On the benefits of lightpath re-provisioning in optical mesh networks

A key means for improving service availability in optical networks is the ability to recover from dual near-simultaneous failures. To date, most studies have focused on improving survivability for single failure events either via proactive or reactive mechanisms. Conversely, lightpath re-provisioning has only recently been considered as an alternative for improving overall network restorability in the event of dual failures. Here, post-failure re-provisioning establishes new backup capacities for unprotected connections in advance of a second failure. In this paper we propose a new re-provisioning algorithm to improve the restorability of shared optical networks and compare its performance with a conventional scheme. Namely, the proposed algorithm only requires re-provisioning of a fraction of unprotected connections, since upon re-routing onto shared backup capacity, some connections are only in a "temporarily unprotected" state. Through simulation analysis, we demonstrate the effectiveness of the proposed approach in improving optical network restorability with and without wavelength conversion.