A positive–negative delayer for slotted OBS networks to enhance two-way signaling scheme

Abstract

Optical burst switching (OBS) is a promising technology for next-generation optical networks and slotted OBS is one of its improved versions. Contention between bursts is the main defect in OBS (as well as slotted OBS) networks. Different strategies are proposed to resolve contentions, such as using fiber delay line (FDL) to delay one of the conflicting bursts, or adopting two-way signaling scheme to gather states of links in advance. Unfortunately, the above two strategies cannot be used together, because FDL would deviate a burst from its planned trajectory, which would eliminate the effect of link state gathering in two-way scheme. In this paper, we design a novel delayer with ordinary FDLs, which can generate both positive and negative delay. The delayer can be used in two-way scheme without affecting the efficacy of link state gathering. Simulation results show that the delayer can greatly reduce the blocking rate of two-way scheme, by just a slight expense of average delay.