Patent ID: 7668164

Claim:
A communication method in an IP based overlay network comprising a number of first sub-networks which all are provided by a first organization and a plurality of external networks which are provided by organizations other than the first organization, wherein a sending host located in one of the first sub-networks wants to communicate with a receiving host that is located in another one of the first sub-networks, which is a destination sub-network, the communication method comprising: the sending host sending a message via the overlay network to the receiving host in an IP datagram that travels along a route comprising selected ones of said external networks to which the first organization has additional nodes connected, wherein the overlay network is under full control of the first organization; the sending host, as sender of the IP datagram, indicating a first address administered by and belonging to a route administering node and a second address belonging to a route server, acting as receiver of the IP datagram, in the destination sub-network; said route server replacing the first and second addresses in the IP datagram with local addresses of the sender and the receiver respectively and forwarding the IP datagram to the local address of the receiving host; the route administering node selecting nodes in a path that the IP datagram must follow from the sending host to the route server in the destination network; assigning the first address, administered by the route administering node, to the selected route; and communicating the assigned first address to the sending host and to the route server, said first address having a relation to the selected route.