VoIP

Preface xvii

PART I PRELIMINARIES

1 Introduction to VoIP Networks 3

1.1 Public Switched Telephone Network (PSTN) 3

1.2 Fundamentals of Internet technology 7

1.3 Performance issues in the Internet 11

1.4 Quality of Service (QoS) guarantees 12

1.5 Summary 15

2 Basics of VoIP 17

2.1 Packetization of voice 17

2.2 Networking technology 18

2.3 Architecture overview 18

2.4 Process of making a VoIP call 22

2.5 Deployment issues 23

2.6 VoIP applications and services 26

2.7 Summary 27

3 VoIP Codecs 29

3.1 Codec design overview 29

3.2 Speech coding techniques 31

3.3 Narrowband codecs 34

3.4 Wideband and multirate codecs 36

3.5 VoIP softwares 37

3.6 Summary 38

4 Performance of Voice Codecs 41

4.1 Factors affecting VoIP quality 41

4.2 Voice quality assessment 43

4.3 Subjective measures and MOS score 44

4.4 Conversational opinion score 45

4.5 E-Model 46

4.6 Sensitivity to loss 48

4.7 Perceptual Evaluation of Speech Quality (PESQ) 50

4.8 Tools for lab testbed setup 53

4.9 Voice input/output tools 55

4.10 Summary 57

5 VoIP Protocols 59

5.1 Introduction 59

5.2 Signaling protocols 61

5.3 Media transport protocols 70

5.4 Summary 71

PART II VOIP IN OVERLAY NETWORKS

6 Overlay Networks 75

6.1 Internet communication overview 75

6.2 Limitations of the Internet 77

6.3 Overlay networks 78

6.4 Applications of overlay networks 82

6.5 Summary 86

7 P2P Technology 87

7.1 P2P communication overview 87

7.2 Classification of P2P networks 89

7.3 Unstructured overlays 90

7.4 Structured overlays - Distributed Hash Tables (DHTs) 92

7.5 Types of DHT 96

7.6 Semi-structured overlays 100

7.7 Keyword search using DHT 101

7.8 Summary 102

8 VoIP over Infrastructure Overlays 103

8.1 Introduction 104

8.2 VoIP over overlay - generic architecture 104

8.3 Methods to enhance VoIP quality 105

8.4 Estimating network quality 110

8.5 Route computation 114

8.6 Perceived enhancement of VoIP quality 115

8.7 Summary 116

9 VoIP over P2P 119

9.1 VoIP over P2P overlay - generic architecture 119

9.2 VoIP issues in P2P overlay 120

9.3 Case study: Skype 122

9.4 Standardization 130

9.5 Summary 130

PART III VOIP IN WIRELESS NETWORKS

10 IEEE 802.11 Wireless Networks 135

10.1 Network architecture overview 135

10.2 Network access management 137

10.3 Basic medium access protocol 139

10.4 Physical layer 142

10.5 Network resource management 144

10.6 IEEE 802.11 standardization overview 147

10.7 Summary 148

11 Voice over IEEE 802.11 Wireless Networks 149

11.1 VoIP overWLAN performance problems 149

11.2 VoIP capacity 151

11.3 VoIP packet prioritization 155

11.4 Handoff performance 157

11.5 Reliable delivery 160

11.6 Client power management 161

11.7 Issues in mesh networks 161

11.8 Summary 163

12 IEEE 802.16 WiMAX 165

12.1 WiMAX overview 165

12.2 IEEE 802.11 MAC protocol architecture 166

12.3 MAC layer framing 168

12.4 Physical layer 170

12.5 Radio resource management 174

12.6 Competing technologies 175

12.7 Summary 176

13 Voice over WiMAX 177

13.1 Introduction 177

13.2 VoIP service delivery overWiMAX network 178

13.3 QoS architecture 179

13.4 Call admission control 181

13.5 Uplink QoS control 181

13.6 Enhanced QoS control for VoIP 182

13.7 MAC enhancement strategies 185

13.8 Comparison with competing technologies 187

13.9 Summary 187

PART IV VOIP IN ENTERPRISE NETWORKS

14 Private Branch Exchange (PBX) 191

14.1 Private Branch Exchange (PBX) 191

14.2 Case study: Asterisk open-source IP-PBX 195

14.3 Summary 206

15 Network Address Translation (NAT) and Firewall 207

15.1 Introduction 208

15.2 NAT fundamentals 208

15.3 Applications of NAT 210

15.4 Types of NAT 212

15.5 Firewall 214

15.6 NAT traversal solutions 214

15.7 NAT traversal in H.323 219

15.8 Summary 220

PART V VOIP SERVICE DEPLOYMENT

16 Supporting Services and Applications 223

16.1 Domain Name System (DNS) 223

16.2 ENUM 225

16.3 Network monitoring 225

16.4 Direct Inward Dialing (DID) 226

16.5 Emergency calling (911) 226

16.6 Fax 227

16.7 Summary 228

17 Security and Privacy 231

17.1 Security and privacy issues 232

17.2 Generic issues 232

17.3 VoIP-related issues 234

17.4 Solutions 236

17.5 Recommendations 239

17.6 Summary 240

18 IP Multimedia Subsystem (IMS) 241

18.1 Introduction 241

18.2 Architecture design goals 242

18.3 IMS advantages 243

18.4 IMS architecture organization 244

18.5 Network Attachment SubSystem (NASS) 246

18.6 Resource Admission Control Subsystem (RACS) 247

18.7 IMS core subsystem 247

18.8 IMS QoS management 249

18.9 QoS provisioning approach 249

18.10 Summary 251

Index 253