UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13G

Under the Securities Exchange Act of 1934
(Amendment No.     )*

Gigamon Inc.

(Name of Issuer)

Common Stock, $0.0001 par value

(Title of Class of Securities)

37518B 10 2

(CUSIP Number)

December 31, 2013

Date of Event Which Requires Filing of the Statement

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

o Rule 13d-1(b)

o Rule 13d-1(c)

x Rule 13d-1(d)

*The remainder of this cover page shall be filled out for a reporting person's initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

CUSIP No. 37518B 10 2						13G
	1.	Name of Reporting Person S.S. or I.R.S. Identification No. of Above Person Highland Management Partners VII, LLC
	2.	Check the Appropriate Box if a Member of a Group
		(a)		o
		(b)		x
	3.	SEC Use Only
	4.	Citizenship or Place of Organization Delaware
Number of Shares Beneficially Owned by Each Reporting Person With			5.		Sole Voting Power 0
			6.		Shared Voting Power 5,774,500
			7.		Sole Dispositive Power 0
			8.		Shared Dispositive Power 5,774,500
	9.	Aggregate Amount Beneficially Owned by Each Reporting Person 5,774,500
	10.	Check Box if the Aggregate Amount in Row (9) Excludes Certain Shares  o
	11.	Percent of Class Represented by Amount in Row (9) 18.6%
	12.	Type of Reporting Person OO

2

CUSIP No. 37518B 10 2						13G
	1.	Name of Reporting Person S.S. or I.R.S. Identification No. of Above Person Highland Management Partners VII Limited Partnership
	2.	Check the Appropriate Box if a Member of a Group
		(a)		o
		(b)		x
	3.	SEC Use Only
	4.	Citizenship or Place of Organization Delaware
Number of Shares Beneficially Owned by Each Reporting Person With			5.		Sole Voting Power 0
			6.		Shared Voting Power 5,774,500
			7.		Sole Dispositive Power 0
			8.		Shared Dispositive Power 5,774,500
	9.	Aggregate Amount Beneficially Owned by Each Reporting Person 5,774,500
	10.	Check Box if the Aggregate Amount in Row (9) Excludes Certain Shares  o
	11.	Percent of Class Represented by Amount in Row (9) 18.6%
	12.	Type of Reporting Person PN

3

CUSIP No. 37518B 10 2						13G
	1.	Name of Reporting Person S.S. or I.R.S. Identification No. of Above Person Highland Capital Partners VII Limited Partnership
	2.	Check the Appropriate Box if a Member of a Group
		(a)		o
		(b)		x
	3.	SEC Use Only
	4.	Citizenship or Place of Organization Delaware
Number of Shares Beneficially Owned by Each Reporting Person With			5.		Sole Voting Power 0
			6.		Shared Voting Power 3,550,158
			7.		Sole Dispositive Power 0
			8.		Shared Dispositive Power 3,550,158
	9.	Aggregate Amount Beneficially Owned by Each Reporting Person 3,550,158
	10.	Check Box if the Aggregate Amount in Row (9) Excludes Certain Shares  o
	11.	Percent of Class Represented by Amount in Row (9) 11.4%
	12.	Type of Reporting Person PN

4

CUSIP No. 37518B 10 2						13G
	1.	Name of Reporting Person S.S. or I.R.S. Identification No. of Above Person Highland Capital Partners VII-B Limited Partnership
	2.	Check the Appropriate Box if a Member of a Group
		(a)		o
		(b)		x
	3.	SEC Use Only
	4.	Citizenship or Place of Organization Delaware
Number of Shares Beneficially Owned by Each Reporting Person With			5.		Sole Voting Power 0
			6.		Shared Voting Power 860,272
			7.		Sole Dispositive Power 0
			8.		Shared Dispositive Power 860,272
	9.	Aggregate Amount Beneficially Owned by Each Reporting Person 860,272
	10.	Check Box if the Aggregate Amount in Row (9) Excludes Certain Shares  o
	11.	Percent of Class Represented by Amount in Row (9) 2.8%
	12.	Type of Reporting Person PN

5

CUSIP No. 37518B 10 2						13G
	1.	Name of Reporting Person S.S. or I.R.S. Identification No. of Above Person Highland Capital Partners VII-C Limited Partnership
	2.	Check the Appropriate Box if a Member of a Group
		(a)		o
		(b)		x
	3.	SEC Use Only
	4.	Citizenship or Place of Organization Delaware
Number of Shares Beneficially Owned by Each Reporting Person With			5.		Sole Voting Power 0
			6.		Shared Voting Power 1,252,828
			7.		Sole Dispositive Power 0
			8.		Shared Dispositive Power 1,252,828
	9.	Aggregate Amount Beneficially Owned by Each Reporting Person 1,252,828
	10.	Check Box if the Aggregate Amount in Row (9) Excludes Certain Shares  o
	11.	Percent of Class Represented by Amount in Row (9) 4.0%
	12.	Type of Reporting Person PN

6

CUSIP No. 37518B 10 2						13G
	1.	Name of Reporting Person S.S. or I.R.S. Identification No. of Above Person Highland Entrepreneurs’ Fund VII Limited Partnership
	2.	Check the Appropriate Box if a Member of a Group
		(a)		o
		(b)		x
	3.	SEC Use Only
	4.	Citizenship or Place of Organization Delaware
Number of Shares Beneficially Owned by Each Reporting Person With			5.		Sole Voting Power 0
			6.		Shared Voting Power 111,242
			7.		Sole Dispositive Power 0
			8.		Shared Dispositive Power 111,242
	9.	Aggregate Amount Beneficially Owned by Each Reporting Person 111,242
	10.	Check Box if the Aggregate Amount in Row (9) Excludes Certain Shares  o
	11.	Percent of Class Represented by Amount in Row (9) 0.4%
	12.	Type of Reporting Person PN

7

CUSIP No. 37518B 10 2 13G

Item 1(a)	Name of Issuer Gigamon Inc.
Item 1(b)	Address of Issuer’s Principal Executive Offices 598 Gibraltar Drive Milpitas, California 95035
Item 2(a)	Name of Person Filing This statement is being filed by the following persons with respect to the shares (the “Shares”) of common stock (“Common Stock”) of the Issuer directly owned by Highland Capital Partners VII Limited Partnership (“HCP VII”), Highland Capital Partners VII-B Limited Partnership (“HCP VII-B”), Highland Capital Partners VII-C Limited Partnership (“HCP VII-C”) and Highland Entrepreneurs’ Fund VII Limited Partnership (“HEF VII” and, collectively, the “Funds”). (a) Highland Management Partners VII Limited Partnership (“HMP VII”), the general partner of each of the Funds; (b) Highland Management Partners VII, LLC (“Highland Management”), the general partner of HMP VII; (c) HCP VII, which directly owns 3,550,158 Shares; (d) HCP VII-B, which directly owns 860,272 Shares; (e) HCP VII-C, which directly owns 1,252,828 Shares; and (f) HEF VII, which directly owns 111,242 Shares. HMP VII, Highland Management, HCP VII, HCP VII-B, HCP VII-C and HEF VII are sometimes individually referred to herein as a “Reporting Person” and collectively as the “Reporting Persons.”
Item 2(b)	Address of Principal Business Office The address of each of the reporting persons is: c/o Highland Capital Partners LLC One Broadway, 16th Floor Cambridge, Massachusetts 02142
Item 2(c)	Citizenship
	HCP VII	Delaware
	HCP VII-B	Delaware
	HCP VII-C	Delaware
	HEF VII	Delaware
	HMP VII	Delaware
	Highland Management	Delaware
Item 2(d)	Title of Class of Securities Common Stock, $0.0001 par value

8

CUSIP No. 37518B 10 2 13G

Item 2(e)			CUSIP Number 37518B 10 2
Item 3	If this statement is filed pursuant to §§ 240.13d-1(b), or 240.13d-2(b) or (c), check whether the person filing is a:
	Not applicable.
Item 4	Ownership
Provide the following information regarding the aggregate number and percentage of the class of securities of the issuer identified in Item 1.
For Highland Management:
		(a)		Amount beneficially owned: 5,774,500 shares of Common Stock
		(b)		Percent of class: 18.6%
		(c)		Number of shares as to which such person has:
				(i)	Sole power to vote or to direct the vote:    0
				(ii)	Shared power to vote or to direct the vote:     5,774,500
				(iii)	Sole power to dispose or to direct the disposition of:    0
				(iv)	Shared power to dispose or to direct the disposition of:    5,774,500
For HMP VII:
		(a)		Amount beneficially owned: 5,774,500 shares of Common Stock
		(b)		Percent of class: 18.6%
		(c)		Number of shares as to which such person has:
				(i)	Sole power to vote or to direct the vote:    0
				(ii)	Shared power to vote or to direct the vote:     5,774,500
				(iii)	Sole power to dispose or to direct the disposition of:
					0

9

		(iv)	Shared power to dispose or to direct the disposition of:    5,774,500
For HCP VII:
	(a)	Amount beneficially owned: 3,550,158 shares of Common Stock
	(b)	Percent of class: 11.4%
	(c)	Number of shares as to which such person has:
		(i)	Sole power to vote or to direct the vote:    0
		(ii)	Shared power to vote or to direct the vote:     3,550,158
		(iii)	Sole power to dispose or to direct the disposition of:    0
		(iv)	Shared power to dispose or to direct the disposition of:    3,550,158
For HCP VII-B:
	(a)	Amount beneficially owned: 860,272 shares of Common Stock
	(b)	Percent of class: 2.8%
	(c)	Number of shares as to which such person has:
		(i)	Sole power to vote or to direct the vote:    0
		(ii)	Shared power to vote or to direct the vote:     860,272
		(iii)	Sole power to dispose or to direct the disposition of:    0
		(iv)	Shared power to dispose or to direct the disposition of:    860,272
For HCP VII-C:
	(a)	Amount beneficially owned: 1,252,828 shares of Common Stock
	(b)	Percent of class: 4.0%
	(c)	Number of shares as to which such person has:
		(i)	Sole power to vote or to direct the vote:    0

10

		(ii)	Shared power to vote or to direct the vote:     1,252,828
		(iii)	Sole power to dispose or to direct the disposition of:    0
		(iv)	Shared power to dispose or to direct the disposition of:    1,252,828
For HEF VII:
	(a)	Amount beneficially owned: 111,242 shares of Common Stock
	(b)	Percent of class: 0.4%
	(c)	Number of shares as to which such person has:
		(i)	Sole power to vote or to direct the vote:    0
		(ii)	Shared power to vote or to direct the vote:     111,242
		(iii)	Sole power to dispose or to direct the disposition of:    0
		(iv)	Shared power to dispose or to direct the disposition of:    111,242

Item 5	Ownership of Five Percent or Less of a Class
	Not applicable.
Item 6	Ownership of More than Five Percent on Behalf of Another Person
	Not applicable.
Item 7	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on By the Parent Holding Company
	Not applicable.
Item 8	Identification and Classification of Members of the Group
	Not applicable.
Item 9	Notice of Dissolution of Group
	Not applicable.

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CUSIP No. 37518B 10 2 13G

Item 10

Certification

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under § 240.14a-11.

SIGNATURE

After reasonable inquiry and to the best of its knowledge and belief, the undersigned certify that the information set forth in this statement is true, complete and correct.

DATED: February 14, 2014.
	HIGHLAND CAPITAL PARTNERS VII LIMITED PARTNERSHIP
	By:	Highland Management Partners VII Limited Partnership, its General Partner
	By:	Highland Management Partners VII, LLC, its General Partner
		By:	/s/ Corey Mulloy
			Authorized Manager
	HIGHLAND CAPITAL PARTNERS VII-B LIMITED PARTNERSHIP
	By:	Highland Management Partners VII Limited Partnership, its General Partner
	By:	Highland Management Partners VII, LLC, its General Partner
		By:	/s/ Corey Mulloy
			Authorized Manager
	HIGHLAND CAPITAL PARTNERS VII-C LIMITED PARTNERSHIP
	By:	Highland Management Partners VII Limited Partnership, its General Partner
	By:	Highland Management Partners VII, LLC, its General Partner
		By:	/s/ Corey Mulloy
			Authorized Manager
	HIGHLAND ENTREPRENEURS’ FUND VII LIMITED PARTNERSHIP
	By:	Highland Management Partners VII Limited Partnership, its General Partner
	By:	Highland Management Partners VII, LLC, its General Partner
		By:	/s/ Corey Mulloy
			Authorized Manager

12

HIGHLAND MANAGEMENT PARTNERS VII LIMITED PARTNERSHIP
By:	Highland Management Partners VII, LLC, its General Partner
	By:	/s/ Corey Mulloy
		Authorized Manager
HIGHLAND MANAGEMENT PARTNERS VII, LLC
	By:	/s/ Corey Mulloy
		Authorized Manager

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CUSIP No. 37518B 10 2

EXHIBIT I

JOINT FILING AGREEMENT

Pursuant to Rule 13d-1(k)(1) under the Securities Exchange Act of 1934, as amended, the undersigned hereby agree that only one statement containing the information required by Schedule 13G need be filed with respect to the ownership by each of the undersigned of the shares of Common Stock of Gigamon Inc.

This Agreement may be executed in any number of counterparts, each of which shall be deemed an original.

EXECUTED as of this 14th day of February, 2014.

HIGHLAND CAPITAL PARTNERS VII LIMITED PARTNERSHIP
By:	Highland Management Partners VII Limited Partnership, its General Partner
By:	Highland Management Partners VII, LLC, its General Partner
	By:	/s/ Corey Mulloy
		Authorized Manager
HIGHLAND CAPITAL PARTNERS VII-B LIMITED PARTNERSHIP
By:	Highland Management Partners VII Limited Partnership, its General Partner
By:	Highland Management Partners VII, LLC, its General Partner
	By:	/s/ Corey Mulloy
		Authorized Manager
HIGHLAND CAPITAL PARTNERS VII-B LIMITED PARTNERSHIP
By:	Highland Management Partners VII Limited Partnership, its General Partner
By:	Highland Management Partners VII, LLC, its General Partner
	By:	/s/ Corey Mulloy
		Authorized Manager

HIGHLAND ENTREPRENEURS’ FUND VII LIMITED PARTNERSHIP
By:	Highland Management Partners VII Limited Partnership, its General Partner
By:	Highland Management Partners VII, LLC, its General Partner
	By:	/s/ Corey Mulloy
		Authorized Manager
HIGHLAND MANAGEMENT PARTNERS VII LIMITED PARTNERSHIP
By:	Highland Management Partners VII, LLC, its General Partner
	By:	/s/ Corey Mulloy
		Authorized Manager
HIGHLAND MANAGEMENT PARTNERSHIP VII, LLC
	By:	/s/ Corey Mulloy
		Authorized Manager