A performance modeling and evaluation of the Cambridge Fast Ring

Performance of the Cambridge Fast Ring (CFR), a high-speed slotted ring with normal slots, is studied. It is shown that the CFR can be represented by a multiqueue multiple cyclic server model with a 1-limited service discipline and with a restriction that only one server at a time can be serving a queue. Exact necessary and sufficient stability conditions are stated. An approximate analytic M/G/1 vacation model in which analysis concentrates on one station while the others are represented by a vacation period is developed to estimate the expected message waiting times. It is shown that the model is accurate and usable over a wide range of parameters. A performance evaluation of the CFR based on this model is presented. The performance is compared to that of a variant which does not restrict the number of slots a station may simultaneously use