Switch Simulations Based on Workload Pattern Generation and Smoothed Periodic Input

Simulation is crucial to performance evaluation of switches. Currently stochastic simulation is the predominant approach, which has two drawbacks: few workload patterns and long simulation times. In this paper, we propose a novel switch simulation method that is based on two techniques: exhaustive workload pattern generation and smoothed periodic input generation. The exhaustive workload pattern generation can produce a huge number of nonuniform workload patterns, which far exceeds the traditional few ones; conclusions based on such truly extensive simulations are much more convincing. The periodic input or cell arrival pattern outperforms the stochastic counterpart in terms of easy repetition and fast convergence of simulation; in particular, among periodic inputs, the smoothed periodic input is most favorable to switch scheduling, and hence switches performing poor with it probably performs worse under others. Combining these two techniques together can systematically identify lots of stuck states at which some switches show poor performances such as low throughput. Specifically, this method discovers that the throughput of iSLIP, FIRM and DRRM, each with one iteration, may be lower than 60% under certain nonuniform and smoothed periodic traffic pattern.