ISO/OSI Reference Model

[lplate80]

Hi all,

I have some questions on OSI reference model.

1. I would like to know where does the OSI layers located - in our computer, harddisk, protocol, software or hardware?

2. How does out software communicate to the Application layer of the OSI model?

3. Can you map the 7 layers in a real world problem?

Thank-you for your help.

[Áedán]

The seven layers are mapped across both software and hardware. Typically the lowest layers (1 and 2) map directly onto the network card hardware, and the higher layers are done in software. That's not always true however, and you can find places where layer 2 is also done in software. On the other hand, I've seen hardware where layer 3 (and layer 7!) is handled.

Remember that the seven layer model is just a model demonstrating "good design". As such, there isn't a standard way for software to communicate with the seventh layer. Different protocols do it different ways.

As far as mapping it onto real world examples, it's sometimes possible, sometimes the system is too monolithic to really be able to do such a thing. The best way is to practice, until you understand where each layer fits, and what it maps onto.

Áedán

[piccoLEW]

for the home user on the internet,
most of it is handled by the tcp/ip protocols.

[Áedán]

TCP/IP is one of the great examples of a protocol that doesn't match up with the seven layers of the OSI stack.