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Delay, echo, codec type, and packet loss all come into play in achieving the quality of PSTN calls in packet-based telephony.

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The throughput optimality of priority management strategies in a single buffer has been studied for a general aggregate arrival law. The tight upper bounds found are useful to understand optimality in the utilization of specific priority schemes such as push-out buffer (POB) and partial buffer sharing (PBS). This paper further focuses on the maximum allowable load max versus the priority mix ␣ for a PBS and a random push-out buffer (RPOB) of size K for a wide variety of arrival processes. The role of priorities in a special type of bursty arrivals, the compound Poisson process with constant burst length and random priority assignment within the burst is found to be less pronounced than that of 'pure' Poisson arrivals. On the other hand, the results for ON-OFF cell arrivals modelled by a MMPP(2), MMPP(3), and higher order Markov modulated processes (MMP) closely follow the behaviour of the maximum allowable load in the RPOB with Poisson arrivals, however, scaled to lower loads. The results indicate that the priority mix distribution within the aggregate arrival flow influences the shape of max (␣)-curve more than the aggregate arrival distribution itself.

In this paper, a discrete‐time multiserver queueing system with infinite waiting room and general independent arrivals is considered. The delay performance of such a system, under a first‐come‐first‐served queueing discipline, is evaluated by means of a purely analytical technique. Specifically, explicit formulae are derived for such quantities as the probability generating function, the mean value and the variance of the delay. The results of the study are useful, for instance, in the context of fast packet switching with output queueing, where the switching elements have their output ports organized in groups, each group corresponding to a separate output queue.