<p>A public network links a plurality of nodes, each associated with at least one network address. A transport network connects a plurality of routers, each of which is also connected to the public network. A database holds geographical location information associated with respective network addresses on the public network. The database is used to determine which of the routers is closest to geographical locations associated with the network addresses. Information is stored that identifies these closest routers. The information is suitable for use in a routing protocol for routing data packets through the transport network to a destination outside the transport network.</p>
