高速网络中的QoS控制（影印版）

PREFACE

1 INTRODUCTION

1.1 Nature of Traffic / 2

1.2 Network Technologies / 2

1.2.1 ATM / 2

1.2.2 Internet Integrated Services (Intserv) / 4

1.2.3 Internet Differentiated Services (Diffserv) / 5

1.2.4 Multiprotocol Label Switching (MPLS) / 6

1.3 QoS Parameters / 7

1.4 QoS Control Methods / 9

1.4.1 Admission Control / 9

1.4.2 Traffic Access Control / 10

1.4.3 Packet Scheduling / 10

1.4.4 Packet Fair Queuing Implementation / 11

1.4.5 Buffer Management / 11

1.4.6 Flow and Congestion Control / 11

1.4.7 QoS Routing / 11

1.5 Summary / 12

References / 13

2 ADMISSION CONTROL

2.1 Deterministic Bound / 18

2.2 Probabilistic Bound: Equivalent Bandwidth / 19

2.2.1 Bernoulli Trials and Binomial Distribution / 20

2.2.2 Fluid-Flow Approximation / 20

2.2.3 Gaussian Distribution / 21

2.2.4 Large-Deviation Approximation / 21

2.2.5 Poisson Distribution / 22

2.2.6 Measurement-Based Methods / 22

2.3 CAC for ATM VBR Services / 23

2.3.1 Worst-Case Traffic Model and CAC / 23

2.3.2 Effective Bandwidth / 24

2.3.3 Lucent's CAC / 25

2.3.4 NEC'sCAC / 27

2.3.5 Tagged-Probability-Based CAC / 30

2.4 CAC for Integrated Services Internet / 43

2.4.1 Guaranteed Quality of Service / 45

2.4.2 Controlled-Load Service / 49

References / 54

3 TRAFFIC ACCESS CONTROL

3.1 ATM Traffic Contract and Control Algorithms / 62

3.1.1 Traffic Contract / 62

3.1.2 PCR Conformance, SCR, and BT / 63

3.1.3 Cell Delay Variation Tolerance / 63

3.1.4 Generic Cell Rate Algorithm / 64

3.2 An ATM Shaping Multiplexer / 66

3.2.1 Regularity Condition Dual Leaky Bucket / 67

3.2.2 ATM Shaping Multiplexer Algorithm / 70

3.2.3 Implementation Architecture / 77

3.2.4 Finite Bits Overflow Problem / 79

3.2.5 Simulation Study / 86

3.2.6 Summary / 89

3.3 An Integrated Packet Shaper / 90

3.3.1 Basics of a Packet Traffic Shaper / 90

3.3.2 Integrating Traffic Shaping and WFI Scheduling / 95

3.3.3 A Logical Structure of the WFI Packet Shaper / 96

3.3.4 Implementation of the WFI Packet Shaper／97

3.4 Appendix: Bucket Size Determination／103

References／107

4 PACKET SCHEDULING

4.1 Overview / 109

4.2 First In, First Out / 111

4.3 Round-Robin / 147 / 112

4.4 Stop-and-Go / 113

4.5 Hierarchical Round-Robin / 115

4.6 Earliest Due Date / 116

4.7 Rate-Controlled Static Priority / 117

4.8 Generalized Processor Sharing / 119

4.9 Weighted Fair Queuing / 123

4.10 Virtual Clock / 127

4.11 Self-Clocked Fair Queuing / 130

4.12 Worst-case Fair Weighted Fair Queuing / 132

4.13 WF2Q+ / 136

4.14 Multiple-Node Case / 137

4.15 Comparison / 139

4.16 A Core-Stateless Scheduling Algorithm / 140

4.16.1 Shaped Virtual Clock Algorithm / 141

4.16.2 Core-Stateless Shaped Virtual Clock Algorithm / 142

4.16.3 Encoding Process / 147

4.16.4 Complexity / 150

References / 150

5 PACKET FAIR QUEUING IMPLEMENTATIONS

5.1 Conceptual Framework and Design Issues / 154

5.2 Sequencer / 156

5.2.1 Store Cells in Logical Queues / 157

5.2.2 Sort Priorities Using a Sequencer / 158

5.3 Priority Content-Addressable Memory / 163

5.3.1 Searching by the PCAM Chip / 163

5.3.2 Block Diagram / 165

5.3.3 Connecting Multiple PCAM Chips / 168

5.4 RAM-Based Searching Engine / 168

5.4.1 Hierarchical Searching / 169

5.4.2 Timestamp Overflow / 172

5.4.3 Design of the RSE / 173

5.4.4 RSE Operations / 173

5.4.5 Write-in Operation / 175

5.4.6 Reset Operation / 176

5.4.7 Search Operation / 177

5.5 General Shaper-Scheduler / 179

5.5.1 Slotted Updates of System Virtual Time / 180

5.5.2 Implementation Architecture / 182

5.6 Timestamp Aging Problem / 188

5.7 Summary / 192

References / 193

6 BUFFER MANAGEMENT

6.1 A Look at ATM Networks / 197

6.1.1 Overview / 198

6.1.2 Self-Calibrating Pushout / 201

6.1.3 TCP/IP over ATM-UBR / 209

6.1.4 Dynamic Threshold with Single Loss Priority / 212

6.2 A Look at the Internet / 213

6.2.1 Tail Drop / 214

6.2.2 Drop on Full / 214

6.2.3 Random Early Detection / 215

6.2.4 Differential Dropping: RIO / 220

6.2.5 Fair Random Early Detection (FRED) / 223

6.2.6 Stabilized Random Early Detection (SRED) / 224

6.2.7 Longest Queue Drop (LQD) / 226

6.3 Summary / 231

References / 232

7 FLOW AND CONGESTION CONTROL

7.1 Overview / 235

7.1.1 Window-Based Flow Control / 236

7.1.2 Rate-Based Flow Control / 238

7.1.3 Predictive Control Mechanism / 239

7.2 ATM Networks / 240

7.2.1 ATM Service Categories / 240

7.2.2 Backlog Balancing Flow Control / 242

7.2.3 ABR Flow Control / 267

7.3 TCP/IP Networks / 276

7.3.1 TCP Overview / 277

7.3.2 TCP Congestion Control / 281

7.3.3 Other TCP Variants / 286

7.3.4 TCP with Explicit Congestion Notification / 289

7.4 EASY Another Rate-Based Flow Control Scheme / 291

References / 292

8 QoS ROUTING

8.1 ATM Signaling and Routing / 300

8.1.1 User-to-Network (UNI) Signaling / 301

8.1.2 PNNI Signaling / 306

8.2 QoS Routing for Integrated Services Networks / 316

8.2.1 Selection of Metrics / 316

8.2.2 Weighted Graph Model / 318

8.2.3 Path Selection Algorithms / 319

8.2.4 Computational Complexity / 325

8.2.5 Further Reading / 326

References / 326

9 DIFFERENTIATED SERVICES

9.1 Service Level Agreement and Traffic Conditioning Agreement / 330

9.1.1 Service Level Agreement / 330

9.1.2 Traffic Conditioning Agreement / 331

9.2 Basic Architecture of Differentiated Services / 332

9.3 Network Boundary Traffic Classification and

Conditioning / 334

9.4 Per-Hop Behaviors and Some Implementation

Examples / 335

9.4.1 Default Behavior / 336

9.4.2 Class Selector / 336

9.4.3 Assured Forwarding / 337

9.4.4 Expedited Forwarding / 338

9.4.5 PHB Implementation with Packet Schedulers / 338

9.5 Conceptual Model / 340

9.5.1 Configuration and Management Interface / 341

9.5.2 Optional QoS Agent Module / 341

9.5.3 Diffserv Functions at Ingress and Egress Interfaces / 341

9.5.4 Shaping and Policing / 341

9.5.5 Traffic Classification / 342

9.5.6 Meters / 342

9.5.7 Action Elements / 342

9.5.8 Queuing Elements / 343

9.5.9 Traffic Conditioning Blocks / 344

References / 344

10 MULTIPROTOCOL LABEL SWITCHING

10.1 Basic Architecture / 349

10.1.1 Label and Label Binding / 349

10.1.2 Label Stack / 250

10.1.3 Route Selection / 352

10.1.4 Penultimate Hop Popping / 352

10.1.5 LSP Tunnels / 353

10.1.6 An Example: Hierarchy of LSP Tunnels / 354

10.1.7 Next-Hop Label Forwarding Entry / 355

10.2 Label Distribution / 356

10.2.1 Unsolicited Downstream vs. Downstream-on-Demand / 356

10.2.2 Label Retention Mode: Liberal vs. Conservative / 357

10.2.3 LSP Control: Ordered vs. Independent / 357

10.2.4 Label Distribution Peering and Hierarchy / 358

10.2.5 Selection of Label Distribution Protocol / 359

10.3 MPLS Support of Differentiated Services / 360

10.4 Label-Forwarding Model for Diffserv LSRs / 363

10.4.1 Incoming PHB Determination / 363

10.4.2 Outgoing PHB Determination with Optimal Traffic Conditioning / 363

10.4.3 Label Forwarding / 364

10.4.4 Encoding Diffserv Information Into Encapsulation Layer / 365

10.5 Applications of Multiprotocol Label Switching / 365

10.5.1 Traffic Engineering / 365

10.5.2 Virtual Private Networks / 370

References / 375

APPENDIX SONET AND ATM PROTOCOLS

A.1 ATM Protocol Reference Model / 379

A.2 Synchronous Optical Network (SONET) / 380

A.2.1 SONET Sublayers / 380

A.2.2 STS-N Signals / 382

A.2.3 SONET Overhead Bytes / 385

A.2.4 Scrambling and Descrambling / 387

A.2.5 Frequency Justification / 388

A.2.6 Automatic Protection Switching (APS) / 389

A.2.7 STS-3 vs. STS-3c / 391

A.2.8 OC-N Multiplexor / 392

A.3 Sublayer Functions in the Reference Model / 393

A.4 Asynchronous Transfer Mode / 395

A.4.1 Virtual Path and Virtual Channel Identifier / 396

A.4.2 Payload Type Identifier / 397

A.4.3 Cell Loss Priority / 398

A.4.4 Predefined Header Field Values / 398

A.5 ATM Adaptation Layer / 399

A.5.1 AAL Type I(AAL1) / 401

A.5.2 AAL Type 2 (AAL2) / 403

A.5.3 AAL Types 3 and 4 (AAL3/4) / 404

A.5.4 AAL Type 5 (AAL5) / 406

References / 408

INDEX