A comprehensive study on backup reprovisioning to remedy the effect of multiple-link failures in WDM mesh networks

As networks grow in size and complexity, both the probability and the impact of failures increase. The preallocated backup bandwidth cannot provide 100% protection guarantee when multiple failures occur in a network. In this study, we consider multiple concurrent failures where concurrent means that a failure occurs before the previous failure is physically repaired, and we present a comprehensive study on backup reprovisioning to combat the effect of multiple-link failures. The basic idea is to reprovision new backups for connections that become unprotected or vulnerable for the next possible failure, due to losing the primary or the backup in the first failure or due to backup resource sharing. The pros and cons of the backup-reprovisioning approach are extensively discussed. A generalized network model which can maximally explore the backup-sharing potential is assumed in this study. We then discuss the complexity of backup reprovisioning under such a network model. A reprovisioning algorithm is proposed which can significantly reduce the connection vulnerability without the knowledge of the location of next failure. The effectiveness of our reprovisioning algorithm is demonstrated through numerical examples.