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                                                                     EXHIBIT 4.5

Number                                                                    Shares
------                                                                    ------
  XX                                                                       XXXXX

                             CABLETRON SYSTEMS, INC.

              Series D Convertible Preferred Stock, $1.00 Par Value

       SEE REVERSE SIDE FOR RESTRICTIONS ON TRANSFER AND CLASSES OF STOCK

       This certifies that -- SPECIMEN - is the owner of -- SPECIMEN - shares,
fully paid and non-assessable, of the Series D Convertible Preferred Stock of
CABLETRON SYSTEMS, INC., a Delaware corporation, transferable only on the books
of the corporation by the holder hereof in person or by attorney upon surrender
of this certificate properly endorsed.

       This certificate and the shares represented hereby are subject to the
General Corporation Law of the State of Delaware and to the Certificate of
Incorporation and the By-laws of the corporation, in each case as from time to
time amended.

       IN WITNESS WHEREOF, CABLETRON SYSTEMS, INC. has caused this certificate
to be signed by its duly authorized officers and its corporate seal to be hereto
affixed this ____day of July, 2001.


--------------------------------               ---------------------------------
Any one of Chairman,                           Any one of Treasurer,
Vice Chairman, President or Vice               Assistant Treasurer, Secretary or
President                                      Assistant Secretary


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                            RESTRICTIONS ON TRANSFER

       The Securities represented hereby have not been registered under the
Securities Act of 1933, As Amended (the "Act"), and may not be offered, sold or
otherwise transferred, assigned, pledged or hypothecated unless and until
registered under the Act or unless the Corporation has received an opinion of
counsel satisfactory to the Corporation and its counsel that such registration
is not required.

       The holder of the securities represented by this certificate is subject
to certain obligations contained in a Standstill Agreement dated as of August
29, 2000, as amended, a copy of which is available for inspection at the
principal office of the issuer hereof, and will be furnished without charge to
the holder of such securities upon written request.

       The powers, designations, preferences and relative participating,
optional or other special rights, and the qualifications, limitations or
restrictions of such preferences and/or rights, of each class of stock of the
Corporation, or series of any such class, are set forth in the Certificate of
Incorporation. The Corporation will furnish a copy of the Certificate of
Incorporation to the holder of this certificate without charge upon request.

                                   ASSIGNMENT

       For value received, the undersigned hereby sells, assigns and transfers
to ___________________________ shares of the capital stock represented by this
certificate, and does hereby irrevocably constitute and appoint
_____________________________ attorney to transfer such stock on the books
______________with full power of substitution in the premises.



Dated _________________

                              Signature of registered owner corresponding
                              exactly to the name of such owner as written on
                              the face of this certificate.