SC 13D/A

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934
(Amendment No. 2)*

REDBACK NETWORKS INC.

(Name of Issuer)

Common Stock, par value $0.0001 per share
(Title of Class of Securities)

757209507
(CUSIP Number)

Carla S. Newell
c/o Technology Crossover Ventures
528 Ramona Street
Palo Alto, California 94301
(650) 614-8200
(Name, Address and Telephone Number of Person
Authorized to Receive Notices and Communications)

April 5, 2004
(Date of Event Which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box. þ

Note: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See §240.13d-7 for other parties to whom copies are to be sent.

^* 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).

	1.	Name of Reporting Person: TCV IV, L.P. See item 2 for identification of the General Partner			I.R.S. Identification Nos. of above persons (entities only):
	2.	Check the Appropriate Box if a Member of a Group (See Instructions):
		(a)	o
		(b)	þ
	3.	SEC Use Only:
	4.	Source of Funds (See Instructions): AF, OO
	5.	Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e): o
	6.	Citizenship or Place of Organization: DELAWARE
Number of Shares Beneficially Owned by Each Reporting Person With
			7.	Sole Voting Power: 7,854,000 SHARES OF COMMON STOCK (A)
			8.	Shared Voting Power: -0- SHARES OF COMMON STOCK
			9.	Sole Dispositive Power: 7,854,000 SHARES OF COMMON STOCK (A)
			10.	Shared Dispositive Power: -0- SHARES OF COMMON STOCK
	11.	Aggregate Amount Beneficially Owned by Each Reporting Person: 7,854,000 SHARES OF COMMON STOCK (A)
	12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions): þ
	13.	Percent of Class Represented by Amount in Row (11): 13.10%
	14.	Type of Reporting Person (See Instructions): PN

(A) Please see Item 5. Includes Preferred Stock immediately convertible into 6,283,200 shares of Common Stock and warrants which can be immediately exercised for a total of 1,570,800 shares of Common Stock.

	1.	Name of Reporting Person: TCV IV STRATEGIC PARTNERS, L.P. See item 2 for identification of the General Partner			I.R.S. Identification Nos. of above persons (entities only):
	2.	Check the Appropriate Box if a Member of a Group (See Instructions):
		(a)	o
		(b)	þ
	3.	SEC Use Only:
	4.	Source of Funds (See Instructions): AF, OO
	5.	Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e): o
	6.	Citizenship or Place of Organization: DELAWARE
Number of Shares Beneficially Owned by Each Reporting Person With
			7.	Sole Voting Power: 292,863 SHARES OF COMMON STOCK (A)
			8.	Shared Voting Power: -0- SHARES OF COMMON STOCK
			9.	Sole Dispositive Power: 292,863 SHARES OF COMMON STOCK (A)
			10.	Shared Dispositive Power: -0- SHARES OF COMMON STOCK
	11.	Aggregate Amount Beneficially Owned by Each Reporting Person: 292,863 SHARES OF COMMON STOCK (A)
	12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions): þ
	13.	Percent of Class Represented by Amount in Row (11): Less than 1%
	14.	Type of Reporting Person (See Instructions): PN

(A) Please see Item 5. Includes Preferred Stock immediately convertible into 234,290 shares of Common Stock and warrants which can be immediately exercised for a total of 58,573 shares of Common Stock.

	1.	Name of Reporting Person: Technology Crossover Management IV, L.L.C. See item 2 for identification of the Managing Members			I.R.S. Identification Nos. of above persons (entities only):
	2.	Check the Appropriate Box if a Member of a Group (See Instructions):
		(a)	o
		(b)	þ
	3.	SEC Use Only:
	4.	Source of Funds (See Instructions): AF, OO
	5.	Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e): o
	6.	Citizenship or Place of Organization: DELAWARE
Number of Shares Beneficially Owned by Each Reporting Person With
			7.	Sole Voting Power: 8,146,863 SHARES OF COMMON STOCK (A)
			8.	Shared Voting Power: -0- SHARES OF COMMON STOCK
			9.	Sole Dispositive Power: 8,146,863 SHARES OF COMMON STOCK (A)
			10.	Shared Dispositive Power: -0- SHARES OF COMMON STOCK
	11.	Aggregate Amount Beneficially Owned by Each Reporting Person: 8,146,863 SHARES OF COMMON STOCK (A)
	12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions): o
	13.	Percent of Class Represented by Amount in Row (11): 13.59%
	14.	Type of Reporting Person (See Instructions): OO

(A) Please see Item 5. Includes Preferred Stock immediately convertible into 6,517,490 shares of Common Stock and warrants which can be immediately exercised for a total of 1,629,373 shares of Common Stock.

	1.	Name of Reporting Person: JAY C. HOAG			I.R.S. Identification Nos. of above persons (entities only):
	2.	Check the Appropriate Box if a Member of a Group (See Instructions):
		(a)	o
		(b)	þ
	3.	SEC Use Only:
	4.	Source of Funds (See Instructions): AF, OO
	5.	Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e): o
	6.	Citizenship or Place of Organization: UNITED STATES CITIZEN
Number of Shares Beneficially Owned by Each Reporting Person With
			7.	Sole Voting Power: 8,146,863 SHARES OF COMMON STOCK (A)
			8.	Shared Voting Power: -0- SHARES OF COMMON STOCK
			9.	Sole Dispositive Power: 8,146,863 SHARES OF COMMON STOCK (A)
			10.	Shared Dispositive Power: -0- SHARES OF COMMON STOCK
	11.	Aggregate Amount Beneficially Owned by Each Reporting Person: 8,146,863 SHARES OF COMMON STOCK (A)
	12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions): o
	13.	Percent of Class Represented by Amount in Row (11): 13.59%
	14.	Type of Reporting Person (See Instructions): IN

(A) Please see Item 5. Includes Preferred Stock immediately convertible into 6,517,490 shares of Common Stock and warrants which can be immediately exercised for a total of 1,629,373 shares of Common Stock.

	1.	Name of Reporting Person: RICHARD H. KIMBALL			I.R.S. Identification Nos. of above persons (entities only):
	2.	Check the Appropriate Box if a Member of a Group (See Instructions):
		(a)	o
		(b)	þ
	3.	SEC Use Only:
	4.	Source of Funds (See Instructions): AF, OO
	5.	Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e): o
	6.	Citizenship or Place of Organization: UNITED STATES CITIZEN
Number of Shares Beneficially Owned by Each Reporting Person With
			7.	Sole Voting Power: -0- SHARES OF COMMON STOCK
			8.	Shared Voting Power: 8,146,863 SHARES OF COMMON STOCK (A)
			9.	Sole Dispositive Power: -0- SHARES OF COMMON STOCK
			10.	Shared Dispositive Power: 8,146,863 SHARES OF COMMON STOCK (A)
	11.	Aggregate Amount Beneficially Owned by Each Reporting Person: 8,146,863 SHARES OF COMMON STOCK (A)
	12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions): o
	13.	Percent of Class Represented by Amount in Row (11): 13.59%
	14.	Type of Reporting Person (See Instructions): IN

(A) Please see Item 5. Includes Preferred Stock immediately convertible into 6,517,490 shares of Common Stock and warrants which can be immediately exercised for a total of 1,629,373 shares of Common Stock.

	1.	Name of Reporting Person: JOHN L. DREW			I.R.S. Identification Nos. of above persons (entities only):
	2.	Check the Appropriate Box if a Member of a Group (See Instructions):
		(a)	o
		(b)	þ
	3.	SEC Use Only:
	4.	Source of Funds (See Instructions): AF, OO
	5.	Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e): o
	6.	Citizenship or Place of Organization: UNITED STATES CITIZEN
Number of Shares Beneficially Owned by Each Reporting Person With
			7.	Sole Voting Power: 341 SHARES OF COMMON STOCK (A)
			8.	Shared Voting Power: 8,146,863 SHARES OF COMMON STOCK (A)
			9.	Sole Dispositive Power: 341 SHARES OF COMMON STOCK (A)
			10.	Shared Dispositive Power: 8,146,863 SHARES OF COMMON STOCK (A)
	11.	Aggregate Amount Beneficially Owned by Each Reporting Person: 8,147,204 SHARES OF COMMON STOCK (A)
	12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions): o
	13.	Percent of Class Represented by Amount in Row (11): 13.59%
	14.	Type of Reporting Person (See Instructions): IN

(A)   Please see Item 5. Includes options issued under the 1999 Director’s Option Plan and held directly by Reporting Person which can be exercised on May 5, 2004 for a total of 341 shares of Common Stock. This also includes Preferred Stock immediately convertible into 6,517,490 shares of Common Stock and warrants which can be immediately exercised for a total of 1,629,373 shares of Common Stock.

ITEM 1. SECURITY AND ISSUER.

This statement relates to shares of common stock, par value $0.0001 per share (the “Common Stock”), of Redback Networks Inc., a Delaware corporation (“Redback” or the “Company”). The Company’s principal executive offices are located at 300 Holger Way, San Jose, CA 95134.

ITEM 2. IDENTITY AND BACKGROUND.

(a)-(c), (f). This statement is being filed by (1) TCV IV, L.P., a Delaware limited partnership (“TCV IV”), (2) TCV IV Strategic Partners, L.P., a Delaware limited partnership (“Strategic Partners IV”), (3) Technology Crossover Management IV, L.L.C., a Delaware limited liability company (“Management IV”), (4) Jay C. Hoag (“Mr. Hoag”); (5) Richard H. Kimball (“Mr. Kimball”); and (6) John L. Drew (“Mr. Drew”). TCV IV, Strategic Partners IV, Management IV, Mr. Hoag, Mr. Kimball and Mr. Drew are sometimes collectively referred to herein as the “Reporting Persons.” The agreement among the Reporting Persons relating to the joint filing of this statement is attached as Exhibit 1 hereto.

TCV IV, Strategic Partners IV and Management IV are each principally engaged in the business of investing in securities of privately and publicly held companies. Management IV is the sole general partner of TCV IV and Strategic Partners IV. The address of the principal business and office of each of TCV IV, Strategic Partners IV and Management IV is 528 Ramona Street, Palo Alto, California 94301.

Mr. Hoag and Mr. Kimball are the managing members of Management IV. Mr. Drew is a non-managing member of Management IV. Mr. Hoag, Mr. Kimball and Mr. Drew are each United States citizens, and the present principal occupation of each is as a venture capital investor. The business address of each of Mr. Hoag, Mr. Kimball and Mr. Drew is 528 Ramona Street, Palo Alto, California 94301.

(d), (e). During the last five years, none of TCV IV, Strategic Partners IV, Management IV, Mr. Hoag, Mr. Kimball or Mr. Drew has (1) been convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors) or (2) been a party to a civil proceeding of a judicial or administrative body of competent jurisdiction and as a result of such proceeding was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws.

ITEM 3. SOURCE AND AMOUNT OF FUNDS OR OTHER CONSIDERATION.

Pursuant to the terms of a Securities Purchase Agreement dated January 2, 2004 (the “Purchase Agreement”) by and among Redback, on the one hand, and TCV IV and Strategic Partners IV (the “TCV IV Funds”), on the other hand, Redback agreed to issue and sell, and TCV IV and Strategic Partners IV agreed to purchase, 628,320 and 23,429 shares, respectively, of the Company’s Series B Convertible Preferred Stock (each, a “Share” and collectively, the “Shares”), at a price of $46.03 per share. Each Share is initially convertible into ten shares of Common Stock. Pursuant to the Purchase Agreement, Redback also agreed to issue to TCV IV and Strategic Partners IV warrants (each, a “Warrant” and collectively, the “Warrants”), at a price of $.01 per underlying share to purchase 1,570,800 and 58,573 shares (the “Warrant Shares”), respectively, of Common Stock at a per share exercise price of $5.00. In consideration for the Shares and Warrants, TCV IV and Strategic Partners IV paid the Company $28,937,277.60 and $1,079,022.60, respectively, upon the closing date for the transaction, January 5, 2004 (the “Closing Date”). On April 5, 2004, the Warrants were amended to shorten the expiration date by three days to January 2, 2011 and to rename them the Series I Warrants.

The source of funds for the acquisition of the Shares and Warrants by the TCV IV Funds was from capital contributions from their respective partners.

The Purchase Agreement is attached as Exhibit 2 and is incorporated by reference herein from Exhibit 2 to the Schedule 13D relating to the common stock of Redback Networks Inc. filed on January 8, 2004.

ITEM 4. PURPOSE OF TRANSACTION.

Purchase Agreement

The TCV IV Funds agreed to purchase, and the Company agreed to sell, the Shares and Warrants pursuant to the Purchase Agreement. In connection with the approval of the Purchase Agreement, the Company’s Board of Directors approved the purchase of up to an additional 3,000,000 shares of Common Stock by the TCV IV Funds in market transactions, privately negotiated transactions or otherwise (the “Market Purchases”).

The Certificate of Designation for Series B Convertible Preferred Stock (the “Certificate of Designation”) provides that the holders of
a majority of the then outstanding Series B Convertible Preferred Stock (the “Series B Preferred Stock”) shall be entitled to elect one director to the Company’s Board of Directors (the “Series B Director”). In the Purchase Agreement, Redback agreed to elect John Drew, a non-managing member of Management IV, to the Company’s Board of Directors as the Series B Director. Mr. Drew became a director effective immediately after of the closing of the acquisition of the Shares and the Warrants. Upon becoming a director, Mr. Drew was granted options to purchase

1,363 shares of Common Stock pursuant to the Company’s Director Stock Option Plan. 25% of such options vest on May 5 of 2004, 2005, 2006 and 2007. In addition, in the Purchase Agreement the Company agreed that if the Series B Preferred Stock is no longer outstanding, then for so long as the TCV IV Funds continue to own at least 7.5% of the outstanding Common Stock of the Company, the Company shall cause an individual designated by the TCV IV Funds to be nominated for election to the Board of Directors of the Company and shall solicit proxies to elect such individual to the Board of Directors to the same extent it does so for the other individuals nominated by the Company for election. For purposes of this provision, the TCV IV Funds shall be deemed to include any shares of Common Stock issuable upon exercise of the Series I Warrants.

Certificate of Designation

The rights and privileges of the Series B Preferred Stock are contained in the Certificate of Designation. The shares of Series B Preferred Stock are convertible at any time, at the option of the holder, into shares of Common Stock. The initial conversion ratio of the Series B Preferred Stock is 10 shares of Common Stock for one share of Series B Preferred Stock. The conversion ratio is subject to certain anti-dilution adjustments related to stock splits, recapitalizations, mergers, reorganizations and the like. The Series B Preferred Stock will automatically convert into Common Stock at the then effective conversion ratio, if at any time after the one-year anniversary of the Closing Date, the closing sales price of the Common Stock is greater than three times the effective conversion price of the Series B Preferred Stock (initially $4.603 per share of Common Stock) on each of 90 consecutive trading days, such 90 trading day period beginning after such one-year anniversary, provided that at such time the registration statement referred to under the heading “Investor Rights Agreement” has been declared effective and is usable.

The Series B Preferred Stock shall accrue a 2% annual dividend, which in certain instances can be paid in additional shares of Series B Preferred Stock. Dividends on the Series B Preferred Stock shall be paid semi-annually on July 1, and January 1, commencing with July 1, 2004. If the Company declares a dividend or distribution on shares of Common Stock, then the Company shall declare an additional dividend on each share of Series B Preferred Stock equal to the amount a holder of a share of Series B Preferred Stock would have received if such holder had converted, at the then effective conversion ratio, a share of Series B Preferred Stock into Common Stock prior to the record date for such dividend or distribution.

Upon a Sale Transaction (as defined in the Certificate of Designation) the holders of the Series B Preferred Stock shall generally be entitled to receive, prior to any payments to the holders of Common Stock, the original issue price of the Series B Preferred Stock ($46.03) per share, plus all accrued and unpaid dividends. The holders of Series B Preferred Stock shall vote with the holders of Common Stock on all matters submitted to the holders of Common Stock for a vote, with each share of Series B Preferred Stock entitled to the number of votes equal to the number of shares of Common Stock issuable upon conversion of such share of Preferred Stock. The consent of the holders of a majority of the Series B Preferred Stock will be required for the Company to take certain actions, which are set forth in the Certificate of Designation.

A copy of the Certificate of Designation is attached as Exhibit 3 and is incorporated by reference herein from Exhibit 3 to the Schedule 13D relating to the common stock of Redback Networks Inc. filed on January 8, 2004.

Investor Rights Agreement

Pursuant to the Purchase Agreement, the Company, the TCV IV Funds entered into an Investor Rights Agreement dated the Closing Date. Pursuant to the Investor Rights Agreement, the Company has agreed to register the resale of the Series I Warrants and shares of Common Stock issuable upon conversion of the Shares and upon exercise of the Series I Warrants, shares of Common Stock acquired in Market Purchases, and certain other shares of Common Stock (the “Registrable Securities”). In addition, subject to certain limitations, the TCV IV Funds have the right to have the Registrable Securities included in any underwritten public offering of equity securities by the Company. The Company is obligated to pay all expenses incurred in connection with such registrations (other than underwriting discounts and commissions, and stock transfer taxes). The Company has agreed to indemnify the TCV IV Funds and related persons against certain liabilities under the securities laws in connection with the sale of securities under such registrations.

A copy of the Investor Rights Agreement is attached as Exhibit 4 and is incorporated by reference herein from Exhibit 4 to the Schedule 13D relating to the common stock of Redback Networks Inc. filed on January 8, 2004.

Amendment of the Investor Rights Agreement

The Company and the TCV IV Funds entered into an Amendment of the Investor Rights Agreement dated April 5, 2004 (the “Amendment”). Pursuant to the Amendment, subject to certain exceptions, the Series I Warrants cannot be transferred prior to October 5, 2004 without the written consent of the Company.

A copy of the Amendment of the Investor Rights Agreement is attached hereto as Exhibit 5 and is incorporated by reference herein.

Third Amendment to the Rights Agreement

In connection with the Purchase Agreement, the Company amended its Rights Agreement, dated as of June 12, 2001 by and between the Company and US Stock Transfer Corporation.

A copy of the amendment to the Rights Agreement is attached as Exhibit 6 and is incorporated by reference herein from Exhibit 6 to the Schedule 13D relating to the common stock of Redback Networks Inc. filed on January 8, 2004.

Series I Warrants

On April 5, 2004, the Warrants were amended to shorten the expiration date by three days to January 2, 2011 and to rename them the Series I Warrants. The Series I Warrants represent the right to purchase shares of the Company’s Common Stock at an exercise price of $5.00 per share. Payment of the exercise price may be made in cash, or through the surrender of Common Stock underlying Series I Warrants with a fair market value equal to the exercise price of the Series I Warrants being exercised (otherwise known as net exercise). The exercise price and the number of shares issuable upon exercise of the Series I Warrants is subject to adjustment under certain circumstances as set forth in the Series I Warrants.

A copy of the form of Series I Warrant issued to the TCV IV Funds is attached hereto as Exhibit 7 and is incorporated by reference herein.

The Reporting Persons acquired the Shares and Series I Warrants for investment purposes. Depending on the factors discussed herein, the Reporting Persons may, from time to time, investigate, evaluate, discuss, negotiate or agree to convert the Shares to Common Stock, exercise all or a portion of the Series I Warrants, make Market Purchases and acquire additional shares of Common Stock from the Company or third party and/or investigate, evaluate, discuss, negotiate or agree to retain and/or sell, exchange or dispose all or a portion of the Shares, Series I Warrants and/or Common Stock issued upon exercise of the Series I Warrants, upon conversion of the Shares or in Market Purchases, in the open market, in privately negotiated transactions to the Company or third parties, in change of control transactions, or otherwise. Any actions the Reporting Persons might undertake will be dependent upon the Reporting Persons’ review of numerous factors, including, among other things, the price levels of the Common Stock; general market and economic conditions; ongoing evaluation of the Company’s business, financial condition, operations and prospects; the relative attractiveness of alternative business and investment opportunities; and other future developments.

Except as set forth above, the Reporting Persons have no present plans or intentions which would result in or relate to any of the transactions described in subparagraphs (a) through (j) of Item 4 of Schedule 13D.

ITEM 5. INTEREST IN SECURITIES OF THE ISSUER.

(a), (b). As of the close of business on April 5, 2004, TCV IV, Strategic Partners IV, Management IV, Mr. Hoag, Mr. Kimball and Mr. Drew owned directly and/or indirectly the following shares of Common Stock:

Name of Reporting	Number of Total Shares			Percentage of Outstanding Shares
Person	of Common Stock			of Common Stock(*)
TCV IV		7,854,000	(1)		13.10	%
Strategic Partners IV		292,863	(2)		Less than 1	%
Management IV		8,146,863	(3)(**)		13.59	%
Mr. Hoag		8,146,863	(3)(**)		13.59	%
Mr. Kimball		8,146,863	(3)(**)		13.59	%
Mr. Drew		8,147,204	(4)(**)		13.59	%

(*)	All percentages in this table are based on 51,789,623 shares of Common Stock of the Company outstanding as reported on the Company’s Form 10-K filed with the Securities and Exchange Commission on March 15, 2004.
(**)	Certain Reporting Persons disclaim beneficial ownership as set forth below.
(1)	Includes Series B Preferred Stock immediately convertible into 6,283,200 shares of Common Stock and Series I Warrants which can be immediately exercised for a total of 1,570,800 shares of Common Stock.
(2)	Includes Series B Preferred Stock immediately convertible into 234,290 shares of Common Stock and Series I Warrants which can be immediately exercised for a total of 58,573 shares of Common Stock.
(3)	Includes Series B Preferred Stock immediately convertible into 6,517,490 shares of Common Stock and Series I Warrants which can be immediately exercised for a total of 1,629,373 shares of Common Stock.
(4)	Includes options issued under the 1999 Director’s Option Plan and held directly by Reporting Person which can be exercised on May 5, 2004 for a total of 341 shares of Common Stock. This also includes Series B Preferred Stock immediately convertible into 6,517,490 shares of Common Stock and Series I Warrants which can be immediately exercised for a total of 1,629,373 shares of Common Stock.

Each of the TCV IV Funds has the sole power to dispose or direct the disposition of the Shares and Series I Warrants which it holds directly, and will have the sole power to dispose or direct the disposition of the shares of Common Stock acquired upon exercise of its respective Series I Warrants, upon conversion of the Shares or pursuant to Market Purchases, if any, made by it. Each of the TCV IV Funds has the sole power to vote or direct the vote of its respective Shares and will have the sole power to vote or direct the vote the Common Stock acquired upon exercise of its respective Series I Warrants, upon conversion of the Shares or pursuant to Market Purchases, if any, made by it.

Management IV as the sole general partner of each of the TCV IV Funds and in such capacity may also be deemed to have the sole power to dispose or direct the disposition of the Shares and the Series I Warrants held by the TCV IV Funds, and the Common Stock which the TCV IV Funds will have acquired upon exercise of the Series I Warrants, upon conversion of the Shares, or pursuant to Market Purchases, if any, made by it, as well as to have the sole power to vote or direct the vote of the Shares held by the TCV IV Funds and the Common Stock which the TCV IV Funds will have acquired upon exercise of the Series I Warrants, upon conversion of the Shares or pursuant to Market Purchases, if any, made by the TCV IV Funds. Management IV disclaims beneficial ownership of such securities except to the extent of its pecuniary interest therein.

Messrs. Hoag and Kimball are the managing members of Management IV and Mr. Drew is a non-managing member of Management IV. Under the operating agreement of Management IV, Mr. Hoag may be deemed to have the sole power to dispose or direct the disposition of the Shares and the Series I Warrants held by the TCV IV Funds, and shares of Common Stock which the TCV IV Funds would own upon exercise of the Series I Warrants, upon conversion of the Shares or pursuant to Market Purchases, if any, made by the TCV IV Funds. Each of Messrs. Kimball and Drew may be deemed to have the shared power to dispose or direct the disposition of the Shares and Series I Warrants held by TCV IV Funds, and shares of Common Stock which the TCV IV Funds would own upon exercise of such Series I Warrants, upon conversion of the Shares or pursuant to Market Purchases, if any, made by the TCV IV Funds. Mr. Hoag may be deemed to have the sole power to vote or direct the vote of the Shares held by the TCV IV Funds and the Common Stock which the TCV IV Funds will have acquired upon exercise of such Series I Warrants, upon conversion of the Shares or pursuant to Market Purchases, if any, made by the TCV IV Funds. Each of Messrs. Kimball and Drew may be deemed to have the shared power to vote or direct the vote of the Shares held by the TCV IV Funds and the Common Stock which the TCV IV Funds will have acquired upon exercise of such Series I Warrants, upon conversion of the Shares or pursuant to Market Purchases, if any, made by the TCV IV Funds. Messrs. Hoag, Kimball and Drew disclaim beneficial ownership of the securities owned by the TCV IV Funds except to the extent of their pecuniary interest therein.

The Reporting Persons may be deemed to be acting as a group in relation to their respective holdings in the Company but do not affirm the existence of any such group.

Except as set forth in this Item 5(a) — (b), each of the Reporting Persons disclaims beneficial ownership of any Common Stock owned beneficially or of record by any other Reporting Person.

(c). Except as set forth herein, none of the Reporting Persons has effected any transactions in the Common Stock of the Company in the last 60 days.

(d). Not applicable.

(e). Not applicable.

ITEM 6. CONTRACTS, ARRANGEMENTS, UNDERSTANDINGS OR RELATIONSHIPS WITH RESPECT TO SECURITIES OF THE ISSUER.

Item 4 above summarizes certain provisions of the Purchase Agreement, the Certificate of Designation, the Investor Rights Agreement, the Amendment of the Investor Rights Agreement, the Third Amendment to the Rights Agreement and the Series I Warrants. A copy of the Purchase Agreement is attached hereto as Exhibit 2 and is incorporated by reference herein from Exhibit 2 to the Schedule 13D relating to the common stock of Redback Networks Inc. filed on January 8, 2004. A copy of the Certificate of Designation is attached hereto as Exhibit 3 and is incorporated by reference herein from Exhibit 3 to the Schedule 13D relating to the common stock of Redback Networks Inc. filed on January 8, 2004. A copy of the Investor Rights Agreement is attached hereto as Exhibit 4 and is incorporated by reference herein from Exhibit 6 to the Schedule 13D relating to the common stock of Redback Networks Inc. filed on January 8, 2004. A copy of the Amendment of the Investor Rights Agreement is attached hereto as Exhibit 5 and is incorporated by reference herein. A copy of the Third Amendment to the Rights Agreement is attached hereto as Exhibit 6 and is incorporated by reference herein from Exhibit 6 to the Schedule 13D relating to the common stock of Redback Networks Inc. filed on January 8, 2004. A copy of the form of Series I Warrant is attached hereto as Exhibit 7 and is incorporated by reference herein.

Except as set forth herein, none of the Reporting Persons has any contracts, arrangements, understandings or relationships (legal or otherwise) with any person with respect to any securities of Redback, including but not limited to any contracts, arrangements, understandings or relationships concerning the transfer or voting of such securities, finder’s fees, joint ventures, loan or option arrangements, puts or calls, guarantees of profits, division of profits or losses, or the giving or withholding of proxies.

ITEM 7. MATERIAL TO BE FILED AS EXHIBITS.

Exhibit 1 Joint Filing Agreement

Exhibit 2 Securities Purchase Agreement, dated January 2, 2004, among Redback Networks, Inc., TCV IV, L.P. and TCV IV Strategic Partners, L.P. (incorporated by reference from Exhibit 2 to the Schedule 13D relating to the common stock of Redback Networks Inc. filed on January 8, 2004)

Exhibit 3 Certificate of Designation of Series B Convertible Preferred Stock of Redback Networks, Inc. (incorporated by reference from Exhibit 3 to the Schedule 13D relating to the common stock of Redback Networks Inc. filed on January 8, 2004)

Exhibit 4 Investor Rights Agreement, dated January 5, 2004, among Redback Networks, Inc., TCV IV, L.P. and TCV IV Strategic Partners, L.P. (incorporated by reference from Exhibit 4 to the Schedule 13D relating to the common stock of Redback Networks Inc. filed on January 8, 2004)

Exhibit 5 Amendment of Investor Rights Agreement, dated April 5, 2004, among Redback Networks Inc., TCV IV, L.P. and TCV IV Strategic Partners, L.P.

Exhibit 6 Third Amendment to the Rights Agreement, dated January 5, 2004, between Redback Networks, Inc. and US Stock Transfer Corporation. (incorporated by reference from Exhibit 6 to the Schedule 13D relating to the common stock of Redback Networks Inc. filed on January 8, 2004)

Exhibit 7 Form of Series I Warrant to Purchase 1,629,373 Shares of Common Stock of Redback Networks Inc. with an exercise price of $5.00 per share, issued to TCV IV, L.P. and TCV IV Strategic Partners, L.P.

Exhibit 8 Statement Appointing Designated Filer and Authorized Signatories dated November 5, 2001(incorporated by reference from Exhibit A to the Schedule 13D/A relating to the common stock of Digital Generation Systems, Inc. filed on March 21, 2002).

SIGNATURE

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

Dated: May 23, 2005

TCV IV, L.P.

By: /s/ Carla S. Newell
Name: Carla S. Newell
Its: Authorized Signatory

TCV IV STRATEGIC PARTNERS, L.P.

By: /s/ Carla S. Newell
Name: Carla S. Newell
Its: Authorized Signatory

TECHNOLOGY CROSSOVER MANAGEMENT IV, L.L.C.

By: /s/ Carla S. Newell
Name: Carla S. Newell
Its: Authorized Signatory

JAY C. HOAG

By: /s/ Carla S. Newell
Name: Carla S. Newell
Its: Authorized Signatory

RICHARD H. KIMBALL

By: /s/ Carla S. Newell
Name: Carla S. Newell
Its: Authorized Signatory

JOHN L. DREW

By: /s/ Carla S. Newell
Name: Carla S. Newell
Its: Authorized Signatory

EXHIBIT INDEX

Exhibit 1 Joint Filing Agreement

Exhibit 2 Securities Purchase Agreement, dated January 2, 2004, among Redback Networks, Inc., TCV IV, L.P. and TCV IV Strategic Partners, L.P. (incorporated by reference from Exhibit 2 to the Schedule 13D relating to the common stock of Redback Networks Inc. filed on January 8, 2004)

Exhibit 3 Certificate of Designation of Series B Convertible Preferred Stock of Redback Networks, Inc. (incorporated by reference from Exhibit 3 to the Schedule 13D relating to the common stock of Redback Networks Inc. filed on January 8, 2004)

Exhibit 4 Investor Rights Agreement, dated January 5, 2004, among Redback Networks, Inc., TCV IV, L.P. and TCV IV Strategic Partners, L.P. (incorporated by reference from Exhibit 4 to the Schedule 13D relating to the common stock of Redback Networks Inc. filed on January 8, 2004)

Exhibit 5 Amendment of Investor Rights Agreement, dated April 5, 2004, among Redback Networks Inc., TCV IV, L.P. and TCV IV Strategic Partners, L.P.

Exhibit 6 Third Amendment to the Rights Agreement, dated January 5, 2004, between Redback Networks, Inc. and US Stock Transfer Corporation. (incorporated by reference from Exhibit 6 to the Schedule 13D relating to the common stock of Redback Networks Inc. filed on January 8, 2004)

Exhibit 7 Form of Series I Warrant to Purchase 1,629,373 Shares of Common Stock of Redback Networks Inc. with an exercise price of $5.00 per share, issued to TCV IV, L.P. and TCV IV Strategic Partners, L.P.

Exhibit 8 Statement Appointing Designated Filer and Authorized Signatories dated November 5, 2001(incorporated by reference from Exhibit A to the Schedule 13D/A relating to the common stock of Digital Generation Systems, Inc. filed on March 21, 2002).

EX-99.1

EXHIBIT 1

JOINT FILING AGREEMENT

In accordance with Rule 13d-1(k) promulgated under the Securities Exchange Act of 1934, as amended, the undersigned hereby agree to the joint filing with all other Reporting Persons (as such term is defined in the Schedule 13D referred to below) on behalf of each of them of a statement on Schedule 13D (including amendments thereto) with respect to the common stock, par value $0.0001 per share, of Redback Networks, Inc., a Delaware corporation, and that this Agreement may be included as an exhibit to such joint filing. This Joint Filing Agreement may be executed in any number of counterparts, all of which taken together shall constitute one and the same instrument.

IN WITNESS WHEREOF, the undersigned hereby execute this Agreement as of the 5th day of April, 2004.

TCV IV, L.P.

By: /s/ Carla S. Newell
Name: Carla S. Newell
Its: Authorized Signatory

TCV IV STRATEGIC PARTNERS, L.P.

By: /s/ Carla S. Newell
Name: Carla S. Newell
Its: Authorized Signatory

TECHNOLOGY CROSSOVER MANAGEMENT IV, L.L.C.

By: /s/ Carla S. Newell
Name: Carla S. Newell
Its: Authorized Signatory

JAY C. HOAG

By: /s/ Carla S. Newell
Name: Carla S. Newell
Its: Authorized Signatory

RICHARD H. KIMBALL

By: /s/ Carla S. Newell
Name: Carla S. Newell
Its: Authorized Signatory

JOHN L. DREW

By: /s/ Carla S. Newell
Name: Carla S. Newell
Its: Authorized Signatory

EX-99.5

EXHIBIT 5

AMENDMENT OF INVESTOR RIGHTS AGREEMENT

THIS AMENDMENT OF INVESTOR RIGHTS AGREEMENT (this “Amendment”), dated as of April 5, 2004, by and among Redback Networks, Inc., a Delaware corporation (along with its successors and assigns, the “Company”) and TCV IV, L.P., a Delaware limited partnership and TCV IV Strategic Partners, L.P., a Delaware limited partnership (collectively, the “Original Holders”). All capitalized terms used herein, which are not defined herein, shall have the meaning assigned to them in the Investor Rights Agreement, dated as of January 5, 2004, by and among the Company and the Original Holders (the “Investor Rights Agreement”).

RECITALS

WHEREAS, the Original Holders acquired from the Company, pursuant to a Securities Purchase Agreement, dated as of January 5, 2004 (the “Purchase Agreement”), shares of the Company’s Series B Convertible Preferred Stock, par value $0.0001 per share, and warrants to purchase 1,629,373 shares of the Company’s Common Stock, in the form attached to the Purchase Agreement (as amended from time to time, the “Warrants”);

WHEREAS, the Original Holders and the Company desire to amend the Investor Rights Agreement as set forth below;

NOW THEREFORE, in consideration of the above recitals and the mutual agreements set forth therein, the parties agree as follows:

1. Amendments. Upon the execution hereof, the Investor Rights Agreement is amended as follows:

A. Definitions.

(i) Registrable Securities. The definition of “Registrable Securities” is amended by deleting the period at the end of the definition and adding the following after clause (B) at the end of the definition:

“or (C) Common Stock issued pursuant to the Primary Shelf Registration.”

(ii) Warrants. The definition of “Warrants” is amended by deleting the period at the end of the definition and adding the following at the end of the definition”

”, as amended from time to time.”

(iii) Sale Transaction. The following new definition shall be added to
Section 1.

“Sale Transaction” shall mean any (i) consolidation or merger of the Company with or into any other corporation or other entity or person in which the stockholders of the Company immediately prior to such consolidation or merger own less than a majority of
the equity interest and voting power of the surviving entity (or of the surviving entity’s parent) immediately after such consolidation or merger, excluding any consolidation or merger effected exclusively to change the domicile of the Company, or (ii) tender offer, corporate reorganization, or other acquisition transaction or series of related transactions, immediately after which the stockholders of the Company immediately prior to such tender offer, corporate reorganization, or other acquisition transaction or series of related transactions own less than a majority of the equity interests and voting power of the Company, or (iii) a direct or indirect sale, lease or other disposition of all or substantially all of the assets of the Company.

B. Restrictions on Transfer of Warrants.

Section 2 of the Investor Rights Agreement is deleted in its entirety and replaced with the following:

“SECTION 2 Restrictions.

(a) General. The Shares and Warrants shall not be sold, assigned, transferred or pledged except upon the conditions specified in Section 4, which conditions are intended to ensure compliance with the provisions of the Securities Act.

(b) Warrants. Until the earliest to occur of:

(i) October 5, 2004;

(ii) the receipt by the Company of aggregate gross proceeds of $10,000,000 or more in one or more financings consummated after April 5, 2004; and

(iii) the execution of an agreement by the Company for, or consummation of, a Sale Transaction; without the written consent of the Company, the Investors will not sell, assign, transfer or pledge the Warrants, other than a transfer or assignment to a subsidiary, affiliated partnership, affiliate or partner of limited liability company member (including limited partners, retired partners, spouses and ancestors, lineal descendants and siblings or such partners or spouses who acquire the Warrants by gift, will or intestate succession) of the Investors, provided that such transferee or assignee agrees to be bound by the provisions of this Section 2(b). Notwithstanding the foregoing, with respect to any agreement executed by the Company for a Sale Transaction, if such agreement is terminated prior to the occurrence of either subparagraph (i) or (ii) of the prior sentence, then the restriction set forth in the previous sentence shall be reinstated (until it would otherwise terminate in accordance with the previous sentence) with respect to any Warrants that have not been previously sold, assigned, transferred or pledged by the Investors.”

C. Mandatory Registrations.

Section 5 of the Investor Rights Agreement is deleted in its entirety and replaced with the following:

“SECTION 5 Mandatory Registration.

(a) Resale Shelf Registration. The Company shall file a registration statement covering the sale or distribution by the Holders, on a delayed or continuous basis, including without limitation, by way of underwritten offering, block sale or other distribution plan designated by the Holders of a majority of the Registrable Securities from time to time, of all of the Registrable Securities on Form S-3 (except if the Company is not then eligible to register for resale the Registrable Securities on Form S-3, in which case such registration shall be on another appropriate form in accordance herewith) (the “Resale Shelf Registration”) within 97 days after the date hereof and shall cause the Resale Shelf Registration to be declared effective by the Commission (and shall take such appropriate actions as are related thereto including, without limitation, the execution of an undertaking to file post-effective amendments, appropriate qualification, if necessary, under applicable blue sky or other state securities laws and appropriate compliance with applicable regulations issued under the Securities Act and any other governmental requirements or regulations) as promptly as possible after the filing thereof, but in any event prior to the date that is 165 days after the date hereof. Once declared effective, the Company shall use its reasonable best efforts to cause (x) the Resale Shelf Registration to be effective until the earlier of (i) five (5) years from January 5, 2004 and (ii) such time as the Holders own shares of Common Stock, or shares of Common Stock issuable upon exercise or conversion of the Registrable Securities, which in the aggregate are less than 5% of the Company’s outstanding shares of Common Stock and the Holders may sell all of their Registrable Securities without registration pursuant to Rule 144 under the Securities Act in any and all three-month periods, and (y) subject to Section 9(j), the Resale Shelf Registration to be useable by the Holders during such entire period. The Company shall not be obligated to take any action to effect the Resale Shelf Registration in any particular jurisdiction in which the Company would be required to qualify to do business, subject itself to general taxation or execute a general consent to service of process in effecting such registration, qualification or compliance unless the Company is already qualified to do business, subject to general taxation or subject to service, as the case may be, in such jurisdiction, except as may be required by the Securities Act.

(b) Primary Shelf Registration. The Company shall file a registration statement covering the issuance by the Company, on a delayed or continuous basis, of shares of Common Stock upon exercise of the Warrants which are not Registrable Securities because they have been sold or transferred pursuant to the Resale Shelf Registration (the “Warrant Shares”) on Form S-3 (except if the Company is not then eligible to register for the issuance of the Warrant Shares on Form S-3, in which case such registration shall be on another appropriate form in accordance herewith) (the “Primary Shelf Registration”) within 97 days after the date hereof and shall use it reasonable best efforts to cause the Primary Shelf Registration to be declared effective by the Commission (and shall take such appropriate actions as are related thereto including, without limitation, the execution of an undertaking to file post-effective amendments, appropriate

qualification, if necessary, under applicable blue sky or other state securities laws and appropriate compliance with applicable regulations issued under the Securities Act and any other governmental requirements or regulations) as promptly as possible after the filing thereof, but in any event prior to the date that is 165 days after the date hereof. The registration statement and the prospectus for the Primary Shelf Registration may be combined with the registration statement and prospectus for the Resale Shelf Registration. Once declared effective, the Company shall use its reasonable best efforts, subject to Section 9(j) to cause the Primary Shelf Registration to be effective until and including the earlier of (i) expiration of the Warrants, currently January 2, 2011, and (ii) such time as all of the Warrants have been exercised for Warrant Shares. The Company shall not be obligated to take any action to effect the Primary Shelf Registration in any particular jurisdiction in which the Company would be required to qualify to do business, subject itself to general taxation or execute a general consent to service of process in effecting such registration, qualification or compliance unless the Company is already qualified to do business, subject to general taxation or subject to service, as the case may be, in such jurisdiction, except as may be required by the Securities Act. The holders of Warrants which are not Registrable Securities because they have been sold or transferred pursuant to the Resale Shelf Registration, whether or not parties to this Agreement or assignees of rights under this Agreement, shall be third party beneficiaries of this Section 5(b).”

D. Registration Procedures.

Section 9 of the Investor Rights Agreement is amended by changing “Section 5” to “Section 5(a)” in the first sentence of that Section 9.

E. Third Parties.

Section 15 of the Investor Rights Agreement is amended by replacing the phrase “Nothing in this Agreement” with the phrase “Except as provided in Section 5(b), nothing in this Agreement”.

F. Amendments and Waiver.

Section 20 of the Investor Rights Agreement is amended by adding the following phrase to the end of the first sentence of that Section:

”; provided, however, that any amendment to Section 5(b) will also require the written consent of the holders of Warrants representing a majority of shares of Common Stock issuable upon exercise of the then outstanding Warrants.”

G. Effect of Amendments

The Investors hereby acknowledge that, although the Company has received a communication from the CUSIP Bureau (which has been disclosed to the Investors) indicating that the amendments to the Warrants would be sufficient to allow the Warrants to bear the same CUSIP number as the Company’s publicly-traded warrants having an exercise price of $5.00 (the “Public $5.00 Warrants”), the Company makes no representation or warranty that the

amendments being effected to the Warrants and the Investor Rights Agreement, including the addition of the Primary Shelf Registration to the Investor Rights Agreement, will actually be sufficient to allow the Warrants to trade fungibly with the Public $5.00 Warrants.

2. Amendment of Warrants. The Company and the Investors agree that (i) each of the Warrants shall be amended to read in their entirety (other than with respect to the name of the holder and the applicable numbers of warrant shares) as set forth in Exhibit A hereto, and (ii) they will exchange the Warrants for such amended warrants promptly after the execution hereof. Upon the execution of this Amendment, all references to the Warrants in the Investor Rights Agreement and elsewhere shall mean the amended Warrants.

3. Confirmation. The Investor Rights Agreement, as amended by this Amendment, is in all respects confirmed and preserved. This Amendment and the Investor Rights Agreement shall henceforth be read together as a single agreement.

4. Counterparts. This Amendment may be executed in any number of counterparts, each of which shall be deemed an original but all of which together shall constitute one and the same instrument.

5. Headings. All section headings herein are inserted for convenience only and shall not modify or affect the construction or interpretation of any provisions of this Amendment.

6. Governing Law. This Amendment shall be governed by the laws of the State of California, without giving effect to its principles on conflict of law. IN WITNESS WHEREOF, the parties have executed this Amendment of Investor Rights Agreement as of the date first above written.

COMPANY:

REDBACK NETWORKS, INC.

By:

INVESTORS:

TCV IV, L.P.
By: Technology Crossover Management IV, L.L.C.
Its: General Partner

By:

Name: Robert C. Bensky Title: Attorney in Fact

TCV IV STRATEGIC PARTNERS, L.P.
By: Technology Crossover Management IV, L.L.C.
Its: General Partner
By:

Name: Robert C. Bensky Title: Attorney in Fact

EX-99.7

EXHIBIT 7

VOID AFTER 5:00 P.M. PACIFIC TIME ON JANUARY 2, 2011
WARRANTS TO PURCHASE SHARES OF COMMON STOCK
REDBACK NETWORKS INC.

NEITHER THIS WARRANT NOR THE SHARES OF COMMON STOCK WHICH MAY BE PURCHASED PURSUANT TO THE EXERCISE OF THIS WARRANT (THE “WARRANT SHARES,” AND TOGETHER WITH THIS WARRANT, THE “SECURITIES”) HAVE BEEN REGISTERED WITH THE SECURITIES AND EXCHANGE COMMISSION OR THE SECURITIES COMMISSION OF ANY STATE IN RELIANCE UPON AN EXEMPTION FROM REGISTRATION UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “SECURITIES ACT”), AND, ACCORDINGLY, MAY NOT BE OFFERED OR SOLD EXCEPT PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT UNDER THE SECURITIES ACT OR PURSUANT TO AN AVAILABLE EXEMPTION FROM, OR IN A TRANSACTION NOT SUBJECT TO, THE REGISTRATION REQUIREMENTS OF THE SECURITIES ACT AND IN ACCORDANCE WITH APPLICABLE STATE SECURITIES LAWS. THIS WARRANT MUST BE SURRENDERED TO THE COMPANY OR ITS TRANSFER AGENT AS A CONDITION PRECEDENT TO THE SALE, PLEDGE OR OTHER TRANSFER OF ANY INTEREST IN ANY OF THE SHARES REPRESENTED BY THIS WARRANT.

CUSIP ___________

SERIES I

THIS CERTIFIES THAT, for value received, [___] (the “Holder”) is the holder of [___] Warrants (the “Warrants”), and is thereby entitled to subscribe for and purchase from REDBACK NETWORKS INC., a Delaware corporation (the “Company”), that number of fully paid and nonassessable shares equal to the Warrants (as adjusted pursuant to Section 2 hereof) (the “Warrant Shares”) of Common Stock of the Company (the “Common Stock”) at the purchase price of U.S. Five Dollars (U.S. $5.00) (as adjusted pursuant to Section 2 hereof) (the “Exercise Price”), upon the terms and subject to the conditions set forth herein. This Warrant will expire and will no longer be exercisable after 5:00 p.m. Pacific Time on January 2, 2011 (the “Expiration Date”).

1. Exercise Rights.

(a) Cash Exercise. The purchase rights represented by this Warrant may be exercised by the Holder at any time during the term hereof, in whole or in part, by surrender of this Warrant with the NOTICE OF EXERCISE (CASH EXERCISE) section of this Warrant completed and duly executed, accompanied by payment to the Company of an amount equal to the Exercise Price then in effect multiplied by the number of Warrant Shares to be purchased by the Holder in connection with such cash exercise of this Warrant, which amount may be paid, at the election of the Holder, by wire transfer or delivery of a certified check payable to the order of the Company to the principal offices of the Company.

(b) Net Issue Exercise. In lieu of exercising the purchase rights represented by this Warrant on a cash basis pursuant to Section 1(a) hereof, the Holder may elect to exercise such rights represented by this Warrant at any time during the term hereof, in whole or in part, on a net-issue basis by electing to receive the number of Warrant Shares which are equal in value to the value of this Warrant (or any portion thereof to be canceled in connection with such net-issue exercise) at the time of any such net-

issue exercise, by delivery to the principal offices of the Company of this Warrant and with the NOTICE OF EXERCISE (NETISSUE EXERCISE) section of this Warrant completed and duly executed, properly marked to indicate (A) the number of Warrant Shares to be delivered to the Holder in connection with such net-issue exercise, (B) the number of Warrant Shares with respect to which the Warrant is being surrendered in payment of the aggregate Exercise Price for the Warrant Shares to be delivered to the Holder in connection with such net-issue exercise, calculated as of the Determination Date (as defined below) and (C) the number of Warrant Shares which remain subject to the Warrant after such net-issue exercise, if any (each as determined in accordance with this Section 1(b)). In the event that the Holder will elect to exercise the rights represented by this Warrant in whole or in part on a netissue basis pursuant to this Section 1(b), the Company will issue to the Holder the number of Warrant Shares determined in accordance with the following formula: X =Y (A-B) / A. For purposes of this formula, X = the number of Warrant Shares to be issued to the Holder in connection with such net-issue exercise; Y = the number of Warrant Shares to be exercised, up to the number of Warrant Shares subject to this Warrant; A = the Fair Market Value of one share of Common Stock; and B = the Exercise Price in effect as of the date of such net-issue exercise (as adjusted pursuant to Section 2 hereof).

(c) Fair Market Value. For purposes of this Section 1, the “Fair Market Value” of the Common Stock will have the following meanings: (i) If the Common Stock is listed for trading on a national securities exchange or admitted for trading on a national market or other quotation system, then the Fair Market Value of Common Stock will be deemed to be the closing price quoted on the principal securities exchange on which the Common Stock is listed for trading, or if not so listed, the average of the closing bid and asked prices for Common Stock quoted on the national market or other quotation system on which Common Stock is admitted for trading, each as published in the Western Edition of THE WALL STREET JOURNAL (or, if such prices are not published in the Western Edition of the WALL STREET JOURNAL, as reported by the applicable authority or association governing trading of the Common Stock), in each case for the ten trading days prior to the Determination Date; and (ii) if the Common Stock is not listed for trading on a national securities exchange or admitted for trading on a national market or other quotation system, then the Fair Market Value of Common Stock will be deemed to be the fair market value of Common Stock as

determined in good faith from time to time by the Board of Directors of the Company (the “Board of Directors”) as at the Determination Date, and receipt and acknowledgment of this Warrant by the Holder will be deemed to be an acknowledgment and acceptance of any such determination of the fair market value of Common Stock by the Board of Directors as the final and binding determination of such Fair Market Value for purposes of this Warrant. The “Determination Date” of Fair Market Value will be the date indicated on the Notice of Exercise (Net Issue Exercise); PROVIDED, HOWEVER, that if the Company does not receive the Notice of Exercise (Net Issue Exercise) within five (5) business days of the date indicated thereon, the Determination Date will be the date the Company receives the Notice of Exercise (Net Issue Exercise).

(d) Certain Distributions. The Company will provide the Holder with prior written notice of any Distribution (as defined below) to be made by the Company after the date hereof and prior to the expiration of this Warrant. Such notice will be delivered to the Holder not less than twenty (20) days prior to the record date for determining stockholders entitled to receive the Distribution. “Distribution” will mean a distribution by the Company to all holders of its shares of Common Stock (i) evidences of indebtedness of the Company to its stockholders, (ii) assets (excluding cash distributions made as a dividend payable out of the lesser of the undistributed earnings for the fiscal year during which the dividend is declared and the retained earnings of the Company) or (iii) rights to subscribe to shares of

Common Stock; PROVIDED, HOWEVER, that the foregoing will not apply to any stockholder rights plan of the Company.

(e) Fractional Shares; Record Ownership of Warrant Shares; Stock Certificates. Upon the exercise of the rights represented by this Warrant, the Company will not be obligated to issue fractional shares of Common Stock, and in lieu thereof, the Company will pay to the Holder an amount in cash equal to the Fair Market Value per share of Common Stock immediately prior to such exercise multiplied by such fraction (rounded to the nearest cent). The Warrant Shares will be deemed to have been issued, and the person in whose name any certificate representing Warrant Shares will be issuable upon the exercise of the rights represented by this Warrant (as indicated in the Notice of Exercise) will be deemed to have become the holder of record of (and will be treated for all purposes as the record holder of) the Warrant Shares represented thereby, immediately prior to the close of business on the date or dates upon which the rights represented by this Warrant are exercised in accordance with the terms hereof. In the event of any exercise of the rights represented by this Warrant, certificates for the Warrant Shares so purchased pursuant hereto will be delivered to the Holder within a reasonable time and, unless this Warrant has been fully exercised or has expired, a new Warrant representing the Warrant Shares with respect to which this Warrant will not have been exercised will also be issued to the Holder within such time. Notwithstanding anything to the contrary in this Warrant, the obligation of the Company to deliver Warrant Shares upon any exercise of this Warrant will be subject to compliance with any law, rule, regulation, order, decree or other similar authority that may be applicable to such issuance. The issuance of certificates for shares of Common Stock upon the exercise of the rights represented by this Warrant will be made without charge to the Holder for any issuance tax in respect thereof; PROVIDED, however, that the Company will not be required to pay any tax which may be payable in respect of any transfer involved in the issuance and delivery of any certificate in a name other than that of the Holder of this Warrant.

2. Adjustment Rights.

(a) Right to Adjustment. The number of Warrant Shares purchasable upon the exercise of the rights represented by this Warrant, and the Exercise Price therefor, will be subject to adjustment from time to time upon the occurrence of certain events, as follows:

(i) Reclassifications. In the event of a reclassification of the Common Stock other than by stock split, subdivision, consolidation or combination thereof, the Company will execute a new Warrant, the terms of which provide that the holder of this Warrant will have the right to exercise the rights represented by such new Warrant, and procure upon such exercise and payment of the same aggregate Exercise Price then in effect, in lieu of the shares of Common Stock previously issuable upon exercise of the rights represented by this Warrant, the kind and amount of shares of stock, other securities, money and property receivable upon such reclassification by a holder of an equivalent number of shares of Common Stock at the time of such reclassification. Such new Warrant will provide for adjustments which are as equivalent as practicable to the adjustments provided for in this Section 2. The provisions of this Section 2(a)(i) will apply with equal force and effect to all successive reclassifications of the Common Stock.

(ii) Stock Splits, Capital Stock Dividends, Combinations and Consolidations. In the event of a stock split, capital stock dividend or subdivision of the outstanding shares of Common Stock, the number of Warrant Shares issuable upon the exercise of the rights represented by this Warrant immediately prior to such stock split, capital stock dividend or subdivision will be proportionately

increased and the Exercise Price then in effect will be proportionately decreased, effective at the close of business on the date of such stock split, capital stock dividend or subdivision, as the case may be. Conversely, in the event of a reverse stock split, consolidation, combination or other similar event of or in respect of the outstanding shares of Common Stock, the number of Warrant Shares issuable upon the exercise of the rights represented by this Warrant immediately prior to such reverse stock split, consolidation, combination or other similar event will be proportionately decreased and the Exercise Price will be proportionately increased, effective at the close of business on the date of such reverse stock split, consolidation, combination or other similar event, as the case may be; provided, however, that the reverse stock split with respect to the Company’s Common Stock which is to occur as part of that certain Plan of Reorganization of the Company which was confirmed by order of the United States Bankruptcy Court for the District of Delaware on December 22, 2003 shall not give rise to any adjustment in the number of Warrant Shares issuable upon the exercise of this Warrant or of the Exercise Price. Nothing in this Warrant will entitle the Holder to receive any capital stock dividend or other distribution to all of the Company’s stockholders until this Warrant will have been exercised.

(iii) Merger or Consolidation. If at any time there will be effected a merger or consolidation of the Company with or into another corporation, or a sale of all or substantially of the Company’s assets, in such way that holders of Common Stock will be entitled to receive stock, securities or assets with respect to or in exchange for their Common Stock, then, as a part of such merger, consolidation or sale, lawful provision will be made so that the Holder will thereafter be entitled to receive upon exercise of its rights to purchase the Warrant Shares, the number of shares of stock or other securities or property resulting from such merger, consolidation or sale, equivalent to that which a holder of the Common Stock deliverable upon exercise of the right to purchase the Warrant Shares under this Warrant would have been entitled in such merger, consolidation or sale if the right to purchase the Warrant Shares had been exercised immediately prior to such transaction. In any such case, appropriate adjustment (as determined in good faith by the Board of Directors) will be made in the application of the provisions of this Warrant with respect to the rights and interests of the Holder after the merger, consolidation or sale to the end that the provisions of this Warrant (including adjustments of the Exercise Price and number of shares of Common Stock purchasable pursuant to the terms and conditions of this Warrant) will be applicable after the transaction, as near as reasonably may be, in relation to any shares or other securities or property deliverable after that transaction upon the exercise of the Holder’s rights to purchase the Warrant Shares.

(b) Adjustment Notices. Upon any adjustment of the Exercise Price, and any increase or decrease in the number of Warrant Shares subject to this Warrant, in accordance with this Section 2, the Company thereafter will give written notice thereof to the Holder at the address of such Holder as shown on the books of the Company, which notice will state the Exercise Price as adjusted and, if applicable, the increased or decreased number of Warrant Shares subject to this Warrant, setting forth in reasonable detail the method of calculation of each such adjustment.

3. Transfer of Warrant. This Warrant and the rights represented hereby may only be transferred in accordance with the conditions set forth in this Section 3. This Warrant and the rights represented hereby may be transferred in whole or in part. In order to effect any transfer or partial transfer of this Warrant, the Holder hereof will deliver this Warrant to the Company with the NOTICE OF TRANSFER section of this Warrant completed and duly executed.

4. Representations and Warranties of the Company. The Company hereby represents and warrants to the Holder that this Warrant has been duly authorized and validly executed and delivered by the

Company and constitutes a valid and legally binding obligation of the Company enforceable against the Company in accordance with its terms, except as enforceability may be limited by bankruptcy, insolvency, reorganization, moratorium, fraudulent conveyance or other similar laws now or hereafter in effect relating to creditors’ rights generally, by an implied covenant of good faith, reasonableness and fair dealing and by general principles of equity (regardless of whether such enforceability is considered in a proceeding in equity or at law). The Warrant Shares have been duly and validly authorized and reserved for issuance by the Company upon the exercise of the rights represented by this Warrant and, when issued upon the exercise of such rights in accordance with the terms and conditions hereof, the Warrant Shares will be duly authorized and validly issued, fully paid and nonassessable shares of Common Stock. At all times during the term hereof, the Company will have authorized and reserved for issuance a sufficient number of shares of Common Stock to provide for the exercise of the rights represented by this Warrant.

5. No Stockholder Rights. Except as otherwise set forth in Section 2 of this Warrant, the Holder (and any transferee hereof) will not be entitled to vote on matters submitted for the approval or consent of the stockholders of the Company or to receive dividends or other distributions declared on or in respect of shares of Common Stock, or otherwise be deemed to be the holder of Common Stock or any other capital stock or other securities of the Company which may at any time be issuable upon the exercise of the rights represented hereby for any purpose, nor will anything contained herein be construed to confer upon the Holder (or any transferee hereof) any of the rights of a stockholder of the Company or any right to vote for the election of directors or upon any matter submitted for the approval or consent of the stockholders, or to give or withhold consent to any corporate action (whether upon any recapitalization, issuance of stock, reclassification of stock, merger or consolidation, conveyance, or otherwise) or to receive notice of meetings, or to receive dividends or subscription rights or otherwise until this Warrant will have been exercised and the Warrant Shares issuable upon the exercise of the rights represented hereby will have become deliverable as provided herein.

6. Miscellaneous. This Warrant and all actions arising out of or in connection with this Warrant will be governed by the internal laws of the State of California as applied to agreements made and performed in California by residents of California. Subject to the restrictions on transfer described in Section 3, the rights and obligations of the Company and the Holder of this Warrant and the Warrant Shares issued or issuable upon the exercise of the rights represented by this Warrant will be binding upon and benefit the successors, assigns, heirs, administrators and transferees of the parties. This Warrant may be terminated in advance of the Expiration Date, and any provision of this Warrant may be amended, waived or modified upon either (i) written consent of the Company and the Holder or (ii) the written consent of the Company and the consent of the holders of Series I Warrants that are exercisable into shares of Common Stock representing at least a majority of the shares of Common Stock into which all then-outstanding Series I Warrants are exercisable, calculated assuming the exercise for cash of all of the then-outstanding Series I Warrants. All notices and other communications provided for hereunder will be in writing and will be deemed to have been duly given if mailed by registered or certified mail, postage prepaid, or by recognized overnight courier, or delivered by personal delivery at the respective addresses of the parties as set forth in this Section 6 or on the register maintained by the Company, or, as to each party, at such other address as will be designated by such party in a written notice to the other party. Notices to the Company will be directed to it at its address at Redback Networks Inc., 300 Holger Way, San Jose, California 95134; Attn: Chief Financial Officer. Notices to the Holder will be directed to it at the most recent address for the Holder provided to the Company by the Holder. Any party hereto may by notice so given change its address for future notice hereunder. Except as otherwise specifically provided herein, notice will conclusively be deemed to have been given when received. In case any

provision of this Warrant is deemed to be invalid, illegal or unenforceable, the validity, legality and enforceability of the remaining provisions will not in any way be affected or impaired thereby. The Company will not, by amendment of its Certificate of Incorporation or through any other means, directly or indirectly, avoid or seek to avoid the observance or performance of any of the terms of this Warrant and will at all times in good faith assist in the carrying out of all such terms and in the taking of all such action as may be necessary or appropriate in order to protect the rights of the holder of this Warrant against impairment. The Company will at no time close its transfer books against the transfer of this Warrant or of any Warrant Shares issued or issuable upon the exercise of the rights represented by this Warrant in any matter which interferes with a timely exercise of such rights. The Company will not, by any action, seek to avoid the observance or performance of any of the terms of this Warrant, but will at all times in good faith seek to carry out all such terms and take all such actions as may be necessary or appropriate in order to protect the rights of the Holder under this Warrant against impairment. Upon receipt of evidence reasonably satisfactory to the Company of the loss, theft, destruction or mutilation of this Warrant and, in the case of any such loss, theft or destruction, upon delivery of an indemnity agreement reasonably satisfactory in form and amount to the Company or, in the case of any such mutilation, upon surrender and cancellation of such Warrant, the Company at the Holder’s expense will execute and deliver to the Holder, in lieu thereof, a new Warrant of like date and tenor.

WITNESS the facsimile signature of the proper officers of the Company.

Dated:

REDBACK NETWORKS INC.

By:

Name:

Title:

NOTICE OF EXERCISE (TO BE COMPLETED ONLY UPON EXERCISE)

TO: Redback Networks Inc.
310 Holger Way, San Jose, California 95134 Attention: Chief Financial Officer

1. The undersigned hereby irrevocably elects to purchase shares of Common Stock of Redback Networks Inc. pursuant to the terms of this Warrant.

2. If CASH EXERCISE, check this box : The undersigned tenders herewith full payment of the aggregate cash exercise price equal to $ U.S. Dollars for such shares in accordance with the terms of this Warrant.

3. If NET-ISSUE EXERCISE, check this box : The undersigned exercises this Warrant on a net-issue basis pursuant to the terms set forth in this Warrant. Net-Issue Information:

(a) Number of Shares of Common Stock to be Delivered:

(b) Number of Shares of Common Stock Surrendered:

(c) Number of Shares Remaining Subject to Warrant, if any:

4. Please issue a certificate or certificates representing said shares of Common Stock in such name or names as specified below:

(Name and Address)

5. The undersigned acknowledges that if the undersigned is deemed to be an affiliate of the Company under the federal securities laws, the undersigned may be subject to certain restrictions on, or subject to certain procedural requirements in connection with, any transfer of the shares of Common Stock issued upon exercise of this Warrant. (Signature must conform in all respects to name of the Holder as set forth on the face of this Warrant)

Dated: By:

(Signature must conform in all respects to name of the Holder as set forth on the face of this Warrant )

NOTICE OF TRANSFER (TO BE COMPLETED ONLY UPON TRANSFER)

TO: Redback Networks Inc.

310 Holger Way, San Jose, California 95134

Attention: Chief Financial Officer

FOR VALUE RECEIVED, the undersigned hereby sells, assigns and transfers unto the right represented by this Warrant, to purchase shares of Common Stock of Redback Networks Inc. Please issue a certificate or certificates representing said Warrant in such name or names as specified below:

Please issue a certificate or certificates representing said shares of Common Stock in such name or names as specified below:

(Name and Address)

The undersigned requests the Company, by written order to exchange or register the transfer of a Warrant or Warrants, and, to the extent the transfer contemplated by this notice is not for the entire number of shares represented by this Warrant, to issue a replacement Warrant Certificate in the name of the undersigned representing the balance of such shares.

Dated: By:

(Signature must conform in all respects to name of the Holder as set forth on the face of this Warrant)