[Year 12 Its] Ongoing misinformation about topology
Allan Barnes
abarnes at aiet.com.au
Fri Aug 25 08:33:24 EST 2006
Hi Frank
I am just going through the final edit of the new edition of the Navigating
Informations Systems book so I have gone back and tried to tidy up the
network topology section as much as I can. Happy to send you a copy of the
book (and other schools that want to have a look at it as well) in about a
week when it has been published.
Kind regards
Allan Barnes, CEO
Australian Institute of Education and Training
Phone: (03) 9387 2051
FAX: (03) 9387 3470
E-mail: abarnes at aiet.com.au
-----Original Message-----
From: is-bounces at edulists.com.au [mailto:is-bounces at edulists.com.au] On
Behalf Of Kevork Krozian
Sent: Tuesday, 22 August 2006 2:27 PM
To: is at edulists.com.au
Subject: Re: [Year 12 Its] Ongoing misinformation about topology
Hi Frank,
I share your frustration and have gone through the same journey.
I would make a couple of points:
1. Even if books still think star networks have a central computer,
ignore it and teach as you know it to be. A star network has a central
concentration device . This is called a switch ( not a computer unless you
have 10, 20 or 30 network cards in them , and NOT a hub because a hub is
really a BUS network with the T-pieces of the old BNC type connectors pulled
into the hub ). With the computer with the 30 network cards , this would
make the concentration device a ROUTER and not a switch.
2. Whether an installation has a hybrid network or not is not the point
when discussing the definition of a star network. Nor is it the point that a
pure STAR network is less common than a hybrid network when asking for a
definition of a star network.
3. As for a TOKEN RING network there are two aspects - the media access
method ( use of a token ) and the topology ( a ring ).
4. There is a difference between a PHYSICAL topology ( a hub presents as
a physical star network ) and a LOGICAL topology ( a hub is a logical BUS
as all nodes are connected to the same wire ). And yes Don Morelli has
accurately pointed out that a Token Ring is a physical STAR and a logical
RING . The media access method is by way of a token. You need a token to
communicate otherwise you are listening. The logical topology is a RING
using a physical topology of a STAR by way of a device called a MSAU -
multi station access unit .
Now, I teach this concept no matter what the text books or study
design says. However others might argue it is too complex for the students.
In the same breath, this is EXACTLY what I teach my Cisco CCNA students who
are often the same faces who appear in my IT Systems class. So why is it
too difficult for one and not the other ?
5. If you want precise definitions and references to your key points ,
ask a qualified , practicing network engineer working in the field. He/she
will tell you what is found out in industry and education and other
installations , and not what is written in books that have information years
out of date. You can consult one or more of these people on the cisco
mailing list at www.edulists.com.au . Subscribe the usual way.
Hope this helped.
Best Wishes
Kevork Krozian
IT Manager , Forest Hill College
k.krozian at fhc.vic.edu.au
http://www.fhc.vic.edu.au
Mobile: 0419 356 034
>>> forster at ozonline.com.au 08/17/06 04:20pm >>>
Its sad that a subject with such potential is being used for the rote
learning of definitions. Do we want walking dictionaries?
"The mind is not a vessel to be filled but a fire to be kindled." Plutarch
(46 - 127)
----- Original Message -----
From: "Allan Barnes" <abarnes at aiet.com.au>
To: "'Year 12 Information Technology Systems Teachers' Mailing List'"
<is at edulists.com.au>
Sent: Thursday, August 17, 2006 12:08 PM
Subject: RE: [Year 12 Its] Ongoing misinformation about topology
>I think the classic definition of a star topology is correct as you have
> stated, however, as you have also stated, it is not often seen in places.
> Nowadays, it is more common to have hybrid networks that are a combination
> of a number of topologies, or two star networks stuck together, and so
> forth.
>
> If we are teaching the true meaning of a star network then essentially we
> have it right, but what we also need to be saying to our students is that
> the star topology is not generally found in industry and it is a mixture
> or
> hybrid.
>
>
>
>
> Kind regards
>
>
> Allan Barnes, CEO
> Australian Institute of Education and Training
> Phone: (03) 9387 2051
> FAX: (03) 9387 3470
> E-mail: abarnes at aiet.com.au
>
>
>
> -----Original Message-----
> From: is-bounces at edulists.com.au [mailto:is-bounces at edulists.com.au] On
> Behalf Of a.hopkins at bcc.vic.edu.au
> Sent: Thursday, 17 August 2006 11:11 AM
> To: Year 12 Information Technology Systems Teachers' Mailing List
> Subject: Re: [Year 12 Its] Ongoing misinformation about topology
>
> Frank's comments strike a chord with me. I came into computer teaching
> without formal qualifications in the area, but having done programming out
> of personal interest for perhaps twenty years. The whole networking and
> hardware side of things was not on my radar. I have found the textbooks
> to
> be lacking in clarity and concision. I don't mind my students knowing
> more
> about networking than I do, because some of them are acquiring that
> knowledge in very practical ways. But other students who aren't attuned
> to
> hardware aspects, and I myself, could surely be served better by the
> textbooks we use. When some time ago I asked my techie about some of the
> explanations offered, he thought they were pretty much irrelevant.
>
> Alex Hopkins
>
>
> Quoting Frank Van Den Boom <vandenboomfj at aquinas.vic.edu.au>:
>
>>
>>
>> There have been several discussions over the past couple of years
>> concerning the poor understanding and confusion about network topology
>> in texts, exam questions etc. I was looking forward to new editions of
>> the texts in the hope that we would finally get it right.
>>
>> I was going through page proofs of the Thomson/Nelson book (new
>> edition of Building Information Systems), and this is what it says
>> about Star network topology.
>>
>> "The most common topology is the star network. The main type of star
>> network has a central computer, usually a server computer, and all
>> computers and devices are connected directly to it. This configuration
>> is useful when the data to be used is required by many people and
>> needs to be centralised so that its integrity and security can be
>> easily managed. The access to the network is usually controlled by the
>> network operating system, that is run from the central computer.This
>> topology operates as a client/server network. A simple star network is
>> a network or segment of a network that is controlled by a switch or
>> hub. In this case the network is operating as a peer-to-peer network
>> as there is no central coordinating computer. There may be various
>> servers operating on the computers."
>>
>> I won't put in the text on Bus and Ring networks other than they do
>> focus more on the protocol and cabling topology. I don't know what the
>> above treatment of star network is based on and I find it all very
>> confusing. There are a ton of questions I would love to ask about this
>> paragraph. For starters - when was the last time any of us
>> saw/installed/used or even read about a star network where all the
>> devices were connected to a central computer? I won't bother with the
>> rest of the questions for now...
>>
>> In looking at the new Janson/Dawson book, at least the focus is
>> largely on the protocol.
>> I have not looked at any other of the new books on this topic but I am
>> not confident that this confusion will go away.
>>
>> So are we really clear on what we are teaching about "topology" ? I'm
>> not. The way the protocol works? The way the cabling is arranged?
>> Do we all realise that even 10 years ago, it was common to find a
>> 24-port token ring hub, which used a star cabling topology to connect
>> its devices, which could have connected to it a bunch of PC's
>> functioning on a peer-to-peer basis as well as a database server which
>> was being used by the same PC's for a client-server application.
>>
>> So often, I read about this stuff in our IPM and IS texts in a way
>> which treats them all as mutually exclusive options.
>>
>> The classic table that all of us have seen showing a list of
>> advantages and disadvantages for each of these topologies in many
>> cases is just a lot of rubbish in my view. For example, bus topologies
>> are cheaper to implement because they use less cable - might be true
>> for coax but not an old UTP/hub installation.
>>
>> I just had a quick look at the VITTA Networking CD to see how it
>> treats protocol - more consistent in what it considers topology to be,
>> but there are still things there that are oversimplified. For example,
>> "A disadvantage of a ring topology is that if any device is added to
>> or removed from the ring, the ring is broken and the segment fails
>> until it is reconnected." In theory that is true, but most places
>> would have used a token ring hub for years, in which case it is
>> irrelevant. But we are not really in a position to show our students
>> this when we teach it, and it is also meaningless in my view.
>> I am not a trained communications person, and only built up an
>> understanding of some of these things in a large network environment
>> that I worked in a few years ago. So there is a good chance that some
>> of my definitions/understanding are not quite right. But I can assure
>> you that the IPM and IS books that I have used for the past 5 years
>> have done very little to clarify much of this.
>>
>> It's probably too late for the authors of the new texts to review this
>> area. Is there some other way we can build a body of content that we
>> agree with, understand and can teach to kids in a meaningful way on
>> this subject?
>>
>> Does anybody else out there feel the same way about this as me???
>>
>> Frank
>>
>>
>
>
>
>
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