Optimized Channel and Delay Selection for Contention Resolution in Optical Networks

Both optical packet switching and optical burst switching provide viable alternatives to the current electronic switching in the backbone. To resolve contention, contiguous packets/bursts are sent over different channels, and/or provided with different Fiber Delay Line (FDL) buffer delays. Typically, the resulting channel and delay selection (CDS) algorithm bases its decision on the horizon value of the different channels. Up to now, a horizon algorithm known as MING (MINimal Gap) was assumed to provide minimal loss. Relying on Markov chain-based performance modeling and a Markov decision process (MDP), we reexamine the optimality of MING. This enables us to construct CDS algorithms that outperform MING, and this for any buffer size, traffic load and packet/burst size distribution. Further, we consider burst-size-dependent and load-dependent scheduling, two stochastic mechanisms that, together with preventive dropping, enhance the algorithm´s performance. The paper presents the developed method in detail, together with detailed results of the performance gain realized.