Impact of IP layer routing policy on multilayer design

In this work we, first, investigate multilayer network planning approaches with different levels of integration by extending a commercial planning tool that accurately models the IP network. The different levels of integration are defined with respect to the degree to which information from the optical layer is considered in the optimization of the IP layer. The impact of traffic demand and topology size is evaluated in terms of the obtained cost savings. Case study results indicate cost savings reaching 25% by holistic multilayer network planning. We then proceed to evaluate the impact of the IP layer routing policy, expressed by the IP link weights, on the cost and latency of a holistic multilayer network design. As many network operators prefer to assign IP link weights based on simple rules that are unaffected by the network conditions, we focus on two weight setting policies that are agnostic to the network conditions: the hop-based policy and the distance-based policy. We find that different IP layer policies may lead to different optimized IP topologies for the same traffic and optical layer topology. It is shown that the optical network´s regeneration requirements affect the optimal policy.