Techniques for QoS Provisioning and Differentiation in OBS Networks

Abstract

In an OBS network, either reactive or proactive techniques are used to resolve the wavelength contentions. Reactive routing is generally online, which responds to contentions, but does not address the more general problem of congestion. Thus, there is a need for an offline network level contention avoidance technique to minimize burst contentions. Proactive routing strategies are generally offline, which avoid wavelength contentions and increase overall performance of burst transmissions by using efficient Routing and Wavelength Assignment (RWA) mechanisms. In this context, proactive routing is a convenient approach since it easily controls the distribution of burst traffic and requires minimum support from the control plane. In this thesis, I have analyzed the efficacy of the RWA approach in providing better QoS guarantees to loss sensitive bursts. Furthermore, the review of slotted-OBS architectures suggests that the synchronization among conflicting bursts is achieved by using fiber delay lines (FDLs) and the switching of a burst in time domain is inevitable even though it uses a non-overlapping path to reach the egress node. In this thesis, I have made an attempt to synchronize bursts only when necessary; i.e. the cases where a path used for transmitting a burst conflicts with another path on a common wavelength across a shared link.