Tier Zero (was Re: Tier 2 - Lease?)

John Dupuy jdupuy-list at socket.net
Fri May 5 20:17:56 UTC 2006

At 07:48 AM 5/5/2006, Peter Cohen wrote:

>On 5/4/06, Aaron Glenn <aaron.glenn at gmail.com> wrote:
>>On 5/4/06, bmanning at vacation.karoshi.com 
>><bmanning at vacation.karoshi.com> wrote:
>> >
>> >         why would anyone do that?
>> >
>> > --bill
>> >
>>Some companies feel entitled to charging more for their routes than
>>they would for simple transit.
>Hopefully this comes out clearly, as writing can be more confusing
>than speaking...
>Are you getting at Inter AS /SLA/QOS that you would get from transit
>vs. best effort peering?   Even that has some issues, the one that
>jumps out to me is hopefully clearly stick figure-diagrammed below:
>AS#x $--SLA-->Transit  ok...
>AS#x $--SLA-->Transit <-(second hop)--Customers/Peers---No Qos/SLA--->
>My point is it is hard to do anything beyond the first AS# for any SLA
>that you would be paying, since after that the packet switches to no
>money packets on a paid connection, pushing out the issue for things
>sent down that pipe...
>Peter Cohen

It was not about the SLA, although in theory, buying transit should 
give the provider more incentive to help.

The off-list discussion was more about avoiding the dependency 
problem of peerings. A "good" peering involves multiple points of 
geographically diverse interconnections. The number and location of 
these interconnections would depend on the unique combination of 
architectures of the two peers. If an AS does not have the traffic 
levels to justify multiple connections into a neighboring AS, relying 
on a single interconnection point is a problem. Even if the 
interconnection does not go down, it might not be a good way to reach 
particular networks in the other AS. Instead, it might be wiser to 
"tune" traffic via a different neighbor using transit.

In other words, it gives you the best of both worlds. Most traffic 
travels directly to/from the SFP provider that serves the 
corresponding networks (like a peer). However, one can use the 
transit option at will for particular routes. And, one can use 
transit via the other SFPs should any transit to an SFP fail (fiber cut, etc.)

Given that transit is pretty cheap, it seems more cost effective, at 
lower traffic levels, to purchase single transit interconnections to 
all the SFPs than attempt true peering at a much larger number of 
interconnections to those same SFPs.

This is getting pretty theoretical, but I was curious if such a 
business model was attempted. The original SAVVIS did this in part 
long ago, but to just three neighbors. (I think they are now part of 
C&W now...I can't keep track of all these mergers.) It sounds like 
Internap is pretty close to this model, although I don't believe they 
have transit to all nine (if my SFP count is correct).


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