FORM OF AMENDMENT TO VOTING AGREEMENT

Exhibit 2.2.1

FORM OF
AMENDMENT TO VOTING AGREEMENT

      This Voting Agreement Amendment ( “ Voting Agreement Amendment ”) is entered into as of November ___, 2008, by and between Brocade Communications Systems, Inc . , a Delaware corporation (“ Parent ”), and the undersigned stockholder (“ Stockholder ”) of Foundry Networks, Inc. , a Delaware corporation (the “ Company ”).

Recitals

      A.  Stockholder Owns certain securities of the Company.

      B.  Parent, Falcon Acquisition Sub, Inc., a Delaware corporation (“ Merger Sub ”), and the Company entered into an Agreement and Plan of Merger dated as of July 21, 2008 (the “ Merger Agreement ”) which provided (subject to the conditions set forth therein) for the merger of Merger Sub into the Company.

      C.  In connection with the execution and delivery of the Merger Agreement, Parent and Stockholder entered into a Voting Agreement (the “ Voting Agreement ”) and Stockholder executed and delivered in favor of Parent an Irrevocable Proxy in the form attached to the Voting Agreement as Exhibit A (the “ Proxy ”).

      D.  Parent, Merger Sub and the Company are entering into a document entitled “Amendment No. 1 to Agreement and Plan of Merger” of even date herewith (the “ Merger Agreement Amendment ”), which amends the Merger Agreement in certain respects, including by, among other things, decreasing the amount of the Merger Consideration (as defined in the Merger Agreement) payable thereunder.

      E.  Pursuant to the terms of the Voting Agreement, the decrease in the Merger Consideration effected by the Merger Agreement Amendment would result in the occurrence of the “Termination Date” under the Voting Agreement unless Parent and Stockholder enter into an amendment to the Voting Agreement that extends the Termination Date to a later date. Parent and Stockholder desire to amend the Voting Agreement to provide that the Termination Date shall not occur by reason of the reduction in the Merger Consideration effected by the Merger Agreement Amendment.

      F.  Stockholder is entering into this Voting Agreement Amendment in order to induce Parent to enter into the Merger Agreement Amendment.

Agreement

          The parties to this Voting Agreement Amendment, intending to be legally bound, agree as follows:

      Section 1. Definitions

           1.1 Definitions. Each capitalized term used but not defined in this Voting Agreement Amendment shall have the meaning assigned to such term in the Voting Agreement.

      Section 2. Amendment to Voting Agreement

           2.1 No Termination Date. Stockholder hereby agrees and acknowledges that notwithstanding anything to the contrary in the Voting Agreement, the Termination Date shall not be deemed to have occurred by reason of either (a) the entering into of the Merger Agreement Amendment or (b) any of the terms of