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 5

1.2.1 Components of a Network 6

1.2.2 Types of Networks 7

1.3 Network Models 8

1.3.1 Open Systems Interconnection Reference Model 9

1.3.2 Internet Model 10

1.3.3 Message Transmission Using Layers 12

1.4 Network Standards 14

1.4.1 The Importance of Standards 14

1.4.2 The Standards-Making Process 15

1.4.3 Common Standards 17

1.5 Future Trends 18

1.5.1 Wireless LAN and BYOD 18

1.5.2 The Internet of Things 18

1.5.3 Massively Online 19

1.6 Implications for Cyber Security 20

Part Two Fundamental Concepts 27

Chapter 2 Application Layer 27

2.1 Introduction 27

2.2 Application Architectures 28

2.2.1 Host-Based Architectures 29

2.2.2 Client-Based Architectures 30

2.2.3 Client-Server Architectures 30

2.2.4 Cloud Computing Architectures 33

2.2.5 Peer-to-Peer Architectures 35

2.2.6 Choosing Architectures 36

2.3 World Wide Web 37

2.3.1 How the Web Works 37

2.3.2 Inside an HTTP Request 38

2.3.3 Inside an HTTP Response 39

2.4 Electronic Mail 41

2.4.1 How Email Works 41

2.4.2 Inside an SMTP Packet 44

2.4.3 Attachments in Multipurpose Internet Mail Extension 45

2.5 Other Applications 45

2.5.1 Telnet 46

2.5.2 Videoconferencing 47

2.6 Implications for Cyber Security 48

Chapter 3 Physical Layer 59

3.1 Introduction 59

3.2 Circuits 61

3.2.1 Circuit Configuration 61

3.2.2 Data Flow 62

3.2.3 Multiplexing 62

3.3 Communication Media 65

3.3.1 Twisted-Pair Cable 65

3.3.2 Coaxial Cable 65

3.3.3 Fiber-Optic Cable 66

3.3.4 Radio 67

3.3.5 Microwave 68

3.3.6 Satellite 68

3.3.7 Media Selection 70

3.4 Digital Transmission of Digital Data 71

3.4.1 Coding 71

3.4.2 Transmission Modes 72

3.4.3 Digital Transmission 73

3.4.4 How Ethernet Transmits Data 74

3.5 Analog Transmission of Digital Data 75

3.5.1 Modulation 75

3.5.2 Capacity of a Circuit 78

3.5.3 How Modems Transmit Data 78

3.6 Digital Transmission of Analog Data 79

3.6.1 Translating from Analog to Digital 79

3.6.2 How Telephones Transmit Voice Data 80

3.6.3 How Instant Messenger Transmits Voice Data 81

3.6.4 Voice over Internet Protocol (VoIP) 82

3.7 Implications for Cyber Security 83

Chapter 4 Data Link Layer 91

4.1 Introduction 91

4.2 Media Access Control 92

4.2.1 Contention 92

4.2.2 Controlled Access 92

4.2.3 Relative Performance 93

4.3 Error Control 94

4.3.1 Sources of Errors 94

4.3.2 Error Prevention 96

4.3.3 Error Detection 97

4.3.4 Error Correction via Retransmission 98

4.3.5 Forward Error Correction 98

4.3.6 Error Control in Practice 99

4.4 Data Link Protocols 100

4.4.1 Asynchronous Transmission 101

4.4.2 Synchronous Transmission 101

4.5 Transmission Efficiency 104

4.6 Implications for Cyber Security 106

Chapter 5 Network and Transport Layers 114

5.1 Introduction 114

5.2 Transport and Network Layer Protocols 116

5.2.1 Transmission Control Protocol (TCP) 116

5.2.2 Internet Protocol (IP) 117

5.3 Transport Layer Functions 118

5.3.1 Linking to the Application Layer 118

5.3.2 Segmenting 119

5.3.3 Session Management 120

5.4 Addressing 123

5.4.1 Assigning Addresses 124

5.4.2 Address Resolution 129

5.5 Routing 131

5.5.1 Types of Routing 132

5.5.2 Routing Protocols 134

5.5.3 Multicasting 136

5.5.4 The Anatomy of a Router 137

5.6 TCP/IP Example 138

5.6.1 Known Addresses 140

5.6.2 Unknown Addresses 141

5.6.3 TCP Connections 142

5.6.4 TCP/IP and Network Layers 143

5.7 Implications for Cyber Security 145

Part Three Network Technologies 162

Chapter 6 Network Design 162

6.1 Introduction 162

6.1.1 Network Architecture Components 163

6.1.2 The Traditional Network Design Process 164

6.1.3 The Building-Block Network Design Process 166

6.2 Needs Analysis 166

6.2.1 Network Architecture Component 168

6.2.2 Application Systems 169

6.2.3 Network Users 169

6.2.4 Categorizing Network Needs 170

6.2.5 Deliverables 171

6.3 Technology Design 171

6.3.1 Designing Clients and Servers 171

6.3.2 Designing Circuits 171

6.3.3 Network Design Tools 174

6.3.4 Deliverables 174

6.4 Cost Assessment 174

6.4.1 Request for Proposal 175

6.4.2 Selling the Proposal to Management 175

6.4.3 Deliverables 176

6.5 Implications for Cyber Security 176

Chapter 7 Wired and Wireless Local Area Networks 182

7.1 Introduction 182

7.2 LAN Components 183

7.2.1 Network Interface Cards 183

7.2.2 Network Circuits 184

7.2.3 Network Hubs, Switches, and Access Points 185

7.2.4 Network Operating Systems 188

7.3 Wired Ethernet 189

7.3.1 Topology 190

7.3.2 Media Access Control 192

7.3.3 Types of Ethernet 193

7.4 Wireless Ethernet 194

7.4.1 Topology 194

7.4.2 Media Access Control 194

7.4.3 Wireless Ethernet Frame Layout 196

7.4.4 Types of Wireless Ethernet 196

7.4.5 Security 198

7.5 The Best Practice LAN Design 199

7.5.1 Designing User Access with Wired Ethernet 200

7.5.2 Designing User Access with Wireless Ethernet 200

7.5.3 Designing the Data Center 203

7.5.4 Designing the e-Commerce Edge 206

7.5.5 Designing the SOHO Environment 206

7.6 Improving LAN Performance 207

7.6.1 Improving Server Performance 208

7.6.2 Improving Circuit Capacity 210

7.6.3 Reducing Network Demand 210

7.7 Implications for Cyber Security 210

Chapter 8 Backbone Networks 220

8.1 Introduction 220

8.2 Switched Backbones 221

8.3 Routed Backbones 224

8.4 Virtual LANs 227

8.4.1 Benefits of VLANs 227

8.4.2 How VLANs Work 229

8.5 The Best Practice Backbone Design 232

8.6 Improving Backbone Performance 233

8.6.1 Improving Device Performance 233

8.6.2 Improving Circuit Capacity 234

8.6.3 Reducing Network Demand 234

8.7 Implications for Cyber Security 234

Chapter 9 Wide Area Networks 243

9.1 Introduction 243

9.2 Dedicated-Circuit Networks 244

9.2.1 Basic Architecture 245

9.2.2 T-Carrier Services 248

9.2.3 SONET Services 249

9.3 Packet-Switched Networks 250

9.3.1 Basic Architecture 250

9.3.2 Frame Relay Services 251

9.3.3 MPLS Services 252

9.3.4 Ethernet Services 252

9.4 Virtual Private Networks 254

9.4.1 Basic Architecture 254

9.4.2 VPN Types 255

9.4.3 How VPNs Work 256

9.5 The Best Practice WAN Design 258

9.5.1 Software Defined WAN 258

9.5.2 Choosing WAN Circuits 259

9.6 Improving WAN Performance 261

9.6.1 Improving Device Performance 261

9.6.2 Improving Circuit Capacity 261

9.6.3 Reducing Network Demand 262

9.7 Implications for Cyber Security 262

Chapter 10 The Internet 274

10.1 Introduction 274

10.2 How the Internet Works 275

10.2.1 Basic Architecture 275

10.2.2 Connecting to an ISP 277

10.2.3 The Internet Today 278

10.3 Internet Access Technologies 279

10.3.1 Digital Subscriber Line 279

10.3.2 Cable Modem 280

10.3.3 Fiber to the Home 282

10.4 The Future of the Internet 283

10.4.1 Internet Governance 283

10.4.2 Building the Future 284

10.5 Implications for Cyber Security 285

Part Four Network Management 292

Chapter 11 Network Security 292

11.1 Introduction 292

11.1.1 Why Networks Need Security 294

11.1.2 Types of Security Threats 294

11.1.3 Network Controls 295

11.2 Risk Assessment 296

11.2.1 Develop Risk Measurement Criteria 297

11.2.2 Inventory IT Assets 298

11.2.3 Identify Threats 299

11.2.4 Document Existing Controls 301

11.2.5 Identify Improvements 304

11.3 Ensuring Business Continuity 304

11.3.1 Virus Protection 304

11.3.2 Denial-of-Service Protection 305

11.3.3 Theft Protection 308

11.3.4 Device Failure Protection 309

11.3.5 Disaster Protection 310

11.4 Intrusion Prevention 313

11.4.1 Security Policy 314

11.4.2 Perimeter Security and Firewalls 314

11.4.3 Server and Client Protection 320

11.4.4 Encryption 323

11.4.5 User Authentication 329

11.4.6 Preventing Social Engineering 332

11.4.7 Intrusion Prevention Systems 333

11.4.8 Intrusion Recovery 335

11.5 Best Practice Recommendations 336

11.6 Implications for Your Cyber Security 338

Chapter 12 Network Management 352

12.1 Introduction 352

12.2 Designing for Network Performance 353

12.2.1 Managed Networks 353

12.2.2 Managing Network Traffic 357

12.2.3 Reducing Network Traffic 358

12.3 Configuration Management 361

12.3.1 Configuring the Network and Client Computers 361

12.3.2 Documenting the Configuration 362

12.4 Performance and Fault Management 364

12.4.1 Network Monitoring 364

12.4.2 Failure Control Function 366

12.4.3...