BFD Configuration on One LAG Member Port
The following figure shows two session endpoints that are connected through a Layer 2 switch using two separate LAGs. Because the LAG member links from R1 are not directly connected to R2, micro-BFD sessions cannot be configured on either of the LAG interfaces on R1 or R2.
If all LAG member links are not directly connected between two session endpoints, the following situation apply:
The BFD session can be configured on one of the member ports of the LAG. Applications are then notified based on the status of the BFD session for this member port alone. If the BFD session running on the member port goes down, applications are notified to act on the link failure even though the LAG remains operational. To avoid this, the holdover timer can be set to a higher time interval so that the session can attempt to transition to another operational LAG member port.
For a detailed configuration example of a single-hop static BFD session for one member link for a LAG interface, refer to Configuration Example: Single-hop Session for One Member Link for a LAG.