Power-Aware Logical Topology Optimization for IP-over-WDM Networks Based on Per-Lightpath Power Consumption Model

This paper considers the problem of logical topology optimization in an IP-over-WDM network, with the objective to minimize the total power consumption used to support the given traffic demands. While there are several power consuming devices in a backbone WDM network, it is assumed that major power consumption occurs at IP router ports, which are termination points of optical connections or lightpaths. The logical topology optimization problem is first formulated as an integer linear programming (ILP) problem that is computationally difficult to solve. To focus on minimizing the power consumption, it is assumed that traffic routing is not limited by link capacities. Two systematic approaches to obtain a lower bound on the power consumption are considered, namely linear programming (LP) relaxation and Lagrangian relaxation. It is shown that both methods result in the same lower bound that corresponds to shortest path routing of traffic. A heuristic based on shortest path routing and pruning of unnecessary lightpaths is then evaluated using simulation results obtained from the heuristic in comparison to the baseline case in which the logical topology is taken to be the same as the physical topology. Finally, WDM networks that support mixed line rates are considered in order to further optimize the power consumption of IP-over-WDM networks in which transmission rates over different wavelength channels are not necessarily equal.