A hybrid protection-restoration mechanism for enhancing dual-failure restorability in optical mesh-restorable networks

Abstract

In this paper, we investigate the problem of enhancing dual-failure restorability in path-protected mesh-restorable optical wavelength division multiplexed (WDM) networks. A key finding of recent studies that have demonstrated the need to survive simultaneous dual-link failures is that designs providing complete (i.e. 100%) protection from all dual-failures may need almost thrice the spare capacity compared to a system that protects against all single-link failures. However, it has also been shown that systems designed for 100% single-link failure protection can provide reasonable protection from dual-link failures. Thus, the motivation of this work is to develop a hybrid mechanism that provides maximum (close to 100%) dual-failure restorability with minimum additional spare capacity. The system architecture considered is a circuit-switched WDM network with dynamic arrival of sessions requests. We also consider sparse wavelength conversion, where only some nodes have converters. We propose an adaptive mechanism, which we term <i>active protection</i>, that builds upon a pro-active path protection to provide complete single-failure restorability and adds dynamic <i>segment-based restoration</i>. The objective is to optimize network survivability (and minimize spare capacity needs) with ragard to dual-link failures while maintaining complete single-failure restorability. The basic premise of the algorithm is to identify scenarios in the dual-link failure model that necessitate additional spare capacity and provide protection for those scenarios only. Our findings indicate that the proposed scheme achieves close to complete (100%) dual-failure restorability with only maximum of 3% wavelength-links needing two backups even at high loads. Moreover, at moderate to high loads, our scheme attains close to 16% improvement over the base model that provides complete single-failure restorability.