Introduction to Computer Networks and

Introduction to Computer Networks and Data Communications – Seventh Edition

Learning Objectives

After reading this chapter you should be able to:

• Define the basic terminology of computer networks • Recognize the individual components of the big picture of computer networks • Outline the basic network connections • Cite the reasons for using a network model and explain how they apply to current network systems • List the layers of the TCP/IP protocol suite and describe the duties of each layer • List the layers of the OSI model and describe the duties of each layer • Compare the OSI and TCP/IP models and list their differences and similarities

Chapter Outline

• Introduction

• The Language of Computer Networks

• The Big Picture of Networks

• Computer Networks – Basic Connections
• Microcomputer to local area network
• Microcomputer to Internet
• Local area network to local area network
• Personal area network to workstation
• Local area network to metropolitan area network
• Local area network to wide area network
• Wide area network to wide area network
• Sensor to local area network
• Satellite and microwave
• Cell phones
• Terminal/microcomputer to mainframe

Chapter 1 (Data Communications and Computer Networks A Business User's Approach, 7e Curt White) (Solution Manual all Chapters) 1 / 4

• Convergence

• Network Architectures
• The TCP/IP protocol suite
• The Open Systems Interconnection (OSI) model
• Logical and physical connections

• Network Connections In Action

• The TCP/IP Protocol Suite In Action

• Summary

Lecture Notes

Introduction

The world of computer networks and data communications is a surprisingly vast and increasingly significant field of study. Once considered primarily the domain of communications engineers and technicians, computer networks now involve business managers, computer programmers, system designers, office managers, home computer users, and everyday citizens. It is virtually impossible for the average person on the street to spend 24 hours without directly or indirectly using some form of computer network. Examples of computer networks include banking, transportation, education, retail sales, and telecommunications.

The Language of Computer Networks

To better understand the area of computer networks, you should understand the basic broad categories of computer networks and data communications. For example, you should be able to

define each of the following terms:

• computer network • local area network • metropolitan area network • wide area network • personal area network • data communications • voice network • data network • telecommunications • network management

Each of these terms is a topic area under the network umbrella. While there may be more broad topic areas, these are the ones that will be discussed in detail in this text. 2 / 4

The Big Picture of Networks

Sometimes a big picture can help to give an idea of what is going on in a particular subject area.Examine Figure 1-1. Try to reach a basic understanding of WAN to WAN connections, LAN to LAN connections, and WAN to LAN connections. Even though each of these connections will be covered in more detail later, they are necessary to understanding the big picture of how networks intercommunicate. You should also know the terms server, bridge, router, hub, node, communications network, and communications line.

Computer Networks - Basic Connections

Understand each of the following connections. Examine the figure from the text or create your own example for each connection. Describe how this connection works in simple terms.

Describe one or more applications that use each connection:

• Microcomputer to local area network • Microcomputer to Internet • Local area network to local area network • Personal area network to workstation • Local area network to metropolitan area network • Local area network to wide area network • Wide area network to wide area network • Sensor to local area network • Satellite and microwave • Cell phones • Terminal/microcomputer to mainframe

Convergence

Convergence is happening at all levels: convergence of products (like the Blackberry), convergence of companies (such as SBC and AT&T), and convergence of technologies (such as token ring giving way to Ethernet). Be sure to talk about forms of convergence in this chapter and all subsequent chapters.

Network Architecture Models

To keep the pieces of a network working together harmoniously and to allow modularity between the pieces, it is necessary to use a network architecture model, or communications model, that places the appropriate network pieces in layers. Each layer in the model defines what services are provided by either hardware or software or both. For example, most organizations that produce some type of product or perform a service have a division of labor.Secretaries do the paperwork; accountants keep the books; laborers perform the manual duties; 3 / 4

scientists design products; engineers test the products; managers control operations. Rarely is one person capable of performing all these duties. Large software applications operate the same way. Different procedures perform different tasks, and the whole would not function without the proper operation of each of its parts. Communications software is no exception. As the size of the applications grows, the need for a division of labor becomes increasingly important.

Know the TCP/IP Protocol Suite (Internet Model) layers including the basic functions performed at each layer: Physical, Network Access Layer, Network, Transport, and Application. The Internet model is the model used to support all activities on the Internet.

Even though the OSI model is not the actual model used to support the Internet, its understanding is necessary as many networks and products often refer to the OSI model for definition.

Logical and Physical Connections

To avoid future confusion, you must know the difference between a logical connection and a physical connection. Note that the only physical connection in a network is at the physical or interface layer. All other connections between peer layers are logical connections and exist in the software only. Examine Figure 1-14.

The TCP/IP Protocol Suite In Action

The In Action example in this first chapter follows a packet as it moves down through the layers of the transmitting device and then up through the layers of the receiving device. Note how a data packet grows with additional information at each layer. This is called encapsulation. Note further how the router only examines the data packet up to the network or IP layer. We will return to this encapsulation numerous times in later chapters.

Quick Quiz

• Identify each of the different forms of network connections and list an example of each.

• Terminal to mainframe – motor vehicle licensing branch • microcomputer to mainframe – business employee accessing corporate database • microcomputer to local area network – student in school lab • microcomputer to Internet – home user via Internet service provider • local area network to local area network – schools and businesses with multiple LANs • local area network to wide area network – school or business connection to Internet or external database service • sensor to local area network – manufacturing plant • satellite and microwave – numerous examples

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