Abstract

We consider a system where the superposition of two heterogeneous Poisson traffic streams is offered to an integrated network link in synchronous transfer mode, where one stream follows the blocked-and-cleared mode (`loss' mode) and the other can wait (finitely) if bandwidth is not available for connection at the time of arrival (`hold' mode); we assume that each stream has different bandwidth requirements per call. A reservation scheme, called anticipated-release policy, is introduced where an arrival is accepted into a waiting room only if the amount of time this customer is expected to wait is within acceptable limits. For such a loss/hold system, we provide analytic performance models for exponential service time distributions for both streams as well as for the non-exponential service time distribution case for the traffic stream in `hold' mode. We also present a method on how to model the waiting time distribution of the traffic stream with `hold' mode. From numerical studies, we observe that blocking can be reduced considerably for both services just by introducing a small waiting room for one traffic class compared to `loss' mode for both traffic classes; further, this holds true for the case when a maximum tolerable time limit is imposed on the waiting. Finally, our results indicate that this loss/hold scenario with limited waiting room appears to be virtually insensitive to the service time distribution of the `hold'-mode traffic.

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