Cogent latency / congestion

Kevin Oberman oberman at
Mon Aug 20 21:13:38 UTC 2007

> Date: Mon, 20 Aug 2007 16:11:44 -0400
> From: Mike Tancsa <mike at>
> Sender: owner-nanog at
> At 03:54 PM 8/20/2007, Dan Armstrong wrote:
> >We're going crazy up here, I'm trying to nail down where exactly the 
> >problem is - We don't use Cogent anywhere, but we're having terrible 
> >problems with Bell and many sites in Europe...
> 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 from a site in Toronto (source 
> IP in AS577) back to me peering with Cogent's router in Toronto... 
> Toronto, Chicago, Kansas, Texas, Washington, Boston, Albany, 
> Toronto.  Thats quite the milk run.  Usually its Toronto, Chicago, Toronto.

Almost certainly the fiber cut of last night. Still down after >19
hours. Not a pretty picture for those lacking diversity between Chicago
and points east.
R. Kevin Oberman, Network Engineer
Energy Sciences Network (ESnet)
Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab)
E-mail: oberman at			Phone: +1 510 486-8634
Key fingerprint:059B 2DDF 031C 9BA3 14A4  EADA 927D EBB3 987B 3751
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