[Year 12 Its] Ongoing misinformation about topology
Anton Yoxon
yox at sosc.vic.edu.au
Fri Aug 25 09:38:34 EST 2006
Alan, could you send a copy to me at South Oakleigh Secondary College as well
Cheers
Anton Yoxon
On Fri, 25 Aug 2006 08:33:24 +1000, Allan Barnes wrote
> 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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> >
> >
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Anton Yoxon
Learning Technologies Manager
yoxon.anton.w at edumail.vic.gov.au
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