Chapter 2 - Networking Standards and the OSI Model

The text begins with network standards organizations and the necessity of maintaining minimum industry standards. The chapter gives a brief description of each following along with the role they play:

• ANSI – American National Standards Institute
• EIA – Electronic Industries Alliance
• IEEE – Institute of Electrical and Electronics Engineers
• ISO – International Organization for Standardization
• ITU – International Telecommunications Union
• ISOC – Internet Society

The OSI model began in the early 1980’s and set universal specifications that made it possible for computer platforms across the world to communicate. The OSI (Open Systems Interconnection) model represents seven layers in network communications. See chart below.

In this model the layers communicate with the same layer from one computer to another. A way to help remember these different layers is to create a sentence using words that begin with the first letter of each layer. For example “Programmers Dare Not Throw Salty Pretzels Away”.

It is important to understand that data issued from a software application are not in the same form as the data that your NIC (network interface card) sends to the network. At each layer of the OSI model, some information is added to the original data. The data requests that transfer between layers is done in the form of protocol data units (PDU). Finally, your request in the form of many frames hits the NIC at the physical layer. The physical layer does not interpret the frames or information it simply transmits them over the broadband.

I found this chapter to have a wealth of information as well as many diagrams and charts. I thought it had a systematic and logical approach in its presentation. It was good foundation material.