Cogent and Level3 Peering Issues

william at william at
Wed Dec 18 16:44:55 UTC 2002

AOL (AS1668) stopped peering with cogent yesterday for reasons they did 
not disclose publicly. Cogent sends same letter to all customers who 
asked for what is going on and in the letter they say that two weeks 
ago, peering to AOL was upgraded to OC48 from OC12 and now for some 
reason AOL stopped peering and if somebody has questions they should call 
AOL to complain .. (with phone# to their NOC provided in the letter 
- not very nice thing to do it like this in my opinion).

Afterwards direct peering to AOL was lost, cogent started sending out all 
their data though Level3 (AOL upstrem), making them pay for that traffic and 
because of amount of data the peering links got congested easily - PAIX 
cogent->level3 peering in bay area for example had > 1 sec latency 
yesterday afternoon. After I spent some time yesterday investigating all 
that I found that actually cogent is only using former netrail (AS4006) 
peering links to send data out to that is going to AS1668 and only some 
of those links. On the other hand most level3 destined data from 
cogent is sent through PSI links (i.e. 16631 174 3356).. So for me 
currently I put up filters to route all AS1668 and Level3 data through 
savvis for routes that look like (16631 4006 3356 ... ) and it works out 
fine for now.

Today I'm going to deal with incoming traffic but the problem I had is 
that I could not find AOL (AS1668) looking glass, traceroute or some other 
tool like that. I checked and was very surprised that large 
network like theirs does not have publicly available looking glass listed.
So those of you who peer with them - how do you deal with network 
troubleshooting when you need to check soemthing from their network side?
If you know where their looking glass is - please send me a link!

P.S. If somebody is seeing level3->cogent route that is congested I'd also 
like to know as this is something I have to deal with today as well. Send 
this traceroute to me privately.

On Wed, 18 Dec 2002, Dale Levesque wrote:

> Anyone happen to have more information on the problems that have been
> happening with the peering between Cogent and Level3. Cogent gives the
> standard answer when you call support, but some more specific
> information would be great.
> Thanks
> Dale

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