[j-nsp] ISIS and BFD

[Pekka Savola]

On Mon, 28 Dec 2009, Bit Gossip wrote:
> rs2 is a IOS router and rc2 is Junos router and they have an established
> ISIS adjacency with BFD; fine. Then with a fw filter I block BFD packets
> reaching RC2; the ISIS session goes down as I would expect but then it
> is re-established. How is that possible the session is re-established
> when BFD packets are blocked?

IS-IS adjacency falls back to non-BFD operation in this case.

The spec says forming adjacencies SHOULD typically be blocked, but 
there's a lot of text there so read the full story: 
http://tools.ietf.org/html/draft-ietf-bfd-generic-05#section-4.1

-- 
Pekka Savola                 "You each name yourselves king, yet the
Netcore Oy                    kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings