IIRC it's still based on the OSI 7-layer model:
1. Application
2. Presentation
3. Session
4. Transport
5. Network
6. Data-Link
7. Physical
The OSI will probably document what each of these layers does in more detail. I can remember roughly what each one is for, but not the intricacies of how they do it (Network+ was a long time ago!)
[EDIT]
This Wikipedia document describes the layers in more detail.
[/EDIT]
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moto
