Patent ID: 8082340

Claim:
A method comprising: establishing a bidirectional forwarding detection (BFD) session over a first link between a monitoring node and a first interface of a monitored node; determining a number of other interfaces of the monitored node on which to establish unidirectional BFD (uBFD) sessions based on a total number of interfaces of the monitored node, the number of other interfaces being less than the total number of interfaces of the monitored node; establishing uBFD sessions from corresponding ones of the number of other interfaces of the monitored node to the monitoring node, the uBFD sessions traversing links other than the first link; detecting failure of the BFD session over the first link between the monitoring node and the first interface of the monitored node; and in response to detecting the failure of the BFD session over the first link between the monitoring node and the first interface of the monitored node, distinguishing between a link failure of the first link between the monitoring node and the first interface of the monitored node and a node failure of the monitored node by determining if at least one uBFD session of the uBFD sessions is still operational after the BFD session has failed, and if so, concluding that the first link has failed, and if not, concluding that the monitored node has failed.