Sprint v. Cogent, some clarity & facts

Patrick W. Gilmore patrick at ianai.net
Mon Nov 3 07:09:28 CST 2008


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.

-- 
TTFN,
patrick





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