PROSPECTUS SUPPLEMENT                           Filed Pursuant to Rule 424(b)(3)
(To Prospectus dated July 26, 2000)                        File Number 333-39692

                                  $500,000,000
                      [REDBACK NETWORKS LOGO APPEARS HERE]

              5% Convertible Subordinated Notes due April 1, 2007
       (and Shares of Common Stock issuable upon conversion of the Notes)

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   This Prospectus Supplement supplements the Prospectus dated July 26, 2000
relating to resales by selling holders of our 5% Convertible Subordinated Notes
due April 1, 2007 (the "Notes") and shares of our common stock into which the
Notes are convertible. This Prospectus Supplement is incorporated by reference
into the Prospectus, and all terms used herein shall have the meaning assigned
to them in the Prospectus. Our common stock is quoted on the Nasdaq National
Market under the symbol "RBAK."

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   The information in the table appearing in the prospectus under the heading
"SELLING HOLDERS" is superseded in part and supplemented by the information
appearing in the following table:



                                                                                            Shares of
                                                        Notes      Number of              Common Stock
                                                    Beneficially   Shares of   Number of  Beneficially
                              Notes                  Owned After  Common Stock Shares of   Owned After
                           Beneficially    Notes     Offering(1)  Beneficially  Common   Offering(1)(2)
                           Owned Prior    Offered    (in $1,000)  Owned Prior    Stock     (in $1,000)
                           to Offering    Hereby    -------------      to       Offered  ---------------
 Name of Selling Holders   (in $1,000)  (in $1,000)   #      %    Offering(2)   Hereby      #       %
 -----------------------   ------------ ----------- ------------- ------------ --------- ---------------
                                                                         
 Goldman Sachs and
  Company................      400          400          0      0    2,097       2,097         0       0

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(1) It is unknown if, when or in what amounts a selling securityholder may
    offer securities for sale and we do not know that the selling
    securityholders will sell any or all of the securities offered hereby.
    Because the selling securityholders may offer all or some of the securities
    pursuant to this prospectus, and because there are currently no other
    agreements, arrangements or understandings with respect to the sale of any
    of the securities that will be held by the selling securityholders, no
    estimate can be given as to the amount of the securities that will be held
    by the selling securityholders after completion of the offering made by
    this prospectus. However, for purposes of this table, we have assumed that,
    after completion of the offering, no securities will be held by the selling
    securityholders.

(2) The number of securities beneficially owned is determined under the rules
    of the SEC and the information is not necessarily indicative of beneficial
    ownership for any other purpose. Under those rules, beneficial ownership
    includes any securities as to which the individual has sole or shared
    voting power or investment power and also any securities which the
    individual has the right to acquire within 60 days after August 23, 2001
    through the exercise of any stock option or other right. The inclusion in
    the table of securities, however, does not constitute an admission that the
    selling securityholders are direct or indirect beneficial owners of those
    securities. The selling securityholders have sole voting power and
    investment power with respect to all securities of capital stock listed as
    owned by the selling securityholders.

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   SEE "RISK FACTORS" BEGINNING ON PAGE 8 OF THE ACCOMPANYING PROSPECTUS TO
READ ABOUT FACTORS YOU SHOULD CONSIDER BEFORE INVESTING IN THE NOTES OR SHARES
OF THE COMMON STOCK OFFERED HEREBY.

  These securities have not been approved or disapproved by the Securities and
                              Exchange Commission
     or any state securities commission nor has the Securities and Exchange
                               Commission or any
    state securities commission passed upon the accuracy or adequacy of this
                                  Prospectus.
           Any representation to the contrary is a criminal offense.

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           The date of this Prospectus Supplement is August 23, 2001.