A performance model for concurrent message transfer on Playthrough rings

The authors present analytical models to approximate average message queueing time, service time, and token round trip time on ring topology local area networks that use a Playthrough protocol. Playthrough's data-link-layer protocol uses a continually circulating control token, source removed update control messages, and destination-removed data messages to achieve concurrent transfer of multiple messages of arbitrary length. The models of data-message service time and token round trip time are used in a queueing system model for average message waiting time in this class of multiserver circuit-switched ring. The collection of analytical models is shown to adequately approximate simulated queueing times for messages transmitted using a shortest-outbound-distance-first queueing discipline. This analysis differs from earlier approximations in that it includes the effects of both bridge traffic and downstream blocking traffic on the waiting times experienced by messages arriving at an arbitrary node.< >