Load Balanced Deflection Routing and Priority Scheduling in OBS Networks

In Optical Burst Switching (OBS) networks, the primary issue is the contention resolution which occurs when two or more bursts contend for the same output port at the same time. Since the deflected route does not consider load balancing, it leads to loss of bursts. In order to minimize the loss, load balancing needs to be performed in the routing. In this paper, we propose a load balanced deflection routing to avoid congestion and preemptive priority scheduling for OBS networks. We determine the primary and alternative paths using the shortest hop path routing (SHPR) and the load of each node is calculated. After every interval, dynamic routing selects the least-congested path as the alternative path and the bursts are deflected into this path. In preemptive priority scheduling, the reservation scheduled for a deflected burst can be preempted by the non-deflected burst. Thus a congestion free load balanced path can be selected using our contention resolution technique. By simulation results, we show that our proposed approach achieves better throughput and packet delivery ratio with less delay.