Patent ID: 7986618

Claim:
A method of operating a selected node to distinguish between failure of a link connected to said selected node and failure of a neighboring node connected to said selected node through said link, said method comprising: pre-configuring an alternate path from said selected node to said neighboring node, said alternate path not including said link; upon detection of a failure of communication from said neighboring node via said link, using said alternate path to verify operation of said neighboring node and determine whether said neighboring node or said link has failed; and rerouting traffic based on whether said neighboring node or said link has failed; wherein determining whether said neighboring node or said link has failed and rerouting traffic comprises: transmitting a message to said neighboring node on said alternate path; if a response to said message is not received, determining that said neighboring node has failed and rerouting traffic around said neighboring node and into a backup tunnel configured to protect said neighboring node; and if a response to said message is received, determining that said link has failed and rerouting traffic around said link and into a backup tunnel configured to protect said link, said alternate path comprising said backup tunnel configured to protect said link; wherein said backup tunnel configured to protect said neighboring node comprises bandwidth to cover failure of said neighboring node and said backup tunnel configured to protect said link comprises bandwidth to cover failure of said link and wherein at least one of said backup tunnels does not comprise bandwidth to cover failure of said neighboring node and said link.