[c-nsp] MPLS VPN over mGRE - PMTUD?

[Alasdair McWilliam]

Hi List,

Apologies if this is hidden in the list somewhere, but I've done a bit of Googling and can't find too much.. so here goes!

I'm looking at implementing an MPLS VPN over mGRE solution to facilitate routing instance segregation across multiple, geographically separate sites, across a third party Layer 3 infrastructure. (12.2SRE for 7200, IOS-XE 3 for ASR1k and looks to be coming into ISR G2 in 15.1T.) However given the mix of GRE encapsulation to provide the PE-PE connectivity, I'm a bit worried that apps might have a hissy fit.

My question is, does anyone know if it's possible to enable PMTUD with this feature? I've got it setup in a lab and the Tunnel0 and Tunnel1 interfaces cannot be directly modified from the CLI (they don't appear in config either...)

The next best thing I can see would be Dynamic L3 VPNs over mGRE, but that isn't available on the platforms I use, and I really don't want to go as far as to enable full blown MPLS over point to point GRE tunnels if I can at all avoid it!

Any tips? :-)

Cheers
Al