Alan Dennis is a Fellow of the Association for Information Systems and a professor of information systems in the Kelley School of Business at Indiana University. He holds the John T. Chambers Chair in Internet Systems, which was established to honor John Chambers, president and chief executive officer of Cisco Systems, the worldwide leader of networking technologies for the Internet.

Alexandra Durcikova is an Associate Professor at the Price College of Business, University of Oklahoma. Alexandra has a PhD in management information systems from the University of Pittsburgh. She has earned an MSc degree in solid state physics from Comenius University, Bratislava, worked as an experimental physics researcher in the area of superconductivity and as an instructor of executive MBA students prior to pursuing her PhD. Alexandra’s research interests include knowledge management and knowledge management systems, the role of organizational climate in the use of knowledge management systems, knowledge management system characteristics, governance mechanisms in the use of knowledge management systems, and human compliance with security policy and characteristics of successful phishing attempts within the area of network security. Her research appears in Information Systems Research, MIS Quarterly, Journal of Management Information Systems, Information Systems Journal, Journal of Organizational and End User Computing, International Journal of Human-Computer Studies, International Journal of Human-Computer Studies, and Communications of the ACM.

Dr. Jerry FitzGerald wrote the early editions of this book in the 1980s. At the time, he was the principal in Jerry FitzGerald & Associates, a firm he started in 1977.

About the Authors v

Preface vi

PART ONE INTRODUCTION 1

Chapter 1 Introduction to Data Communications 1

1.1 Introduction 1

1.2 Data Communications Networks 4

1.2.1 Components of a Network 4

1.2.2 Types of Networks 5

1.3 Network Models 7

1.3.1 Open Systems Interconnection Reference Model 7

1.3.2 Internet Model 9

1.3.3 Message Transmission Using Layers 10

1.4 Network Standards 13

1.4.1 The Importance of Standards 13

1.4.2 The Standards-Making Process 13

1.4.3 Common Standards 15

1.5 Future Trends 16

1.5.1 Wireless LAN and BYOD 16

1.5.2 The Internet of Things 17

1.5.3 Massively Online 17

1.6 Implications for Cyber Security 18

PART TWO FUNDAMENTAL CONCEPTS 25

Chapter 2 Application Layer 25

2.1 Introduction 25

2.2 Application Architectures 26

2.2.1 Host-Based Architectures 27

2.2.2 Client-Based Architectures 28

2.2.3 Client-Server Architectures 28

2.2.4 Cloud Computing Architectures 31

2.2.5 Peer-to-Peer Architectures 33

2.2.6 Choosing Architectures 34

2.3 World Wide Web 35

2.3.1 How the Web Works 35

2.3.2 Inside an HTTP Request 36

2.3.3 Inside an HTTP Response 37

2.4 Electronic Mail 39

2.4.1 How Email Works 39

2.4.2 Inside an SMTP Packet 42

2.4.3 Attachments in Multipurpose Internet Mail Extension 43

2.5 Other Applications 43

2.5.1 Telnet 44

2.5.2 Instant Messaging 45

2.5.3 Videoconferencing 45

2.6 Implications for Cyber Security 47

Chapter 3 Physical Layer 57

3.1 Introduction 57

3.2 Circuits 59

3.2.1 Circuit Configuration 59

3.2.2 Data Flow 60

3.2.3 Multiplexing 60

3.3 Communication Media 63

3.3.1 Twisted Pair Cable 63

3.3.2 Coaxial Cable 64

3.3.3 Fiber-Optic Cable 64

3.3.4 Radio 65

3.3.5 Microwave 66

3.3.6 Satellite 66

3.3.7 Media Selection 68

3.4 Digital Transmission of Digital Data 69

3.4.1 Coding 69

3.4.2 Transmission Modes 69

3.4.3 Digital Transmission 71

3.4.4 How Ethernet Transmits Data 72

3.5 Analog Transmission of Digital Data 73

3.5.1 Modulation 73

3.5.2 Capacity of a Circuit 76

3.5.3 How Modems Transmit Data 76

3.6 Digital Transmission of Analog Data 77

3.6.1 Translating from Analog to Digital 77

3.6.2 How Telephones Transmit Voice Data 77

3.6.3 How Instant Messenger Transmits Voice Data 79

3.6.4 Voice over Internet Protocol (VoIP) 80

3.7 Implications for Cyber Security 80

Chapter 4 Data Link Layer 88

4.1 Introduction 88

4.2 Media Access Control 89

4.2.1 Contention 89

4.2.2 Controlled Access 89

4.2.3 Relative Performance 90

4.3 Error Control 91

4.3.1 Sources of Errors 91

4.3.2 Error Prevention 93

4.3.3 Error Detection 94

4.3.4 Error Correction via Retransmission 95

4.3.5 Forward Error Correction 95

4.3.6 Error Control in Practice 97

4.4 Data Link Protocols 97

4.4.1 Asynchronous Transmission 97

4.4.2 Synchronous Transmission 98

4.5 Transmission Efficiency 101

4.6 Implications for Cyber Security 103

Chapter 5 NETWORK AND TRANSPORT LAYERS 110

5.1 Introduction 110

5.2 Transport and Network Layer Protocols 112

5.2.1 Transmission Control Protocol (TCP) 112

5.2.2 Internet Protocol (IP) 113

5.3 Transport Layer Functions 114

5.3.1 Linking to the Application Layer 114

5.3.2 Segmenting 115

5.3.3 Session Management 116

5.4 Addressing 119

5.4.1 Assigning Addresses 120

5.4.2 Address Resolution 125

5.5 Routing 127

5.5.1 Types of Routing 128

5.5.2 Routing Protocols 130

5.5.3 Multicasting 132

5.5.4 The Anatomy of a Router 133

5.6 TCP/IP Example 134

5.6.1 Known Addresses 136

5.6.2 Unknown Addresses 137

5.6.3 TCP Connections 138

5.6.4 TCP/IP and Network Layers 139

5.7 Implications for Cyber Security 141

PART THREE NETWORK TECHNOLOGIES 159

Chapter 6 Network Design 159

6.1 Introduction 159

6.1.1 Network Architecture Components 159

6.1.2 The Traditional Network Design Process 161

6.1.3 The Building-Block Network Design Process 162

6.2 Needs Analysis 164

6.2.1 Network Architecture Component 165

6.2.2 Application Systems 166

6.2.3 Network Users 166

6.2.4 Categorizing Network Needs 166

6.2.5 Deliverables 167

6.3 Technology Design 168

6.3.1 Designing Clients and Servers 168

6.3.2 Designing Circuits 168

6.3.3 Network Design Tools 170

6.3.4 Deliverables 171

6.4 Cost Assessment 171

6.4.1 Request for Proposal 171

6.4.2 Selling the Proposal to Management 173

6.4.3 Deliverables 173

6.5 Implications for Cyber Security 173

Chapter 7 Wired and Wireless Local Area

Networks 177

7.1 Introduction 177

7.2 LAN Components 178

7.2.1 Network Interface Cards 179

7.2.2 Network Circuits 179

7.2.3 Network Hubs, Switches, and Access Points 180

7.2.4 Network Operating Systems 183

7.3 Wired Ethernet 184

7.3.1 Topology 184

7.3.2 Media Access Control 187

7.3.3 Types of Ethernet 188

7.4 Wireless Ethernet 189

7.4.1 Topology 189

7.4.2 Media Access Control 189

7.4.3 Wireless Ethernet Frame Layout 190

7.4.4 Types of Wireless Ethernet 191

7.4.5 Security 192

7.5 The Best Practice LAN Design 193

7.5.1 Designing User Access with Wired Ethernet 194

7.5.2 Designing User Access with Wireless Ethernet 195

7.5.3 Designing the Data Center 197

7.5.4 Designing the e-Commerce Edge 199

7.5.5 Designing the SOHO Environment 200

7.6 Improving LAN Performance 202

7.6.1 Improving Server Performance 203

7.6.2 Improving Circuit Capacity 204

7.6.3 Reducing Network Demand 204

7.7 Implications for Cyber Security 205

Chapter 8 Backbone Networks 214

8.1 Introduction 214

8.2 Switched Backbones 215

8.3 Routed Backbones 218

8.4 Virtual LANs 221

8.4.1 Benefits of VLANs 221

8.4.2 How VLANs Work 223

8.5 The Best Practice Backbone Design 226

8.6 Improving Backbone Performance 227

8.6.1 Improving Device Performance 227

8.6.2 Improving Circuit Capacity 228

8.6.3 Reducing Network Demand 228

8.7 Implications for Cyber Security 228

Chapter 9 Wide Area Networks 237

9.1 Introduction 237

9.2 Dedicated-Circuit Networks 238

9.2.1 Basic Architecture 238

9.2.2 T-Carrier Services 241

9.2.3 SONET Services 243

9.3 Packet-Switched Networks 243

9.3.1 Basic Architecture 243

9.3.2 Frame Relay Services 245

9.3.3 IP Services 246

9.3.4 Ethernet Services 246

9.4 Virtual Private Networks 247

9.4.1 Basic Architecture 247

9.4.2 VPN Types 248

9.4.3 How VPNs Work 248

9.5 The Best Practice WAN Design 251

9.6 Improving WAN Performance 252

9.6.1 Improving Device Performance 252

9.6.2 Improving Circuit Capacity 253

9.6.3 Reducing Network Demand 253

9.7 Implications for Cyber Security 254

Chapter 10 The Internet 265

10.1 Introduction 265

10.2 How the Internet Works 266

10.2.1 Basic Architecture 266

10.2.2 Connecting to an ISP 268

10.2.3 The Internet Today 269

10.3 Internet Access Technologies 270

10.3.1 Digital Subscriber Line 270

10.3.2 Cable Modem 271

10.3.3 Fiber to the Home 273

10.3.4 WiMax 274

10.4 The Future of the Internet 274

10.4.1 Internet Governance 274

10.4.2 Building the Future 276

10.5 Implications for Cyber Security 277

PART FOUR NETWORK MANAGEMENT 284

Chapter 11 Network Security 284

11.1 Introduction 284

11.1.1 Why Networks Need Security 286

11.1.2 Types of Security Threats 286

11.1.3 Network Controls 287

11.2 Risk Assessment 288

11.2.1 Develop Risk Measurement Criteria 289

11.2.2 Inventory IT Assets 290

11.2.3 Identify Threats 291

11.2.4 Document Existing Controls 293

11.2.5 Identify Improvements 296

11.3 Ensuring Business Continuity 296

11.3.1 Virus Protection 296

11.3.2 Denial-of-Service Protection 297

11.3.3 Theft Protection 300

11.3.4 Device Failure Protection 301

11.3.5 Disaster Protection 302

11.4 Intrusion Prevention 305

11.4.1 Security Policy 306

11.4.2 Perimeter Security and Firewalls 306

11.4.3 Server and Client Protection 312

11.4.4 Encryption 315

11.4.5 User Authentication 321

11.4.6 Preventing Social Engineering 324

11.4.7 Intrusion Prevention Systems 325

11.4.8 Intrusion Recovery 327

11.5 Best Practice Recommendations 328

11.6 Implications for Your Cyber Security 330

Chapter 12 Network Management 340

12.1 Introduction 340

12.2 Designing for Network Performance 341

12.2.1 Managed Networks 341

12.2.2 Managing Network Traffic 345

12.2.3 Reducing Network Traffic 346

12.3 Configuration Management 349

12.3.1 Configuring the Network and Client Computers 349

12.3.2 Documenting the Configuration 350

12.4 Performance and Fault Management 351

12.4.1 Network Monitoring 351

12.4.2 Failure Control Function 353

12.4.3 Performance and Failure Statistics 355

12.4.4 Improving Performance 358

12.5 End User Support 358

12.5.1 Resolving Problems 358

12.5.2 Providing End User Training 360

12.6 Cost Management 360

12.6.1 Sources of Costs 360

12.6.2 Reducing Costs 363

12.7 Implications for Cyber Security 364

Appendices (Online)

Glossary (Online)

Index 373

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