We began this chapter with a look at the importance of network models, including the reasons for their modular nature. A look at the OSI model stressed the importance of understanding the concept of layered communication, protocol data units, and the functions of each layer. Do not underestimate the importance of remembering not only the various functions of each, but also the protocols, data units, services, and types of equipment found at each layer.
A look at the TCP/IP model provided a comparison with the OSI model, including the mappings between the layers of each. Examining the data encapsulation process helped to provide perspective on how a real network protocol goes about preparing data for network transmission.
Finally, an overview of the Cisco network design model provided insight into Cisco’s perspective on the proper design of hierarchical networks. Be sure to understand not only the layers but also the equipment and functional details of each.