Performance Comparison of Wavelength Routing Optical Networks with Chordal Ring and Mesh-Torus Topologies

Abstract

In this paper, we present a comparison of the blocking performance in wavelength routed optical networks with chordal ring and mesh-torus topologies. The comparison is focused on chordal rings with a chord length of N +3, being N the number of nodes, since this chord length leads to the smallest network diameter. This performance comparison revealed an important feature of chordal rings: very small blocking gains were observed, due to the increase of the node degree from 3 (chordal ring with a chord length of N+3) to 4 (mesh-torus). The comparison is made for networks with 100 and 1600 nodes. The influence of wavelength interchange on these small gains is also investigated: the node degree gain is very small and increases slightly as the converter density increases. Thus, if a small blocking performance degradation is allowed, the choice of a chordal ring with a chord length of N+3, instead of a mesh-torus, leads to a reduction in the number of network links, and hence in the total cable length, since the number of links in a N-node chordal ring is 3N, and the number of links in a N-node mesh-torus is 4N.