Analysis of demand-priority access using a priority queue with server vacations and message dependent switchover times

Abstract

In this paper, we analyse the message waiting times in a local area network (LAN) that uses the demand-priority access method. This is a priority-based round-robin arbitration method where the central controller (the repeater) polls its connected ports to determine which have transmission requests pending and the requests' priority classes. We model it as a 2-priority M/G/1 queue with multiple server vacations and switchover time between service periods. The service discipline is nonpreemptive and the length of the switchover time is dependent upon the priority class of the preceding message served as well as that of the message to be served next. We provide an approximate analysis for the waiting times of both message classes and derive expressions for the Laplace-Stieltjes transforms (LST) of the stationary distributions and the mean waiting times. We conclude with numerical and simulation results to show the applicability and accuracy of the analytical model. © J.C. Baltzer AG, Science Publishers.