Throughput analysis of multi-input & single-output channels in core routers of optical burst switching networks

Abstract

We describe here a new burst scheduling algorithm to avoid burst overlapping in the egress router of optical burst switching (OBS) network, and hence to improve the quality of service (QoS) in developing several optical networks to fulfill the increasing demand of Internet facilities. We consider TAG (tell-and-go) protocol where many lightpaths pass in a given link and burst overlap may occur. In an intermediate node having many incoming links and one outgoing link at lower traffic loads, we found the conditions for the burst controls, either passing of all bursts or blocking of some bursts in the egress nodes of optical domain. It is shown that in low traffic loads, burst blocking can be made zero but in higher traffic loads there is burst blocking, which can be reduced using different sets of fiber delay lines (FDLs) for which minimum usage of wavelengths can be achieved. The relation between number of burst blocking and the requirements of FDLs are shown. We used time-based assembly algorithm in an assembly node to build the burst at low and high traffic loads. The analysis for throughput depending on burst size, inter-arrival time, and sizes of fiber delay lines (FDLs), is made and improvement of throughput using FDLs is shown. Passing of bursts at the input channel and hence the priority of channels depending upon the burst size, intermediate gap between two successive bursts in the input channels, the arrival time for the first burst in the second & third input channels, and the FDL used in core nodes are shown.