Performance of a Packet Switch with Shared Buffer and Input Queueing

High performance of advanced packet switches can be achieved by providing queueing both at the input ports as well as at the output ports. This paper considers such a switch where output buffer sharing is introduced. A better memory utilization is expected when the output queueing space is shared among all the output ports as opposed to having dedicated queues at each output port. An analytical approach is presented for the performance study of this new scheme. The investigation is based on two performance measures: the average delay and the maximum throughput of the switch. Analytic results for these measures are derived. It is demonstrated that the scheme of output sharing offers significant improvements over the scheme of dedicated output queueing. It is found that the total output queueing space can be reduced by 70 percent, or more, while maintaining the same performance as in the scheme with dedicated output queues.