On the effectiveness of buffer sharing in multimedia server network switches with self-similar traffic

This paper evaluates the gain in throughput achieved by the use of a shared buffer to realize the output queues of switching elements in the presence of self-similar multimedia traffic. Unlike previous studies, we focus on credit-based systems typical of networks used in parallel multimedia servers. It is generally believed that buffer sharing improves performance in the presence of non-uniform traffic. With self-similar traffic exhibiting burstiness over all time-scales, however, we show that buffer sharing is a superior design choice only when the total buffer capacity is more than a certain minimum threshold. We explain the non-trivial reasons for the existence of this threshold through an analysis based on head-of-line blocking probabilities. The results presented here have implications in switch design, especially in systems where the total buffering capacity may be limited.