Link scheduling state information based offset management for fairness improvement in WDM optical burst switching networks

Abstract

In wavelength division multiplexed (WDM)-based optical burst switching (OBS) networks, bursts that traverse longer paths are more likely to be dropped compared to bursts that traverse shorter paths resulting in a fairness problem. Fairness here refers to having, for all ingress–egress node pairs in a network, a burst to have equal likelihood to get through independent of the hop length involved. In this paper, we develop a link scheduling state based fairness improvement method which can be used in a classless as well as a multi-class environment. The basic idea is to collect link scheduling state information and use it to determine the offset times for routes with different hop lengths. By using the online link state information, this method periodically computes and adapts the offset times needed, thus inherently accounting for the traffic loading patterns and network topological connectivity. It also ensures that the delay experienced by a burst is low and shorter-hop bursts are not over-penalized while improving the performance of longer-hop bursts. The effectiveness of the proposed method is evaluated through simulation experiments.