Re: Loop Prevention MPLS VPN

Hi ,

Kindly go through the topic of Down-bit and Domain Tag related to OSPF and
MP-BGP redistribution.

I hope it will help you out.

Also any suggestions are always welcome.....

On Wed, Dec 1, 2010 at 11:55 PM, David Mahler <dave.mahler_at_gmail.com> wrote:

> Hello,
>
> This looked like an interesting scenario to test out so I did in dynamips.
> I have a loopback (100.0.0.100/8) on PE3 being redistributed into vrf OSPF
> with CE2 and into MP-BGP with PE1 and PE2. PE1 and PE2 are redistributing
> from MP-BGP into OSPF vrf with CE1.
>
> What I found was that while CE1 does have the ospf route for
> 100.0.0.0/8(type <http://100.0.0.0/8%28type> 5 E2 in the database) PE1 and
> PE2 are only installing
> the MP-BGP route
> in their routing tables. PE1 and PE2 do have 100.0.0.0/8 in their OSPF
> databases though - they are just not installing it in their routing tables
> for the vrf at all.
>
> There may be something fundamental I am missing in this scenario or the
> description, but there looks to be something inherent with MP-BGP and OSPF
> that I don't yet know (rather new to MPLS L3 VPNs). Seems despite OSPFs
> lower AD, the MP-BGP routes (AD 200) are still preferred on the PEs.
> Logically this makes sense as a loop prevention mechanism though - I will
> definitely research this more - but just throwing that out there if there
> is
> further comment on it before I RTFM.
>
>
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-- 
Thanks & Regards,
Vivek Vidhate.
Blogs and organic groups at http://www.ccie.net