Exhibit 3.3


                           CERTIFICATE OF AMENDMENT

                                    TO THE

               AMENDED AND RESTATED CERTIFICATE OF INCORPORATION

                                      OF

                            SYCAMORE NETWORKS, INC.


                   _________________________________________

                     Pursuant to Section 242 of the General
                    Corporation Law of the State of Delaware
                   _________________________________________


          Sycamore Networks, Inc., a Delaware corporation (hereinafter called
the "Corporation"), does hereby certify as follows:

          FIRST: The first paragraph of Article Fourth of the Corporation's
Amended and Restated Certificate of Incorporation is hereby amended to read in
its entirety as set forth below:

          FOURTH: The total number of shares of all classes of stock which the
          Corporation shall have authority to issue is 2,505,000,000 shares,
          consisting of (i) 2,500,000,000 shares of Common Stock, $.001 par
          value per share ("Common Stock"), and (ii) 5,000,000 shares of
          Preferred Stock, $.01 par value per share ("Preferred Stock.).

          SECOND: The foregoing amendment was duly adopted in accordance with
Section 242 of the General Corporation Law of the State of Delaware.

          IN WITNESS WHEREOF, Sycamore Networks, Inc. has caused this
Certificate to be duly executed in its corporate name this 14/th/ day of
December, 2000

                                    SYCAMORE NETWORKS, INC.


                                    By: /s/ Daniel E. Smith
                                       ------------------------

                                    Name:  Daniel E. Smith
                                    Title: President and Chief Executive Officer