An exact model for the queueing analysis of a non-preemptive MMPP/D/1 priority system for ATM applications

This paper studies an exact model of a queueing system having two priority classes and a non-preemptive priority service discipline with constant service times. For each priority class, arrivals occur for two separate queues with infinite buffers and are modelled as two independent Markov modulated Poisson processes. The queue length densities of this system are computed. The results obtained are compared with simulations and with results obtained from an approximate model proposed earlier. The exact results agree well with simulations over all ranges of high and low priority traffic. The computational effort is less for the approximate approach but its results are found to be accurate only if the maximum average load offered to the server is not too high. We also extend the exact analysis to the case where the low priority queue is of finite size. The approach given may be used to analyze ATM systems operated with a non-preemptive priority service discipline. The approach may also be generalized to systems with more than two priority classes