Delay analyses of token-passing protocols with limited token holding times

The primary concern of this paper is delay analysis of IEEE 802.4 token-bus, IEEE 802.5 token-ring, and Fiber Distributed Data Interface (FDDI) when all the network traffic is of the highest priority class. We model them in an unified manner as a cyclic-service system with exhaustive time-limited service policies. We have specifically pointed out two variants of the time-limited service policies-nonpreemptive and look-ahead. The former models the token-bus, and the latter models the token-ring and FDDI. The major result of this paper is an iterative algorithm to approximate the mean delays for the nonpreemptive policy. Numerical results show that the algorithm is reasonably accurate for both deterministic and exponential frame sizes. Last, we apply the algorithm to the performance analysis of a token-bus. In the appendix, we also outline a similar approach for the look-ahead policy