Minimizing the number of constraints for Shared Backup Path Protection (SBPP) in Shared Risk Link Group (SRLG) optical mesh networks

Path-arc Integer Linear Programming (ILP) models for Shared Backup Path Protection (SBPP) in optical mesh networks generally contain many redundant constraints for calculating shared backup capacity. This greatly increases the computational time of the ILP solvers. In this paper, we first identify the sharing relationship between working and backup capacities, which facilitates the development of two novel algorithms for minimizing the number of constraints in ILP models for SBPP in mesh networks. Next, we consider the more realistic case of Shared Risk Link Group (SRLG) networks, where some optical fibers have the same risk of a physical cut due to being bundled in the same conduit. We propose a path-arc ILP model for SBPP in SRLG networks and minimize the number of constraints in this ILP model using the proposed algorithms. Simulation results show a remarkable reduction of around 50% in the number of constraints, which significantly improves the computational complexity of the model.