OSI Model and Physical Mediums

[boxerboy1168]

Hello all,

Studying for Net+ and hopefully Sec+ once I finish. While studying the OSI model I've come to a question that I am having a hard time finding an answer to.

Does each layer of the OSI model have a physical medium through which is communicates?

It would really help me understand the overall structure better. Here's an example:

On layer 2 the MAC address is the address of the individual NICs corresponding to the send/ receiver of each transmission.

Obviously the application and session layer don't have a physical medium as they are application based.

 

[jsmithepa]

I am not sure why you are confused but I offer you to think the OSI-7 as a 7-layers onion.

One thing you will find why they did it this way is, it helps troubleshoot problems immensely. So to any trouble one ask, is layer1 OK? (connector in place? getting the LEDs on the RJ45 blinking correctly?), if that's OK then you move on to asking layer2 is OK and so forth.

A common thing you will see when sign on to a Cisco router (the business kind), you type a command like SHOWme Interface X, and it says something like LINK STABLISHED (meaning layer-2 talking to each other), IP IS blah-blah (if you have IP, it means layer3 is working, and layer3 doesn't work if layer-2 is down.