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

Thanks Brian D. and Brian M. for your explanations. That makes sense. I did
forget about the the fact that it "disconnects" you from the superbackbone.
I remember a while back doing labs with multiple areas in MPLS env, need to
revisit that.

So going back to my original question, the only way to do provide LSA 3
over Inter-AS Option A is to use eBGP and include ext community between the
ASBRs, no tricks to get it working with OSPF.

Thanks again,

Tom Kacprzynski

On Fri, Mar 8, 2013 at 3:10 PM, Brian Dennis <bdennis_at_ine.com> wrote:

> If you use "capability vrf-lite" then you're saying the router is not
> connected to the "MPLS Super Backbone" so I don't see why it would
> continue to behave as if it was.
>
>
> > 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.
>
> You can think of the disabling of the checks as a byproduct of the router
> disconnecting itself from the "MPLS Super Backbone". It also stops the
> router from being an ABR for the VRF's OSPF process. When it's enabled it
> needs to be an ABR to generate the type 3 LSAs even if it's only in a
> single non-area 0 area. Many people stumble across this issue when the PE
> to CE link isn't in area 0 but area 0 is "behind" the CE.
>
> --
> Brian Dennis, CCIEx5 #2210 (R&S/ISP-Dial/Security/SP/Voice)
> bdennis_at_ine.com
>
> INE, Inc.
> http://www.INE.com
>
>
>
>
> On 3/8/13 10:32 AM, "Tom Kacprzynski" <tom.kac_at_gmail.com> wrote:
>
> >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
> >
> >
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> >
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Received on Fri Mar 08 2013 - 15:56:16 ART