From: karl@ddsw1.mcs.com (Karl Denninger)
Subject: Re: How to network 3-4 home machines cheaply?
Date: Mon, 14 Dec 1992 02:09:06 GMT
Organization: MCSNet, Chicago, IL

In article <1992Dec10.153444.9033@tinman.mke.ab.com> tdphette@mke.ab.com (Thad Phetteplace x4461) writes:
>css@tron.stx.com (Chris Shenton) writes:
>: 
>: My housemate and I want to network our machines (3 UNIX and 1 LISP)
>: together. Three of these have Thicknet connectors, one has no ethernet
>: yet. What's the cheapest way to connect 'em all up?
>: 
>: Seems like running a thicknet rib in the attic and buying all the
>: transceivers and cables would be real pricey. And I can't even
>: directly connect two machines, can I?
> 
>You cannot connect two endpoint thicknet nodes directly together. 
>There must be a properly terminated bus between the nodes.  

Correct.  One possibility is a multidrop transceiver (several makes; Canary
makes one) with a short piece of coax & 2 terminators.  This may be cheaper 
than two separate transceivers, but then again it might not.

Note that if you do this with a multiport transceiver you still need
external media of SOME type.  DO NOT get a multiport 10BaseT transceiver or
you'll need another transceiver on the other end to meet the media
requirement!  With a thin coax transceiver the requirement can be met with a 
few feet of coax, 2 terminators and a T connector.

>: I could get a few Thick-to-10BaseT transceivers, but wouldn't I then
>: have to buy a 10BaseT hub to interconnect them? What would be the
>: price on a 4-8 channel hub? Could I at least connect two machines by a
>: direct (point-to-point) 10BaseT line?
>
>You cannot directly connect two 10BaseT trancievers,  You need some
>sort of hub in the middle to assert the the signals properly.  

Incorrect.  You >can< directly connect TWO, and ONLY TWO, 10BaseT devices
without a hub.  The pairs are 1/2 & 3/6.  You flip them in the cable and
presto -- it works.

This is explicitly allowed in the specifications.

>I don't
>have prices for 4-8 channel concentrators, we buy 100+ channel boxes
>here at Allen-Bradley.  I'm guessing they are more expensive than
>you'd be willing to pay.

An 8 port concentrator can be had for ~$300.00 if you shop around hard.

>: Getting a Thicknet-to-Thinnet seems like it might work, then I connect
>: 'em all up with coax ``T'' connectors. Is this doable?
>
>Yes, and probably much cheaper than buying twisted pair tranceivers and
>a hub.  This is actually a very popular choice for many small business.
>Twisted pair doesn't start to pay for itself until the number of nodes
>reaches a certain point (definetly more than 4).
>
>Last time I checked you could get a transceiver as cheap as $50 if you
>shop around.  I forget how much coax costs but I remember it was cheap
>in comparison to the other costs involved (less that $1 per foot).

Yep.  However, be careful with the connectors.  The "twist on" ones at Rat
Shack look attractive, but have a nasty failure rate if the cable gets
flexed.

--
Karl Denninger (karl@ddsw1.MCS.COM, <well-connected>!ddsw1!karl)
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