Efficient simulation of delay in tandem networks using splitting

The complexity of modern networks and the stringent quality of service requirements that result in very small important event probabilities can render standard Monte Carlo (MC) simulation intractable. Accelerated simulation using splitting can potentially overcome these difficulties, but conventional methods cannot be successfully applied to systems for which the occurrence of the important event does not temporally coincide with the conditions that lead to it. Cell delay experienced through single and tandem switches exhibits this behavior. We develop two enhanced splitting methods based on a splitting technique which was previously used to estimate rate delay probabilities through a single switch. The enhanced methods accurately capture the queueing behavior that leads to excessive cell delay through tandem switches. We use the enhanced methods to efficiently estimate rate delay probabilities for tagged traffic traversing tandem switches in the presence of background traffic. The enhanced methods penetrate into a significantly higher delay (lower probability) region compared to the previous method. Speedup over standard MC simulation is observed to be inversely proportional to the probability being estimated.