Path: utzoo!bnr-vpa!bnr-fos!bigsur!bnrgate!kratz
From: kratz@bnrgate.bnr.ca (Geoff Kratz)
Newsgroups: comp.protocols.tcp-ip
Subject: Re: Thinwire vs. Thickwire
Summary: A (very brief) overview of UTP
Message-ID: <96@bnrgate.bnr.ca>
Date: 5 Oct 89 12:30:03 GMT
References: <68@lcc.la.Locus.COM> <8909291306.AA06775@jvnca.csc.org> <1989Oct4.174149.9451@ux1.cso.uiuc.edu>
Organization: Bell-Northern Research, Ltd., Ottawa, CANADA
Lines: 87

Before I start, I want to say this I do not want to bash thin-net.  The
purpose of this is more to provide an alternative for those people who
are now (will soon be) building a LARGE ethernet site.

In article <1989Oct4.174149.9451@ux1.cso.uiuc.edu>, melanie@ph-meter.beckman.uiuc.edu (Melanie Anderson) writes:
> In article <68@lcc.la.Locus.COM>, eric@lcc.la.Locus.COM (Eric Peterson) writes:
> > 
> > In article <8909291306.AA06775@jvnca.csc.org> aggarwal@JVNCA.CSC.ORG
> (Vikas Aggarwal none) writes:
>  
> enough thinwire bashing, already.
> 
> im coming into this debate late; but let me throw in my 2pence anyhow:
> 
> some background:
> 
> the design goal of the network was to provide high connectivity to 
> every office, lab, conference room and public area.  therefore every room in
> the building (excluding bathrooms and kitchens!) has at least one
> connection to the building network. this presented some interesting cable
> design problems, resulting in (if you dont belive me do the math) the
> discovery that it would be 1. enormously expensive 2. very difficult 3.
> would not meet connectivity requirements to use thick ethernet.

It would have been as trivial with UTP.  We are located in a number
of buildings, but a prototypical one would be:

      1000-2000 people
      about 1000+ machines (workstations, mainframes, PC's, Macs)
      about 4000+ ports of repeaters (on the hubs, bridges and delnis)

And we move equipment around a LOT.

Using UTP allowed us to put the backbone in a central location, and then
build a star from there.  Since we already have 4-pair cables running to
the floor, wiring was cheap.  We did find, though, that the cost per seat
was about $800 when installation of the cable was included (that includes
the prices of the twisted pair, MAU, hubs, bridges and delnis).  Cheaper,
of course, when the cable was already in place.  And it can get as good
as $400-500 per seat (depending on numbers).

> it WORKS, it works GREAT. i have had zero problems with the wiring, ~zero
> problems with the repeaters (out of over 700 repeater ports i have had 1
> fail). somebody comes in, they get a chunk of cable from central stores for
> 6 bucks, they come to me, i give them a new IP number and tell them what
> their default gateway ip address is (for those brain-dead ips out there!),
> they go up to their office, they plug in, and off they go!

We tried thin in a few locations, and got burned by poor construction (this
is probably not true of all manufacturers thing products).  Just shifting
a workstation could cause the T-connector to come off the BNC, thus causing
a break and taking out the entire segment.

We find that with UTP, a MAU can die and have no adverse affect on the net
(depends on the type of death of course.  If it just fails and stops functioning
no problem.  If it decides to transmit junk, that's a different story).

On the rare occasion that a hub decides to lose its mind, the effect can vary
(depends on where the hub is located in the topology).  At most, though,
you will lose a segment behind a bridge.  We have yet to have a bad bridge
or hub take out the entire subnet within a building.

> i strongly believe, however, that whatever your wiring application, 
> that ribs-n-spine be used in any new large network. saves you much time and
> effort and grief. it is flexible, reconfigurable, and expandable. try to
> divvy your network up into ribs and then firewall them off from each other
> so that one looney machine wont crash everyone.

Yup, same with UTP.  You use hubs to build a star, use the bridges as
traffic filters and use routers to build multiple backbones.  As well,
moves involve moving a pair of jumper wires on a BIXX block.

> whatever you do, PLAN for cut wires, smushed connectors, gonzo 
> transcievers, crazy ethernet cards, and broken software. DONT assume 
> all computers will play well with others. expect the worst because it 
> WILL happen. 

You betcha!  And expect some of the users to get "creative" too.

Large sites do present an interesting problem and an incredible opportunity
to do it right (or screw it up REAL GOOD!) whether it is thick, thin or
UTP.
-- 
Geoff Kratz         Bell-Northern Research, Ltd.    Ph: (613) 763-5784
Internet Systems      P.O. Box 3511, Station C      FAX:(613) 763-3283
                    Ottawa Ontario Canada K1Y 4H7
BITNET: kratz@bnr.ca