2-SRLG-connected partitioning in optical networks

Partitioning a large network into a connected hierarchy is a proven technique for scalability, manageability, and reliability. Although a significant body of works is devoted to this area of interest, a reference to partitioning schemes where each partition remains 2-connected is missing. In optical networks, a failure of a physical component disrupts multiple logical links that share the component. Such a shared risk link group (SRLG) failure is more common than a single link or node failure in the logical topology. In this paper, we introduce the k-SRLG-connected partitioning problem for optical networks, where k ≥ 1. A logical topology is said to be k-SRLG-connected if its nodes remain connected upon any k-1 SRLG failures. We particularly focus on k = 2. Without 2-SRLG-connectivity, a partition can neither provide protection by allocating two SRLG-disjoint paths, nor provide restoration after a failure. Moreover, a single SRLG failure can split the partition into multiple disconnected components, resulting in the failure of the hierarchical network organization itself. We show that finding a 2-SRLG-connected partitioning for a given network is NP-complete and provide a distributed heuristic approach. Simulation results verify that the proposed 2-SRLG-connected partitioning scheme performs better than traditional 1-connected partitioning approaches with regard to survivability and system stability.