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

  • From: Daniel Golding
  • Date: Fri Sep 28 20:56:13 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 <> 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 (, 64 hops max, 52 byte packets
1 ( 0.336 ms
2 ( 0.509 ms
3 ( 1.163 ms
4 ( 2.757 ms
5 ( 2.958 ms
6 ( 2.525 ms
7 ( 4.183 ms
8 ( 2.637 ms
9 ( 3.806 ms
10 ( 69.022 ms
11 ( 69.491 ms
12 ( 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

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.)