Computation of Regeneration Sites in Survivable Cost-efficient Translucent Optical Networks

Survivability refers to the ability of networks to withstand failures and is one of the most important aspects of network planning and design. If the network is designed to survive failures then it will be capable of providing continuous services without disruption. In this paper, we address the problem of designing translucent optical WDM networks capable of withstanding any arbitrary single fiber-link failure. If an optical signal is propagated beyond a permissible distance also known as optical reach its quality degrades to a level which demands re-amplification, re-shaping and re-timing, a process known as 3R-regeneration. Since employing nodes with regeneration capability incur additional cost, ideally only a subset of the nodes in the network must be identified as regeneration sites. A cost-efficient survivable network design must then ensure that there is minimum number of regeneration sites. Since the Regenerator Placement Problem (RPP) is NP-Hard [1]; we propose heuristics for computing as few regeneration sites as possible to make a translucent network survive the impact of a fiber-link failure. We propose an ILP for getting optimal solution in small networks. We also propose two heuristic strategies namely; Survivable Link based computation of regenerator sites (SLCRS) and Survivable Segment based computation of regenerator sites (SSCRS). We compare the performance of the proposed strategies with some of the existing strategies. Performance comparisons show that our proposed SSCRS can be used to design survivable translucent optical networks with fewer regeneration sites