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Path: utzoo!watmath!clyde!floyd!cmcl2!philabs!mcnc!unc!rentsch
From: rentsch@unc.UUCP (Tim Rentsch)
Newsgroups: net.lan
Subject: Re: Ethernet cable length query - (nf)
Message-ID: <6986@unc.UUCP>
Date: Mon, 26-Mar-84 19:09:50 EST
Article-I.D.: unc.6986
Posted: Mon Mar 26 19:09:50 1984
Date-Received: Wed, 28-Mar-84 01:04:12 EST
References: <2832@fortune.UUCP>, <1151@cbosgd.UUCP>
Organization: CS Dept., U. of N. Carolina at Chapel Hill
Lines: 27

Interesting that connecting your transceiver tap causes your 750 to reboot,
whose controller are you using?  (For that matter, which driver are you
using?  The standard 4.2 one?)

My experience with transceivers is that any idiot can use 3Com transceivers
and make them work (at least this idiot could), but some finesse is required
for the pressure tap kind.  Most of the pressure tap kind (DEC, Interlan,
...?) are physically similar and I have heard that they are all made by a
separate company (Singer, as I recall).  Quite plausible, from my handling
of Interlan transceivers and looking at photographs of the DEC stuff.  I
have heard of a pressure tap transceiver that is spring loaded and so
"cannot" be overtightened.  Personally, I would recommend the connectorizing
(aka 3Com) type, once you realize that the cable should never be cut but
just screwed and unscrewed.

Another thing:  there are at least two companies (DEC and TCL) that make a
box (DEC calls its box a DELNI) which allow multiple controllers to be
plugged into a single xcvr.  In fact, as long as you can fit all your
devices (maximum of 8) into the one box, the cable is optional.  (Just try
explaining to your boss that you are getting an ethernet without the ether.)
Both DEC and TCL's boxes can be cascaded another level, making a total of 64
devices running off of one xcvr.  One very appropriate use for these things
is to get around the problem of having to run scads of wire when all you
really need is scads of xcvr outlets.  Or use them for after-the-fact
reconfiguring (e.g., more devices in a single office).

Tim