A method of operating a data transport system, wherein the data transport system comprises: a plurality of nodes (20,21) linked by the Internet (10,11); and a plurality of routers, each having a respective geographical location, and a transport network connecting the routers, wherein each router is also connected to the Internet, wherein each node is associated with at least one public IP address; the transport network is a private network with access control; and the data transport system further comprises a database comprising geographical location information associated with respective IP prefixes on the Internet, the geographical location information representing the physical locations of respective nodes associated with the IP prefixes, wherein the method comprises: for substantially every IP prefix in a global BGP Internet routing table, using the database of geographical location information and the geographical locations of the plurality of routers to determine a respective closest one of said routers to a geographical location associated with the IP prefix, according to a predetermined physical-distance metric; and storing, by a route server, information identifying said closest routers, the information being suitable for use in a routing protocol for routing data packets through the private transport network to destinations (20,21) outside the private transport network, wherein the data packets exit the private transport network at routers, of said plurality of routers, that are closest to respective destinations of the data packets outside the private transport network, according to the predetermined physical-distance metric. a plurality of nodes (20,21) linked by the Internet (10,11); and a plurality of routers, each having a respective geographical location, and a transport network connecting the routers, wherein each router is also connected to the Internet, wherein each node is associated with at least one public IP address; the transport network is a private network with access control; and the data transport system further comprises a database comprising geographical location information associated with respective IP prefixes on the Internet, the geographical location information representing the physical locations of respective nodes associated with the IP prefixes, for substantially every IP prefix in a global BGP Internet routing table, using the database of geographical location information and the geographical locations of the plurality of routers to determine a respective closest one of said routers to a geographical location associated with the IP prefix, according to a predetermined physical-distance metric; and storing, by a route server, information identifying said closest routers, the information being suitable for use in a routing protocol for routing data packets through the private transport network to destinations (20,21) outside the private transport network, wherein the data packets exit the private transport network at routers, of said plurality of routers, that are closest to respective destinations of the data packets outside the private transport network, according to the predetermined physical-distance metric.