Kautz graphs as attractive logical topologies in multihop lightwave networks

Abstract

In this paper, we propose Kautz graphs as attractive logical topologies for multihop WDM lightwave networks. Logical topologies proposed in the literature include the ShuffleNet, De Bruijn graph, Manhattan Street Network, and Hypercube. We show that for a given nodal in-degree and out-degree and average number of hops between stations, a network based on Kautz graphs can support a much larger number of stations than competing topologies ( ShuffleNet and De Bruijn networks). Our experimental and analytical results show that despite its larger size (more number of stations), a Kautz graph based network shows similar delay and throughput performance as a De Bruijn graph based network. Further, a topology based on Kautz graph has more uniform optical channel loading and utilizes the installed network capacity more efficiently than a De Bruijn network. In addition, fault tolerance properties of Kautz graphs are better than those of De Bruijn graphs. To deal with non-uniform and asymmetric traffic, an adaptive routing scheme is proposed for Kautz networks, which relieves the network of congestion bottlenecks resulting from non-uniform traffic. Finally, we give the VLSI design and layout a router for Kautz graph-based networks using OASIS ( Open Architecture Silicon Implementation Software).