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
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