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Contents
Introduction xvi
Part I Fundamental QoS Concepts 3
Chapter 1 Quality of Service: An Overview 5
Understanding QoS 5
Definition of QoS 5
Managed Unfairness 6
Predictability: The Goal of QoS 7
Congestion Management 9
Deploying QoS in the WAN/LAN: High-Level Overview 9
Why QoS Is Necessary in the WAN 10
Why QoS Is Necessary in a Switched Environment 10
Cisco AVVID 11
QoS in the AVVID Environment 12
Overview of Integrated and Differentiated Services 13
Integrated Services Versus Differentiated Services 13
Definition of Integrated Services 14
Definition of DiffServ 16
Differentiated Services: A Standards Approach 20
RFC 2475: Terminology and Concepts 21
RFC 2474: Terminology and Concepts 21
Assured Forwarding Versus Expedited Forwarding 23
Summary 28
Chapter 2 End-to-End QoS: Quality of Service at Layer 3 and Layer 2 31
QoS Components 31
Congestion Management 32
Congestion Management Mechanisms 33
Scheduling 35
Congestion Avoidance 35
Random Early Detection (RED) 36
Token Bucket Mechanism 41
Traffic Shaping 44
Policing 44
QoS Signaling 46
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Link Efficiency 47
Link Fragmentation and Interleaving (LFI) 48
Real Time Protocol Header Compression (cRTP) 50
Classification and Marking at Layer 3 51
IP Precedence and the Type of Service Byte 51
The Differentiated Services Field (DS Field) 52
Per-Hop Behaviors 53
RFC 2597: The Assured Forwarding PHB 54
RFC 2598: The Expedited Forwarding PHB 56
Classification and Marking at Layer 2 58
Mapping Layer 2 to Layer 3 Values 58
A General View of QoS on the Catalyst Platforms 59
Catalyst QoS Classification 60
Catalyst QoS Marking 60
Catalyst QoS Policing 60
Catalyst QoS Congestion Management 61
Congestion Avoidance 61
Cisco Catalyst QoS Trust Concept 61
The Cisco IP Phone 62
Voice VLANs and Extended Trust 63
Summary 65
Chapter 3 Overview of QoS Support on Catalyst Platforms and Exploring
QoS on the Catalyst 2900XL, 3500XL, and Catalyst 4000
CatOS Family of Switches 67
Catalyst Feature Overview 68
Input Scheduling 69
Classification and Marking 70
Policing 71
Congestion Management 72
Material Presentation for Catalyst Switching Platforms 73
QoS Support on the Catalyst 2900XL and 3500XL 74
Catalyst 2900XL Product Family Delineation 75
Catalyst 2900XL and 3500XL QoS Architectural Overview 75
Software Requirements 76
Input Scheduling 76
Classification/Reclassification 77
Congestion Management 79
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Case Study: Classification and Output Scheduling on Cisco Catalyst 3500XL Switches 79
Summary 81
QoS Support on the Catalyst 4000 CatOS Family of Switches 82
Catalyst 4000 Product Family Delineation 82
Catalyst 4000 CatOS Family of Switches QoS Architectural Overview 83
Software Requirements 83
Input Scheduling 84
Classification, Marking, and Trusting 86
Congestion Management 87
Case Study: Output Scheduling on the Catalyst 4000 Series Switches 89
Summary 91
Chapter 4 QoS Support on the Catalyst 5000 Family of Switches 95
Catalyst 5000 Family of Switches QoS Architectural Overview 95
Software Requirements 97
Hardware Requirements 97
Enabling QoS Features on the Catalyst 5000 Family of Switches 100
Input Scheduling 100
Classification and Marking 104
Classification and Marking of Untagged Frames Based on Ingress Port 104
Classification of Tagged Frames Based on Ingress Port 104
Classification and Marking Based on Destination VLAN and MAC 105
Classification and Marking Based on ACE 106
Extended Trust Option 112
Congestion Avoidance 113
Case Study 116
Summary 118
Part II Advanced QoS Concepts 121
Chapter 5 Introduction to the Modular QoS Command-Line Interface 123
MQC Background, Terms, and Concepts 123
Step 1: The Class Map 124
Configuring the Class Map 124
Class Map Options: A Closer Look 126
Class Map Configuration Example 131
Step 2: The Policy Map 132
Configuring the Policy Map 133
Policy Map Options: A Closer Look 134
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Policy Map Configuration Example 135
Step 3: Attaching the Service Policy 137
Summary 140
Chapter 6 QoS Features Available on the Catalyst 2950 and 3550 Family of Switches 143
Catalyst 2950 and Catalyst 3550 Family of Switches QoS Architectural Overview 144
Software Requirements 147
Input Scheduling 149
Classification and Marking 150
Internal DSCP and Mapping Tables 150
Ingress Port CoS Configuration 152
Trust DSCP 154
Trust IP Precedence 155
Voice VLANs and Extended Trust 156
Trust Cisco IP Phone Device 156
Classifying Traffic by Using ACLs 157
Classification Passthrough Option 159
Ingress DSCP Mutation 160
Policing 162
Policing Resources and Guidelines 163
Class Maps and Policy Maps 163
Ingress and Egress Policing 164
Individual and Aggregate Policing 166
Port-Based, VLAN-Based, and Per-Port Per-VLAN-Based Policing 168
Policing Actions 169
Congestion Management and Avoidance 175
Congestion Management with the Catalyst 2950 and 3550 Family of Switches 176
Congestion Avoidance with the 3550 Family of Switches 181
Transmit Queue Size 185
Auto-QoS 187
Auto-QoS Classification 187
Auto-QoS Congestion Management 188
Case Study 191
Summary 196
Chapter 7 QoS Features Available on the Catalyst 4000 IOS Family of Switches and the
Catalyst G-L3 Family of Switches 199
QoS Support on the Catalyst 4000 IOS Family of Switches 200
Catalyst 4000 IOS Family of Switches QoS Architectural Overview 201
Software Requirements 202
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Global Configuration 205
Input Scheduling 205
Internal DSCP 206
Classification and Marking 206
ACL-Based Classification 211
Policing 214
Congestion Management 224
Auto-QoS 233
Case Study 233
QoS Support on the Catalyst 2948G-L3, 4908G-L3, and Catalyst 4000 Layer 3 Services
Module 238
Catalyst 2948G-L3, 4908G-L3, and 4232-L3 Services Module QoS Architectural
Overview 239
The WS-X4232-L3 Services Module Architecture 239
Software Requirements 240
Global Configuration 240
Classification 241
Output Scheduling 241
Per-Port Traffic Shaping 243
Rate Limiting 244
Case Study 245
Summary 247
Chapter 8 QoS Support on the Catalyst 6500 249
Catalyst 6500 Architectural Overview 250
Software and Hardware Requirements 253
Identifying the Catalyst Software 255
Enabling QoS on the Switch 257
Input Scheduling 257
Configuring Receive Queue Tail-Drop Thresholds 262
Mapping CoS to Queues and Drop Thresholds 263
Input Scheduling and Congestion Avoidance for 1p1q0t and 1p1q8t 265
Configuring the Receive Queue Size Ratio 268
Classification and Marking 269
Port-Based Versus VLAN-Based QoS 269
Classification Based on Destination MAC Address and VLAN 271
Trust 271
Classification and Marking Using ACLs and ACEs 276
Mapping 290
CoS-to-DSCP Mapping 291
Precedence-to-DSCP Mapping 293
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