FitzGerald J., Dennis A., Durcikova A. Business Data Communications and Networking
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BRIEF CONTENTS
PART ONE INTRODUCTION 1
Chapter 1 Introduction to Data Communications 2
PART TWO FUNDAMENTAL CONCEPTS 37
Chapter 2 Application Layer 38
Chapter 3 Physical Layer 76
Chapter 4 Data Link Layer 118
Chapter 5 Network and Transport Layers 147
PART THREE NETWORK TECHNOLOGIES 195
Chapter 6 Wired and Wireless Local Area Networks 196
Chapter 7 Backbone Networks 238
Chapter 8 Wide Area Networks 268
Chapter 9 The Internet 310
PART FOUR NETWORK MANAGEMENT 337
Chapter 10 Network Security 338
Chapter 11 Network Design 408
Chapter 12 Network Management 448
PART FIVE APPENDICES 481
Appendix A Connector Cables 482
Appendix B Spanning Tree Protocol 493
Appendix C IP Telephony 497
Appendix D Cellular Technologies 500
Appendix E TCP/IP Game 502
Appendix F Windows Server 513
Glossary 525
Index 555
CONTENTS
PART ONE
INTRODUCTION 1
CHAPTER 1
INTRODUCTION TO DATA
COMMUNICATIONS 2
1.1 INTRODUCTION 4
1.1.1 A Brief History of Communications
in North America 5
1.1.2 A Brief History of Information
Systems 7
1.1.3 A Brief History of the Internet 9
1.2 DATA COMMUNICATIONS NETWORKS 11
1.2.1 Components of a Network 12
1.2.2 Types of Networks 12
1.3 NETWORK MODELS 15
1.3.1 Open Systems Interconnection
Reference Model 16
1.3.2 Internet Model 18
1.3.3 Message Transmission Using Layers 19
1.4 NETWORK STANDARDS 22
1.4.1 The Importance of Standards 22
1.4.2 The Standards-Making Process 22
1.4.3 Common Standards 24
1.5 FUTURE TRENDS 26
1.5.1 Pervasive Networking 26
1.5.2 The Integration of Voice, Video, and
Data 27
1.5.3 New Information Services 28
1.6 IMPLICATIONS FOR MANAGEMENT 29
SUMMARY 30
PART TWO
FUNDAMENTAL
CONCEPTS
37
CHAPTER 2
APPLICATION LAYER 38
2.1 INTRODUCTION 40
2.2 APPLICATION ARCHITECTURES 40
2.2.1 Host-Based Architectures 41
2.2.2 Client-Based Architectures 42
2.2.3 Client-Server Architectures 43
2.2.4 Peer-to-Peer Architectures 46
2.2.5 Choosing Architectures 47
2.3 WORLD WIDE WEB 49
2.3.1 How the Web Works 49
2.3.2 Inside an HTTP Request 50
2.3.3 Inside an HTTP Response 51
2.4 ELECTRONIC MAIL 53
2.4.1 How Email Works 54
2.4.2 Inside an SMTP Packet 57
2.4.3 Attachments in Multipurpose Internet
Mail Extension 58
2.5 OTHER APPLICATIONS 58
2.5.1 Telnet 59
2.5.2 Instant Messaging 60
2.5.3 Videoconferencing 61
2.6 IMPLICATIONS FOR MANAGEMENT 63
SUMMARY 64
CONTENTS xi
CHAPTER 3
PHYSICAL LAYER 76
3.1 INTRODUCTION 78
3.2 CIRCUITS 79
3.2.1 Circuit Configuration 79
3.2.2 Data Flow 80
3.2.3 Multiplexing 81
3.2.4 How DSL Transmits Data 87
3.3 COMMUNICATION MEDIA 88
3.3.1 Twisted Pair Cable 88
3.3.2 Coaxial Cable 89
3.3.3 Fiber-Optic Cable 89
3.3.4 Radio 91
3.3.5 Microwave 92
3.3.6 Satellite 93
3.3.7 Media Selection 94
3.4 DIGITAL TRANSMISSION OF DIGITAL
DATA 95
3.4.1 Coding 95
3.4.2 Transmission Modes 97
3.4.3 Digital Transmission 98
3.4.4 How Ethernet Transmits Data 99
3.5 ANALOG TRANSMISSION OF DIGITAL
DATA 100
3.5.1 Modulation 101
3.5.2 C apacity of a Circuit 104
3.5.3 How Modems Transmit Data 104
3.6 DIGITAL TRANSMISSION OF ANALOG
DATA 105
3.6.1 Translating from Analog
to Digital 105
3.6.2 How Telephones Transmit Voice
Data 106
3.6.3 How Instant Messenger Transmits
Vo i c e D at a 108
3.6.4 Voice over Internet Protocol
(VoIP) 108
3.7 IMPLICATIONS FOR MANAGEMENT 109
SUMMARY 109
CHAPTER 4
DATA LINK LAYER 118
4.1 INTRODUCTION 120
4.2 MEDIA ACCESS CONTROL 120
4.2.1 Contention 121
4.2.2 Controlled Access 121
4.2.3 Relative Performance 122
4.3 ERROR CONTROL 123
4.3.1 Sources of Errors 123
4.3.2 Error Prevention 125
4.3.3 Error Detection 126
4.3.4 Error Correction via
Retransmission 128
4.3.5 Forward Error Correction 130
4.3.6 Error Control in Practice 131
4.4 DATA LINK PROTOCOLS 131
4.4.1 Asynchronous Transmission 132
4.4.2 Synchronous Transmission 133
4.5 TRANSMISSION EFFICIENCY 136
4.6 IMPLICATIONS FOR MANAGEMENT 139
SUMMARY 140
CHAPTER 5
NETWORK AND TRANSPORT
LAYERS 147
5.1 INTRODUCTION 149
5.2 TRANSPORT AND NETWORK LAYER
PROTOCOLS 150
5.2.1 Transmission Control Protocol
(TCP) 151
5.2.2 Internet Protocol (IP) 151
5.3 TRANSPORT LAYER FUNCTIONS 152
5.3.1 Linking to the Application
Layer 153
5.3.2 Segmenting 154
5.3.3 Session Management 155
5.4 ADDRESSING 157
5.4.1 Assigning Addresses 158
5.4.2 Address Resolution 162
5.5 ROUTING 165
5.5.1 Types of Routing 167
5.5.2 Routing Protocols 168
5.5.3 Multicasting 171
5.5.4 The Anatomy of a Router 172
5.6 TCP/IP EXAMPLE 174
5.6.1 Known Addresses, Same
Subnet 174
5.6.2 Known Addresses, Different
Subnet 177
xii CONTENTS
5.6.3 Unknown Addresses 178
5.6.4 TCP Connections 179
5.6.5 TCP/IP and Network Layers 179
5.7 IMPLICATIONS FOR MANAGEMENT 182
SUMMARY 182
PART THREE
NETWORK
TECHNOLOGIES 195
CHAPTER 6
WIRED AND WIRELESS LOCAL AREA
NETWORKS 196
6.1 INTRODUCTION 198
6.1.1 Why Use a LAN? 198
6.1.2 Dedicated-Server versus Peer-to-Peer
LANs 199
6.2 LAN COMPONENTS 201
6.2.1 Network Interface Cards 201
6.2.2 Network Circuits 201
6.2.3 Network Hubs, Switches, and Access
Points 203
6.2.4 Network Operating Systems 206
6.3 WIRED ETHERNET 208
6.3.1 Topology 208
6.3.2 Media Access Control 211
6.3.3 Types of Ethernet 212
6.4 WIRELESS ETHERNET 213
6.4.1 Topology 213
6.4.2 Media Access Control 213
6.4.3 Wireless Ethernet Frame
Layout 215
6.4.4 Types of Wireless Ethernet 215
6.4.5 Security 216
6.5 THE BEST PRACTICE LAN DESIGN 218
6.5.1 Wired Ethernet 219
6.5.2 Wireless Ethernet 220
6.5.3 Designing for SOHO
Environments 222
6.6 IMPROVING LAN PERFORMANCE 223
6.6.1 Improving Server Performance 224
6.6.2 Improving Circuit Capacity 226
6.6.3 Reducing Network Demand 226
6.7 IMPLICATIONS FOR MANAGEMENT 227
SUMMARY 227
CHAPTER 7
BACKBONE NETWORKS 238
7.1 INTRODUCTION 239
7.2 BACKBONE NETWORK COMPONENTS 240
7.2.1 Switches 240
7.2.2 Routers 240
7.2.3 Gateways 242
7.2.4 A Caution 243
7.3 BACKBONE NETWORK
ARCHITECTURES 243
7.3.1 Backbone Architecture Layers 243
7.3.2 Switched Backbones 244
7.3.3 Routed Backbones 249
7.3.4 Virtual LANs 252
7.4 THE BEST PRACTICE BACKBONE
DESIGN 258
7.5 IMPROVING BACKBONE
PERFORMANCE 260
7.5.1 Improving Computer and Device
Performance 260
7.5.2 Improving Circuit Capacity 260
7.5.3 Reducing Network Demand 261
7.6 IMPLICATIONS FOR MANAGEMENT 261
SUMMARY 262
CHAPTER 8
WIDE AREA NETWORKS 268
8.1 INTRODUCTION 270
8.2 CIRCUIT-SWITCHED NETWORKS 271
8.2.1 Basic Architecture 271
8.2.2 Plain Old Telephone Service 272
8.2.3 Integrated Services Digital Network
(ISDN) 272
8.3 DEDICATED-CIRCUIT NETWORKS 273
8.3.1 Basic Architecture 273
8.3.2 T Carrier Services 278
8.3.3 Synchronous Optical Network 279
8.4 PACKET-SWITCHED NETWORKS 279
8.4.1 Basic Architecture 280
8.4.2 Asynchronous Transfer Mode 282
CONTENTS xiii
8.4.3 Frame Relay 283
8.4.4 Ethernet Services 284
8.4.5 Multi-Protocol Label Switching 285
8.5 VIRTUAL PRIVATE NETWORKS 286
8.5.1 Basic Architecture 286
8.5.2 VPN Types 287
8.5.3 How VPNs Work 288
8.6 THE BEST PRACTICE WAN DESIGN 292
8.7 IMPROVING WAN PERFORMANCE 294
8.7.1 Improving Device Performance 294
8.7.2 Improving Circuit Capacity 295
8.7.3 Reducing Network Demand 296
8.8 IMPLICATIONS FOR MANAGEMENT 297
SUMMARY 297
CHAPTER 9
THE INTERNET 310
9.1 INTRODUCTION 311
9.2 HOW THE INTERNET WORKS 312
9.2.1 Basic Architecture 312
9.2.2 Connecting to an ISP 314
9.2.3 The Internet Today 316
9.3 INTERNET ACCESS TECHNOLOGIES 317
9.3.1 Digital Subscriber Line (DSL) 318
9.3.2 Cable Modem 320
9.3.3 Fiber to the Home 322
9.3.4 WiMax 323
9.4 THE FUTURE OF THE INTERNET 324
9.4.1 Internet Governance 324
9.4.2 Building the Future 325
9.5 IMPLICATIONS FOR MANAGEMENT 328
SUMMARY 328
PART FOUR
NETWORK MANAGEMENT
337
CHAPTER 10
NETWORK SECURITY 338
10.1 INTRODUCTION 339
10.1.1 Why Networks Need Security 341
10.1.2 Types of Security Threats 342
10.1.3 Network Controls 342
10.2 RISK ASSESSMENT 345
10.2.1 Develop a Control Spreadsheet 345
10.2.2 Identify and Document
the Controls 349
10.2.3 Evaluate the Network’s Security 350
10.3 ENSURING BUSINESS CONTINUITY 351
10.3.1 Virus Protection 351
10.3.2 Denial of Service Protection 352
10.3.3 Theft Protection 356
10.3.4 Device Failure Protection 356
10.3.5 Disaster Protection 357
10.4 INTRUSION PREVENTION 361
10.4.1 Security Policy 362
10.4.2 Perimeter Security and Firewalls 362
10.4.3 Server and Client Protection 369
10.4.4 Encryption 374
10.4.5 User Authentication 382
10.4.6 Preventing Social Engineering 385
10.4.7 Intrusion Prevention Systems 387
10.4.8 Intrusion Recovery 388
10.5 BEST PRACTICE RECOMMENDATIONS 390
10.6 IMPLICATIONS FOR MANAGEMENT 391
SUMMARY 392
CHAPTER 11
NETWORK DESIGN 408
11.1 INTRODUCTION 410
11.1.1 The Traditional Network Design
Process 410
11.1.2 The Building-Block Network Design
Process 411
11.2 NEEDS ANALYSIS 413
11.2.1 Geographic Scope 414
11.2.2 Application Systems 415
11.2.3 Network Users 416
11.2.4 Categorizing Network Needs 417
11.2.5 Deliverables 417
11.3 TECHNOLOGY DESIGN 418
11.3.1 Designing Clients and Servers 418
11.3.2 Designing Circuits and Devices 419
11.3.3 Network Design Tools 420
11.3.4 Deliverables 420
xiv CONTENTS
11.4 COST ASSESSMENT 421
11.4.1 Request for Proposal 422
11.4.2 Selling the Proposal to
Management 422
11.4.3 Deliverables 423
11.5 DESIGNING FOR NETWORK
PERFORMANCE 424
11.5.1 Managed Networks 424
11.5.2 Network Circuits 428
11.5.3 Network Devices 430
11.5.4 Minimizing Network Traffic 432
11.5.5 Green IT 436
11.6 IMPLICATIONS FOR MANAGEMENT 437
SUMMARY 439
CHAPTER 12
NETWORK MANAGEMENT 448
12.1 INTRODUCTION 449
12.2 ORGANIZING THE NETWORK
MANAGEMENT FUNCTION 450
12.2.1 The Shift to LANs and the Internet 450
12.2.2 Integrating LANs, WANs, and
the Internet 451
12.2.3 Integrating Voice and Data
Communications 452
12.3 CONFIGURATION MANAGEMENT 454
12.3.1 Configuring the Network and Client
Computers 454
12.3.2 Documenting the Configuration 454
12.4 PERFORMANCE AND FAULT
MANAGEMENT 456
12.4.1 Network Monitoring 456
12.4.2 Failure Control Function 459
12.4.3 Performance and Failure Statistics 462
12.4.4 Improving Performance 465
12.5 END USER SUPPORT 466
12.5.1 Resolving Problems 466
12.5.2 Providing End User Training 467
12.6 COST MANAGEMENT 467
12.6.1 Sources of Costs 467
12.6.2 Reducing Costs 470
12.7 IMPLICATIONS FOR MANAGEMENT 472
SUMMARY 473
PART FIVE
APPENDICES 481
APPENDIX A
CONNECTOR
CABLES 482
APPENDIX B SPANNING TREE
PROTOCOL 493
APPENDIX C IP TELEPHONY 497
APPENDIX D CELLULAR
TECHNOLOGIES 500
APPENDIX E TCP/IP GAME 502
APPENDIX F WINDOWS SERVER 513
GLOSSARY 525
INDEX 555
Part One
INTRODUCTION
Courtesy Cisco Systems, Inc. Unauthorized use not permitted.
Network equipment from Cisco Systems, Inc.
CHAPTER1
INTRODUCTION TO DATA
COMMUNICATIONS
The Three Faces of Networking
The Three Faces of Networking
Fundamental Concepts Network Technologies
Network Management
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Application layer
Network layer
Data Link layer
Physical layer
LAN
WLAN
Backbone
WAN
Internet
Transport layer
CHAPTER OUTLINE 3
THIS CHAPTER introduces the basic concepts of data com-
munications and shows how we have progressed from paper-based systems
to modern computer networks. It begins by describing why it is important
to study data communications and how the invention of the telephone, the
computer, and the Internet has transformed the way we communicate.
Next, the basic types and components of a data communication network
are discussed. The importance of a network model based on layers and the
importance of network standards are examined. The chapter concludes with
an overview of three key trends in the future of networking.
OBJECTIVES
▲
Be aware of the history of communications, information systems, and the Internet
Be aware of the applications of data communication networks
Be familiar with the major components of and types of networks
Understand the role of network layers
Be familiar with the role of network standards
Be aware of three key trends in communications and networking
CHAPTER OUTLINE
▲
1.1 INTRODUCTION
1.1.1 A Brief History of Communications
in North America
1.1.2 A Brief History of Information
Systems
1.1.3 A Brief History of the Internet
1.2 DATA COMMUNICATIONS NETWORKS
1.2.1 Components of a Network
1.2.2 Types of Networks
1.3 NETWORK MODELS
1.3.1 Open Systems Interconnection
Reference Model
1.3.2 Internet Model
1.3.3 Message Transmission Using Layers
1.4 NETWORK STANDARDS
1.4.1 The Importance of Standards
1.4.2 The Standards-Making Process
1.4.3 Common Standards
1.5 FUTURE TRENDS
1.5.1 Pervasive Networking
1.5.2 The Integration of Voice, Video, and
Data
1.5.3 New Information Services
1.6 IMPLICATIONS FOR MANAGEMENT
4 CHAPTER 1 INTRODUCTION TO DATA COMMUNICATIONS
1.1 INTRODUCTION
What Internet connection should you use? Cable modem or DSL (formally called Digital
Subscriber Line)? Cable modems are supposedly six times faster than DSL, providing
data speeds of 10 mbps to DSL’s 1–5 Mbps (million bits per second). One cable company
used a tortoise to represent DSL in advertisements. So which is faster? We’ll give you
a hint. Which won the race in the fable, the tortoise or the hare? By the time you
finish this book, you’ll understand which is faster and why, as well as why choosing the
right company as your Internet service provider (ISP) is probably more important than
choosing the right technology.
Over the past decade or so, it has become clear that the world has changed forever.
We continue to forge our way through the Information Age—the second Industrial Rev-
olution, according to John Chambers, CEO (chief executive officer) of Cisco Systems,
Inc., one of the world’s leading networking technology companies. The first Industrial
Revolution revolutionized the way people worked by introducing machines and new
organizational forms. New companies and industries emerged and old ones died off.
The second Industrial Revolution is revolutionizing the way people work through
networking and data communications. The value of a high-speed data communication
network is that it brings people together in a way never before possible. In the 1800s, it
took several weeks for a message to reach North America by ship from England. By the
1900s, it could be transmitted within the hour. Today, it can be transmitted in seconds.
Collapsing the information lag to Internet speeds means that people can communicate
and access information anywhere in the world regardless of their physical location. In
fact, today’s problem is that we cannot handle the quantities of information we receive.
Data communications and networking is a truly global area of study, both because
the technology enables global communication and because new technologies and applica-
tions often emerge from a variety of countries and spread rapidly around the world. The
World Wide Web, for example, was born in a Swiss research lab, was nurtured through
its first years primarily by European universities, and exploded into mainstream popular
culture because of a development at an American research lab.
One of the problems in studying a global phenomenon lies in explaining the differ-
ent political and regulatory issues that have evolved and currently exist in different parts
of the world. Rather than attempt to explain the different paths taken by different coun-
tries, we have chosen simplicity instead. Historically, the majority of readers of previous
editions of this book have come from North America. Therefore, although we retain a
global focus on technology and its business implications, we focus exclusively on North
America in describing the political and regulatory issues surrounding communications
and networking. We do, however, take care to discuss technological or business issues
where fundamental differences exist between North America and the rest of the world
(e.g., ISDN [integrated services digital network]) (see Chapter 8).
One of the challenges in studying data communications and networking is that
there are many perspectives that can be used. We begin by examining the fundamental
concepts of data communications and networking. These concepts explain how data is
moved from one computer to another over a network, and represent the fundamental
“theory” of how networks operate. The second perspective is from the viewpoint of the
technologies in use today—how these theories are put into practice in specific products.