Packet Guide to Core Network Protocols

Chapter 1. Networking Models

Mod-el: noun: 1–structural design, 2–a miniature representation, 3–an example for emulation or imitation

—The Merriam-Webster Dictionary

Basic network architecture and construction is a good starting point when trying to understand how communication systems function, even though the topic is a bit dull. Architectures are typically based on a model showing how protocols and functions fit together. Historically, there have been many models used for this purpose, including, but not limited to, Systems Network Architecture (SNA-IBM), AppleTalk, Novell Netware (IPX/SPX), and the Open System Interconnection (OSI). Most of these have gone the way of the dodo due to the popularity of TCP/IP. TCP/IP stands for Transmission Control Protocol/Internet Protocol, and represents a suite of protocols used on almost all modern communication systems. As the name suggests, this is the language of the Internet. This chapter focuses on the practical TCP/IP model, using the OSI model as a reference point.

What Is a Model?

A model is a way to organize a system’s functions and features to define its structural design. A design can help us understand how a communication system accomplishes tasks to form a protocol suite. To help wrap our heads around models, communication systems are often compared to the postal system (Figure 1-1). Imagine writing a letter and taking it to the post office. At some point, the mail is sorted and then delivered via some transport system to another ...