The invention relates to an inter-domain router, for an Internet Protocol communications network, including a processing module to generate as a function of routing data outgoing messages intended for other routers which comprise information data representative of routes for routing IP datagrams and a control module to analyze at least some of the routing data, in order to define route aggregates as a function of selected configuration information, and for delivering output data representative of the route aggregates, so that the processing module can generate outgoing messages including information data representative of the route aggregates.