The Physical Connection
Management (PCM) belongs to functional blocks of the Connection Management (CMT) in the FDDI ring.The Physical Connection Management (PCM) ensures the availability of the medium via the Entity Coordination Management (ECM). The PCM essentially consists of a finite state machine and the PCM pseudo-code. The state machine contains all the states and timing information of the PCM and provides the signaling on the optical conductor. The PCM pseudo-code specifies the bits to be transmitted and processes the incoming bits from the partner PCM instance.