Real-world telecommunication networks consist of a stack of technologically different subnetworks, so-called layers, which are strongly interdependent. These layers have a client-server relation: each layer is embedded into another one, i.e., links of a client layer are realized by paths in a server layer. For example, one layer may correspond to an Internet (IP) backbone network whose links are realized by light-paths in an underlying optical fiber layer, a so-called DWDM network. In this project we develop mathematical models and algorithms for a joint planning of several network layers. Such an integrated planning approach is of increasing importance for network providers because of its potential for cost and energy reductions.

Our aims are twofold: On the one hand, we want to develop realistic models and suitable algorithms which can be used for solving real-world problems in practice. To achieve this goal, we cooperate with several telecommunication companies. On the other hand, we want to further understand the mathematical structure of these planning problems, in order to get quality guarantees for obtained solutions and to further improve existing solution methods.