INPUT VS. OUTPUT QUEUEING ON A SPACE-DIVISION PACKET SWITCH.

Using Markov chain models, queueing theory, and simulation, a thorough comparison of input versus output queueing on an N multiplied by N crossbar packet switch is presented. The authors quantify the performance improvements provided by output queueing for a simple model in which packet arrivals on the N input trunks are governed by independent and identical Bernoulli processes. In any given time slot, the probability that a packet will arrive on a particular input is p; thus p represents the average utilization of each input. Each packet has equal probability 1/N of being addressed to any given output, and successive packets are independent. It is shown that, if possible, it is better to queue on the outputs than the inputs of a space-division packet switch.