[Year 12 SofDev] Software development key knowledge

[Matheson, Heath A]

Thanks for your reply Robert,

 

Once again, different resources I look at give different layers to these
devices. I like your version and I'll run with it, accept I think the
fact that NIC's "transform" data to binary contributes to them being on
layer 2.  They are not just carrying data which I think is the sole role
of layer 1.  I'm not surprised or confused, I'm very accepting that
that's the way things will always be with SD.  I just try and work out
what level of understanding you need for the exam. Hopefully some trial
questions will help us out soon. 

As Mark mentioned recently, I've found that sometimes the less you know
about the technical detail of topics in this course the easier it is to
dumb down for the students. 

 

Regarding the network diagrams in the first outcome, since Paula
suggested we could teach network topologies I am certainly going to
cover network diagrams at the same time. 

 

Thanks again for the info.

 

Heath Matheson

 

From: sofdev-bounces at edulists.com.au
[mailto:sofdev-bounces at edulists.com.au] On Behalf Of Timmer-Arends
Sent: Monday, 14 March 2011 6:02 PM
To: Year 12 Software Development Teachers' Mailing List
Subject: Re: [Year 12 SofDev] Software development key knowledge

 

Hello again Heath

 

I didn't see the second question and since no one else appears to have
responded (probably sensibly having a day off) I'll give it a go

 

Question: Is it possible to classify switches hubs and NICs into the
physical layer because they are hardware and the cables plug into them,
while the data travelling through these devices is on an upper level? Or
is a NIC always on the data layer and switches somewhere between data
and network layers?

 

Switches hubs etc cannot be placed in the physical layer simply because
they are hardware - afterall the computer we transmit messages from is
also hardware. It depends on what protocol issues they have to deal with
(possibly via firmware programming). So

- hubs are purely layer 1 since all they do is send a received signal to
all ports - they in effect just repeat the signal, they have no
understanding of the content of that signal

- switches need to know which port to send received data down so they
need to know about physical addressing within a network which means
being able to read data link (layer 2) frames

- routers need to know about the end to end addressing so they operate
up to the network layer (3)

- NICs transform computer 1's and 0's into whatever the transmission
medium requires so they are definitely layer 1. But it could depend on
the kind of network they connect into; for example, collision detection
in Ethernet is done in hardware on the NIC, but I'm pretty sure that
collision detection (and then dealing with it) is a layer 2 function - I
stand to be corrected on this. Also NICs are responsible for MAC
addresses which is a layer 2 function. 

 

I hope this is helpful

 

Regards

Robert T-A

Brighton SC

 

 

 


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