The authors model the delay-throughput performance of a class of multiple-access circuit-switched ring local area networks that allow multiple messages to be transferred concurrently on the ring. In particular, they model analytically the PLAYTHROUGH protocol under assumptions of uniform and symmetric traffic, infinite buffers, and a first-in, first-out (FIFO) queueing discipline at each station to predict message mean waiting times that adequately approximate waiting times observed through simulation. The queue is analyzed at an arbitrary station as a M/G/1 vacation system having a Bernoulli schedule with parameter p. Expressions for the vacation duration and p are derived in terms of service times and competing traffic intensities on PLAYTHROUGH rings. The vacation period is modeled as a series of subvacations because the server is allowed to take multiple subvacations when the queue is nonempty. Application of this modeling strategy is shown to provide good agreement between analytical predictions and simulation results. The performance of this class of networks is compared with that of token rings.>

Analytical models are presented and shown to approximate adequately simulation results for average message queuing time, service time, and control frame round trip time on ring-topology local area networks. These LANs use a PLAYTHROUGH protocol, a data link layer medium access control protocol that achieves concurrent transfer of multiple messages of arbitrary length. The analytical predictions of data message service time and control frame round trip time are used in a queuing system model of average message waiting times versus throughput for this class of multiserver circuit-switched ring under assumptions of uniform and symmetric traffic and a shortest outbound distance first service discipline at each node. The analytical models are validated using simulation results. The analysis includes both the effects of competing traffic originating at other nodes on the ring and the effects of the medium access control mechanism overhead on the waiting times experienced by messages arriving at an arbitrarily chosen node.>

The authors model delay-throughput performance of high- and low-priority message transfer on PLAYTHROUGH rings and compare analytical approximations to simulation results. Both analytical and simulation results show that high-priority messages gain rapid access to the ring independently of low-priority traffic intensity. The analytical model predictions for both service time and queueing time are in good agreement with simulation results for both priority classes. The models presented are completely analytical and do not rely on curve fitting of simulation data to predict message waiting time.>

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.>