High-speed calculation method for large-scale multi-layer network design problem

Multi-layer network optimization has been studied for efficient use of network resources by solving Mixed Integer Linear Programming (MILP) problem. Here, the multi-layer network consists of lambda-layer network and IP-layer network. However, when applying this MILP problem for a large-scale network with a few hundred nodes, huge amount of variables are used and cannot be handled by middle size computers. In order to cope with this problem, some heuristic methods have been proposed and evaluated from viewpoints of accuracy and calculation time for their computation results. These heuristic methods reduce variables at lambda-layer and also decompose the original MILP problem into smaller sub-problems and induce an approximate solution by solving these smaller MILP problems. However, these heuristic methods cannot obtain accurate results in many cases. In this paper, we propose a novel variable reduction method at both lambda-layer and IP-layer by excluding long hop routes. We evaluate our proposed method and the conventional methods and show the availability of our method.