A two-stage QoT-aware protection procedure for dependable connection establishment in survivable SRLG-constrained WDM translucent networks

Abstract

In this paper, we address, for the first time as far as we know, the problem of provisioning connection requests with fault-tolerant requirements - referred to as Dependable connections (D-connections) - in survivable translucent wavelength-routed optical networks impaired with physical-layer effects taking into consideration Shared Risk Link Group (SRLG) constraints. Due to the complexity of the investigated problem, we, here, propose a practical heuristic algorithm that computes in a reasonable computational time a near-optimal routing solution, for a given set of D-connections to be set up, with the objective of maximizing the number of accommodated requests whilst guaranteeing an admissible Quality of Transmission (QoT) for all set up primary and backup lightpaths, given a limited amount of available network resources. The proposed heuristic integrates an original Two-Stage Protection (TSP) procedure which ensures fast recovery to all established D-connections from any possible SRLG-failure based on a combination of the Path Protection (PP) scheme broadly known for its resource utilization efficiency, and the Partial Path Protection (PPP) scheme widely recognized for its effectiveness in avoiding topology traps. The integrated protection procedure relies on a generic purpose-built auxiliary graph model that may support various factors of network heterogeneity through the manipulation of different edges in the constructed auxiliary graph. During the primary and backup computation processes, TSP procedure attempts to minimize network resource consumption by allowing the simultaneous use of two efficient resource sharing techniques combined, to the best of our knowledge, for the first time under a static traffic pattern, and performed in such a way that the 100% fault-recoverability is still guaranteed for all set up connections. The effectiveness of the adopted protection procedure is demonstrated through extensive numerical experiments carried out on different network topologies. The obtained simulation results prove that thanks to such an approach our heuristic algorithm achieves better performance either in terms of network blocking performance or in terms of resource utilization efficiency when compared to conventional protection approaches.