A transmission system including a plurality of edge routers. The system manages a plurality of virtual networks, each network linking a plurality of remote networks therebetween. An edge router manages a topology table that indicates one or more adjacent edge routers for a given virtual network and at least one remote network identifier for an adjacent edge router. A route change made in relation to a remote network of a given virtual network is detected on the edge router. On the basis of the topology table, one or more adjacent edge routers and the corresponding remote network identifiers are determined for the virtual network. The route change is transmitted to said adjacent edge routers by indicating the corresponding remote network identifiers.