Effect of burst length on loss probability in OBS networks with void-filling scheduling

Abstract

Optical burst switching (OBS) is a new transport architecture for the next generation optical internet infrastructure which is necessary for the increasing demand of high speed data traffic. Optical burst switching stands between optical packet switching, which is technologically difficult, and optical circuit switching, which is not capable of efficiently transporting bursty internet traffic. Apart from its promising features, optical burst switching suffers from high traffic blocking probabilities. Wavelength conversion coupled with fiber delay lines (FDL) provide one of the best means of contention resolution in optical burst switching networks. In this thesis, we examine the relation between burst loss probability and burst sizes for void filling scheduling algorithms. Simulations are performed for various values of the processing and switching times and for different values of wavelengths per fiber and FDL granularity. The main contribution of this thesis is the analysis of the relationship between burst sizes and processing time and FDL induced voids. This in turn creates a better understanding of the burstification and contention resolution mechanisms in OBS networks. We show that voids generated during scheduling are governed by the FDL granularity and the product of the per-hop processing delay and residual number of hops until the destination. We also show that differentiation between bursts with different sizes is achieved for different network parameters and a differentiation mechanism based on burst lengths is proposed for OBS networks.