Patent ID: 6963926
Filing Date: 2005-11-08
Classification: H04L,H04Q

Abstract:
1. A method of routing a message in a communications network of interconnected nodes, the nodes being arranged to generate messages, each message having a destination information element containing the identity of a destination node for that message, a source information element containing the identity of the source node of that message, and a virtual source information element initially containing the identity of that source node, and each of the nodes having a respective routing table containing respective entries corresponding to source node/destination node pairs, each entry being in the form of a ranked pair of alternative next hop routes, the method comprising a said node: (a) comparing its own node identity with the destination node identity of a message to be routed; and, when it is not the destination node for that message, (b) comparing its own node identity with the virtual source node identity of that message, and, if there is a match at step (b), else, wherein step (c) comprises the substeps of (e) accessing its routing table in accordance with the virtual source node/destination node pair of that message to find the corresponding entry, (f) forwarding the message to the higher ranking next hop route of that corresponding entry, and in the event that step (f) fails, (g) forwarding the message to the lower ranking next hop route of that corresponding entry, and in the event that step (g) fails, (h) replacing the content of the virtual source information element of the message with the node identity of the node from which that message was received, and (i) sending that message back to that node from which it was received; and wherein step (d) comprises the substeps of (j) accessing its routing table in accordance with the virtual source node/destination node pair of that message to find the corresponding entry, (k) forwarding the message to a preselected one of the ranked pair of alternative next hop routes of that corresponding entry, and in the event that step (k) fails, (l) replacing the content of the virtual source information element of the message with its own node identity and performing step (c).