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Re: Sprint v. Cogent, some clarity & facts

  • From: Patrick W. Gilmore
  • Date: Mon Nov 03 08:10:54 2008

On Nov 3, 2008, at 2:35 AM, Paul Wall wrote:
On Mon, Nov 3, 2008 at 1:26 AM, Patrick W. Gilmore <[email protected]> wrote:
1. Neither Sprint nor Cogent have transit
Both Sprint & Cogent are transit-free networks. (Notice how I carefully
avoided saying "tier one"?)

How do you explain Cogent's arrangement with NTT (AS 2914)? If it's not transit, what is it?

I do not know, and neither do you. But I do know it is not "transit", at least not to Sprint.

It is trivial to prove to yourself if Cogent has transit. Find me any AS path in the global table showing "_TF1_TF2_174_", there "TF1" and "TF2" are the ASNs of two of the other 13 transit free networks. (Modulo a few leaked prefixes, which always seem to crop up. For instance, if a network has 40K prefixes in its cone, showing O(10) paths is not proof.)

This is a positive test - if you see it, you know they have transit, if you do not see it, you do not know they do not have transit. But combined with bifurcation when Sprint drops peering to Cogent, one can _know_ Cogent does not have full transit, or partial transit to Sprint. It is possible (although I personally believe unlikely) Cogent has partial transit to some other transit free network that you cannot see right now because their peering to that network is up and overriding the AS paths in the global table. But that doesn't matter to this discussion.

Does Akamai have peering arrangements with Cogent directly?

That is none of your business, not to mention completely irrelevant to the topic at hand as Akamai is neither a network nor transit free.