Fahmy,

The message I posted yesterday seems lost.
You can forget about the OSI 7-layer stuff, and go straight to TCP/IP, which dominates the network today. For reference books, I think that TCP/IP series from Douglas Comer are great. You can start with "
Internetworking with TCP/IP Vol. I: Principles, Protocols, and Architecture".

Searching on Internet itself might get something surprising.

Regards,
Oliver