The MPLS-OPS Archive

["tim pittman" <tpittman@frontrunner.eu.com>]

I think Rays issue is if a VPN destn. is actually reachable via two PE's
(PE1 and PE2).
eg a CE is dual homed to two PE's, PE1 and PE2.

Then on PE3 because you can't iBGP load share via an RR, then only one iBGP
route to the VPN destination (via either PE1 or PE2) is ever seen by PE3.
The RR only passes on its best route.

So doesn't matter that IGP on PE3 may then load share over differnet
internal paths
to reach either PE1 or PE2 , PE3 only ever sees one egress PE to reach the
VPN destination.

I guess iBGP load sharing without RR's would let PE3 see both PE1 and PE2 as
equal
cost exit points and you could then use both, but don't think (with cisco)
you can do it with RR's.

tim

-----Original Message-----
From: Peter J. Welcher [mailto:p.welcher@att.net]
Sent: 20 December 2001 13:25
To: mpls-ops@mplsrc.com
Subject: MPLS load balancing



Hi, Ray. I may be missing what you're trying to do, but
I suspect from the CE-CE you're trying to load balance
for MPLS VPN's.

If you're doing MPLS VPN, BGP / MBGP is only used for the
next hop (exit from the SP cloud) determination. If the next
hop is a loopback on the PE router, the IGP is used for path
to that loopback. The IGP should load balance equal cost routes,
and MPLS label paths will also do this.

HTH


Raymond Cheung wrote:
>
> Hello,
>
> Has anyone tried BGP load balancing in a MPLS network with route
reflectors?
> I have no problem to get the load balancing working without route
> reflectors. But since route reflector can only advertise one best path for
a
> prefix, so I have to use different RD to make vpnv4 addresses look
different
> on route reflectors. The problem is, after using different RD (still same
> route-targets), CE-CE reachability is broken.
> Please let me know if you have done this..
> Much appreciated.
>
> best regards,
>
> Raymond Cheung
> Senior Network Engineer (CCIE R&S)
> Schlumberger Network Solutions
> Tel: 713-513-3285
> Tel: 713-513-3000
>
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