IP Quality of Service

Srinivas Vegesna1578701163, 9781578701162

This design guide, for anyone planning to deploy quality of service (QoS) in Cisco networks, provides complete coverage of Cisco IP QoS features and functions and offers case studies and configuration examples. Emphasis is on real-world applications. Chapters are in sections on IP QoS, internetworking with IP QoS, and traffic engineering. Appendices cover the Cisco modular QoS command-line interface, packet switching mechanisms, routing policies, RTP, and link-layer fragmentation and interleaving. Material is written for internetworking professionals who are responsible for designing and maintaining IP services for corporate intranets and for service provider network infrastructures

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Table of contents :
Trademark Acknowledgments……Page 2
Packet Classification……Page 27
DSCP……Page 28
Case Study 3-1: Packet Classification and Marking Using IP Precedence……Page 29
IP Precedence Using CAR……Page 30
Case Study 3-2: Packet Classification and Marking Using QoS Groups……Page 31
Case Study 3-3: Enforcing IP Precedence Setting……Page 32
The Need for Traffic Rate Management……Page 33
Traffic Policing……Page 34
The Traffic Matching Specification……Page 35
The Traffic Measurement Instrumentation……Page 36
The Action Policy……Page 38
Case Study 3-4: Limiting a Particular Application’s Traffic Rate at a Service Level……Page 39
Case Study 3-5: Limiting Traffic Based on IP Precedence Values……Page 40
Case Study 3-8: Preventing Denial-of-Service Attacks……Page 41
Case Study 3-9: Enforcing Public Exchange Point Traffic……Page 42
Traffic Measuring Instrumentation……Page 43
Case Study 3-10: Shaping Traffic to the Access Rate……Page 44
Shaping Traffic Using GTS……Page 45
Shaping Traffic Using DTS……Page 46
Shaping Incoming and Outgoing Traffic of a Host Through GTS……Page 47
Case Study 3-12: Shaping Frame Relay Traffic on Receipt of BECNs……Page 48
Shaping Frame Relay Traffic Through DTS……Page 49
Frequently Asked Questions……Page 50
References……Page 51
Scheduling for Quality of Service (QoS) Support……Page 52
The Max-Min Fair-Share Allocation Scheme……Page 53
Sequence Number Computation-Based WFQ……Page 55
Flow-Based WFQ……Page 58
WFQ Implementation……Page 61
Case Study 4-1: Flow-Based WFQ……Page 62
Case Study 4-3: WFQ Scheduling Among Voice and FTP Flow Packets……Page 63
Case Study 4-4: Flow-Based DWFQ……Page 64
Case Study 4-5: Higher Bandwidth Allocation for Critical Traffic……Page 65
Case Study 4-6: Higher Bandwidth Allocation Based on Input Interface……Page 66
Case Study 4-7: Bandwidth Assignment per ToS Class……Page 67
ToS-Based DWFQ……Page 68
Case Study 4-8: Bandwidth Allocation Based on the QoS Group Classification Without Using Modular QoS CLI……Page 69
Case Study 4-9: IP Traffic Prioritization Based on IP Precedence……Page 70
Case Study 4-11: Packet Prioritization Based on Source Address……Page 71
Case Study 4-12: Minimum Interface Bandwidth for Different Protocols……Page 72
Scheduling Mechanisms for Voice Traffic……Page 74
Case Study 4-13: Strict Priority Queue for Voice……Page 75
Frequently Asked Questions……Page 76
References……Page 77
An Illustration of MWRR Operation……Page 78
MWRR Implementation……Page 86
Case Study 5-1: Class-Based MWRR Scheduling……Page 87
Modified Deficit Round Robin (MDRR)……Page 88
An MDRR Example……Page 89
MDRR on the RX……Page 94
Case Study 5-2: Bandwidth Allocation and Minimum Jitter Configuration for Voice Traffic with Congestion Avoidance Policy……Page 95
References……Page 97
TCP Slow Start and Congestion Avoidance……Page 98
TCP Traffic Behavior in a Tail-Drop Scenario……Page 99
RED—Proactive Queue Management for Congestion Avo……Page 100
Packet Drop Probability……Page 101
WRED Implementation……Page 102
Case Study 6-1: Congestion Avoidance to Enhance Link Utilization by Using WRED……Page 103
Case 6-2: WRED Based on Traffic Classes Using Modular QoS CLI……Page 104
Flow WRED……Page 105
Case Study 6-3: Congestion Avoidance for Nonadaptive Flows……Page 106
SPD……Page 107
Case Study 6-4: Preventing Bad IP Packet Smurf Attacks by Using SPD……Page 109
Frequently Asked Questions……Page 111
References……Page 112
RSVP Operation……Page 113
RSVP Messages……Page 115
Distinct Reservations……Page 116
Shared Reservations……Page 117
Service Types……Page 118
RSVP Media Support……Page 119
Case Study 7-1: Reserving End-to-End Bandwidth for an Application Using RSVP……Page 120
Case Study 7-2: RSVP for VoIP……Page 124
Frequently Asked Questions……Page 125
References……Page 126
ATM Cell Format……Page 127
ATM QoS……Page 129
ATM Service Classes……Page 130
VP Shaping……Page 131
Case Study 8-2: VP Traffic Shaping……Page 132
ATM Interworking with IP QoS……Page 134
Case Study 8-3: Differentiated IP Packet Discards at ATM Edges……Page 137
Case Study 8-4: Differentiated Services……Page 139
Frame Relay……Page 140
Frame Relay Congestion Control……Page 141
VC Traffic Shaping……Page 142
FECN/BECN Integration……Page 143
Frame Relay Fragmentation……Page 144
Case Study 8-6: Frame Relay Traffic Shaping with QoS Autosense……Page 145
Case Study 8-7: Adaptive Traffic Shaping and BECN/FECN Integration……Page 146
Case Study 8-8: Using Multiple PVCs to a Destination Based on Traffic Type……Page 148
Case 8-11: Frame Relay Fragmentation……Page 150
The IEEE 802.3 Family of LANs……Page 151
Expedited Traffic Capability……Page 152
Initialization……Page 154
RSVP Extensions……Page 155
Frequently Asked Questions……Page 156
References……Page 157
Forwarding Component……Page 158
Control Component……Page 159
Downstream Label Allocation……Page 160
Upstream Label Allocation……Page 161
Label Encapsulation……Page 162
Case Study 9-1: Downstream Label Distribution……Page 164
MPLS QoS……Page 167
Case Study 9-2: MPLS CoS……Page 168
LER……Page 169
MPLS VPN……Page 170
Case Study 9-3: MPLS VPN……Page 171
MPLS VPN QoS……Page 176
Differentiated MPLS VPN QoS……Page 177
Guaranteed QoS……Page 178
End-to-End Guaranteed Bandwidth……Page 179
Frequently Asked Questions……Page 180
Part III: Traffic Engineering……Page 181
The Layer 2 Overlay Model……Page 182
RRR……Page 183
TE Trunk Definition……Page 185
Resource Class Affinity……Page 186
Distribution of Link Resource Information……Page 187
TE Tunnel Setup……Page 188
TE-RSVP……Page 189
OSPF Modifications……Page 190
Case Study 10-1: MPLS TE Tunnel Setup and Operation……Page 191
Summary……Page 201
Frequently Asked Questions……Page 202
References……Page 203
Appendix A. Cisco Modular QoS Command-Line Interface……Page 204
Traffic Class Definition……Page 205
Policy Definition……Page 206
Hierarchical Policies……Page 207
Intra-Feature Execution Order……Page 208
Route-Cache Forwarding……Page 210
CEF Advantages……Page 211
Distributed CEF (DCEF)……Page 212
Case Study B-1: Deploying CEF in a Backbone Router……Page 213
Summary……Page 218
Policy-Based Routing……Page 219
Case Study C-1: Routing Based on IP Precedence……Page 220
Case Study C-2: Routing Based on Packet Size……Page 221
QoS Policy Propagation Using BGP……Page 222
Case Study C-3: QoS for Incoming and Outgoing Traffic……Page 223
Summary……Page 225
References……Page 226
The Nagle Algorithm……Page 227
References……Page 228
Appendix F. Link-Layer Fragmentation and Interleaving……Page 229
References……Page 230
Appendix G. IP Precedence and DSCP Values……Page 231