1.6 Summary

The large set of technologies, products, and interconnection schemes make networking a complex subject. Many organizations have defined competing standards, and most networks incorporate components that use multiple standards. Furthermore, no single theory exists that can be used to explain how the pieces fit together. Consequently, the terminology and jargon used in networking are complex and confusing. To master such complexity, it is important to focus on understanding concepts and terminology.
The text, which focuses on concepts, is divided into four parts. Chapters in the first part describe data transmission and modems, those in the second pan cover packet communication, those in the third explain internetworking, and those in the fourth exanrjne ho \, network applications operate.

1. 5 Organization Of The Text

Following the introductory chaplets, the text is divided into four major parts. The first pan describes data transmission. It explains thai at the lowest level, electrical signals traveling across wires are used 1o carry information, and shows how data can be encoded using electrical signals. The chapters in the first part do not provide details for engineers who design networking hardware. Instead, [hey provide general descriptions
of the principles and practical realities of data transmission and their consequences for computer networks.

The second part of the text focuses on packet transmission. It explains why computer networks use packets, and shows how data is grouped into packets for transmission. This section introduces the two basic categories of computer networks Local Area Networks and Wide Area Networks. It explains the differences between the two categories and reviews example technologies. Finally, the section discusses the important concepts of addressing and routing. It explains how a network routes a packet to its destination.

The third part of the text covers internetworking-the important idea that allows heterogeneous network technologies to be combined into a large, seamless communication system. The text explains TCP/IP, the protocol technology used in the global Internet.
The fourth part of the text explains networking applications. It focuses on how applications use the underlying network to communicate. The chapters begin by explaining the client-server model of interaction, Later chapters use the model to explain how application programs provide services such as electronic mail and Web browsing.

1.4 Concepts And Terminology

This text is written to help overcome the complexity. The text focuses on concepts and avoids unnecessary detail. It explains the purpose of each networking technology, gives the advantages and disadvantages, and describes some of the consequences of using the technology. Whenever possible, the text uses analogies and illustrations to simplify explanations.

In addition to covering concepts and technologies, the text introduces networking terminology. When a new concept is introduced, terminology for that concept is defined. The text also notes popular abbreviations and synonyms that professionals use. The terminology is summarized in a G1ossary in Appendix 1 that serves as a quick reference for the many terms and acronyms defined throughout the text.

1.3 Mastering The Complexity

To master the complexity, one must look beyond the details and concentrate on understanding concepts. For example, although it is not important to understand the details of wires used to connect computers to a specific network, it is important to understand the few basic categories of wiring schemes that exist and the advantages of each. Similarly, although it is not important to learn the details of how a particular communication protocol handles a congested network, it is important to know what congestion is and why it must be handled.