"vpn exchange point"

Fri Jul 23 16:45:07 UTC 2010

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 ASes 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 behavior -option b doesn't suffer from some of the inherent drawbacks of opt ab 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 additional per-vrf ip lookup on the ASBRs
The tradeoff is however -less control over the routes advertised between the 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 configuring RT rewrites on ASBRs -opt ab will take care of that for you

adam
-----Original Message-----
From: David Freedman [mailto:david.freedman at uk.clara.net] 
Sent: Friday, July 23, 2010 5:21 PM
To: Vitkovsky, Adam
Cc: Christopher Morrow; Michael Dillon; nanog at 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_optab.html

Dave.