Traffic grooming for survivable WDM mesh networks

This paper addresses the problem of dynamically establishing dependable low-rate traffic stream connections in WDM mesh networks with traffic grooming capabilities. To establish a dependable connection, we set up link-disjoint primary and backup traffic stream paths between the source and destination and use backup multiplexing to reduce the overhead of backup traffic streams. We present a dynamic algorithm to obtain the optimal spare capacity on a wavelength on a link when a number of backup traffic streams are multiplexed onto it. We propose two schemes for grooming traffic streams onto wavelengths: Mixed Primary-Backup Grooming Policy (MGP) and Segregated Primary-Backup Grooming Policy (SGP). We illustrate how these schemes can be applied in a WDM mesh network scenario along with a routing and wavelength assignment algorithm. We conduct simulation experiments to evaluate the effectiveness of the proposed schemes on different network topologies, using different routing and wavelength assignment methods. The effect of change in granularity and change in the number of alternate paths on the grooming policies are also presented. From the simulation results, it is inferred that SGP is useful in network topologies, such as mesh-torus, characterized by good connectivity and a good amount of traffic switching and mixing at the nodes. On the other hand, MGP is useful in network topologies, such as a ring, characterized by low connectivity and high load correlation.