EXHIBIT A --------- Agreement of Joint Filing ------------------------- The undersigned hereby agree that a single Schedule 13G (or any amendment thereto) relating to the Common Stock of iBEAM Broadcasting Corporation shall be filed on behalf of each...

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                                   EXHIBIT A
                                   ---------

                           Agreement of Joint Filing
                           -------------------------

      The undersigned hereby agree that a single Schedule 13G (or any amendment
thereto) relating to the Common Stock of iBEAM Broadcasting Corporation shall be
filed on behalf of each of the undersigned and that this Agreement shall be
filed as an exhibit to such Schedule 13G.

Date:  February 14, 2001

Entities:     Accel VI L.P.
              Accel VI Associates L.L.C.
              Accel Internet Fund II L.P.
              Accel Internet Fund II Associates L.L.C.
              Accel Keiretsu VI L.P.
              Accel Keiretsu VI Associates L.L.C.
              Accel Investors '98 L.P.
              Accel Investors '99(C) L.P.
                                         By:  /s/ X. Xxxxxx Sednaoui
                                           -------------------------
                                            X. Xxxxxx Sednaoui,
                                            Attorney-in-fact for the
                                            above-listed entities

Individuals:  Xxxxx X. Xxxxxx
              Xxxxxx X. Xxxxxxxxx
              X. Xxxxxx Sednaoui
              Xxxxx X. Xxxxxx
              J. Xxxxx Xxxxxx            By:  /s/ X. Xxxxxx Sednaoui
                                           -------------------------
                                            X. Xxxxxx Sednaoui,
                                            Attorney-in-fact for the
                                            above-listed individuals