Re: MPLS VPN doubt

Hemanth,

The main reason why the same IPv4 route from a customer being assigned two
different RD's is for the purpose of load sharing.

In the BGP world or VPNv4 world, its always the best route that matters by
default.

In a PE to PE VPNv4 communication for a dual homed customer, we can achieve
load sharing by using the multipath feature
max path ibgp xx import 2 under the vrf of the egress PE.

But in complex scenarios when a RR is required, we may have to uniquely
advertise both the routes
In the normal case when a dual homed customer uses one RD, the RR sends the
best path from the ingress PE to the egress PE resulting in one route
getting installed at the egress PE.

Now if we use two different RD's for the same IPv4 route, the RR would
reflect both the routes to the egress PE.
And along with the multipath feature enabled in the egress PE we would have
two routes in the RIB and can achieve load sharing.

Hope that helped ;)

Best Regards,
Tharak Abraham Luke

On Thu, Jun 30, 2011 at 6:19 PM, HEMANTH RAJ <hemanthrj_at_gmail.com> wrote:

> Hey all
> In MPLS Fundamentals, the page number is 205 in pdf . heck for the line
> The
> function of RD in the second paragraph
> It is written such as that in complex VPN they use two different RD's for a
> VPN
>
>
> On Thu, Jun 30, 2011 at 3:23 PM, Carlos G Mendioroz <tron_at_huapi.ba.ar
> >wrote:
>
> > I can not imagine a need to do so. I've never seen a way to do so either.
> > (Note that he was not implying that *the same network* gets
> > different RDs, just the same VRF)
> >
> > On the other hand, the show command displays "RD xx default for VRF yy",
> > and that makes me believe that someone did think about being able to
> change
> > that, something like a route-map set action.
> >
> > Would you please quote the paragraph that says so ?
> >
> > -Carlos
> >
> >
> > Raghava Rao @ 30/06/2011 06:32 -0300 dixit:
> >
> > No, AFAIK..
> >>
> >> RD as you know distinguishes the same set of routes between two vrf's
> >>
> >> And why will you reuse the same IP address's in your vrf's again and
> >> distinguish it?? inside your own vrf's?
> >>
> >> You will never use the same ip addresses in your network, right?? then
> why
> >> do you need different RD inside the vrf?
> >>
> >> HTH
> >>
> >> Raghava Rao
> >>
> >> On Thu, Jun 30, 2011 at 2:37 PM, HEMANTH RAJ <hemanthrj_at_gmail.com>
> wrote:
> >>
> >> Hi fellows
> >>> I have a doubt regarding MPLS L3 VPN, Can we use two different RD's in
> >>> the
> >>> same VRF. Is it possible. In MPLS Fundamentals, I came across a
> sentence
> >>> which says that two different RD's are possible for the same VRF.
> >>> Can anyone shed some light on it.
> >>>
> >>>
> >>>
> >>> --
> >>> Problems arise because we talk,problems are not solved because we don't
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> >>> So good or bad talk to your affectionate one's freely.
> >>>
> >>> Yours Friendly,
> >>> H P HEMANTH RAJ
> >>> CCIE#28593 (R&S)
> >>> Cisco Systems
> >>>
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> >>
> >>
> > --
> > Carlos G Mendioroz <tron_at_huapi.ba.ar> LW7 EQI Argentina
> >
>
>
>
> --
> Problems arise because we talk,problems are not solved because we don't
> talk
> So good or bad talk to your affectionate one's freely.
>
> Yours Friendly,
> H P HEMANTH RAJ
> CCIE#28593 (R&S)
> Cisco Systems
>
>
> Blogs and organic groups at http://www.ccie.net
>
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Received on Thu Jun 30 2011 - 19:32:15 ART