A Novel Cooperation Method for Routing and Wavelength Assignment in Optical Burst Switched Networks

Abstract

In Optical Burst Switching (OBS) networks, one of the main problems is collision between bursts. Most of the previous collision avoidance algorithms divide the Routing and Wavelength Assignment (RWA) problem into two partial problems and treat them separately. This paper focuses on the collision avoidance problem in distributed OBS networks. Our proposal involves cooperation between the routing and the wavelength assignment tasks. The main idea is to classify each wavelength at an output link of a node as suited either to sending or to relaying data bursts. The wavelength most suitable for transmitting bursts changes along the transmission route. Thus, we introduced a novel index called the Suitability Index (SI). The SI is a priority index assigned to each pair of output link and wavelength, and its value represents the suitability of that pair for sending or relaying data bursts. The proposed method uses the SI for both routing selection and wavelength assignment. Simulation results show that the proposed method can reduce the burst loss probability, particularly for long distance transmissions. As a result, unfairness in the treatment of short hop and long hop bursts can be reduced.