BFD over LAG links

The router supports the application of BFD to monitor individual LAG link members to speed up the detection of link failures. When BFD is associated with an Ethernet LAG, BFD sessions are setup over each link member, and are referred to as micro-BFD sessions. A link is not operational in the associated LAG until the associated micro-BFD session is fully established. In addition, the link member is removed from the operational state in the LAG if the BFD session fails.

When configuring the local and remote IP address for the BFD over LAG link sessions, the local-ip parameter should always match an IP address associated with the IP interface to which this LAG is bound.  In addition, the remote-ip parameter should match an IP address on the remote system and should also be in the same subnet as the local-ip address. If the LAG bundle is re-associated with a different IP interface, the local-ip and remote-ip parameters should be modified to match the new IP subnet. The local-ip and remote-ip values do not have to match in the case of hybrid mode, q-tag, or QinQ tagging.