Abstract: A programmable multispeed communication apparatus includes a plurality of identical media access control (MAC) units for use with a programmable data processing system. The MAC units when multiplexed and connected to a communication media achieve a transmission speed n·s where n is the number of MAC units and s is the speed of the individual MACs. If one or more but not all of the MAC units fail, the apparatus will operate in degraded mode with the remaining active MAC units. User frames are sequentially numbered, partitioned into sequentially numbered partitions which are assigned to one or more MAC's. Each of the partitions includes a prefix which includes the sequential frame number, the sequential partition number and an indicator for distinguishing the last partition of a frame from the other partitions of that frame.