From: craig@cattnts.canada.ncr.com (Craig Campbell)
Subject: Re: Repeaters
Organization: AT&T / NCR Canada Ltd., Toronto, Canada
Date: Wed, 15 Apr 1992 18:36:30 GMT

In article <1992Apr13.121215.1@pa881a.inland.com> nason@pa881a.inland.com writes:
>In article <1992Apr10.140813.1@economics.adelaide.edu.au>, tanemeth@economics.adelaide.edu.au writes:
>> In article whinery@nancy.uhcc.Hawaii.Edu (Alan Whinery) writes:
>>>...
>>> Thin coax is 1) a much better signal path than twisted pair, able to
>>> go almost twice as far as an ethernet plus 2) you can put 29 stations
>>> on a thin coax segment, vs 1 on a twisted pair segment.

True, but rather pointless since 10BaseT uses a hub and star configuration,
not a line with taps attached.  10BAseT does also NOT require terminators,
and has line noise identification and isolation (at least the implementations
I'm familiar with do).  That means that the network will not go down, no 
matter what happens to a single cable or machine.  (OK, a lightning strike
MIGHT cause some problems.  Use fibre for lightning prone areas. :-))
Coax ethernets are well known for being tempramental.  As one customer put it,
you diagnose an ethernet problem by autopsy.

>>> Thus, coax,
>>> though slightly more expensive is much more valuable once installed.

>> We are going to have to differ on that one!  The only place for thin ethernet
>> cable is inside the wiring closet, to connect hubs together.  Thick cable has
>> no place anywhere (well, newly installed, anyway).  Anyone who is installing
>> thin ethernet cable now is probably VERY misguided.

If your ethernet gets accidentally cut, what happens to your network?
Answer DEATH.

If a piece of your 10BaseT get cut, what happens?
Answer:  The two segments around the cut can't communicate with each
other (the wire is broken after all), while the rest of the
network (two smaller networks now) continue to function normally.

>I don't think so.  Twisted pair provides little noise immunity, 
					  ^^^^^^ ^^^^^ ^^^^^^^^

Sorry I can't quote sources, but AT&T has maintained for some time that 
unshielded twisted pair actually has certain properties which result in a
high level of noise immunity.  Now if you're running your cables by working 
Tesla coils, there may be some problems...:-)

>and is always the worst choice (cheap).
     ^^^^^^^^^^^^^^^^^^^^^^^^^^

Again, such broad sweeping statements are less than wise.  I have worked in
buildings wired with nothing but (cheap) unshielded twisted pairs using
a Universal Premisses Distribution System.  This provided reliable, flexable
connectivity for voice (analog and digital) communications, data communications
including telephone, serial, 10BaseT (10 Mbit) and 1Mbit network communications.

There were never ANY problems attributed to the method of wiring.  The
flexability was a great asset (same connectors for voice or data -- RJ45).

Your statements are either ill informed or you are making assumptions about
the environment (extremely hostile) that the rest of us know nothing about.

>We install networks in a high noise environment, thick wire is the ONLY choice. 
Really?  How about fibre?  Fibre/unshielded twisted pair combinations?
There are always other options.  How do you know 10BaseT UTP won't work?
Have you tried it?

>So to say that thick-wire has no use anywhere is presumptutous, short sighted
>and grossly mis-informed.  

>Using twisted-pair, zip cord or any other piece of junk picked up to throw
>together a network to save a nickle, will in the end bite you back.  

So much for 10BaseT research...it has resulted in junk... (heavy sarcasm).

>You get what you pay for!!!

Only if you are lucky.  If you waste your money on primitive technologies,
then you can join the Swiss Watch Making Industry.  (Digital watches are
just a fad. -- Where are they now?)

>John M. Nason
>Hardware Engineer, Inland Steel Company.

Hardware, she's a changing John....better try and keep up....


-- 
Craig Campbell		|	These opinions are entirely the result of a 
Systems Engineer	|	small butterfly crashing into the far side
NCR Canada,		|	of the planet.  Chaos Rules.
an AT&T Company		|	I speak for no one, except, possibly, myself.
Xref: sparky comp.dcom.lans.ethernet:602 comp.sys.sun.misc:1902