Efficient algorithms for routing dependable connections in WDM optical networks

We consider the problem of establishing dependable connections in WDM netwo rks with dynamic traffic demands. We call a connection with fault-tolerant requirements as a dependable connection (D-connection). We consider the sin gle-link failure model in our study and recommend the use of a proactive ap proach, wherein a D-connection is identified with the establishment of the primary lightpath and a backup lightpath at the time of honoring the connec tion request. We develop algorithms to select routes and wavelengths to est ablish D-connections with improved blocking performance. The algorithms use the backup multiplexing technique to efficiently utilize the wavelength ch annels. To further improve channel utilization, we propose a new multiplexi ng technique called primary-backup multiplexing. Here, a connection may not have its backup lightpath readily available throughout its existence. We d evelop algorithms based on this technique to route D-connections with a spe cified restoration guarantee. We present an efficient and computationally s imple heuristic to estimate the average number of connections per link that do not have backup lightpaths readily available upon a link failure. We co nduct extensive simulation experiments on different networks to study the p erformance of the proposed algorithms.