Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uwm.edu!uakari.primate.wisc.edu!aplcen!jhunix!ecf_hap
From: ecf_hap@jhunix.HCF.JHU.EDU (Andrew Poling)
Newsgroups: comp.protocols.tcp-ip
Subject: Re: Thick or Thin
Summary: but LOTS of workstations DO already have a thinnet xcvr
Keywords: thinnet, thicknet, costs, transceivers, xcvrs
Message-ID: <2781@jhunix.HCF.JHU.EDU>
Date: 4 Oct 89 02:12:12 GMT
Expires: 3 Nov 89 00:00:00 GMT
References: <42457@sgi.sgi.com>
Reply-To: andy@gollum.hcf.jhu.edu (Andy Poling)
Followup-To: comp.protocols.tcp-ip
Organization: The Johns Hopkins University - HCF
Lines: 68

In article <42457@sgi.sgi.com> ian@lassen.wpd.sgi.com (Ian Clements) writes:
[...]
> I disagree.  Remember that you need one transceiver for each workstation
>regardless of whether or not you use thick, thin or twisted pair (assuming that
>no workstation already has a thinnet xcvr installed).  I'm calling the xcvr
>costs a wash even though there is a $50 difference between thin and twisted
>pair (thin being least expensive and twisted pair most expensive).


I've been watching this discussion go by and I want on.  Over and over I've
been muttering to myself, "But they've probably already bought a thinnet
xcvr - whether they know it or not".

Fact is, a whole bunch of workstations come from the factory with a xcvr on
board and that cute little BNC connector on the back.  And what about
PCs/compatibles?  Almost EVERY ethernet card that I've laid eyes on for PCs
has both thick and thinnet interfaces.  Some machines are even available ONLY
with thinnet interfaces (DEC VS2000's come immediately to mind - there must
be others, though).  In order to put a machine like this on thicknet or
twisted-pair, you must insert a $1,000-or-so repeater of some sort.  Uh-oh,
kinda makes those sweeping generalizations start looking like expensive
oversights.

When considering the relative costs of thicknet, thinnet, and twisted-pair,
you have to consider that alot of machines come thinnet ready.  If we're
figuring the costs of putting such machinery on alternate cable types, we
have to admit that we're buying two xcvrs for each machine and leaving one
idle.  We may also end up jacking up our repeater-count converting from one
cable type to another.

We've been using thinnet more and more, recently, for in-building wiring
for several reasons:
	1) it's smaller in diameter and more flexible and thus easier to
		put in place than thicknet (twisted-pair likewise)
	2) thinnet cable termination is a breeze compared to xcvr cable
		termination (we're talking about putting a connector on
		the end of the cable - fabricating custom-length cables)
	3) when we want to put several machines in one room, we can
		daisy-chain
	4) people with thinnet-ready equipment save money - no additional
		cost for a xcvr
	5) people with DB-15 interfaces spend less because thinnet costs
		considerably less than xcvr cable per foot and we can put
		the thinnet xcvr very close to the machine

We still use thicknet for the "backbone" (inter-building cabling) and for
some "building risers" for mostly obvious reasons:
	1) greater allowable cable length - important with our geography
		and layout
	2) greater (perceived at least) durability under the sometimes
		adverse conditions encountered - I'm not sure that there
		isn't sufficiently sturdy thinnet cable available nowadays;
		in fact, I'm sure there probably is
	3) the best reason of all - alot of our cabling of this type
		predates the wide availability and usage of thinnet


I mostly wanted to point out some easily overlooked "hidden" costs.  It's
amaizing how fast the costs can climb when you start figuring in repeaters
and pairs of xcvrs.

-Andy

--
Andy Poling                              Internet: andy@gollum.hcf.jhu.edu
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