When BFD support is configured with IS-IS as a registered protocol
with BFD, IS-IS receives forwarding path detection failure messages from BFD.
BFD support for IS-IS can be configured in either router address-family
configuration mode or interface configuration mode. IS-IS IPv6 runs in
IS-IS BFD supports both IPv4 and IPv6 on the same adjacency for
single-topology mode. If BFD is enabled for both IPv4 and IPv6, IS-IS sends two
BFD session creation requests to BFD. For single-topology mode, the IS-IS
adjacency state can only be up if both BFD sessions are up. If either of the
BFD sessions is down, the associated IS-IS adjacency state is also down.
When IS-IS BFD IPv6 is disabled on an interface, IS-IS removes related
BFD sessions for IPv6 from the adjacent device. When the IS-IS adjacency entry
is deleted, all BFD sessions are also deleted. IS-IS requests BFD to remove
each BFD session that it has requested when any of the following events occur:
The IS-IS instance is deleted or un-configured.
The IS-IS adjacency entry is deleted.
IS-IS BFD is disabled on the next hop interface for an