Parallel link server architecture: a novel contention avoidance mechanism in OBS networks

Abstract

Optical burst switching (OBS) is thought to be the best way to adapt bursty traffic of IP-based next generation network services. However, there are a lot of challenges to make OBS networking a reality. Of most concern is burst contention avoidance. The major contention avoidance resolutions in literature are wavelength conversion, fiber delay lines, and deflecting routing. They are very vulnerable to network load and may suffer from severe data loss in case of heavy traffic. Even at moderate traffic, contention caused by using these methods lead to burst blocking and data losses. In this article, a novel contention avoidance technique is presented by using the parallel link server (PLS) architecture, which may overcome the lack of information at the edge node and the absence of global coordination among nodes. Using Poisson and Self-Similar traffic arrival models, the proposed mechanism is compared with the traditional single link server architecture through simulation in the 14-node national science foundation network. The numerical results show that this architecture, without additional other methods, can obtain burst blocking and data dropping probabilities with almost two orders of magnitudes less than those in the single link server architecture. Gains are achieved by less than 7% increase in end-to-end delay when carrying coordinated traffic and a load under 0.45.