Exhibit 10.1

STARENT NETWORKS, CORP.

Restricted Stock Unit Agreement

Granted under 2007 Stock Incentive Plan

This Restricted Stock Unit Agreement (this “Agreement”) is made as of
[                    ], 20[    ] between Starent Networks, Corp., a Delaware
corporation (the “Company”), and [                    ] (the “Participant”).

For valuable consideration, receipt of which is acknowledged, the parties hereto
agree as follows:

 

  1. Grant of Restricted Stock Units.

This Agreement evidences the grant by the Company on [                    ],
20[    ], (the “Grant Date”) to the Participant of [                    ]
restricted stock units of the Company (individually, an “RSU” and collectively,
the “RSUs”). Each RSU represents the right to receive one share of the common
stock, $0.001 par value per share, of the Company (“Common Stock”) as provided
in this Agreement. The shares of Common Stock that are issuable upon vesting of
the RSUs are referred to in this Agreement as “Shares.” The Participant agrees
that the Shares shall be subject to (without limitation) the forfeiture
provisions set forth in Section 2 of this Agreement and the restrictions on
transfer set forth in Section 4 of this Agreement.

 

  2. Vesting; Forfeiture.

(a) This award shall vest as to 25% of the original number of RSUs on the first
anniversary of the Grant Date and as to an additional 25% of the original number
of RSUs on each succeeding anniversary of the Grant Date until the fourth
anniversary of the Grant Date.

(b) If the Participant ceases to be employed by the Company before the RSUs
vest, the RSUs shall be immediately forfeited to the Company. For purposes of
this Agreement, employment with the Company shall include employment with a
parent or subsidiary of the Company.

 

  3. Distribution of Shares.

(a) The Company will distribute to the Participant (or to the Participant’s
estate in the event that his or her death occurs after a vesting date but before
distribution of the corresponding Shares), as soon as administratively
practicable after each vesting date (each such date of distribution is
hereinafter referred to as a “Settlement Date”), the Shares of Common Stock
represented by RSUs that vested on such vesting date.

(b) The Company shall not be obligated to issue to the Participant the Shares
upon the vesting of any RSU (or otherwise) unless the issuance and delivery of
such Shares shall comply with all relevant provisions of law and other legal
requirements including, without limitation, any applicable federal or state
securities laws and the requirements of any stock exchange upon which shares of
Common Stock may then be listed.

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  4. Restrictions on Transfer.

The Participant shall not sell, assign, transfer, pledge, hypothecate or
otherwise dispose of, by operation of law or otherwise (collectively “transfer”)
any RSUs, or any interest therein, except by will or the laws of descent and
distribution.

 

  5. Dividend and Other Shareholder Rights.

Except as set forth in the Plan, neither the Participant nor any person claiming
under or through the Participant shall be, or have any rights or privileges of,
a stockholder of the Company in respect of the Shares issuable pursuant to the
RSUs granted hereunder until the Shares have been delivered to the Participant.

 

  6. Provisions of the Plan; Reorganization Event.

(a) This Agreement is subject to the provisions of the Plan, a copy of which is
furnished to the Participant with this Agreement.

(b) Upon the occurrence of a Reorganization Event (as defined in the Plan), the
repurchase and other rights of the Company hereunder shall inure to the benefit
of the Company’s successor and shall apply to the cash, securities or other
property which the RSUs were converted into or exchanged for pursuant to such
Reorganization Event in the same manner and to the same extent as they applied
to the RSUs under this Agreement. If, in connection with a Reorganization Event,
a portion of the cash, securities and/or other property received upon the
conversion or exchange of the RSUs is to be placed into escrow to secure
indemnification or similar obligations, the mix between the vested and unvested
portion of such cash, securities and/or other property that is placed into
escrow shall be the same as the mix between the vested and unvested portion of
such cash, securities and/or other property that is not subject to escrow.

 

  7. Withholding Taxes; No Section 83(b) Election.

(a) No Shares will be delivered pursuant to the vesting of an RSU unless and
until the Participant satisfies any federal, state or local withholding tax
obligation required by law to be withheld in respect of this award. The
Participant acknowledges and agrees that to satisfy any such tax obligation, the
Company shall sell, or arrange for the sale of, such number of the Shares to be
distributed upon the Settlement Date as is sufficient to generate net proceeds
sufficient to satisfy the Company’s minimum statutory withholding obligations
with respect to the income recognized by the Participant upon the lapse of the
forfeiture provisions (based on minimum statutory withholding rates for federal
and state tax purposes, including payroll taxes, that are applicable to such
income), and the Company shall retain such net proceeds in satisfaction of such
tax withholding obligations. The Participant hereby appoints the President and
the Secretary of the Company, and each of them acting singly, his or her
attorney in fact, to sell the Participant’s Shares in accordance with this
Section 7. The Participant agrees to execute and deliver such documents,
instruments and certificates as may reasonably be required in connection with
the sale of the Shares pursuant to this Section 7. The Participant represents to
the Company that, as of the date hereof, he or she is not aware of any material
nonpublic information about the Company or the Common Stock. The Participant and
the Company have

 

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structured these terms and conditions to constitute a “binding contract”
relating to the sale of Common Stock pursuant to this Section 7, consistent with
the affirmative defense to liability under Section 10(b) of the Securities
Exchange Act of 1934 under Rule 10b5-1(c) promulgated under such Act.

(b) The Participant has reviewed with the Participant’s own tax advisors the
federal, state, local and foreign tax consequences of this investment and the
transactions contemplated by this Agreement. The Participant is relying solely
on such advisors and not on any statements or representations of the Company or
any of its agents. The Participant understands that the Participant (and not the
Company) shall be responsible for the Participant’s own tax liability that may
arise as a result of this investment or the transactions contemplated by this
Agreement. The Participant acknowledges that no election under Section 83(b) of
the Internal Revenue Code of 1986 may be filed with respect to this award.

 

  8. Miscellaneous.

(a) No Rights to Employment. The Participant acknowledges and agrees that the
vesting of the RSUs pursuant to Section 2 hereof is earned only by continuing
service at the will of the Company (not through the act of being hired or
purchasing shares hereunder). The Participant further acknowledges and agrees
that the transactions contemplated hereunder and the vesting schedule set forth
herein do not constitute an express or implied promise of continued engagement
as an employee or consultant for the vesting period, for any period, or at all.

(b) Assignment. The Company shall have the right to assign this Agreement, or
any portions thereof, including its rights with respect to the forfeiture of the
RSUs pursuant to Section 2 above, to any person or persons.

(c) Severability. The invalidity or unenforceability of any provision of this
Agreement shall not affect the validity or enforceability of any other provision
of this Agreement, and each other provision of this Agreement shall be severable
and enforceable to the extent permitted by law.

(d) Waiver. Any provision for the benefit of the Company contained in this
Agreement may be waived, either generally or in any particular instance, by the
Board of Directors of the Company.

(e) Binding Effect. This Agreement shall be binding upon and inure to the
benefit of the Company and the Participant and their respective heirs,
executors, administrators, legal representatives, successors and assigns,
subject to the restrictions on transfer set forth in Section 4 of this
Agreement.

(f) Notice. All notices required or permitted hereunder shall be in writing and
deemed effectively given upon personal delivery or five days after deposit in
the United States Post Office, by registered or certified mail, postage prepaid,
addressed to the other party hereto at the address shown beneath his or its
respective signature to this Agreement, or at such other address or addresses as
either party shall designate to the other in accordance with this Section 8(f).

 

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(g) Pronouns. Whenever the context may require, any pronouns used in this
Agreement shall include the corresponding masculine, feminine or neuter forms,
and the singular form of nouns and pronouns shall include the plural, and vice
versa.

(h) Entire Agreement. This Agreement and the Plan constitute the entire
agreement between the parties, and supersedes all prior agreements and
understandings, relating to the subject matter of this Agreement.

(i) Amendment. This Agreement may be amended or modified only by a written
instrument executed by both the Company and the Participant.

(j) Governing Law. This Agreement shall be construed, interpreted and enforced
in accordance with the internal laws of the State of Delaware without regard to
any applicable conflicts of laws.

(k) Participant’s Acknowledgments. The Participant acknowledges that he or she:
(i) has read this Agreement; (ii) has been represented in the preparation,
negotiation, and execution of this Agreement by legal counsel of the
Participant’s own choice or has voluntarily declined to seek such counsel;
(iii) understands the terms and consequences of this Agreement; and (iv) is
fully aware of the legal and binding effect of this Agreement.

(l) Unfunded Rights. The right of the Participant to receive Common Stock
pursuant to this Agreement is an unfunded and unsecured obligation of the
Company. The Participant shall have no rights under this Agreement other than
those of an unsecured general creditor of the Company.

IN WITNESS WHEREOF, the Company has caused this option to be executed under its
corporate seal by its duly authorized officer. This option shall take effect as
a sealed instrument.

 

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