ISO OSI reference model

A comprehensive tutorial is available at tutorialsweb on ISO OSI model. OSI model is the basic building block of CCNA certification preparation, and it is highly required that a CCNA aspirant has a solid understanding of different layers of OSI model. The contents of the tutorial are given below:
The OSI (Open Systems Interconnection) Model
Information Exchange Process
Relationship between the OSI Model and Networking Devices
Repeaters, Bridges, Routers, Gateways and other network components
Glossary of Networking Terms
Read complete tutorial on ISO OSI model for CCNA preparation.