Patent ID: 9231838
Filing Date: 2016-01-05
CPC Classification: H04L

Claim Text:
1. A method at a local host node of locating Layer-3 (L3) connection failures involving a remote host node that is linked to the local host node via multiple L3 communication paths defined by unique pairings of multiple local network attachment points at the local host node and multiple remote network attachment points at the remote host node, said method comprising: establishing a Bidirectional Forwarding Detection (BFD) session for each of the L3 communication paths, wherein a network topology uniquely pairs at least one of the local network attachment points with more than one of the remote network attachment points such that said at least one of the local network attachment points is common to two or more of the L3 communication paths between the local and remote host nodes; monitoring BFD status information for each BFD session ( detecting an L3 connection failure based on determining that at least one of the BFD sessions is down; determining an apparent location of the L3 connection failure by analyzing the pattern of up and down indications in the BFD status information in conjunction with knowledge of the network topology determining from the BFD status information whether the L3 connection failure has taken down an active one of the L3 communication paths and, if so, switching communications traffic from the active L3 communication path to a backup one of the L3 communication paths; wherein, in the case that the BFD status information indicates that the L3 connection failure has taken down a backup L3 communication path but not the active L3 communication path, leaving the communications traffic on the active L3 communication path and raising a low-priority alarm to indicate the L3 connection failure and corresponding loss of path redundancy.