XO - a Tier 1 or not?

Justin M. Streiner streiner at cluebyfour.org
Tue Jul 28 11:30:38 CDT 2009

On Tue, 28 Jul 2009, Joe Provo wrote:

> On Tue, Jul 28, 2009 at 11:30:47AM -0400, Justin M. Streiner wrote:
>> 1. The provider does not buy IP transit from anyone - all traffic is moved
>>   on settlement-free public or private interconnects.  That's not to say
>>   that the provider doesn't buy non-IP services (IRUs, lambdas, easements,
>>   etc) from other providers on occasion.
> Purchasing other services is sometimes seen as a settlement, generally
> based upon which end of the transaction one is sitting.

Sure, that's possible.  The agreements can be structured in many different 
ways.  Since they're often covered by nondisclosure agreements, only a 
handful of people on either end know the full details.

Many of the peering agreements I've seen either worked the cost structure 
on a rotating (provider A buys the first link, provider B buys the 
second, etc) or a split (the two providers split the costs of the links) 
basis.  Discussions about more advanced topics like traffic levels and 
settlement fall-back clauses are somewhat out of scope for this thread.

>> 2. The provider lives in the default-free zone, which is pretty much a
>>   re-statement of point 1.
> Running without default (using full table, "default-free zone")  Has
> nothing to do with who you pay for what.

Agreed.  I brought it up because it's a common (but not entirely accurate) 
assumption that providers who live in the DFZ are Tier 1 providers.

> Discussion of "tiers" will inevitably reach topics of marketing &
> market dominance [eg "tier one in my home region" for many PTTs]
> and generally are not any kind of useful technical metric.  In fact,
> it can easily be argued that the networks which run without any form
> of contractually binding vector for their customer's traffic are more
> fragile than those who have one or more paths with dollars (and various
> levels of penalties) attached.

Agreed again, but it's something that operators will continue to deal with 
as long as some providers continue to play up their tier status and 
customers continue to attach some relevance or assumptions of performance 
or reliability to it.


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