[8161] in North American Network Operators' Group
Re: consistent policy != consistent announcements
daemon@ATHENA.MIT.EDU (the Riz)
Thu Mar 13 15:24:20 1997
From: the Riz <riz@boogers.sf.ca.us>
To: vaf@valinor.barrnet.net (Vince Fuller)
Date: Thu, 13 Mar 1997 11:54:40 -0800 (PST)
Cc: randy@psg.com, SEAN@sdg.dra.com, nanog@merit.edu
In-Reply-To: <CMM.0.90.2.858281395.vaf@valinor.barrnet.net> from Vince Fuller at "Mar 13, 97 11:29:55 am"
Vince Fuller wrote:
> >From our point of view, we aren't seeing any route which can be used for
> shortest-exit to your multi-homed customers. Why? Probably because we don't
> peer with the other ISP which serves those customers. The result is that we
> have to backhaul traffic to other interconnect points, something which is
> expensive for us and inconsistant with our normal peering policy.
>
> I can see why you present inconsistant routes to us but I'm not sure that I
> understand why you'd prefer a customer prefix via a direct connection to them
> at one point in your network but via a connection to another provider at a
> different point in your network. That would seem internally inconsistant to
> me. Is this deliberate behavior to do shortest-exit within your network toward
> your customer?
>
> --Vince
>
The scenario I can think where this would happen is using BGP
route-reflectors internally to reduce the intermeshing requirements for
IBGP peers. Since a route-reflector only propagates the best route, it is
quite easy to get different as-paths in different parts of the network.
Not an ideal situation, to be sure, but "correcting" this behaviour is more
than a simple fix.
+j
--
Jeff Rizzo http://boogers.sf.ca.us/~riz
