Providing absolute QoS in an OBS/WR architecture

Abstract

By employing optical burst switching (OBS) in its metropolitan portion and wavelength routing (WR) in the backbone portion, the hybrid OBS/WR architecture provides end-to-end all-optical connections to end users while inheriting the fine granularity of OBS and the low loss probability of WR. However, the original OBS/WR architecture can provide only relative quality of service (QoS). That is, the burst loss possibilities of high-priority traffic flows are guaranteed to be lower than those of low-priority traffic flows, but the upper burst loss bound cannot be guaranteed with this model. We propose a call admission control (CAC) scheme to provide absolute QoS in an OBS/WR architecture and a dynamical priority allocation algorithm (DPAA) to enhance the blocking probability performance of the proposed CAC scheme. We first analyze the burst loss performance of traffic flows in the OBS/WR architecture. Based on the analytical results, a CAC scheme is proposed to provide absolute burst loss guarantee. Besides the CAC scheme, we also design a DPAA that assigns priorities to incoming traffic flows according to their QoS requirements to further improve the performance. The analysis and simulation results show that the proposed CAC scheme guarantees upper burst loss bound to different traffic flows while achieving significantly higher bandwidth utilization than other existing absolute QoS schemes in conventional OBS networks, and the proposed DPAA can achieve lower blocking probability than the original CAC scheme while maintaining the absolute QoS.