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Re: Tier Zero (was Re: Tier 2 - Lease?)
- From: John Dupuy
- Date: Fri May 05 16:19:31 2006
At 07:48 AM 5/5/2006, Peter Cohen wrote:
It was not about the SLA, although in theory, buying transit should
give the provider more incentive to help.
On 5/4/06, Aaron Glenn <firstname.lastname@example.org> wrote:
On 5/4/06, email@example.com
> why would anyone do that?
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
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...
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).