Newsgroups: comp.dcom.lans
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: Re: In search of an inexpensive fiber "backbone"
Message-ID: <1988Oct9.015656.13814@utzoo.uucp>
Organization: U of Toronto Zoology
References: <1581@csun.edu>
Date: Sun, 9 Oct 88 01:56:56 GMT

In article <1581@csun.edu> djc@csun.edu (Dave Crawford) writes:
>... we hoped that we
>could use relatively inexpensive fiber-optic transceivers rather
>than fiber repeaters or star-topology hubs...

Uh, say what?  You are assuming that your coax experience carries over
to fiber unchanged.  Sorry:  it doesn't.  There is no such thing as an
"inexpensive fiber-optic transceiver".  With coax, it's fairly trivial
to put a bidirectional tap into the side of the cable without any other
adverse effects.  With fiber, THIS IS NOT TRUE.  (Unless somebody has
come up with something new recently.)  In fiber, that operation is
impossibly difficult.

>... Is there an advantage in using
>repeaters and/or a central hub?  This is a far more expensive
>solution to the problem.

Using repeaters would be expensive (and would make the repeaters crucial
to continued functioning of your network).  But I don't understand why
you think a star hub is expensive.  Pull *one* cable, with eight fibers
in it, along your route.  Put your hub somewhere along it.  Use two
of the fibers to connect each node to the hub.  If you put your hub in
the central segment, you can get by with four-fiber cable.

The reason why you should use repeaters or a central hub is because that
is the practical solution with current fiber technology.
-- 
The meek can have the Earth;    |    Henry Spencer at U of Toronto Zoology
the rest of us have other plans.|uunet!attcan!utzoo!henry henry@zoo.toronto.edu