Sprint v. Cogent, some clarity & facts

Nicolas Antoniello nantoniello at antel.net.uy
Mon Nov 3 18:34:16 UTC 2008

Sorry for my possible ignorance, but could you explain me what are you
calling "transit-free"?
I mean, the ISP I work for, has contract for several STM-4 links with
Sprint (at least for 8 years now), and for sure they do have transit, at
least for us (as we publish our customers ASs to them and they publish
them to other carriers). ¿is that what you call transit?

Thanks in advance,

Patrick W. Gilmore wrote:
> On Nov 3, 2008, at 2:35 AM, Paul Wall wrote:
>> On Mon, Nov 3, 2008 at 1:26 AM, Patrick W. Gilmore <patrick at ianai.net>
>> 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.

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