Patent ID: 7483391

Claim:
A method of maintaining proximity information in an overlay network, wherein the overlay network is a logical representation of a physical network, the method comprising: determining whether a network condition occurred, the network condition being associated with a region in the overlay network; determining distances of each of a first plurality of nodes in the physical network to each of a second plurality of landmark nodes in the physical network, the first plurality of nodes comprising a first node, and the landmark nodes being different from the first plurality of nodes; storing a proximity information in the region, wherein the proximity information includes locations of the first plurality of nodes the physical network; updating the proximity information stored in the region if a change associated with the first plurality of nodes in the physical network occurred; and transmitting the proximity information to the first node operable to route a message to the region in response to the network condition occurring, wherein the first node obtains the distances of each of the first plurality of nodes to each of the second plurality of landmark nodes.