Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!uwm.edu!ux1.cso.uiuc.edu!ux1.cso.uiuc.edu!uxh.cso.uiuc.edu!german
From: german@uxh.cso.uiuc.edu
Newsgroups: comp.dcom.lans
Subject: Re: Why Ethernet-over-twisted-pair, any
Message-ID: <11000015@uxh.cso.uiuc.edu>
Date: 29 Nov 89 10:38:57 GMT
References: <4645@blake.acs.washington.edu>
Lines: 47
Nf-ID: #R:blake.acs.washington.edu:4645:uxh.cso.uiuc.edu:11000015:000:2571
Nf-From: uxh.cso.uiuc.edu!german    Nov 28 23:50:00 1989


Well here is my $0.02 on the issue of using UTP for ethernet.

Cost/flexibility/managment.

If I were to design and pull networks just to hit a few office with very
little change anticipated then I might consider a thin coax daisy chained
option, but I would tend to avoid this as a general solution.

If I were to use thin coax I would pull home runs to a central location,
repeat every segment from a concentrator that per port network managment.
I would tend to use something SNMP based.  This is an expensive solution,
but one that in a large environment would isolate faults, provide centralized
managment of the physical plant.

I currently lean towards using UTP distribution.  I will feel alot more
comfortable once 10baseT is approved as I really would like to have the
flexibility to choose my comonents from multiple vendors.  In our environment
we have 4 pairs of UTP at every location with a telephone that is reserved
for data.  Thus I can avoid additional labor and material costs for the
distribution into the offices.  I run every connection back to a repeated/
managed port in a central location.  The connection in the office can be
as unobtrusive as an 8 wire jumper cable from the jack location to a jack
on a 10baseT card.  With quantity (100) discounts we can approach a solution
that would allow us to connect a PC (ISA bus) to a building ethernet for
less than $400 per machine for the ethernet card/jumper cable/multiport
repeater w/ network managment.  This assumes we can fully utilize the 8 or
12 port 10baseT cards in a central concentrator.

This is not a general solution and is very dependent on the site.  Distances
are often the limiting factor when choosing UTP and large buildings will
require that you have more than one location for the concentrators.
4 floors is about the limit you can stretch to from a central location
depending on the distance to the far corner riser.  In some cases we will
end up with a hybrid network.

What is important to me may not be the deciding factors for your design and
it is always important to get a feel for what the users want before you
dump some design on them.  In large departmental networks (>100 nodes)
we very strongly recommend some sort of network managment to be built in.
As the users become more dependent on the network to get their work done
the more important reliability becomes.


         Greg German (german@sonne.CSO.UIUC.EDU) (217-333-8293)
US Mail: Univ of Illinois, CSO, 1304 W Springfield Ave, Urbana, IL  61801
Office:  129 Digital Computer Lab., Network Design Office