Exhibit 10.1

STARENT NETWORKS, CORP.

Form of Non-Employee Director
Nonstatutory Stock Option Agreement
Granted Under 2007 Stock Incentive Plan

1.                                        Grant of Option .

This agreement evidences the grant by Starent Networks, Corp., a Delaware corporation (the “Company”), on            , 200[ ] (the “Grant Date”) to [                  ], a director of the Company (the “Participant”), of an option to purchase, in whole or in part, on the terms provided herein and in the Company’s 2007 Stock Incentive Plan (the “Plan”), a total of [                 ] shares (the “Shares”) of common stock, $0.001 par value per share, of the Company (“Common Stock”) at $[          ] per Share.  Unless earlier terminated, this option shall expire at 5:00 p.m., Eastern time, on [               ] (the “Final Exercise Date”).

It is intended that the option evidenced by this agreement shall not be an incentive stock option as defined in Section 422 of the Internal Revenue Code of 1986, as amended, and any regulations promulgated thereunder (the “Code”).  Except as otherwise indicated by the context, the term “Participant”, as used in this option, shall be deemed to include any person who acquires the right to exercise this option validly under its terms.

2.                                        Vesting Schedule .

(a)                                   This option will become exercisable (“vest”) as to 20% of the original number of Shares (the “Initial Vesting Amount”) on the first anniversary of the Grant Date and as to an additional 5% of the original number of Shares at the end of each successive three-month period following the first anniversary of the Grant Date until the fifth anniversary of the Grant Date (the “End Date”).

(b)                                  The right of exercise shall be cumulative so that to the extent the option is not exercised in any period to the maximum extent permissible it shall continue to be exercisable, in whole or in part, with respect to all Shares for which it is vested until the earlier of the Final Exercise Date or the termination of this option under Section 3 hereof or the Plan.

(c)                                   Notwithstanding Section 2(a) above, in case of (i) the consolidation or merger of the Company with or into any other corporation or other entity (other than a merger or consolidation in which all or substantially all of the individuals and entities who were beneficial owners of the outstanding securities entitled to vote generally in the election of directors of the Company immediately prior to such transaction beneficially own, directly or indirectly, more than 50% of the outstanding securities entitled to vote generally in the election of directors of the resulting, surviving or acquiring corporation in such transaction), or (ii) the sale of all or substantially all of the properties and assets of the Company as an entirety to any other person (either event being hereinafter referred to as a “Change of Control Event”), then 100% of the Shares shall become fully vested upon the consummation of such Change of Control Event.

3.                                        Exercise of Option .

(a)                                   Form of Exercise .  Each election to exercise this option shall be in writing, signed by the Participant, and received by the Company at its principal office, accompanied by this agreement, and payment in full in the manner provided in the Plan.  The Participant may purchase less than the number of shares covered hereby, provided that no partial exercise of this option may be for any fractional share.

(b)                                  Continuous Relationship with the Company Required .  Except as otherwise provided in this Section 3, this option may not be exercised unless th