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RE: Sticky stuff.

From: Paul Leach <paulle@microsoft.com>
Date: Fri, 9 Aug 1996 11:37:05 -0700
Message-Id: <c=US%a=_%p=msft%l=RED-77-MSG-960809183705Z-16599@tide21.microsoft.com>
To: "'sfwhite@incontext.ca'" <sfwhite@incontext.ca>, "'hardie@nasa.gov'" <hardie@nasa.gov>
Cc: "'http-wg%cuckoo.hpl.hp.com@hplb.hpl.hp.com'" <http-wg%cuckoo.hpl.hp.com@hplb.hpl.hp.com>
In many cities, to "build out" (as they say in the cable TV biz) the
"cable plant" to be two way is a major undertaking that will take years.
Whereas, sending requests by modem over telephone line and receiving the
response over the cable, is something that can be installed with no
upgrade to the cable plant. The high profile tests often use the
glitzier two-way technology, but cable companies are very attracted to
the other because it could be deployed more rapidly (this information
from my stint in Interactive TV).

Since nothing is ever simple, it is also true that many cable systems
have no spare channels in the downstream direction, and that when the
solve that problem they also make it two way; but most cable modems that
I know of are still bandwidth asymmetric.

Also, the telco's are talking about "ADSL" which is typically something
like 64 kbits from the home, and 1.5 mbits to the home. (Other variants
exist with higher bandwidth in both directions, but the degree of
asymmetry is about the same.)

Paul

>----------
>From: 	hardie@merlot.arc.nasa.gov[SMTP:hardie@merlot.arc.nasa.gov]
>Subject: 	Re: Sticky stuff.
>
>Stephen White writes:
>> just as a datapoint, the cable modem installations in the toronto area
>> (which are now actual production services, not beta tests) use two-way 
>> communication over the cable lines.  they're not assymetrical.
>> 
>
>Several of the systems being tested in the U.S. use two-way
>communication over cable lines, but are still bandwidth-assymetric.
>As I understand it, they use several frequency bands (each band being
>equivalent to what would deliver a standard cable channel) in the
>downstream portion, but only a part of one in upstream portion.  The
>system in Toronto may,of course, be designed very differently.
>
>
>				Ted Hardie
>				NASA Science Internet
>
>
>
>
>
Received on Friday, 9 August 1996 11:39:05 EDT

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