A review on a new conservation law in optical burst switching networks

A major challenge in optical burst switching (OBS) networks is how to provide quality of service (QoS). One scheme is burst preemption, in which a high priority burst can preempt a low priority one if there is no available output channel. To analyze the performance of prioritized preemption scheme, a conservation law is widely used without proof in the literature. In this paper, we show that the original conservation law does not hold if the mean burst length of different classes is unequal. We then present an exact model for burst blocking probabilities of multiple priority classes with unequal mean burst lengths by considering the effects of blocking probabilities and preemption probabilities on the mean overall service time. We also propose an approximate model. Our extensive simulation results show that the approximation model can yield accurate solutions under different traffic conditions.