The invention relates to a communications network planning system, in which an overview of sub-networks within a communications network is provided on a graphical user interface. The system is also provided with a selector field for selecting a graphical representation of a sub-network, comprising a hierarchically structured display of node types in the respective sub-network and a display of the links that exist between said node types. In addition, the system comprises a selector field for selecting a combined graphical representation of a respective section of interconnected sub-networks in the region of a sub-network gateway, said representation comprising a hierarchically structured display of node types that are present in the respective sub-network gateway region and a reproduction of connections that exist between said node types. The system is also provided with a control unit for controlling the graphical user interface according to selection entries that have been received by an input unit.