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

The authors consider the IEEE 802.4 token-bus, IEEE 802.5 token-ring, and Fiber Distributed Data Interface (FDDI) network standards. They perform the delay analyses for these token-passing network standards when all the network traffic is of the highest priority class. They model them in an unified manner as a cyclic-service system with exhaustive time-limited service policies. They have specifically considered 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 is an algorithm to approximate the mean delays for the nonpreemptive policy. Numerical results show that the algorithm is reasonably accurate for deterministic and exponential frame sizes. The algorithm is applied to the performance analysis of a token-bus. A similar approach for the look-ahead policy is outlined