i think the cogent depeering thing is a myth of some kind

Daniel Golding dgolding at t1r.com
Sat Sep 29 00:41:56 UTC 2007


This is the scenario. Peer B is send lots of outbound to Peer A.

Peer A depeers Peer (well former Peer) B. Why? Well, Peer A is having  
ratio problems with other Peers C-F. Keep reading...

After depeering, some of (now former) Peer B's outbound traffic to  
Peer A will now flow over links from Peer B to Peers C-F, before  
finally terminating at Peer A. Peer A sees their ratios with Peers C- 
F improve.

This is a proven maneuver and Cogent is not the first to do it. Of  
course, it gets more complex with multihoming and the assumptions of  
a meshy enough connectivity to ensure this will happen.

This is better explained with a whiteboard. That full explanation was  
missing from the writeup that is posted (and I'll allow it to stay up  
for now), because that report was aimed at folks who may not be fully  
conversant in peering - financial professionals. BTW, thanks for  
dropping me an email to ask me about it, before posted to NANOG.

As far as reachability from one provider to another - I've heard that  
one can make routing changes quickly and easily on this crazy  
Internet thing. Perhaps in the 24 hours since I wrote that, a few  
changes occurred?


On Sep 28, 2007, at 6:00 PM, Paul Vixie wrote:

> at <http://www.e-gerbil.net/cogent-t1r> there is a plain text  
> document with
> the following HTTP headers:
> 	Date: Fri, 28 Sep 2007 21:56:34 GMT
> 	Server: Apache/2.2.3 (Unix) PHP/5.2.3
> 	Last-Modified: Fri, 28 Sep 2007 19:15:53 GMT
> 	ETag: "92c1e1-a85-43b36ea5bcc40"
> 	Content-Length: 2693
> 	Content-Type: text/plain
> the plain text title is:
> 	Cogent shows hypocrisy with de-peering policy
> the plain text authorship is ascribed to:
> 	Dan Golding
> the first plain text assertion that caught my eye was:
> 	Cogent, has, in fact, de-peered other Internet networks in the  
> last 24
> 	hours, including content-delivery network Limelight Networks and
> 	wholesale transit provider nLayer Communications, along with several
> 	European networks.
> since i appear to be reaching the aforementioned web server by a  
> path that
> includes cogent-to-nlayer, i think this part of the plain text is  
> inaccurate.
> traceroute to www.e-gerbil.net (, 64 hops max, 52 byte  
> packets
>  1  rc-main.f1.sql1.isc.org (  0.336 ms
>  2 (  0.509 ms
>  3  gig-0-1-0-606.r2.sfo2.isc.org (  1.163 ms
>  4  g0-8.core02.sfo01.atlas.cogentco.com (  2.757 ms
>  5  t4-2.mpd01.sfo01.atlas.cogentco.com (  2.958 ms
>  6  g3-0-0.core02.sfo01.atlas.cogentco.com (  2.525 ms
>  7  p6-0.core01.sjc04.atlas.cogentco.com (  4.183 ms
>  8  g3-3.ar1.pao1.us.nlayer.net (  2.637 ms
>  9  ge-2-1-1.cr1.sfo1.us.nlayer.net (  3.806 ms
> 10  so-0-2-0.cr1.ord1.us.nlayer.net (  69.022 ms
> 11  60.po1.ar1.ord1.us.nlayer.net (  69.491 ms
> 12  0.tge4-4.ar1.iad1.us.nlayer.net (  81.580 ms
> ...
> the second plain text assertion which caught my eye was:
> 	Why is this happening? There are a few possibilities. First, Cogent
> 	may simply want revenue from the networks it has de-peered, in the
> 	form of Internet transit. Of course, few de-peered networks are
> 	willing to fork over cash to those that have rejected them. Another
> 	possibility is that Cogent is seeing threats from other peers
> 	regarding its heavy outbound ratios, and it seeks to disconnect
> 	Limelight and other content-heavy peers to help balance those ratios
> 	out.
> this makes no sense, since dan golding would know that cogent's  
> other peers
> would not be seeing traffic via cogent from the allegedly de-peered  
> peers.
> so, i think the document is a hoax of some kind.  (i saw it  
> mentioned here.)

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