Caps (was Re: AT&T UVERSE Native IPv6, a HOWTO)

Phil Karn karn at
Mon Dec 9 03:55:41 UTC 2013

On 12/06/2013 05:54 AM, Mark Radabaugh wrote:

> Currently, without a limit, there is nothing to convince a end user to
> make any attempt at conserving bandwidth and no revenue to cover the
> cost of additional equipment to serve high bandwidth customers.    By
> adding a cap or overage charge we can offer higher speed plans.

Why is that?

Just guarantee each user a data rate that depends on how much he pays.
Charge him by what it costs you to build and maintain that much
capacity. Lots of mechanisms exist to do this: token bucket, etc.

He gets more than his guaranteed capacity only when others don't use
theirs. Otherwise he won't. If that's unacceptable to him, then he has
the choice of paying you more to upgrade your network or waiting for
others to stop using their guarantees.

It costs you nothing to let people use capacity that would otherwise go
to waste, and it increases the perceived value of your service. Your
customers will eventually find themselves depending on that excess
capacity often enough that at least some will be willing to pay you more
to guarantee that it'll be there when they really want it.

Nothing says you have to carry a customer for less than your incremental
cost of servicing his account, or that you can't add a reasonable profit
margin. But if you can make your customers realize that they're paying
you for a guarantee that most ISP users don't get now they may find it
entirely worthwhile, especially given the very large economies of scale
that often exist in data communications.


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