Patent ID: 7978612

Claim:
A method comprising: receiving, at a node in a communications network, an update message for a distance vector routing protocol from a first neighbor of a plurality of neighbors, wherein the update message indicates a destination in the communications network and a least total cost of reaching that destination from the first neighbor, wherein the node is configured to filter at least one change in cost for a selected network address such that it is not forwarded; sending, to a different neighbor of the plurality of neighbors, the update message, wherein if the change in cost for the selected network address is for a sole address provided in the update message, then the update message is not forwarded by the node; sending the update message to the different neighbor of the plurality of neighbors if the node is a relay node for the first neighbor, wherein the relay node is a node preferred by the first neighbor to update a particular node a certain number of hops from the first neighbor; determining whether the update message is for a filtered node address; and sending to the different neighbor a poison update message that indicates a prohibitive cost to reach the filtered node address through the node.