Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!aramis.rutgers.edu!geneva.rutgers.edu!hedrick
From: hedrick@geneva.rutgers.edu (Charles Hedrick)
Newsgroups: comp.dcom.lans
Subject: Re: Ethernet max length problems
Keywords: repeaters? ethernet too long
Message-ID: 
Date: 25 Sep 89 17:28:19 GMT
References: <634@elan.elan.com>
Organization: Rutgers Univ., New Brunswick, N.J.
Lines: 25
To: jlo@elan.com

The answers people have been giving you are right as far as they go,
but have not mentioned something.  Most typically large thin-net
installations are done in relatively small pieces, using a thin-net
multiport repeater to connect them.  The problem with thin-net is that
you daisy-chain it, so that if somebody disconnects one machine it
affects every other machine down the line.  It's rather hard to
maintain a network that has 100 machines daisy-chained.  So the idea
is that you daisy-chain small groups of machines that are fairly close
together, and then use a multiport repeater to connect the groups.  A
multiport takes something like 8 segments of thinnet and one of
thicknet.  If your systems are fairly close together, you may be able
to use just a single multiport repeater.  If you have a larger
installation, you install a thicknet as a "backbone", and then have
several multiport repeaters connected by the thicknet backbone.

I'm sure you can get a conventional repeater (i.e. a thing that
connects two segments) for thin-net, but normally what you find for
thin-net are multiport repeaters.  Just about all the standard
Ethernet vendors make them: We tend to use Cabletron, but DEC
certainly makes them (DEMPR), and I'm sure 3Com and all the other
Ethernet vendors do as well.

At some point you'll want to use a bridge or router rather than
just a repeater.  Do that when you have enough traffic that you
don't really want all the machines on the same network.