MPLS Inter-AS Option A using OSPF (capability vrf-lite)

I was playing around with MPLS Inter-As option A (back to back vrf) and
wanted to lab all routing protocols that are used between the ASBRs on
their respective subinterfaces. I used eBGP, EIGRP and OSPF. I had some
problems with OSPF where I could not get the LSA 3 to be reassembled at the
other end of the VPN. This leads me to a very specific question: When
using OSPF in Inter-AS Option A, is it possible to reassemble the internal
OSPF (LSA 3) route on the other end of the VPN? I've tried it with EIGRP
and that worked but with OSPF I only see External LSA 5 routes.

Here is a sample topology:

CE--(OSPF)---PE----*(AS1)*----*ASBR1---*(OSPF)*--ASBR2*---*(AS2)*
---PE---(OSPF)--CE

I know that usually you would use eBGP as the routing protocol between the
ASBRs but I wanted to try using OSPF. The problem I'm encountering has to
do with "capability vrf-lite" on the PEs. When I enter that command on one
ASBR it doesn't reassemble OSPF routes as LSA 3 but as LSA 5. I've checked
the domain ID and they are matching.

Based on my observation it looks like when you apply the "capability
vrf-lite" command on a PE(in this case the ASBR), it will always
redistribute OSPF routes as external LSA 5, no matter what domain-id you
are using.

Capability vrf-lite is usually used on CEs that have OSPF running on vrfs.
When enabled, it disables checks like for Downward bit and domain tag.
Looks like another feature of this is to always redistribute M-BGP routes
as External LSA 5, even if domain ID matches and extended communities are
propagated.

Has anyone seen something like that?

Thanks

Tom Kacprzynski

Blogs and organic groups at http://www.ccie.net
Received on Fri Mar 08 2013 - 09:32:03 ART