[c-nsp] 7200 MPLS MTU Issues

[Kenny Stoltz]

I seem to have stumbled across a known problem that isn't well
documented by cisco, and it appears that some other members have also
gotten bitten by it.

I was attempting to use MPLS for VPN traffic and discovered when I
turned on MPLS for our network that the 7200s which we use extensively
around the network do not support more than 1500 byte packets on their
interfaces (specifically PA-FE-TX and FX), meaning that 4 and 8 bytes
are cut off because of labels, and this is causing problems certain
customers interacting with bad firewalls. I am desparate to make this
work though I do not want to upgrade the routers to NPE-G1s to fix it.

Does anyone has any suggestions on ways to work around this?
Unfortunately I can't break customers or the bank so a software/config
fix would be really nice, but it doesn't sound like that's possible.

Ironically, cisco claims that the 7200 can /do/ MPLS... This is almost
laughable if it can't exceed 1500 bytes.

Any advice would be grrrrrrrreatly appreciated.

~!kenny