Re: MPLS Route Targets

:)
No emotions attached here, just trying to get a clear view of tecnology.
(Even though I have latin blood in my veins, so beware... LOL)

So let's get back to your ... "period!", remove any "this is it, final
sentence (TM)" and see:

My point is that BGP routes (elects best path) to destinations,
which in the case of vpnv4 are RD+ipv4 prefix.
In so doing, it will not use metrics (LPref, Path length, etc) to
choose best PATH if the destination is not the same, it will just
transport both (assuming we have two) routes to all places as they
would be two different routes.

This is only relevant iff (if and only if) you have the same network
at two different PEs. If not, routes are different no matter what RD
you use, so your comment on RDs and central site does not apply here.
(I'm not saying that each site in a VPN has to have the same RD,
ok ?)

So with your complete attention, I'm saying that if the RDs of two VRFs
that have access to the same network do not match, the route that will
be used by some (other) site to reach that network might not be based
on BGP metrics. I've to check this though. In any case, both routes
will be visible at the originating PE. Conceptually, they would be two
routes.

-Carlos

Paul Negron @ 23/8/2010 11:50 -0300 dixit:
> Carlos,
>
> Just so you know...I am writing this email with a complete calm demeanor, so
> don't feel threatened. I am simply in complete disagreement with your point
> and don't feel it is an issue that we can disagree agreeable on. I do not
> want others to think you may be correct on an issue that is poorly
> documented.
>
> RD's do not have to match ....period! You can see the route easily in the
> other RD section under BGP even when the RD's don't match.
> They are only used to present the potential overlapping addressing
> condition. Also, if you are running Overlapping VPN's, which RD is the
> Central Site going to get? It can only match one site or the other if I take
> your view.
>
> There are many that have thought as you have and ended up reconfiguring MANY
> MANY sites due to poor planning. I do not speak from a position of "I
> Think" mentality. I am using may large SP's as an example.
>
> Look back in the thread. I never over simplified the issue by stating that
> the RD is a "syntax need". You cannot run MPLS VPN without them.
>
> As for your example in the thread below which stated: "If your customer has
> two entry/exit points to the same network across different PEs, THEY BETTER
> MATCH (RDs) for BGP being able to know they actually are the same network
> and route based on metrics."
>
> You have my complete attention now. What would happen if the RD's did not
> match in your example?
>
> Paul

-- 
Carlos G Mendioroz  <tron_at_huapi.ba.ar>  LW7 EQI  Argentina
Blogs and organic groups at http://www.ccie.net