流控制传输协议SCTP参考指南PDF|Epub|txt|kindle电子书版本网盘下载

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4.6 Chunk Rejections During an Association Setup 1O1

1 Introduction and Overview1

1.1 IP Networking Basics1

1.1.1 How Messages Are Delivered in an IP Network2

1.1.2 IP Protocols5

1.1.3 IP Multi-homing6

1.2 What Is SCTP？6

1.2.1 Where Does SCTP Fit in the IP Architecture？7

1.3 Motivation for Developing SCTP8

1.3.1 TCP Limitations8

1.3.2 UDP Limitations10

1.3.3 SCTP Enhancements over TCP and UDP10

1.4 A Short History of SCTP Development11

1.4.1 Early Works Before the IETF and MDTP11

1.4.2 IETF Refinements13

1.5.1 Do We Really Need a New Transport Protocol？14

1.5 Major General SCTP Issues Debated in the IETF14

ContentS15

FOREWORD15

1.5.2 Over UDP Versus Over IP16

1.6 Organization of this Book17

PREFACE17

1.7 Summary19

1.8 Questions19

2 SCTP Endpoint and Association21

2.1 SCTP Transport Address21

2.2 SCTP Endpoint22

2.2.1 Multi-homed SCTP Endpoint22

2.3 SCTP Association24

2.4.1 Functional View of an Association26

2.4 Operation of an SCTP Association26

2.4.2 Functional Responsibilities of an SCTP Endpoint28

2.4.3 Operation States of an Association30

2.5 IETF Debate and Issues33

2.6 Summary33

2.7 Questions34

3 Format of SCTP Messages35

3.1 Basic Lavout—The Bits on the Wire35

3.1.1 The SCTP Common Header36

3.1.2 Elements in a Chunk37

3.1.3 Defined Chunk Types and Extensibility38

3.1.4 General Rules When Dealing with Chunks41

3.1.5 Chunk Parameters42

3.2.1 The INIT Chunk44

3.2 Basic Chunk Descriptions44

3.1.6 Other Considerations44

3.2.2 The INIT-ACK Chunk50

3.2.3 The COOKIE-ECHO Chunk54

3.2.4 The COOKIE-ACK Chunk55

3.2.5 The DATA Chunk55

3.2.6 The SACK Chunk58

3.2.7 The HEARTBEAT Chunk60

3.2.8 The HEARTBEAT-ACK Chunk61

3.2.9 The SHUTDOWN chunk62

3.2.10 The SHUTDOWN-ACK Chunk63

3.2.11 The SHUTDOWN-COMPLETE Chunk64

3.2.12 The ERROR Chunk65

3.2.13 The Error Cause Parameters65

3.2.14 The ABORT Chunk72

3.3 IETF Debate and Issue73

5.13 Questions l75

3.4 Summary75

3.5 Questions75

4 Setup of an Association77

4.1.1 Formulating the Chunk79

4.1 The INIT Chunk79

4.1.2 INIT Parameters80

4.1.3 Timer and Retransmission for INIT83

4.2 The INIT-ACK Response83

4.2.1 Formulating the Response84

4.2.2 INIT-ACK Parameters85

4.2.3 Preventing Resource Attacks89

4.3 The COOKIE-ECHO Chunk89

4.3.1 Formulating the Chunk91

4.3.2 Bundling Data with the COOKIE-ECHO91

4.3.3 Timer and Retransmission for COOKIE-ECHO91

4.4 The COOKIE-ACK Chunk92

4.4.1 Validating and Unpacking the Cookie93

4.4.2 Formulating the COOKIE-ACK95

4.4.3 Bundling DATA and SACK with COOKIE-ACK96

4.5 Address Usage When Starting an Association97

4.6.1 When Is an INIT Not Acceptable？102

4.6.2 When Is a Cookie Not Worth Eating？102

4.7 Handling Unexpected Initialization Chunks103

4.7.1 Association Tie-Tags and Their Values104

4.7.2 Handling Overlapping Initialization Chunks105

4.7.3 Case Study 1：Initialization Collision 11O4.7.4 Case Study 2：Peer Restart119

4.7.5 A Lost COOKIE-ACK121

4.8 IETF Debate and Issues122

4.9 Summary124

4.10 Questions124

5.1.1 How User Messages Are Sent125

5.1 User Message Transfer Overview125

5 User Data Transfer125

5.1.2 How User Messages Are Received129

5.1.3 Summary of Data Transfer Overview131

5.2 Obeying the Transmission Rules132

5.2.1 Congestion Window and Receiver Window132

5.2.2 Rules for Data Transmission132

5.3 Acknowledgment Rules137

5.3.1 Where Should a SACK Be Sent？137

5.3.2 When Should a SACK Be Sent？138

5.3.3 What Should Be Reported in a SACK？142

5.3.4 Revoking an Acknowledgment by the Receiver146

5.3.5 Processing of Received SACK by Data Sender148

5.4 Management of Retransmission Timer151

5.4.1 Determine Retransmission Timeout（RTO）151

5.4.2 Retransmission Timer Rules154

5.4.3 Handling Retransmission Timer Expiration156

5.5.1 Selection of Primary Transport Address158

5.5 Multi-homed Data Sender and Receiver158

5.5.2 Transferring Data between Multi-homed Endpoints159

5.5.3 Sending a SACK on Duplicate Data161

5.6 Stream Identifier and Stream Sequence Number162

5.6.1 Ordered and Unordered Message Delivery164

5.7 Passing a Payload Protocol Identifier165

5.8 Fragmentation and Bundling of User Messages166

5.8.1 When Should User Messages Be Fragmented？166

5.8.2 How Should a User Message Be Fragmented？167

5.8.3 Reassembling a Fragmented Message at the Data Receiver168

5.8.4 User Message Bundling169

5.9 Adler-32 Checksum171

5.9.1 Generation of the Adler-32 Checksum by the Data Sender171

5.1O.1 Handling a Data Chunk with an Invalid Stream Identifier172

5.10 Error Handling172

5.9.2 Validation of the Adler-32 Checksum by the Data Receiver172

5.10.2 Handling an Empty Data Chunk173

5.10.3 Handling Out-of-State Data173

5.11 IETF Debate and Issues173

5.12 Summary175

6 Congestion Control and Avoidance177

6.1 The Cause of Network Congestion Collapse177

6.2 Basic Concept of Congestion Control178

6.3 SCTP Congestion Control Algorithm180

6.3.1 How Does Your cwnd Grow？183

6.3.2 How Does Your cwnd Shrink？185

6.4 Interesting Details of the Algorithms186

6.5 Path MTU Discovery193

6.5.1 A Refresher on How PMTU Works193

6.5.2 PMTU Discovery in SCTP195

6.6 Explicit Congestion Notification196

6.7 IETF Debate and Issues197

6.8 Summary199

6.9 Questions200

7 Failure Detection and Recovery201

7.1 The Types of Failure SCTP Detects201

7.1.1 Unreachable Destination Address201

7.1.2 Unreachable Peer Endpoint202

7.2 How to Detect an Unreachable Address203

7.2.1 Using HEARTBEAT Chunks to Monitor Reachability204

7.2.2 Address-Unreachability Detection Algorithm205

7.2.3 More on Using the SCTP HEARTBEAT209

7.2.4 Handling an Unreachable Pfimary Destination Address213

7.3 How to Detect an Unreachable Peer213

7.3.1 When an Association Enters the Dormant State216

7.4.1 Maximizing Path Diversity218

7.4 Fault Resilience Communication and Routing Configuration218

7.4.2 Asymmetric Multi-homing Configuration220

7.4.3 Effects of Source Address Selection222

7.5 IETF Debate and Issues225

7.6 Summary226

7.7 Questions226

8 Auxiliary SCTP Packet Handling Functions229

8.1 Handling Out-of-the-Blue SCTP Packets229

8.2 SCTP Packet Verification Tag Rules231

8.2.1 Basic Verification Tag Rules232

8.2.2 Special Verification Tag Rules232

8.3 IETF Debate and Discussion235

8.4 Summary236

8.5 Questions236

9 Close of an Association237

9.1 The Graceful Shutdown238

9.1.1 Sending SHUTDOWN239

9.1.2 Receiving SHUTDOWN241

9.1.3 Sending SHUTDOWN-COMPLETE242

9.1.4 Race Conditions and Lost Messages244

9.2 The Abortive Shutdown248

9.2.1 ABORT Usage248

9.2.2 Sending an ABORT248

9.2.3 Receiving an ABORT249

9.3 IETF Debate and Issues250

9.4 Summary250

9.5 Questions251

10 LANA and Future Extension of SCTP253

1O.1 SCTP Port Number Assignment253

1O.2 IETF Chunk Extensions254

10.4 IETF Extensions to Error Causes255

1O.3 IETF Parameter Extensions255

1O.5 Payload Protocol Identifier256

1O.6 Summary256

11 A Sockets API for SCTP257

11.1 A Quick Review of the TCP Sockets API258

11.1.1 The Server-Side Application258

11.1.2 The Client-Side Application259

1 1.2 The TCP-Style SCTP Sockets API Extension261

11.3 The UDP-Style SCTP Sockets API Extension262

11.3.1 A View of a Client Using a UDP-Style SCTP socket263

11.3.2 A View of a Server Using a UDP-Style SCTP Socket265

11.4 Common API Mechanisms for Both Models267

11.4.1 Using the sendmsg（）and recvmsg（）Calls with SCTP268

11.4.2 Notification Information270

11.5 Summary277

11.6 Questions278

12 Comparing SCTP to TCP279

12.1 The Similarities between SCTP and TCP279

12.1.1 Startup279

12.1.2 Reliability and Ordering279

12.1.3 Congestion Control280

12.1.4 Closing Down280

12.2 The Differences Between SCTP and TCP280

12.2.1 Differences at Startup280

12.2.2 Head-of-Line Blocking281

12.2.3 Message Boundaries282

12.2.4 Unordered Delivery283

12.2.5 Selective Acknowledgment284

12.2.6 Multi-homing284

12.2.7 A Closing Difference285

12.3 Summary285

12.4 Questions286

13 Using Streams in SCTP287

13.1 A File Transfer Application287

13.2 A Telephone Call Control Application289

13.3 A Web Browser290

13.4 Summary291

13.5 Questions291

14 A User Space Implementation of SCTP293

14.1 The Big Picture293

14.2 Data Structures295

14.3 Events and the API297

14.4 Association Setup298

14.4.1 When an Upper Layer Issues an Associate Primitive298

14.4.2 When a Peer Sends the SCTP Endpoint an INIT303

14.5 Data Transfer309

14.5.1 SACK Processing310

14.5.2 Inbound DATA Chunk Processing311

14.5.3 Finishing Off by Sending313

14.6 Congestion Control,PMTU,and RTO315

14.6.1 Congestion Control315

14.6.2 PMTU Discovery316

14.6.3 RTO Calculation317

14.7 Fault Management318

14.8 Tag and Out-of-the-Blue Handling320

14.9 Association Close-Down321

14.9.1 At the Upper Layer's Request321

14.9.2 Reception of a SHUTDOWN322

14.10 Summary323

REFERENCES325

GLOSSARY AND ABBREVIATIONS329

INDEX335