A scalable optimisation approach to minimising IP protection capacity for Long-Reach PON

Mass deployment of fibre access networks is without doubt the next short to medium term goal of many network operators around the globe. Long-Reach Passive Optical Network (LR-PON) has been proposed as a solution to help spreading mass deployment of Fibre-to-the-premises (FTTP), by sensibly reducing the cost per customer compared to current commercially available technologies. This paper addresses the issue of reducing protection costs on LR-PON deployment by reducing active network protection resources by spreading the load generated by a node failure over the network. Here we present a novel scalable optimisation approach to this problem that is able to find solutions for typical sized European countries in very limited time (i.e., within 30 minutes). We present a constraint optimisation formulation of the problem and propose a hybrid approach that decomposes the problem in to two subproblems and solves them using local search and systematic search respectively. The scalability of our approach is demonstrated by performing experiments using real datasets corresponding to three European countries: Ireland, UK and Italy. Our results show that the LR-PON deployment strategy that minimises the overall protection capacity rather than just minimising fibre distances in the LR-PON can indeed significantly reduce total over-provision by increasing the total distance-based cost marginally.