content: <PAGE>
  
                        SECURITIES AND EXCHANGE COMMISSION
  
                              Washington, D.C. 20549
  
                                     Form 8-K
  
                                  Current Report
  
      Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934
  
        Date of Report (Date of earliest event reported):  October 5, 1999
  
  
                              FOUNDRY NETWORKS, INC.
              (Exact name of registrant as specified in its charter)
  
                                     000-26689
                             (Commission File Number)
  
  
  Delaware                                   77-0431154
  (State or other jurisdiction of            (I.R.S. Employer Identification No.)
  incorporation)
  
  
                           680 W. Maude Avenue, Suite 3
                                Sunnyvale, CA 94086
              (Address of principal executive offices, with zip code)
  
                                  (408) 530-3300
               (Registrant's telephone number, including area code)
  <PAGE>
  
  Item 5.  Other Events.
  
       Foundry Networks, Inc. announced on October 5, 1999 that based on its
  preliminary estimates, revenues for the quarter ended September 30, 1999 will be
  in the range of approximately $36 million to $38 million, exceeding the
  Company's internal expectations for this quarter.
  
       The Company's press release with regard to this development is attached
  hereto as Exhibit 99.1.
  
  Item 7.    Financial Statements and Exhibits.
  
        (c)  Exhibits.
  
        Exhibit 99.1  Press Release dated October 5, 1999 announcing revenue
                      estimates for the third quarter of 1999.
  
                                        -2-
  <PAGE>
  
                                    SIGNATURES
  
  
       Pursuant to the requirements of the Securities Exchange Act of 1934, the
  Registrant has duly caused this report to be signed on its behalf by the
  undersigned hereunto duly authorized.
  
  
                                     FOUNDRY NETWORKS, INC.
  
  
  
  Date:  October 7, 1999             By: /s/ Timothy D. Heffner
                                         -----------------------
                                         Timothy D. Heffner
                                         Vice President, Finance & Administration,
                                         Chief Financial Officer
  
                                        -3-
  <PAGE>
  
                                 INDEX TO EXHIBITS
                                 -----------------
  
  Exhibits
  --------
  
  Exhibit 99.1   Exhibit 99.1 Press Release dated October 5, 1999 announcing
                 revenue estimates for the third quarter of 1999.
  
                                        -4-
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text: SECURITIES AND EXCHANGE COMMISSION
  
                              Washington, D.C. 20549
  
                                     Form 8-K
  
                                  Current Report
  
      Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934
  
        Date of Report (Date of earliest event reported):  October 5, 1999
  
                              FOUNDRY NETWORKS, INC.
              (Exact name of registrant as specified in its charter)
  
                                     000-26689
                             (Commission File Number)
  
  Delaware                                   77-0431154
  (State or other jurisdiction of            (I.R.S. Employer Identification No.)
  incorporation)
  
                           680 W. Maude Avenue, Suite 3
                                Sunnyvale, CA 94086
              (Address of principal executive offices, with zip code)
  
                                  (408) 530-3300
               (Registrant's telephone number, including area code)
  Item 5.  Other Events.
  
       Foundry Networks, Inc. announced on October 5, 1999 that based on its
  preliminary estimates, revenues for the quarter ended September 30, 1999 will be
  in the range of approximately $36 million to $38 million, exceeding the
  Company's internal expectations for this quarter.
  
       The Company's press release with regard to this development is attached
  hereto as Exhibit 99.1.
  
  Item 7.    Financial Statements and Exhibits.
  
        (c)  Exhibits.
  
        Exhibit 99.1  Press Release dated October 5, 1999 announcing revenue
                      estimates for the third quarter of 1999.
  
                                        -2-
  SIGNATURES
  
       Pursuant to the requirements of the Securities Exchange Act of 1934, the
  Registrant has duly caused this report to be signed on its behalf by the
  undersigned hereunto duly authorized.
  
                                     FOUNDRY NETWORKS, INC.
  
  Date:  October 7, 1999             By: /s/ Timothy D. Heffner
                                         -----------------------
                                         Timothy D. Heffner
                                         Vice President, Finance & Administration,
                                         Chief Financial Officer
  
                                        -3-
  INDEX TO EXHIBITS
                                 -----------------
  
  Exhibits
  --------
  
  Exhibit 99.1   Exhibit 99.1 Press Release dated October 5, 1999 announcing
                 revenue estimates for the third quarter of 1999.
  
                                        -4-