Routing Scheme for OBS Networks

Abstract

We observe that routing, in optical burst switching (OBS) networks, is basically motivated by reducing contention-induced loss and not by the objective of global resource optimization. Here, we propose a routing scheme for OBS networks that minimizes the burst loss probability of individual bursts and at the same time achieves the routing goal of maximization of the minimum unutilized bandwidth of links in the network. All OBS nodes periodically exchange their scheduler-state information, and hence all nodes learn the topology of the network along with the occupancy states of each link. Based on this information the end-to-end wavelength availability states of the routes are computed, and bursts are then routed through the path that is likely to give minimum loss. The scheme can be applied in both source-routing and hop-by-hop-routing modes with provision for deflection routing in each mode. We studied the performance of the proposed scheme through simulation and found that it reduces the loss rates significantly. The performance in the source-routing mode was found to be better for small and medium-sized networks, whereas the performance for the hop-by-hop-routing mode was found to be better for larger networks.