[j-nsp] ISIS and BFD

[martin.mogensen at bt.com]

>To me it seems that this particular point is currently not clearly defined
> (see also the differing views on this in this thread:
>http://www.ietf.org/mail-archive/web/rtg-bfd/current/msg00745.html).
>
>Looking at the implementations of three particular vendors, all three of
>them behave differently in this regard.

The feedback I've had previously from Juniper is the re-establishment of the adjacency even though BFD is filtered is intended behaviour. A BFD session isn't a requirement for re-establishing the adjacency - BFD is instead used for tearing down the adjacency in case of BFD timeout *after* the BFD session has been established. 

Cheers
Martin