**Exhibit10.1**

**STARENT NETWORKS, CORP.**

Form of Non-Employee DirectorNonstatutory Stock Option AgreementGranted Under 2007 Stock Incentive Plan

# 1.                                       Grantof 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, inwhole or in part, on the terms provided herein and in the Company’s 2007 StockIncentive Plan (the “Plan”), a total of[                 ]shares (the “Shares”) of common stock, $0.001****parvalue per share, of the Company (“Common Stock”) at$[          ] per Share.  Unless earlier terminated, this option shallexpire at 5:00 p.m., Eastern time, on [               ]****(the “Final Exercise Date”).

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

# 2.                                       VestingSchedule.

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

## (b)                                 Theright of exercise shall be cumulative so that to the extent the option is notexercised in any period to the maximum extent permissible it shall continue tobe exercisable, in whole or in part, with respect to all Shares for which it isvested until the earlier of the Final Exercise Date or the termination of thisoption under Section 3 hereof or the Plan.

## (c)                                  NotwithstandingSection 2(a) above, in case of (i) the consolidation or merger of the Companywith or into any other corporation or other entity (other than a merger orconsolidation in which all or substantially all of the individuals and entitieswho were beneficial owners of the outstanding securities entitled to votegenerally in the election of directors of the Company immediately prior to suchtransaction beneficially own, directly or indirectly, more than 50% of theoutstanding securities entitled to vote generally in the election of directorsof the resulting, surviving or acquiring corporation in such transaction), or(ii) the sale of all or substantially all of the properties and assets of theCompany as an entirety to any other person (either event being hereinafter referredto as a “Change of Control Event”), then 100% of the Shares shall become fullyvested upon the consummation of such Change of Control Event.

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# 3.                                       Exerciseof Option.

## (a)                                  Formof Exercise.  Each election toexercise this option shall be in writing, signed by the Participant, andreceived 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 thenumber of shares covered hereby, provided that no partial exercise of thisoption may be for any fractional share.

## (b)                                 ContinuousRelationship with the Company Required. Except as otherwise provided in this Section 3, this option may notbe exercised unless the Participant, at the time he or she exercises thisoption, is, and has been at all times since the Grant Date, an employee orofficer of, or consultant or advisor to, the Company or any other entity theemployees, officers, directors, consultants, or advisors of which are eligibleto receive option grants under the Plan (an “Eligible Participant”)

## (c)                                  Terminationof Relationship with the Company.  Ifthe Participant ceases to be an Eligible Participant for any reason, then,except as provided in paragraphs (d) and (e) below, the right to exercisethis option shall terminate****threemonths after such cessation (but in no event after the Final Exercise Date), providedthat this option shall be exercisable only to the extent that theParticipant was entitled to exercise this option on the date of such cessation.  Notwithstanding the foregoing, if theParticipant, prior to the Final Exercise Date, violates the non-competition orconfidentiality provisions of any employment contract, confidentiality andnondisclosure agreement or other agreement between the Participant and theCompany, the right to exercise this option shall terminate immediately uponwritten notice to the Participant from the Company describing such violation.

## (d)                                 ExercisePeriod Upon Death or Disability.  Ifthe Participant dies or becomes disabled (within the meaning ofSection 22(e)(3) of the Code) prior to the Final Exercise Date while he orshe is an Eligible Participant and the Company has not terminated suchrelationship for “cause” as specified in paragraph (e) below, this option shallbe exercisable, within the period of one year following the date of death ordisability of the Participant, by the Participant (or in the case of death byan authorized transferee), providedthat this option shall beexercisable only to the extent that this option was exercisable by theParticipant on the date of his or her death or disability, and further providedthat this option shall not be exercisable after the Final Exercise Date.

## (e)                                  Terminationfor Cause.  If, prior to the FinalExercise Date, the Participant’s employment or other relationship with theCompany is terminated by the Company for Cause (as defined below), the right toexercise this option shall terminate immediately upon the effective date ofsuch termination of employment or other relationship.  If the Participant is party to an employment,consulting or severance agreement with the Company that contains a definitionof “cause” for termination of employment or other relationship, “Cause” shallhave the meaning ascribed to such term in such agreement.  Otherwise, “Cause” shall mean willfulmisconduct by the Participant or willful failure by the Participant to performhis or her responsibilities to the Company (including, without limitation,breach by the Participant of any provision of any employment, consulting,advisory, nondisclosure, non-competition or other similar agreement between theParticipant and the Company), as determined by the Company, which determination

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## shall be conclusive.  TheParticipant shall be considered to have been discharged for “Cause” if theCompany determines, within 30 days after the Participant’s resignation, thatdischarge for cause was warranted.

# 4.                                       Withholding.

No Shares will be issued pursuant to the exercise ofthis option unless and until the Participant pays to the Company, or makesprovision satisfactory to the Company for payment of, any federal, state orlocal withholding taxes required by law to be withheld in respect of thisoption.

# 5.                                       Nontransferabilityof Option.

This option may not be sold, assigned, transferred,pledged or otherwise encumbered by the Participant, either voluntarily or byoperation of law, except by will or the laws of descent and distribution, and,during the lifetime of the Participant, this option shall be exercisable only bythe Participant.

# 6.                                       Provisionsof the Plan.

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

IN WITNESS WHEREOF, theCompany has caused this option to be executed under its corporate seal by itsduly authorized officer.  This optionshall take effect as a sealed instrument.
| ** ** |   |   | **STARENT NETWORKS, CORP.** |
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| ** ** |   |   |                        | ** ** |
| ** ** |   |   |                        | ** ** |
| Dated:     |   |   | By:                         |   |   |
|       |   |   |                        | Name: |   |   |
|       |   |   |                        | Title: |   |   |

 

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PARTICIPANT’S ACCEPTANCE

The undersigned hereby accepts the foregoing optionand agrees to the terms and conditions thereof. The undersigned hereby acknowledges receipt of a copy of the Company’s2007 Stock Incentive Plan.
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|   |   | Address:     |   |   |
|   |   |         |   |   |
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**EXHIBITA**

**NOTICE OF STOCK OPTION EXERCISE**
|   | Date: |   |
|--------|-------|--------|

Starent Networks, Corp.30 International PlaceTewksbury, MA 01876

Attention:  Treasurer

Dear Sir or Madam:

I am the holder of anNonstatutory Stock Option granted to me under the Starent Networks, Corp. (the “Company”)2007 Stock Incentive Plan on                      forthe purchase of                        sharesof Common Stock of the Company at a purchase price of $                    pershare.

I hereby exercise myoption to purchase                       sharesof Common Stock (the “Shares”), for which I have enclosed                       inthe amount of $                       Please register my stock certificate as follows:
|             | * * | * * |   | *(check applicable box)* |
|-------------|----------|----------|--------|--------------------------|
|        | * * | * * |   | * *                 |
| Name(s):    |     |     |   |                     | o | TEN COM |
|        |     |     |   |                     |   |   |
|        |     |     |   |                     | o | TEN ENT |
|        |     |     |   |                     |   |   |
| Address:    |     |     |   |                     | o | JT TEN |
|        |     |     |   |                     |   |   |
| Tax I.D. #: |     |     |   |                     | o | UNIF GIFT MIN ACT |

 
| Very truly yours, |
|-------------------|
|              |
|              |
|              |   |
| (Signature)       |

 

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