[Year 12 SofDev] Network Diagrams - Physical or Logical

[Timmer-Arends]

I would have thought that from a conceptual point of view at least, the 
serial depiction is ok (provided the order is correct) because a firewall is 
essentially an intelligent filter, examining packets that come in and using 
a set of rules and procedures to determine which can be released into the 
(local) network; ie a box with an 'in' and an 'out'. In fact it used to be 
the case that if you used a computer to implement a hardware level firewall 
you had to provide it with two nics, one for the incoming traffic from the 
internet, the other for the outgoing traffic into the LAN.

One of the threads that has interested me in recent months has been the 
whole discussion about the level of knowledge students should be expected to 
have re the study; eg networking: routers v switches v hubs; messages v 
frames v packets; etc. What concerns me is that we seem to not be making a 
clear enough distinction between how something works conceptually, and how 
the concepts are physically implemented; and I think the distinction is 
important as far as the teaching of the study goes. Personally I think that 
the concepts should form the basis of the study, but some would no doubt say 
that students need a solid practical knowledge that will help them in the 
workforce (in which case I would say they should be doing a Cisco course 
etc)

Regards
Robert T-A
Brighton SC


----- Original Message ----- 
From: "Neil Wallace" <neil at norwood.vic.edu.au>
To: "'Year 12 Software Development Teachers' Mailing List'" 
<sofdev at edulists.com.au>
Sent: Friday, March 28, 2008 2:24 PM
Subject: RE: [Year 12 SofDev] Network Diagrams - Physical or Logical


> You must also be marking SAC 1 now huh??? My comments below refer to the
> network diagram as a physical diagram. I use the DFD's and Data 
> Dictionaries
> for logical representations in this SAC.
>
> I get similar things Kevin, but I don't have a problem with the serial
> representation. In many practical instances that kids are familiar with
> firewall features are built into the switch and router. A home ADSL router
> that provides firewall, VoIP, wireless and switching (OK maybe hub) 
> services
> is an example.
>
> I usually walk the kids through what they may have at home, then tour the
> server room and switch cabinets when doing the network structure side of
> things.
>
> So, please all shoot me down if I am out of line here, but as long as the
> modem or router, firewall and switch are all in place in the network 
> diagram
> (in that order from external to internal) I feel OK with that.
>
> And we haven't got to talking about DeMilitarised Zones for safety in
> isolation of onsite servers yet either. . . .
>
> Enjoy your break.
>
> Neil Wallace
> Norwood Secondary College
>
> -----Original Message-----
> From: sofdev-bounces at edulists.com.au 
> [mailto:sofdev-bounces at edulists.com.au]
> On Behalf Of Kevin Feely
> Sent: Friday, 28 March 2008 1:14 PM
> To: sofdev at edulists.com.au
> Subject: [Year 12 SofDev] Network Diagrams - Physical or Logical
>
> Hi All
> Just to clarify one part of these things that i get a number of students
> representing firewalls inaccurately.
> I find some students like to connect them all up in series (see attached
> picture), so that from the switch they go to a firewall, then to a router
> then to the phone lines to the internet.
> Or even worse the go from the switch to a firewall and then to the 
> internet
> with no mention of a router or modem.
> I have always put, or seen installed, firewalls (hardware, naturally)
> connected  to the network switch (doesn't matter which one) and thats it.
> There is no "throughput". ie as you represent a server ,as basically thats
> what they are.
> The router (or modem if you want to go back a few years) is the throughput
> device, on one side the phone line (PSTN, ADSL, CABLE, ETC) and on the 
> other
> the network connection to switch via ethernet, to switch from pc via usb
> from router, or to switch from pc via serial from modem.
> Is this a problem to your students or is it just me?
>
> regards
> kevin
>
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