QoS-based routing with dynamic delay constraint blocking island algorithm

The thesis extends an existing QoS-based routing algorithm named Delay Constrained Blocking Island (DCBI). The extended algorithm, named Dynamic DCBI (DDCBI) takes into account dynamic aspects of the network state, such as queuing delay, in order to ensure the computation of routes that meet end-to-end delay constraints. Moreover, DDCBI checks periodically the end-to-end delay of the flows in progress. If the delay rises above the delay constraint, the path is recomputed. This is especially important for long-living demands, such as VPN applications. The performance of the DDCBI algorithm is investigated by simulation. The simulation is performed on the Network Simulator (ns) environment developed at Berkley. The analysis shows that the DDCBI algorithm has, indeed, the potential to achieve better end-to-end delay, and thus better QoS for delay-sensitive applications.