A Simulation Methodology to Study Input Buffering in ATM Switches

This paper presents a performance study of input buffering in Asynchronous Transfer Mode switches. The main performance metrics are average cell wait ing time and output port contention under a variety of load conditions and operating environments. Re sults show that as the percent utilization increases, the average cell wait time increases. Analysis of out put port contention shows that it increases with the increase in utilization, and the number of conflicts increases with both the utilization and the input queues. The results are presented in a series of curves that present the number of cells delivered during output conflicts versus percent utilization. The soft ware developed offers several benefits: it provides a flexible approach to investigate performance of input queueing under a variety of conditions. The simula tion duration, interarrival distribution, number of input queues and maximum queue size can all be varied simply by editing the initialization file; no recompiling of source code is required. It allows for modification and extensibility with only minor soft ware changes. It does not contain operating-specific function calls; thus, it can be used without changes on standard DOS-based PCs or UNIX-based systems.