Cogent latency / congestion
mike at sentex.net
Tue Aug 21 01:02:15 UTC 2007
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.
> 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.
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