[100124] in North American Network Operators' Group
Re: more-specifics via IX
daemon@ATHENA.MIT.EDU (Bradley Urberg Carlson)
Wed Oct 17 22:58:11 2007
In-Reply-To: <EEEC0CBD-A476-407D-A210-FC8FDD59177A@packetrade.com>
Cc: nanog@merit.edu, Iljitsch van Beijnum <iljitsch@muada.com>
From: Bradley Urberg Carlson <buc@visi.com>
Date: Wed, 17 Oct 2007 21:55:25 -0500
To: Stephen Wilcox <steve.wilcox@packetrade.com>
Errors-To: owner-nanog@merit.edu
Thanks for the suggestions.
On Oct 17, 2007, at 6:06 PM, Stephen Wilcox wrote:
> well.. the problem of course is that you pull in the traffic from the
> aggregate transit prefix which costs you $$$ but then you offload it
> to the customer via a peering link for which you are not being paid
A bigger problem is that my IX peer pays less to my customer for
transit. If my customer notices that transit traffic has been going
around him, he may be grumpy. I prefer happy customers.
> its a pain but you cant stop the customer from doing it.. you can
> however filter your customers prefix at the IX (an ASN filter would be
> easiest)
In this case, the IX peer had let their transit provider (my customer)
source the routes, then later advertised their own routes at the IX
using their own ASN (so inconsistent source-as, and my as-path filter
missed them). I don't think they were trying to steal bandwidth; just
sloppy networking.
I can either build a big import filter, dropping routes offered to me
at the IX that are subnets of routes advertised to me by my transit
customers (doesn't scale); or just audit customer routes versus peer
routes periodically, looking for "bandwidth stealers". It sounds like
that is the usual approach.
-Bradley
