[14777] in North American Network Operators' Group
Re: [nanog] Re: Microsoft offering xDSL access
daemon@ATHENA.MIT.EDU (Karl Denninger)
Fri Jan 23 17:06:01 1998
Date: Fri, 23 Jan 1998 15:40:20 -0600
From: Karl Denninger <karl@mcs.net>
To: Paul A Vixie <paul@vix.com>
Cc: nanog@merit.edu
In-Reply-To: <199801231955.LAA02823@wisdom.rc.vix.com>; from Paul A Vixie on Fri, Jan 23, 1998 at 11:55:19AM -0800
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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