FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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(Print or Type Responses)

1. Name and Address of Reporting Person *   MATRIX PARTNERS VI LP ET AL 2. Date of Event Requiring Statement (Month/Day/Year) 06/05/2007 3. Issuer Name and Ticker or Trading Symbol Starent Networks, Corp. [STAR] (Last) (First) (Middle) C/O MATRIX PARTNERS BAY COLONY CORP CTR, 1000 WINTER STREET, SUITE 4500 4. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director __X__ 10% Owner _____ Officer (give title below) _____ Other (specify below) 5. If Amendment, Date Original Filed(Month/Day/Year) (Street) WALTHAM, MA 02451 6. Individual or Joint/Group Filing(Check Applicable Line) _X_ Form filed by One Reporting Person ___ Form filed by More than One Reporting Person (City) (State) (Zip) Table I - Non-Derivative Securities Beneficially Owned

1.Title of Security (Instr. 4) 2. Amount of Securities Beneficially Owned (Instr. 4) 3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5) 4. Nature of Indirect Beneficial Ownership (Instr. 5) Common Stock 6,272,920 (1) I See Footnote (2) Common Stock 2,092,730 (1) I See Footnote (3) Common Stock 701,089 (1) I See Footnote (4)

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.			SEC 1473 (7-02)
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Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
MATRIX PARTNERS VI LP ET AL C/O MATRIX PARTNERS BAY COLONY CORP CTR 1000 WINTER STREET, SUITE 4500 WALTHAM, MA 02451	Â	  X	Â	Â

Signatures

/s/ Timothy A. Barrows ** Matrix VI Management Co., L.L.C. By: Timothy A. Barrows, Managing Member		06/05/2007
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 5(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1)	Consists of shares of common stock issued upon the automatic conversion of shares of Series A Convertible Preferred Stock, Series B Convertible Preferred Stock, Series C Convertible Preferred Stock, Series D Convertible Preferred Stock and Series E Convertible Preferred Stock of Starent Networks, Corp. upon the effectiveness of the Registration Statement on Form S-1 relating to Starent Network, Corp.'s initial public offering.
(2)	Represents securities held by Matrix Partners VI, L.P. Matrix VI Management Co., L.L.C. ("Matrix VI LLC") is the general partner of Matrix Partners VI, L.P. Timothy Barrows, as a Managing Member of Matrix VI LLC, has sole voting and dispostive power with respect to the shares held by those entities. Mr. Barrows disclaims beneficial ownership of such shares, except to the extent of his pecuniary interest therein.
(3)	Represents securities held by Matrix VI Parallel Partnership-A, L.P. Matrix VI LLC is the general partner of Matrix VI Parallel Partnership-A, L.P. Timothy Barrows, as a Managing Member of Matrix VI LLC, has sole voting and dispostive power with respect to the shares held by those entities. Mr. Barrows disclaims beneficial ownership of such shares, except to the extent of his pecuniary interest therein.
(4)	Represents securities held by Matrix VI Parallel Partnership-B, L.P. Matrix VI LLC is the general partner of each Matrix VI Parallel Partnership-B, L.P. Timothy Barrows, as a Managing Member of Matrix VI LLC, has sole voting and dispostive power with respect to the shares held by those entities. Mr. Barrows disclaims beneficial ownership of such shares, except to the extent of his pecuniary interest therein.

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