No problem.
1. The RD (according to the RFC) doesn't need to be globally significant.
It makes life MUCH easier if it is. Providers use this to signify a "VPN
ID" (maybe a customer number for billing?). But within the VRF, you can
have multiple route-target imports and exports from different RD's or
communities, so that's where you get the idea that it doesn't HAVE to be
global in nature.
The "route target both 100:1" will put the import/export on one line. You
can also use "import map (name)" to use route-map filtering...
2. The PEs use MBGP to exchange information. That track next hop routers,
or particularly, the exit PE router for other ends of a VPN. You can use
MPLS LDP to then set up a path to get to the exit PE through normal IP
routing/MPLS switching. Each of your PEs will be a meshed MBGP neighbor
with all other PEs. your Core routers will only NEED to know the internal
(IGP) structure of how to get to the IP used as next-hop in from one PE to
another.
I probably made that more confusing than necessary in the last post or two,
and I apologize for that.... the core routers do not need to be a part of
the MBGP process. It won't harm anything if they are, but there's no need
for that to happen.
I have a PDF file to send you... It's about 10 meg in size though. I'm
travelling at the moment, and don't care to sit around forever on a dialup
line! :) However, I'll e-mail it to you this coming weekend, and it'll help
put some of this in a better perspective for you.
Scott
-----Original Message-----
From: Vinod Anthony Joseph Cherunni [mailto:vac@dsqworld.com]
Sent: Thursday, October 05, 2000 10:54 AM
To: smorris@mentortech.com
Cc: cisco-nsp@puck.nether.net
Subject: RE: [nsp] REG: MPLS VPN route exchange
Hi,
Thanks so much for everything.. Can I take the privilege to further bother
you on the same issues you had mailed me on.
Assume I have a configuration like this -
ip vrf VPN-A
rd 100:1
route-target export 100:1
route-target import 100:1
1. The route-target here implies that routes belonging to VRF-A with RD of
100 will be exported, & routes belonging to RD 100 will be imported, Now if
RD's have local significance, how will the source which exchanges routing
information with this router be identified.
Because in the BGP configuration, when I set up an IBGP session with an
internal PE router which may be catering to multiple VPN clients, how will I
ensure which RD routes are exchanged or exported to which RD (VPN), Or else
is the VRF identifier globally significant, which is taken into
consideration while exchanging routes.
2. I am still unclear on how the Core routers, who do not share VPN route
information do forwarding, becos when a core router recieves a packet from a
VPN source (Private IP address space) destined for another private address
space, how will it decide on forwarding, because there would be no entry in
its routing table.
Kindly adviceds
Thanks & Kind regards,
Vinod.
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