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From: dglo@zodiac.ADS.COM (Dave Glowacki)
Newsgroups: comp.dcom.lans,comp.protocols.tcp-ip
Subject: Re: experience using commercial cable TV as a MAN.
Message-ID: <9456@zodiac.ADS.COM>
Date: 10 Oct 89 17:35:19 GMT
References: <160@ursa-major.SPDCC.COM> <164@ursa-major.SPDCC.COM>
Sender: news@zodiac.ADS.COM
Reply-To: dglo@ads.com (Dave Glowacki)
Organization: Advanced Decision Systems, Mt. View, CA
Lines: 34

In article <164@ursa-major.SPDCC.COM> eli@ursa-major.spdcc.COM (Steve Elias) writes:
> dyer@ursa-major.spdcc.COM (Steve Dyer) writes:
>>Has anyone ever investigated using a couple of channels from a town's
>>cable TV system as the basis of a metropolitan-area network? 
>
>	look no further, Steve!  the cities of Springfield, Mass and
>	St. Paul, Minnesota have linked their respective ethernets
>	over their local cable systems -- the result for each is a 
>	full speed ethernet that spans many buildings, many miles apart.

St. Paul's broadband link is half-speed, but full speed links are doable
(if you can get 'em past the politicians :-)  Unfortunately, this link
is only used as a glorified Appletalk network link (or was when I left the
city 8 months ago.)  In its infinite wisdom, the rest of the city is
"networked" up over another chunk of broadband via a bunch of glorified
terminal servers.

>>like this *might* work with broadband modems and the right link-level hardware.
>	naturally, there are some gotchas with this technology.  the local
>	cable system has to be fairly high quality stuff.  some cable 
>	companies are fairly lax about attenuations and other nifty RF stuff;
>	such conditions would cause many physical layer 802.4 errors.

The BIGGEST gotcha when I worked at St. Paul was the problems caused by
the cable company searching for cable pirates.  The network would go
down without warning about once a month because of that.

>>I'd appreciate hearing from people who know a little bit more about
>>the issues and whether or not this is completely unrealistic.

Send mail to pwcs.StPaul.GOV and they can probably answer some of your
questions or give you pointers to the right people.
-- 
Dave Glowacki          dglo@ads.com          Advanced Decision Systems