Minimizing Preemption Probability to Efficiently Support Service Differentiation in Just-in-Time Based OBS Networks

Preemptive contention resolution schemes are very effective solutions for providing service differentiation in optical burst switching networks. However, they cannot be applied together with the just-in-time signaling protocol because of the great loss in efficiency in terms of wavelength utilization and maximum achieved throughput that results when the number of preemptions becomes too large. This paper presents a preemption based service differentiation solution that is suitable for the just-in-time optical burst switching paradigm thanks to the fact that it can minimize the preemption probability (i.e., the probability of observing a preemption when a contention occurs). The proposed technique combines a conventional preemption scheme at core nodes and an improvement of the recently proposed burst cluster transmission scheme at edge nodes. In particular, bursts are created at their ingress node and combined into chains, arranging them in order of decreasing priority. Some traffic scenarios are analyzed by simulation to evaluate the performance of the proposed method.