At 05:43 PM 8/20/2007, Steve Gibbard wrote:
On Mon, 20 Aug 2007, Mike Tancsa wrote:
Bell uses Cogent in a large way. The second traceroute was from an
IP in their AS (577) out. I am prepending out Cogent, but Bell
does everything it can not to use Teleglobe so I am having problems
influencing their routes to come back that way. They also have a
very odd path out of Chicago. This is
Bear in mind that doing "everything they can not to use Teleglobe"
probably involves local preference. Local preference comes before
AS path length in the BGP selection order, so nothing you can do
with prepending is going to help.
Yes, I realize that. I think its because they (Bell) pay Teleglobe
for transit, so they dont want to use it where possible. Back when I
signed up with Teleglobe, I was hoping there were some community
tricks I could use to influence bell's local pref, but because they
buy transit from Teleglobe, this was not implemented. I think the
only thing I could do would be to withdraw the prefixes from Cogent
or resort to deaggregation so that they would follow a more specific prefix.
---Mike
You'll need to either keep them from seeing the undesirable path
at all (drop the announcement, ask your upstreams to limit its
propagation, etc.) or convince Bell not to use it. Depending on
the setup, you may be able to limit route propagation with
communities, or it may require some phone calls.
-Steve
