This thesis describes the development of a simulation and capacity management tool for generic networks. As a case study KPN's Ethernet network is analysed. The tool can be used to calculate various network metrics that are used in complex network studies. It can also be used to display a geographically correct view of the network, as well as a graph view. Extensive filtering functions allow the user to analyse different parts or layers of the network. Multiple vpns can be defined over the network and traffic can be simulated for these vpns. At each node and every link the simulated traffic can be monitored and logged. This is done for different scenarios in the case study network. Finally a way to optimise the logical topology at different traqffic loads is investigated.