Pospectus Supplement No. 1                      Filed Pursuant To Rule 424(b)(3)
To Prospectus Dated November 17, 1999                 Registration No. 333-90011


                                 C-COR.net CORP.

                        1,794,802 Shares of Common Stock


     This  Prospectus  Supplement  supplements  information  contained  in  that
certain  Prospectus of C-COR.net Corp. (the "Company")  dated November 17, 1999,
relating to the resale by the selling  shareholders  listed therein of shares of
Common Stock, par value of $0.10 per share (the "Common Stock"), of the Company.
This Prospectus  Supplement is not complete without, and may not be delivered or
utilized except in connection with, the Prospectus,  including any amendments or
supplements  thereto.  All  capitalized  terms  used  but  not  defined  in this
Prospectus Supplement shall have the meanings given them in the Prospectus.

     The section entitled  "SELLING  SHAREHOLDERS,"  beginning on page 14 of the
Prospectus is amended to restate the information with respect to James T. Chang.
The information set forth below replaces the information in the Prospectus.



                                                      Securities Owned                                 Securities Owned
                                                      Prior to Offering                                 After Offering
                                    ---------------------------------------------------        --------------------------------
                                                          Shares of                              Number of
                                      Shares of         Common Stock        Percent of           Shares of          Percent of
Name of Selling Shareholder         Common Stock       Offered Hereby      Common Stock        Common Stock        Common Stock
- --------------------------------    ------------       --------------      ------------        ------------        ------------

                                                                                                          
James T. Chang..................        2,735                2,735               *                     0                 *


- -----------------------
*Less than one percent.


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     AN INVESTMENT IN THE SHARES OFFERED HEREBY  INVOLVES A HIGH DEGREE OF RISK.
SEE "RISK FACTORS" BEGINNING ON PAGE 4 OF THE PROSPECTUS.

                  --------------------------------------------



     NEITHER THE  SECURITIES AND EXCHANGE  COMMISSION  NOR ANY STATE  SECURITIES
COMMISSION HAS APPROVED OR  DISAPPROVED  OF THESE  SECURITIES OR PASSED UPON THE
ACCURACY  OR ADEQUACY  OF THE  PROSPECTUS  OR THIS  PROSPECTUS  SUPPLEMENT.  ANY
REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE.

           The date of this Prospectus Supplement is December 3, 1999.