[c-nsp] LDP based VPLS on IOS-XR

[Curtis Piehler]

Curious to see if anyone else has had this issue.  Currently running IOS XR
5.1.3 on ASR9000 routers.  Yes it's old but has been stable.  RSP-4Gs with
Typhoon like cards (MOD80-TR).

Issue is thus:  Configured LDP based VPLS with a bridge group and bridge
domain.  Max MAC limit of 500.  I used one router as the central bridge
group with spoke routers as P2P PWs into the bridge domain.  Hierarchical
VPLS if you will.  As soon as I put a bunch of active MACs through the
bridge group from the spoke PWs the router housing the bridge domain
started locking up the NPs on the line cards, to the point where they would
kernel dump and reload themselves.  There are three Typhoon line cards in
the chassis and all of them ended up kernel dumping.  In the bridge domain
I do not have the ACs in a VFI since I need them to toward to each other
and split horizon would prevent that. When the line cards finished
reloading all seemed OK for 10 minutes but I did not want to risk another
cascading effect so I removed the bridge domain and built a normal P2P PW
between the two spoke routers.

XR TAC indicates it is likely a software bug in the older code where the
router may not like some type of a VPLS/MPLS packet where once it enters
the line card(s) causes them to lock up.

I noticed the line cards locking up earlier on occasion when I put 3 or 4
MACs through the bridge group with test ICMP traffic across the end
points.  When I put the production VLANs through the bridge group with a
lot more active MACs and traffic the line cards nearly immediately started
locking up and eventually kernel dumping/reloading.

Curtis