Input queueing of an internally non-blocking packet switch with two priority classes

Abstract

This paper analyzes an N × N non-blocking packet switch with two priority classes which can be used to support traffics with different requirements. Real time traffic such as voice is assigned high priority to satisfy its strict delay requirement while data traffic uses a lower priority and utilizes the remaining system capacity. The switch operation Is slotted, and at each time slot packets arrivals at the inputs have Bernoulli distributions with different probabilities for high and low priority classes. Packets of both priority classes can be queued when waiting for service and the service discipline is FCFS within each priority class. This Is in contrast with [6] where only low priority packets are queued. The priority discipline is preemptive at both the inputs and outputs where high priority packets always prevail over low priority packets. The paper provides explicit expressions for blocking probabilities and average delays. It also studies system stability and shows that the maximum throughput can in fact be higher than with no priority. © 1989 IEEE.