Asynchronous Transfer Mode (ATM) switching systems have been developed in order to support the new traffic patterns in telecommunication networks. An ATM switching system is composed of identical basic switching building blocks called switching elements that have been arranged in a particular topology. The basic function of a switching element is to buffer cells that are destined for the same outlet. Currently, two major buffering strategies are available for use in switching elements, input buffering and output buffering. Each buffering strategy affects the performance of the switching element in the areas of delay, cell loss and the number of buffers required to operate at a particular traffic rate.

In this paper, we present the results of both theoretical analysis and computer simulation of input buffering. Examination of average cell waiting times shows that as the utilization increases, the cell waiting time increases up to the point of input queue saturation. As the number of input queues is increased, the average cell time wait increases, i.e., the delay is higher at lower utilizations. The resulting curves agree favorably when compared with existing literature. Also, the analysis of ouput port contention shows that the contention increases with the utilization and that the number of output port conflicts increases with both the utilization and the number of input queues. These results are presented in a series of new curves that present the number of cells delivered during output conflicts versus utilization. We believe that the contention curves present a new technique of reviewing the simulation results because such results were never reported before.