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From: kwe@bu-it.bu.edu (Kent England)
Newsgroups: comp.dcom.lans
Subject: Re: What *is* "twisted pair"?
Message-ID: <72856@bu.edu.bu.edu>
Date: 22 Jan 91 17:56:27 GMT
References: <3832@mentor.cc.purdue.edu> <1991Jan16.175003.2978@zoo.toronto.edu> <6314@ecs.soton.ac.uk>
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In article <6314@ecs.soton.ac.uk>, tjc@ecs.soton.ac.uk (Tim Chown) writes:
> 
> You mention that you run the twisted pair back to a central hub. Does
> this mean a separate connection to each office from the hub? 
> 
	10BaseT or twisted pair Ethernet requires a star configured
topology, but other media, like thin coax or AUI cables, can be used
to achieve a star topology.  Many users will accept 10BaseT since the
wire is already installed or they believe that it will be cheap to
install, so they seredipitously receive a star topology without having
to learn why they need it.

	Insist on a star topology for one simple reason: When you have
one end of a cable in your hand in the user's office, only a star
topology allows you with reasonable assurance to know where the other
end is and what it is connected to.  This sounds trivial, but it is
not and that is why almost everyone with field experience has adopted
the idea of *structured* wiring (aka star topologies).

	Remember that star topologies can be configured into rings and
busses as needed, so star topologies are also popular in installing
fiber backbones and fiber wiring.  Not every wiring plan in the world
is a star or should be so (the national fiber optic network comes to
mind), but most so-called horizontal wiring is becoming star or
structured.

	Topology is the key, not the medium.  10BaseT takes advantage
of the topology to do such things as link status, but that could be
done with star-wired thin-net, too.  FDDI-to-the-desktop will also
benefit from star topology, no matter what medium you end up using.

	--Kent