Contrary Index Spectrum Allocations Scheme for Primary and Backup Routes in Survivable Mixed Grid Optical Networks

Abstract

Survivability is a critical issue in optical network design, particularly when it comes to minimizing redundant backup resources needed for rerouting failed connections. In this paper, we present a Contrary Index Spectrum Assignment with Shared Path Protection (CISA-SPP) strategy for assigning primary and backup routes in a mixed grid optical network. In the proposed CISA approach, spectrum allocation for the primary route is conducted in increasing index order, while for backup routes, the spectrum is allocated in decreasing index order. This reversal of indexing reduces spectrum contention with existing connections and enhances resource sharing for backup routes. We compare the CISA-SPP strategy with three traditional survivable strategies: Dedicated Path Protection (DPP), Partial Path Protection (PPP), and Shared Path Protection (SPP). The results demonstrate that the proposed strategy achieves lower bandwidth blocking probability, more efficient resource allocation for backup routes, and improved resources overbuild ratio compared to the existing strategies.