Optimal multicommodity flows over an existing DWDM multi-overlay

The goal of this work is to design a low-cost resilient multi-overlay, where a data network is on top of an optical transport network. The data network is built over an existing DWDM network, and should fulfill traffic demands in the data nodes. The main challenge is that a single failure in the transport layer causes multiple simultaneous failures in the data layer. A mathematical model to design a multi-overlay with the desired properties is here proposed. The problem belongs to the class of NP-Hard problems, and has been heuristically addressed in previous works. Here, a Decomposition approach is introduced, where the problem is solved in two steps by means of linear relaxations. The solution is competitive with previous heuristics using real-life instances coming from the Uruguayan Telecommunication Operator ANTEL, and suggests a modest percentage of cost-reduction in some instances, which mean millionaire savings in practice.