A multi-layer approach for load balancing in optical burst switching networks

In optical burst switching (OBS) networks, contention is reckoned as a major issue since it not only reduces the efficiency and utilization of resources, but can also trigger TCP congestion control strategies. Contention can be reduced by avoiding multi layer network congestion through load balancing. This paper presents the results of a study of Split-TCP based deflection routing for load balancing to reduce network congestion and hence contention in OBS networks. Initially, in transport layer N:1:N Split TCP approach is enforced over the ingress node. The data bursts upon reaching the OBS routing and burst management layer are segmented and probed for contention. If contention occurs, then the flow is prioritized and deflected to a random free output link. The adaptability of the network to time varying loads and the overall efficacy of this technique in limiting burst losses are assessed through this study. We compare the efficiency of the above scheme with similar implementation of Sack TCP in OBS layer. By simulation results, we show that the Split TCP deflection routing approach offers efficient load balancing, with more than 50% reduction in end to end delay and a quadruple increase in throughput when compared to Sack deflection routing.