Impact of Dual-Link Failures on Impairment-Aware Routed Networks

This paper evaluates the impact of dual-link failures on single-link failure resilient networks, while physical layer constraints are taken into consideration during demand routing, as dual link failures and equivalent situations appear to be quite probable in core optical networks. In particular, a shared backup path protection scheme is used as a basis and an impairment-aware routing scheme is compared against classical minimum hop routing. Both approaches employ impairment-aware routing on the primary path, while impairment-aware is compared to min-hop on the backup path. The main metric used to illustrate the performance of the two schemes is the blocking occurring in the process of restoring the established connections that are affected by a dual-link failure. Simulation results show low restoration blocking, thus high ability of a single-failure resilient network to handle dual link failures, identifying the impairment-aware scheme as the choice of preference for both primary and backup paths when the path quality has to be considered