on the date hereof.

                           c.       Notwithstanding  clause  (ii)(B) of the
second sentence of Section 5.2(a), (i) nothing herein shall restrict the ability
of the Company to amend or terminate the plans and programs referred to in such
clause (ii)(B) with respect to employees of the Company generally from time to
time in its sole discretion, and (ii) the Company shall in no event be required
to provide any benefits otherwise required by such clause (ii)(B) after such
time as the

                                       6
<PAGE>   7
Executive becomes entitled to receive benefits of the same type from another
employer or recipient of the Executive's services (such entitlement being
determined without regard to any individual waivers or other similar
arrangements).

                  5.3      TERMINATION BY THE EXECUTIVE OTHER THAN FOR GOOD
                           REASON.

         The Executive may terminate his employment on at least 30 days' and not
more than 60 days' written notice given to the Company. If the Executive
terminates his employment and the termination is not covered by Section 4 or
5.2, (i) the Executive shall receive Annual Salary and other benefits (but, in
all events, and without increasing the Executive's rights under any other
provision hereof, excluding any bonuses not yet paid) earned and accrued under
this Agreement prior to the termination of employment (and reimbursement under
this Agreement for expenses incurred prior to the termination of employment);
and (ii) the Executive shall have no further rights to any other compensation or
benefits hereunder on or after the termination of employment, or any other
rights hereunder, except as required by law.

         6.       OTHER PROVISIONS.

                  6.1 SEVERABILITY. The Executive acknowledges and agrees that
he has had an opportunity to seek advice of counsel in connection with this
Agreement. If it is determined that any of the provisions of this Agreement, or
any part thereof, is invalid or unenforceable, the remainder of the provisions
of this Agreement shall not thereby be affected and shall be given full effect,
without regard to the invalid portions.

                  6.2      DISPUTE RESOLUTION.

                           a.       Any and all claims,  disputes,  and
controversies between the Executive and the Company with respect to
interpretation, construction, breach, enforceability, and/or enforcement of the
terms and provisions of this Agreement (a "Dispute") shall be finally

                                       7
<PAGE>   8
resolved as provided in this Section 6.2 by binding arbitration. Arbitration
shall be the exclusive means for determination of all matters as above provided,
and neither party shall otherwise institute any action or proceeding in any
court of law or equity, state or federal, other than respecting enforcement of
the arbitrator's decision or award hereunder. The foregoing shall be a bona fide
defense in any action or proceeding where the matter in dispute was to be
arbitrated or is being arbitrated pursuant to this Agreement.

                           b.       The Company (or its  successor  in interest)
or the Executive shall have the right to submit a Dispute to arbitration, by
delivery to the other, by certified mail, of a written notice and demand for
arbitration of such Dispute. Arbitration shall be by the American Arbitration
Association (the "AAA") in accordance with its Rules applicable to such Disputes
(the "Rules"), by a neutral and impartial arbitrator acceptable to the Company
and the Executive. If such an arbitrator has not been selected by the Company
and the Executive within sixty days after AAA first provides a list of eligible
arbitrators, or within thirty days after the occurrence of a vacancy, a neutral
and impartial arbitrator shall be selected and appointed by the American
Arbitration Association, in accordance with its Rules. Unless otherwise required
under applicable law, the arbitration proceedings shall be conducted in the city
where the principal place of business of the Company is situated at the date of
this Agreement or a city mutually agreed to by the parties, and the procedural
rules of the place of arbitration shall apply. Each party shall be entitled to
be represented by legal counsel.

                           c.       The arbitration  proceedings  (including
discovery and the giving of testimony) shall be conducted in strictest
confidence pursuant to a confidentiality agreement signed by the parties and
devised to protect the confidentiality of and valuable rights of the Company in
the Confidential Company Information (as defined in the Employee Patent and

                                       8
<PAGE>   9
Secrecy Agreement) and trade secrets as well as the confidentiality of any other
confidential information included in such proceedings. The arbitrator shall have
the power and authority to make such decisions and awards as he or she deems
appropriate, consistent with applicable law. To the extent applicable law sets
particular requirements for the conduct of such arbitration proceedings, such
as, any with respect to discovery, cross-examination, testimony, or availability
of rights and remedies, the arbitration proceedings shall be conducted in
compliance with those requirements.

                           d.       Subject to applicable  law, the arbitrator
may grant compensatory damages and costs to the prevailing party (but not
punitive or exemplary damages and attorneys' fees and costs related to punitive
or exemplary damages) and injunctions that he or she may deem necessary or
advisable directed to or against a party, including a direction or order
requiring specific performance of any covenant, agreement or provision of this
Agreement as a result of a breach or threatened breach. Any decision or award of
the arbitrator shall be final, binding, and conclusive upon the parties and said
decision and award may be entered as a final judgment in any court of competent
jurisdiction.

                           e.       Subject to the foregoing,  the costs of such
arbitration shall be borne equally by the parties, except that each party shall
bear its own attorneys fees and costs.

                  6.3 NOTICES. Any notice or other communication required or
permitted hereunder shall be in writing and shall be delivered personally,
telegraphed, telexed, sent by facsimile transmission or sent by certified,
registered or express mail, postage prepaid. Any such notice shall be deemed
given when so delivered personally, telegraphed, telexed or sent by facsimile
transmission or, if mailed, five days after the date of deposit in the United
States mails as follows:

                                       9
<PAGE>   10

(i)     If to the Company, to:

         Castle Networks, Inc.
         68 Tadmuck Road
         Westford, Massachusetts 01886
         Attention: Board of Directors

         with a copy to:

         Rogers & Wells LLP
         200 Park Avenue
         New York, New York 10166
         Attention: John A. Healy, Esq.

(ii)     If to the Executive, to the address set
         forth above.

         with a copy to:

         Hale and Dorr LLP
         60 State Street
         Boston, Massachusetts 02109
         Attention: Mark G.  Borden, Esq.

Any such person may by notice given in accordance with this Section 6.3 to the
other parties hereto designate another address or person for receipt by such
person of notices hereunder.

                  6.4 ENTIRE AGREEMENT. Other than with respect to the
agreements attached hereto as Exhibits A and B entered into by the Company and
the Executive dated as of the date hereof, as they may be amended from time to
time, which agreements shall survive in their entirety without regard to this
Agreement, this Agreement contains the entire agreement between the parties with
respect to the subject matter hereof and supersedes all prior agreements,
written or oral, with respect thereto.

                  6.5 WAIVERS AND AMENDMENTS. This Agreement may be amended,
superseded, canceled, renewed or extended, and the terms hereof may be waived,
only by a

                                       10
<PAGE>   11
written instrument signed by the parties or, in the case of a waiver, by the
party waiving compliance. No delay on the part of any party in exercising any
right, power or privilege hereunder shall operate as a waiver thereof, nor shall
any waiver on the part of any party of any such right, power or privilege nor
any single or partial exercise of any such right, power or privilege, preclude
any other or further exercise thereof or the exercise of any other such right,
power or privilege.

                  6.6 GOVERNING LAW. THIS AGREEMENT SHALL BE GOVERNED BY AND
CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE COMMONWEALTH OF MASSACHUSETTS
WITHOUT REGARD TO PRINCIPLES OF CONFLICTS OF LAW.

                  6.7 ASSIGNMENT. This Agreement, and the Executive's rights and
obligations hereunder, may not be assigned by the Executive; any purported
assignment by the Executive in violation hereof shall be null and void. In the
event of any sale, transfer or other disposition of all or substantially all of
the Company's assets or business, whether by merger, consolidation or otherwise,
the Company may assign this Agreement and its rights hereunder.

                  6.8 WITHHOLDING. The Company shall be entitled to withhold
from any payments or deemed payments any amount of tax withholding required by
law.

                  6.9 BINDING EFFECT. This Agreement shall be binding upon and
inure to the benefit of the parties and their respective successors, permitted
assigns, heirs, executors and legal representatives.

                  6.10 COUNTERPARTS. This Agreement may be executed by the
parties hereto in separate counterparts, each of which when so executed and
delivered shall be an original but all such counterparts together shall
constitute one and the same instrument. Each counterpart may consist of two
copies hereof each signed by one of the parties hereto.

                                       11
<PAGE>   12
                  6.11 SURVIVAL. Anything contained in this Agreement to the
contrary notwithstanding, the provisions of Sections 6.2, 6.3 and 6.8, and the
other provisions of this Section 6 (to the extent necessary to effectuate the
survival of Sections 6.2, 6.3 and 6.8), shall survive termination of this
Agreement and any termination of the Executive's employment hereunder.

                  6.12 NON-DISPARAGEMENT. While Executive's non-competition
obligations under Exhibit A are in effect, the Executive shall not publish any
statement or make any statement under circumstances reasonably likely to become
public that is critical of the Company or any of its affiliates, or in any way
adversely affecting or otherwise maligning the Company's business or the
reputation of the Company or any of its affiliates.

                  6.13 EXISTING AGREEMENTS. The Executive represents to the
Company that he is not subject or a party to any employment or consulting
agreement, non-competition covenant or other agreement, covenant or
understanding which might prohibit him from executing this Agreement or limit
his ability to fulfill his responsibilities hereunder.

                  6.14 HEADINGS. The headings in this Agreement are for
reference only and shall not affect the interpretation of this Agreement.

                  6.15 EFFECTIVE DATE. Notwithstanding, anything to the contrary
herein, this Agreement shall become effective only upon the Effective Time (as
defined in the Merger Agreement), and this Agreement shall automatically be void
upon any termination of the Merger Agreement prior to the Effective Time.

         IN WITNESS WHEREOF, the parties hereto have signed their names as of
the day and year first above written.

                                            CASTLE NETWORKS, INC.

                                       12
<PAGE>   13
                                            By:/s/ Stephen R. Kelly
                                               _______________________________

                                            Name:   Stephen R. Kelly
                                                 _____________________________

                                            Title:  Executive Vice President
                                                    and Treasurer
                                                  ____________________________

                                            By:  /s/ Thomas M. Burkardt
                                               _______________________________
                                                              Executive

                                       13

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