OSI Model

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#2
I always suggest my students break big problems down into smaller problems. It works well no matter what course I'm leading. OSI is a great example of breaking network communications down into smaller, more manageable challenges. It also highlights how there isn't always one solution to a challenge or problem. The big challenge with the OSI model is that if you focus on the different protocols in one table it can get really complex. So I use a white board to show how just one protocol works across the layers of the stack (usually starting with HTTP). Then another (email). Then another. Then as an activity I ask the students to map another two or three protocols across the different layers.
 
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#3
Well, these days, CompTIA is moving more to the four-layer model TCP/IP Model rather than the seven layer OSI model. I think the seven layer OSI model teaches a lot of good things, but it's also easier to teach by starting with TCP/IP and then expanding knowledge to the seven layer. Network+ also, for the first time, explicitly defined reading packet headers in the Objectives, so this, I believe, is better achieved with the TCP/IP Four Layer.

So, I'd start there, and then do up some kind of step up lessons to break out the OSI model.

/r
 
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#4
I particularly like to explain the OSI reference model. I've been using a beer factory as a playful example to compare with (storytelling), beginning with bottles in the production line, where they are all sent, one after another, through a machine belt (PHY - bits). They need to be organized at the end of the production line, which means, to send them to warehouses you need to put them into crates (that all have limited sizes) (LINK - Frames). In the warehouse, to send beers to bars/pubs/supermarkets you'll need to organize, preparing to transport, as you cannot send in individually crates, you should organize them into pallets (NETWORK - packets), and so on. Of course, here I put a very summarized example, but I hope I could help you with some ideas. It takes me around 15~20 minutes to explain the concepts during classes, and it helps students to understand the idea of the OSI reference model.
 
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#6
Samuel Graeff said:
I particularly like to explain the OSI reference model. I've been using a beer factory as a playful example to compare with (storytelling), beginning with bottles in the production line, where they are all sent, one after another, through a machine belt (PHY - bits). They need to be organized at the end of the production line, which means, to send them to warehouses you need to put them into crates (that all have limited sizes) (LINK - Frames). In the warehouse, to send beers to bars/pubs/supermarkets you'll need to organize, preparing to transport, as you cannot send in individually crates, you should organize them into pallets (NETWORK - packets), and so on. Of course, here I put a very summarized example, but I hope I could help you with some ideas. It takes me around 15~20 minutes to explain the concepts during classes, and it helps students to understand the idea of the OSI reference model.
Click to expand...
Everything is better with beer.

I used dry erase markers linked together to represent the header being added to the packet and taken off as traffic moved up and down the stack. Shipping a package also is a good analogy. Trying to find the "why" with each layer is important here when trying to explain the model - for example, why is there a session layer? What does it do for me, specifically? That sort of thing.

/r
 
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#7
Rick Butler said:
Well, these days, CompTIA is moving more to the four-layer model TCP/IP Model rather than the seven layer OSI model. I think the seven layer OSI model teaches a lot of good things, but it's also easier to teach by starting with TCP/IP and then expanding knowledge to the seven layer. Network+ also, for the first time, explicitly defined reading packet headers in the Objectives, so this, I believe, is better achieved with the TCP/IP Four Layer.

So, I'd start there, and then do up some kind of step up lessons to break out the OSI model.

/r
Click to expand...
I beg you, if you are going to teach using the TCP/IP (DoD) model, use the Five Layer TCP/IP model so that I can use the terms Layer 2 and Layer 3 switches and we all agree upon what that means :)
 
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#8
Andrew H said:
I beg you, if you are going to teach using the TCP/IP (DoD) model, use the Five Layer TCP/IP model so that I can use the terms Layer 2 and Layer 3 switches and we all agree upon what that means :)
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*laughs*

So I would like to introduce the newest networking model... the 22 layer engineering specification. We like to break things down very succinctly. ;)
 
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#10
Lee McWhorter said:
One of my students a few years ago came up with his own versions to learn the layers...

Please Do Not Teach Students Pointless Acronyms
or
Please Do Not Teach Sh*tty Pointless Acronyms

:) :p
Click to expand...
Not the worst one I have ever heard
 
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#11
Rick Butler said:
Well, these days, CompTIA is moving more to the four-layer model TCP/IP Model rather than the seven layer OSI model. I think the seven layer OSI model teaches a lot of good things, but it's also easier to teach by starting with TCP/IP and then expanding knowledge to the seven layer. Network+ also, for the first time, explicitly defined reading packet headers in the Objectives, so this, I believe, is better achieved with the TCP/IP Four Layer.

So, I'd start there, and then do up some kind of step up lessons to break out the OSI model.

/r
Click to expand...
The DOD is what we are currently using than the OSI model
 
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#13
When I explain the OSI model or the TCP/IP model, I tell students that when a situation arises and there is intermittent or no connectivity, there are only so many places you can troubleshoot. Start at one layer and work your way through them.

Is it plugged in?
Check the ARP cache
Check the IP address
etc.
 
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#14
Gregory Childers said:
When I explain the OSI model or the TCP/IP model, I tell students that when a situation arises and there is intermittent or no connectivity, there are only so many places you can troubleshoot. Start at one layer and work your way through them.

Is it plugged in?
Check the ARP cache
Check the IP address
etc.
Click to expand...
Good point, co'z later in module 5, the students will learn the use of TCP/IP model to troubleshooting.
You can introduce early on the top-down / bottom-up troubleshooting methodology, to show the practical use of TCP/IP relating to troubleshooting.

As for my classes, I show them a packet capture, so they can see the data per layer, then just say Layer 1 is with the cables. :D
 
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