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RE: Peering vs SFI (was Re: Cogent/Level 3 depeering)

  • From: Schliesser, Benson
  • Date: Fri Oct 07 12:57:24 2005

Paul Vixie wrote:
> [email protected] ("Schliesser, Benson") writes:
>> Would you care to speculate on which party receives the greater
>> the sender of bytes, or the receiver of bytes?
>> If both the sender and receiver are being billed for the traffic by
>> their respective (different) service providers (all other issues
>> equal) is one provider in a better position than the other?
> If it's still common for one to be billed only for "highest of in vs.
> then there's no way to compare the benefits since there's always a
> direction and it won't be symmetric among flow endpoints.

Thank you, Paul. I'd be interested in your feedback on these thoughts of
mine below.

I do believe it is typical, perhaps with some variance but usually
amounting to the same thing, that end-users are billed for the "highest
of in vs. out" traffic, roughly the capacity they are provisioned. Thus
if I may, I'll build on this to make a more concrete statement: each
party in a peering relationship receives equal value for traffic
exchanged. (traffic volume at the SFI translates into revenue from

Things aren't so simple in reality, though: you have to look at the
element left out of my statement above, the "cost" of traffic exchanged.
If one peer terminates more traffic than it originates, and the
originating peer is performing "hot-potato" routing, then the
terminating peer typically has a higher cost burden as it has to
transport the traffic the greater distance. However the opposite holds
true if the originating peer is performing "cold-potato" routing.

Thus, such things exist as traffic in/out ratios between peers. But this
is a blunt tool which seems to help enforce the exclusivity of the
Tier-1 club, and actually acts as a barrier to competition. That is,
anybody with a different traffic pattern (i.e., because of a different
business model) will be excluded from the club despite the fact that
they bring equal value in the form of traffic volume to the
relationship. And club-outsiders are subject to increased relative
operating costs (cost of revenue) compared to club-insiders.

So what is the solution? "Warm-potato" routing seems possible
technically, providing an approximation of cost-burden fairness. Is the
benefit worth the complexity to manage in practice? And clearly, I'm not
advocating endless open peering--the revenue element of the equation
(customers) must exist. So what is the best way to determine the
criteria by which a network is determined to be a "peer"?


Benson Schliesser
(email) mailto:[email protected]

I barely understand my own thoughts, much worse those of my betters.
Thus, the opinions expressed herein are not necessarily those of my
employer. Ponder them at your own risk.