[j-nsp] BFD on ISIS and graceful-switchover

[Yastrebov, Valery]

I guess I know answer but just to make sure anyone knows is it possible to use two RE (M40e) in graceful-switchover mode plus ISIS (exactly with BFD).

So when making "request chassis routing-engine master switch"   BFD session goes down, after ISIS adj goes down for a few seconds and there're no "non-stop forwarding" till second RE is booted. Without BFD it's really "non-stop forwarding" (except couple lost packets :-)  ) in the process of changing RE.