A Combinatorial Optimisation Approach to the Design of Dual Parented Long-Reach Passive Optical Networks

Abstract

We present an application focused on the design of resilient long-reach passive optical networks. We speci?cally consider dual parented networks whereby each customer must be connected to two metro sites via a local exchange sites. An important property of such a placement is resilience to single metro node failure. The objective of the application is to determine the optimal position of a set of metro-nodes such that the total optical ?bre length is minimised. We prove that the decision variant of this problem is NP-Complete. We present three alternative combinatorial optimisation approaches to ?nding an optimal metro node placement using: a mixed integer linear programming formulation of the problem; a hybrid approach that uses clustering as a preprocessing step; and, ?nally, a local search approach. We consider a detailed case-study based on a network for Ireland. The hybrid approach scales well and ?nds solutions that are close to optimal, with a runtime that is two orders-of-magnitude better than the MIP model. The local search approach is consistently good on all benchmarks.