[f-nsp] stuck transit LSP's

[Ben Cornish]

Hey All,

For the purpose of this issue / explanation.. We run lots of brocade LSP's over top of a Cisco MPLS network.
Mostly of ASR 1K's and 7600's - all running LDP and RSVP dual stack for transiting these LSP's. brocade MLX / CER's / CES's on the edge.
The Cisco routers are simply transiting the LSP's.

Everything works as expected except after we see a OSPF topology change. For example a carrier link drop and come back.
After this event, we see the odd LSP just sit in a up/down state. As in over a hundred FRR around the issue yet one of 2 just don't.
It seems the cisco is still signals back to the brocades that the tunnel is ok - when its clearly not. The brocades all indicate tunnels are fine.
The tunnel remains down and each end believes its up. The only identifications we see is the 'show mpls traffic-eng tunnels' is its  up/down - on the cisco transiting LSP device.
We see next to no pattern and the issue when repeats doesn't always affect the same LSP's.

The only resolution is to tear the LSP down manually and bring it back.  Re-optimisation doesn't work.

Curious if anyone has seen an issue like this ? or any suggestions ?