1 EXHIBIT 7 AGREEMENT AS TO JOINT FILING OF SCHEDULE 13D Each of the undersigned hereby affirms that it is individually eligible to use Schedule 13D and agrees that this Schedule 13D is filed on its behalf. Dated: March 8, 1999

   1
                                                                       EXHIBIT 7

                  AGREEMENT AS TO JOINT FILING OF SCHEDULE 13D

Each of the undersigned hereby affirms that it is individually eligible to use
Schedule 13D and agrees that this Schedule 13D is filed on its behalf.

Dated:  Xxxxx 0, 0000

                                  XXXXXXX


                                  By:  /s/  Xxxxx Xxxxxxx         
                                     -------------------------------------------
                                     Name:  Xxxxx Xxxxxxx
                                     Title: Chairman and Chief Executive Officer


                                  ALCATEL DATA NETWORKS, S.A.


                                  By:  /s/  Xxxxxxx Xxxxxxx
                                     -------------------------------------------
                                     Name:  Xxxxxxx Xxxxxxx
                                     Title: Chairman and Chief Executive Officer


                                  ZEUS ACQUISITION CORP.


                                  By:  /s/  Olivier Houssin       
                                     -------------------------------------------
                                     Name:  Olivier Houssin
                                     Title: Chairman