On the effectiveness of alternative paths in QoS routing

We propose a routing strategy in which connection requests with specific bandwidth demands can be assigned to one of several alternative paths connecting the source to the destination. The primary goal of this multiple-path approach is to compensate for the inaccuracy of the knowledge available to routing nodes, caused by the limited frequency of link state (LS) information exchanges. We introduce a collection of K-shortest path routing schemes and investigate their performance under a variety of traffic conditions and network configurations. We subsequently demonstrate that K-shortest path routing offers a lower blocking probability in all scenarios and more balanced link utilization than other routing methods discussed in the literature. With our approach, it is possible to reduce the frequency of link state exchanges, and the incurred bandwidth overhead, without compromising the overall performance of the network. Based on the proposed routing scheme, we investigate different link state dissemination algorithms, which are aimed at reducing the communication overhead by prioritizing the scope and differentiating the qualitative content of LS update messages. Copyright (C) 2004 John Wiley Sons, Ltd.