Efficient heuristic for routing static dependable connections in WDM networks with SRLGs

Planning effective fault-recovery mechanisms is widely considered as one of the most critical challenges that need to be addressed when designing all-optical WDM transport networks. Networks providing such facilities are said to be survivable, that is, networks which are able to continue performing their designated set of functions during and after the occurrence of a network component failure. Many studies dealing with the network survivability problem have been carried out, during the two past decades, and several fault-recovery schemes have been proposed. The main objective is minimizing the total bandwidth consumption while guaranteeing the recoverability of established connections. In this paper, we present an original heuristic approach that tackles the problem of establishing static connections with fault-tolerant requirements commonly referred to as dependable connections (D-connections) taking into consideration the Shared Risk Link Group (SRLG) constraint. We call a SRLG, a subset of links in the network that share the risk of failure at the same time. Based on the Partial Path Protection (PPP) recovery scheme, our approach aims at minimizing the total required network resources reserved for protection using two different resource sharing techniques - namely, backup multiplexing and primary-backup multiplexing. We hope by doing so, maximizing the overall network throughput. To the best of our knowledge, this is the first attempt to include the primary-backup multiplexing concept to improve resource utilization when providing protection for static traffic without compromising the 100% fault-survivability guarantee in optical networks with SRLG constraints. The effectiveness of the proposed heuristic is demonstrated through illustrative numerical examples.