VoIP技术与应用PDF电子书下载

Chapter 1 Introduction 1

Introduction 2

What Does Carrier Grade Mean? 2

What Does VoIP Mean? 3

A Little About IP 4

Why VoIP? 5

Why Carry Voice? 5

Why Use IP for Voice? 6

Lower Equipment Cost 7

Voice/Data Integration and Advanced Services 9

Lower Bandwidth Requirements 12

The Widespread Availability of IP 13

The VoIP Market 14

VoIP Challenges 15

Speech Quality 16

Network Reliability and Scalability 19

Managing Access and Prioritizing Traffic 20

VoIP Implementations 20

IP-Based PBX Solutions 21

IP Voice Mail 22

Hosted PBX Solutions 22

IP Call Centers 23

IP User Devices 24

Overview of Following Chapters 24

Chapter 2 Transporting Voice by Using IP 29

Introduction 30

Overview of the IP Protocol Suite 31

Internet Standards and the Standards Process 34

The Internet Society 34

The Internet Architecture Board(IAB) 35

The Internet Engineering Task Force(IETF) 35

The Internet Assigned Numbers Authority(IANA) 36

The Internet Standards Process 36

The Internet Engineering Steering Group(IESG) 36

IP 38

The IP Header 38

IP Routing 39

The Transmission Control Protocol(TCP) 44

The TCP Header 45

TCP Connections 47

The User Datagram Protocol(UDP) 49

Voice over UDP, not TCP 51

The Real-Time Transport Protocol(RTP) 52

RTP Payload Formats 53

The RTP Header 57

Mixers and Translators 61

The RTP Control Protocol(RTCP) 62

RTCP Sender Report(SR) 64

RTCP Source Description Packet(SDES) 67

RTCP Receiver Report(RR) 67

RTCP BYE Packet 68

Application-Defined RTCP Packet 69

Calculating Round-Trip Time 70

Calculating Jitter 70

Timing of RTCP Packets 71

IP Multicast 72

IP Version 6 Header 74

IP Version 6 74

IP Version 6 Addresses 75

IP Version 6 Header Extensions 78

Interoperating IP Version 4 and IP Version 6 81

Other Supporting Functions and Protocols 82

IP Security 83

Domain Name Service(DNS) 84

Path MTU Discovery 85

Chapter 3 Speech-Coding Techniques 87

Introduction 88

Voice Quality 89

A Little About Speech 90

Voice Sampling 93

Quantization 94

Types of Speech Coders 96

G.711 97

Adaptive DPCM(ADPCM) 98

Analysis-by-Synthesis(AbS)Codecs 98

G.728 LD-CELP 99

G.723.1 ACELP 101

G.729 103

Selecting Codecs 105

Cascaded Codecs 106

Tones,Signals,and DTMF Digits 107

Chapter 4 H.323 111

Introduction 112

The H.323 Architecture 113

Overview of H.323 Signaling 115

Overview of H.323 Protocols 117

H.323 Addressing 119

Codecs 120

RAS Signaling 120

Gatekeeper Discovery 122

Endpoint Registration and Registration Cancellation 125

Endpoint Location 127

Admission 128

Bandwidth Change 130

Status 132

Disengage 133

Resource Availability 134

Request in Progress 134

Call Signaling 134

Setup 137

Call Proceeding 137

Release Complete 138

Connect 138

Alerting 138

Progress 138

Facility 139

Interaction between Call Signaling and H.245 Control Signaling 139

Call Scenarios 140

Basic Call without Gatekeepers 140

A Basic Call with Gatekeepers and Direct-Endpoint Call Signaling 141

A Basic Call with Gatekeeper/Direct-Routed Call Signaling 142

A Basic Call with Gatekeeper-Routed Call Signaling 144

Optional Called-Endpoint Signaling 146

H.245 Control Signaling 148

H.245 Message Groupings 148

The Concept of Logical Channels 149

H.245 Procedures 149

Fast-Connect Procedure 155

H.245 Message Encapsulation 158

An Ad-Hoc Conference 160

Conference Calls 160

A Pre-Arranged Conference 160

Chapter 5 The Session Initiation Protocol(SIP) 163

Introduction 164

The Popularity of SIP 164

SIP Architecture 165

SIP Network Entities 166

SIP Call Establishment 168

SIP Advantages over Other Signaling Protocols 169

Overview of SIP Messaging Syntax 170

SIP Requests 172

SIP Responses 173

SIP Addressing 176

SIP Addressing 177

Message Headers 177

Registration 184

Examples of SIP Message Sequences 184

Invitation 186

Termination of a Call 188

Redirect and Proxy Servers 188

Redirect Servers 189

Proxy Servers 191

The Session Description Protocol(SDP) 195

The Structure of SDP 195

SDP Syntax 197

Usage of SDP with SIP 203

Negotiation of Media 204

Usage of SIP for Features and Services 206

Call Forwarding 208

Consultation Hold 209

SIP Extensions and Enhancements 211

The SIP 183 Session-Progress Message 212

The SIP INF0 Method 213

The SIP-Supported Header 214

Reliability of Provisional Responses 216

Integration of SIP Signaling and Resource Management 218

Interworking 223

PSTN Interworking 224

Interworking with H.323 227

Summary 231

Chapter 6 Media Gateway Control and the Softswitch Architecture 233

Introduction 234

Separation of Media and Call Control 234

Softswitch Architecture 236

Requirements for Media Gateway Control 238

Protocols for Media Gateway Control 239

MGCP 240

The MGCP Model 241

MGCP Endpoints 241

MGCP Calls and Connections 243

Overview of MGCP Commands 244

Overview of MGCP Responses 249

Command and Response Details 251

Call Setup Using MGCP 257

Call Setup Based on Detected Events 260

MGCP Events,Signals,and Packages 263

Internetworking between MGCP and SIP 264

MGCP Call Release 266

MEGACO/H.248 267

MEGACO Architecture 267

Overview of MEGACO Commands 272

Descriptors 274

Packages 283

MEGACO Command and Response Details 284

Call Setup Using MEGACO 290

MEGACO Call Setup Based on Detected Events 295

Interworking between MEGACO and SIP 301

Chapter 7 VoIP and SS7 303

Introduction 304

The SS7 Protocol Suite 306

The Message Transfer Part 306

ISUP and SCCP 307

SS7 Network Architecture 308

Signaling Points 310

Signal Transfer Point 310

Service Control Point(SCP) 311

Message Signal Units(MSUs) 312

SS7 Addressing 313

The ISDN User Part(ISUP) 314

Performance Requirements for SS7 316

Sigtran 318

Sigtran Architecture 320

SCTP 325

M3UA Operation 337

M2UA Operation 345

Interworking SS7 and VoIP Architectures 347

Interworking Softswitch and SS7 347

Interworking H.323 and SS7 352

Chapter 8 Quality of Service 355

Introduction 356

The Need for QOS 356

End-to-End QOS 358

It s Not Just the Network 359

Overview of QOS Solutions 360

More Bandwidth 360

QOS Protocols and Architectures 361

QOS Policies 365

The Resource-Reservation Protocol(RSVP) 365

RSVP Syntax 366

Establishing Reservations 367

Guaranteed Service 378

Reservation Errors 378

Controlled-Load Service 379

Removing Reservations and the Use of Soft State 380

DiffServ 381

DiffServ Architecture 382

The Need for Service-Level Agreements(SLAs) 383

Per-Hop Behaviors(PHBs) 384

Multi-Protocol Label Switching(MPLS) 387

MPLS Architecture 388

FECs and Labels 390

Actions at LSRs 392

Label-Switched Paths 394

MPLS Traffic Engineering 394

Combining QOS Solutions 401

Further Information 401

Chapter 9 Accessing the Network 403

Modems 404

Introduction 404

ISDN 406

BRI 407

Primary Rate Interface(PRI) 409

The Future of ISDN 409

Digital Subscriber Line(DSL) 410

DSL Variants 411

The ADSL Architecture 415

DSL Modulation 418

DSL Challenges 419

Using the Cable TV Infrastructure 421

Hybrid-Fiber Coax 421

Data Transmission over the HFC Network 422

The Packet Cable Architecture 423

Fixed Wireless Access 425

LMDS 425

Mobile Services 427

The Evolution to 3G for GSM 428

The Evolution to 3G for IS-136 TDMA 431

The Evolution to 3G for IS-95 CDMA 432

Chapter 10 Fax over IP(FoIP) 433

Introduction 434

Today s Fax Service 434

T.4 and T.30 434

Real-Time Fax 438

Sending Fax Messages over IP 440

Fax and H.323 445

TCP or UDP 446

Fax and SIP,SDP,and RTP 447

E-Mail-Based Fax 448

References 451

Glossary 459

Index 467