Guaranteeing synchronous messages with arbitrary deadline constraints in an FDDI network

Issues related to guaranteeing synchronous messages with arbitrary deadline constraints in a fiber distributed data interface (FDDI) network are addressed. It is shown that several network parameters must be set carefully if message deadlines are to be satisfied. Message deadlines can only be met if sufficient synchronous bandwidth is allocated to each mode. Thus, proper synchronous bandwidth allocation is essential if deadlines are to be guaranteed. The target token rotation time (TTRT) determines both the speed of token circulation and the network utilization available to user applications. TTRT should also be chosen carefully to ensure that the token circulates fast enough while maintaining a high available utilization. Sufficient buffer space must be provided for outgoing messages, otherwise messages could be lost due to buffer overflow. An integrated method for allocating the synchronous bandwidth and selecting TTRT so that the time constraints of synchronous messages with arbitrary deadlines are guaranteed to be met is proposed and analyzed