[c-nsp] BGP neighbor fall-over vs BFD

[Oliver Boehmer (oboehmer)]

>
>Can someone shed some light on this? What is fall-over really doing and
>when might it be useful?


sorry for the confusion ;-)   neighbor fall-over (without the BFD keyword)
is for multihop/non-directly-connected peers like the default behaviour
fast-external-fallover for directly connected neighbours: the session will
be torn down. It works by monitoring/tracking the next-hop address, so if
something removes the route to the peer, the session will be torn down. It
works pretty much the same way as Next-hop-Tracking (monitoring the RIB),
but it tears down the session (while NHT only declares the nexthop as
invalid).

"fall-over bfd" isn't monitoring the RIB, it uses BFD to monitor neighbour
reachability & liveliness, and it will tear down the session if BFD
signals a failure.

So fall-over is actually much more than a single feature.. did I apologize
for the confusion? ;-)

	oli