[128043] in North American Network Operators' Group
RE: "vpn exchange point"
daemon@ATHENA.MIT.EDU (Vitkovsky, Adam)
Fri Jul 23 12:45:36 2010
From: "Vitkovsky, Adam" <avitkovsky@emea.att.com>
To: David Freedman <david.freedman@uk.clara.net>
Date: Fri, 23 Jul 2010 18:45:07 +0200
In-Reply-To: <4C49B358.6050603@uk.clara.net>
Cc: "nanog@nanog.org" <nanog@nanog.org>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
Yes please -option d also known as option AB
-it's the same as option b with addition of VRFs on the ASBRs
-it might as well be viewed as a natural step between opt a and opt b
-opt ab offers the same great control over the routes advertised between AS=
es as opt a -though provides for better scalability by introducing mp-ebgp =
session between ASBRs
By removing the VRFs from the ASBRs and turning off the default mp-ibgp beh=
avior -option b doesn't suffer from some of the inherent drawbacks of opt a=
b like:
Increased memory demands because ASBRs have to store routes in the per-vrf =
RIBs in addition to mp-bgp database
Opt b has also streamlined the forwarding process by omitting the additiona=
l per-vrf ip lookup on the ASBRs
The tradeoff is however -less control over the routes advertised between th=
e AS domains
One advantage that comes naturally with opt ab is -you don't need to worry =
about the import/export RTs not matching in two different ASes and configur=
ing RT rewrites on ASBRs -opt ab will take care of that for you
adam
-----Original Message-----
From: David Freedman [mailto:david.freedman@uk.clara.net]=20
Sent: Friday, July 23, 2010 5:21 PM
To: Vitkovsky, Adam
Cc: Christopher Morrow; Michael Dillon; nanog@nanog.org
Subject: Re: "vpn exchange point"
If you are going to go multi-VLAN data plane (as opposed to multi-label)
then 10A will cause you scaling issues as you'll need multiple BGP peers
(or static routing),
I'd prefer to use
http://tools.ietf.org/html/draft-kulmala-l3vpn-interas-option-d-02
which already has implementations, i.e
(albeit differently named)
http://www.cisco.com/en/US/docs/ios/mpls/configuration/guide/mp_vpn_ias_opt=
ab.html
Dave.
