[nanog] Re: Microsoft offering xDSL access

Karl Denninger karl at mcs.net
Fri Jan 23 21:40:20 UTC 1998

On Fri, Jan 23, 1998 at 11:55:19AM -0800, Paul A Vixie wrote:
> > HTTP is not nearly as cacheable as you would think, and caching it has some
> > bad side effects in many cases - which your customers will likely bitch 
> > about.
> (temptation to advertise a product here resisted with some difficulty.)
> > Let's say that you can cache 50% of the HTTP traffic, which frankly, from
> > what I've seen is HIGHLY aggressive, but I'll be nice and give you that for
> > the sake of argument.
> 50% is easy with two level caching.  you just need fat pipes between the two
> levels, and high availability at the root of the hierarchy, and a LOT of users
> to help get as much variety as possible in the requests.  i've seen 65% when
> the wind was behind it.
> > Ok, so its only 500:1 assuming 50% effectiveness on the HTTP side.
> > 
> > It still won't work.
> > 
> > Now, if you intend to rate-shape (as opposed to tossing packets on the floor
> > when you get overcommitted) then you ARE committing fraud if you don't tell
> > the truth about it.  And, frankly, the customer really gets hosed with this
> > kind of model - because you have to be pretty predictive for this to give
> > you any kind of net gain in effective utilization, which means you apply the
> > chokes BEFORE the peak levels get hit.
> and this differs from the cable modem internet market in precisely which way?

Uh, it doesn't :-)

(I've done the analysis of this for a cable company a couple of years ago).

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