Analysing Timed-Token Ring Protocols Using the Power Series Algorithm

Abstract

We analyze in this paper the performance of Token Ring Protocols with constraints on the cycle times. Each station may have a different cycle time constraint, and a different number of buffers. We consider two types of service discipline in the different stations: (i) the 1-limited case, where at most one packet may be transmitted from each queue at each visit of the token, provided that the cycle time constraints are satisfied, and (ii) the exhaustive service discipline where in each queue, packets are transmitted till either the queue empties or the cycle time constraint in that queue is violated. The system we analyze approximates both the FDDI protocol (Fiber Distributed Data Interface) and the IEEE 802.4 Token Bus Standard. Based on a power-series algorithm, we obtain the expected throughput and delay in every station, as well as the first two moments of the queues' length.