Contention Resolution for Optical Switching: Tuning the Channel and Delay Selection Algorithm

Optical packet switching and burst switching provide future-proof alternatives to the current electronic switching in the backbone. To resolve burst (or packet) contention, fiber delay lines are put to use as buffers, as vital part of a channel and delay selection (CDS) algorithm. In case no void-filling is applied, earlier studies pointed out that minimal loss is obtained by selecting delay lines and channels according to a minimal gap (MING) strategy. The current contribution reexamines this strategy, and presents a general CDS optimization method based on a Markov decision process. Applying this method to a specific setting, we found that several well-tuned CDS algorithm outperform MING. Exact expressions are given for a two-channel configuration with general inter-arrival times and fixed burst sizes. Detailed results for CDS optimization of a specific setting are included, showing that the traffic load has a crucial impact on the optimum found. Some CDS algorithms consistently outperform MING (for any value of the load), whereas others are only optimized for either high or low traffic load.