Cisco DQOS exam certification guide: IP telephony self-study

Wendell Odom, Michael Cavanaugh1587200589, 9781587200588

Prepare of the IP Telephony Focused Certifications with the official DQOS/QOS test preparation guide. * Master over 20 Quality of Service (QoS) features, including both MQC-enabled and non-MQC features * QoS feature comparisons show differences, benefits and similarities, helping the reader identify the optimal QoS array for their network * Use as a reference to QoS technologies, and prepare for the DQOS exam with the only Cisco authorized exam preparation bookQuality of Service (QoS) is an essential element to building a flexible, accessible, and efficient network. Its role in multiple technologies underlines the need for most networking professionals to master the features that implement QoS. QoS, and specifically the QoS features that an IT professional implements on different technologies, helps prioritize and guide traffic flows in a manner that maximizes the client experience. This prioritization is just one element of QoS, and numerous features can be used to determine this flow. As more complex technologies like Voice over IP are implemented on networks, QoS will become more vital. This is especially true when these technologies increase the number of those accessing and using the network.

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Table of contents :
“Do I Know This Already?” Quiz……Page 40
QoS: Tuning Bandwidth, Delay, Jitter, and Loss Questions……Page 41
Traffic Characteristics of Voice, Video, and Data Questions……Page 42
Foundation Topics……Page 43
QoS: Tuning Bandwidth, Delay, Jitter, and Loss……Page 44
Bandwidth……Page 46
QoS Tools That Affect Bandwidth……Page 48
Delay……Page 50
Serialization Delay……Page 51
Propagation Delay……Page 53
Queuing Delay……Page 55
Shaping Delay……Page 57
Network Delay……Page 59
Delay Summary……Page 60
QoS Tools That Affect Delay……Page 61
Jitter……Page 64
QoS Tools That Affect Jitter……Page 65
QoS Tools That Affect Loss……Page 66
Traffic Characteristics of Voice, Video, and Data……Page 69
Voice Basics……Page 70
Voice Bandwidth Considerations……Page 73
Voice Delay Considerations……Page 76
Voice Jitter Considerations……Page 85
Voice Loss Considerations……Page 86
Video Basics……Page 89
Video Bandwidth Considerations……Page 91
Video Delay Considerations……Page 92
Video Jitter Considerations……Page 93
Data Traffic Characteristics……Page 94
IP Data Basics……Page 95
Data Bandwidth Considerations……Page 100
Data Jitter Considerations……Page 101
Data Loss Considerations……Page 102
Comparing Voice, Video, and Data: Summary……Page 103
Foundation Summary……Page 104
Q&A……Page 116
“Do I Know This Already?” Quiz……Page 120
QoS Tools Questions……Page 121
Integrated Services Questions……Page 122
Classification and Marking……Page 123
Classification and Marking Tools……Page 126
Queuing……Page 127
Queuing Tools……Page 128
Shaping and Policing……Page 130
Shaping and Policing Tools……Page 132
Congestion Avoidance……Page 133
Link Efficiency……Page 134
Link-Efficiency Tools: Summary……Page 136
Call Admission Control and RSVP……Page 137
CAC Tools……Page 138
Management Tools……Page 139
Summary……Page 140
The Good-Old Common Sense QoS Model……Page 141
GOCS Flow-Based QoS……Page 142
GOCS Class-Based QoS……Page 145
Classification and Marking at the Edge……Page 146
DiffServ Specifications and Terminology……Page 151
DiffServ Per-Hop Behaviors……Page 156
The Class Selector PHB and DSCP Values……Page 158
The Assured Forwarding PHB and DSCP Values……Page 162
The Expedited Forwarding PHB and DSCP Values……Page 165
DiffServ Classifiers and Traffic Conditioners……Page 166
The Integrated Services QoS Model……Page 170
Foundation Summary……Page 174
Q&A……Page 189
“Do I Know This Already?” Quiz Questions……Page 192
Classification and Marking Concepts Questions……Page 193
CAR, PBR, and CB Marking Questions……Page 194
Classification……Page 195
Marking……Page 199
IP Header QoS Fields: Precedence and DSCP……Page 200
LAN Class of Service (CoS)……Page 203
Summary of Marking Fields……Page 205
Classification and Marking Design Choices……Page 207
Class-Based Marking (CB Marking)……Page 212
Network-Based Application Recognition (NBAR)……Page 222
CB Marking show Commands……Page 226
Committed Access Rate (CAR)……Page 230
CAR Marking Summary……Page 237
Policy-Based Routing (PBR)……Page 238
VoIP Dial Peer……Page 244
Summary of Classification and Marking QoS Features……Page 251
Foundation Summary……Page 254
Q&A……Page 266
“Do I Know This Already?” Quiz……Page 270
WFQ and IP RTP Priority Questions……Page 271
Comparing Queuing Options Questions……Page 272
Queuing Concepts……Page 273
Output Queues, TX Rings, and TX Queues……Page 276
Queuing on Interfaces Versus Subinterfaces and Virtual Circuits (VCs)……Page 282
Queuing Tools……Page 285
FIFO Queuing……Page 286
Priority Queuing……Page 288
Custom Queuing……Page 291
Weighted Fair Queuing (WFQ)……Page 294
WFQ Classification……Page 295
WFQ Scheduler: The Net Effect……Page 296
WFQ Scheduling: The Process……Page 297
WFQ Drop Policy, Number of Queues, and Queue Lengths……Page 301
WFQ Configuration……Page 303
WFQ Summary……Page 308
Class-Based WFQ (CBWFQ)……Page 309
CBWFQ Configuration……Page 312
CBWFQ Summary……Page 324
Low Latency Queuing (LLQ)……Page 325
LLQ Configuration……Page 327
LLQ with More Than One Priority Queue……Page 332
IP RTP Priority……Page 333
IP RTP Priority Configuration……Page 334
Summary of Queuing Tool Features……Page 336
Foundation Summary……Page 338
Priority Queuing and Custom Queuing……Page 350
CBWFQ, LLQ, IP RTP Priority……Page 351
Comparing Queuing Tool Options……Page 353
“Do I Know This Already?” Quiz……Page 356
Policing with CAR and CB Policer Questions……Page 357
Shaping with FRTS, GTS, DTS, and CB Shaping……Page 358
Traffic-Policing and Traffic-Shaping Concepts……Page 359
When and Where to Use Shaping and Policing……Page 360
Policing—When and Where?……Page 361
Traffic Shaping—When and Where?……Page 364
How Shaping Works……Page 367
Traffic Shaping, Excess Burst, and Token Buckets……Page 372
Traffic-Shaping Adaption……Page 374
Where to Shape: Interfaces, Subinterfaces, and VCs……Page 375
Queuing and Traffic Shaping……Page 377
CAR Internals……Page 380
CB Policing Internals……Page 385
Policing, but Not Discarding……Page 387
Generic Traffic-Shaping Configuration……Page 388
Class-Based Shaping Configuration……Page 394
Distributed Traffic Shaping (DTS) Configuration……Page 406
Frame Relay Traffic Shaping (FRTS) Configuration……Page 407
Traffic-Policing Tools……Page 425
Class-Based Policing Configuration……Page 427
Committed Access Rate (CAR) Configuration……Page 435
Foundation Summary……Page 442
Shaping and Policing Concepts……Page 458
Traffic Shaping……Page 459
Traffic-Policing Tools……Page 460
“Do I Know This Already?” Quiz……Page 462
WRED Questions……Page 463
FRED Questions……Page 464
TCP and UDP Reactions to Packet Loss……Page 465
Tail Drop, Global Synchronization, and TCP Starvation……Page 469
Random Early Detection (RED)……Page 471
How WRED Weights Packets……Page 474
WRED and Queuing……Page 478
WRED Configuration……Page 480
WRED Summary……Page 492
Flow-Based WRED (FRED)……Page 493
FRED Configuration……Page 496
Foundation Summary……Page 503
Congestion-Avoidance Concepts and Random Early Detection (RED)……Page 512
Flow-Based WRED (FRED)……Page 513
Link-Efficiency Tools……Page 516
Compression Questions……Page 517
Link Fragmentation and Interleave Questions……Page 518
Payload and Header Compression……Page 519
Payload Compression……Page 521
Header Compression……Page 522
Payload Compression Configuration……Page 523
TCP and RTP Header Compression Configuration……Page 527
Link Fragmentation and Interleaving……Page 531
Multilink PPP LFI……Page 534
Maximum Serialization Delay and Optimum Fragment Sizes……Page 535
Frame Relay LFI Using FRF.12……Page 536
Choosing Fragment Sizes for Frame Relay……Page 540
Fragmentation with More Than One VC on a Single Access Link……Page 541
Multilink PPP Interleaving Configuration……Page 543
Frame Relay Fragmentation Configuration……Page 552
FRF.11-C and FRF.12 Comparison……Page 562
Foundation Summary……Page 565
Compression Tools……Page 573
LFI Tools……Page 574
Call Admission Controland QoSSignaling……Page 578
“Do I Know This Already?” Quiz……Page 579
Call Admission Control Overview……Page 581
Call Rerouting Alternatives……Page 582
Bandwidth Engineering……Page 583
CAC Mechanisms……Page 589
CAC Mechanism Evaluation Criteria……Page 590
Physical DS0 Limitation……Page 591
Max-Connections……Page 593
Voice over Frame Relay—Voice Bandwidth……Page 600
Trunk Conditioning……Page 603
Local Voice Busyout……Page 606
Measurement-Based Voice CAC……Page 608
SAA Service……Page 609
Advanced Voice Busyout……Page 610
PSTN Fallback……Page 612
IP Destination Caching……Page 613
PSTN Fallback Configuration……Page 615
PSTN Fallback Scalability……Page 618
PSTN Fallback Summary……Page 619
Resource-Based CAC……Page 621
Gateway Calculation of Resources……Page 622
RAI in Service Provider Networks……Page 623
RAI in Enterprise Networks……Page 625
RAI Configuration……Page 626
RAI Platform Support……Page 627
Location-Based CAC Operation……Page 628
Locations and Regions……Page 629
Calculation of Resources……Page 631
Location-Based CAC Summary……Page 632
Single-Zone Topology……Page 633
Multizone Topology……Page 634
Gatekeeper in CallManager Networks……Page 638
Zone Bandwidth Calculation……Page 639
Zone Bandwidth Configuration……Page 641
Gatekeeper Zone Bandwidth Summary……Page 642
Integrated Services / Resource Reservation Protocol……Page 643
RSVP Levels of Service……Page 644
RSVP Operation……Page 645
RSVP/H.323 Synchronization……Page 648
RSVP Synchronization Configuration……Page 649
Classification for Voice Packets into LLQ……Page 652
Bandwidth per Codec……Page 653
Subnet Bandwidth Management……Page 654
RSVP Configuration……Page 655
Monitoring and Troubleshooting RSVP……Page 658
RSVP CAC Summary……Page 661
Foundation Summary……Page 663
Local-Based CAC……Page 691
Resources-Based CAC……Page 692
“Do I Know This Already?” Quiz……Page 694
QoS Management Tools Questions……Page 695
QoS Design Questions……Page 696
QoS Device Manager……Page 697
QoS Policy Manager……Page 699
Service Assurance Agent……Page 701
Service Management Solution……Page 703
QoS Design for the Cisco QoS Exams……Page 705
Four-Step QoS Design Process……Page 706
Step 2: Characterize the Network……Page 707
Step 3: Implement the Policy……Page 708
Step 4: Monitor the Network……Page 709
Voice and Video: Bandwidth, Delay, Jitter, and Loss Requirements……Page 710
Voice and Video QoS Design Recommendations……Page 713
Foundation Summary……Page 716
QoS Management……Page 721
QoS Design……Page 722
“Do I Know This Already?” Quiz……Page 724
Buffer Overflow (Overrun)……Page 727
Marking and Classification……Page 728
Layer 3-to-Layer 2 Classification Mapping……Page 730
Layer 2 Queues……Page 731
Drop Thresholds……Page 732
Trust Boundries……Page 733
Supervisor and Switching Engine……Page 735
Policy Feature Card……Page 738
Ethernet Interfaces……Page 739
QoS Flow on the Catalyst 6500……Page 743
Ingress Queue Scheduling……Page 744
Layer 2 Switching Engine QoS Frame Flow……Page 746
Egress Queue Scheduling……Page 747
Catalyst 6500 QoS Summary……Page 750
Cisco Catalyst 4500/4000 QoS Features……Page 754
Supervisor Engine I and II……Page 755
Supervisor Engine III and IV……Page 756
Cisco Catalyst 3550 QoS Features……Page 758
Cisco Catalyst 3524 QoS Features……Page 759
QoS Configurations on Catalyst Switches……Page 760
Configuration of a Catalyst Switch Using Catalyst OS……Page 761
Configuring QoS for the Catalyst OS Switch……Page 762
CoS-to-Egress Queue Mapping for the Catalyst OS Switch……Page 763
Layer-2-to-Layer 3 Mapping……Page 764
Configuring Trust Boundaries for a Catalyst OS Switch……Page 765
Configuring Untagged Frames for the Catalyst OS Switch……Page 766
Configuring QoS Access Lists in the Catalyst OS Switch……Page 767
Connecting a Catalyst OS Switch to WAN Segments……Page 768
Displaying QoS Settings for the Catalyst OS Switch……Page 769
Configuration of a Catalyst Switch Using IOS……Page 773
Enabling QoS for the Catalyst IOS Switch……Page 774
CoS-to-Egress Queue Mapping for the Catalyst IOS Switch……Page 775
Layer 2-to-Layer 3 Mapping……Page 776
Configuring Trust Boundaries for a Catalyst IOS Switch……Page 777
Configuring QoS Access Lists in the Catalyst IOS Switch……Page 778
Displaying QoS Settings for the Catalyst IOS Switch……Page 780
Foundation Summary……Page 784
Catalyst 6500 Series of Switches……Page 797
Catalyst 3550/3524 Series of Switches……Page 798
Appendix B……Page 0
QoS: Tuning Bandwidth, Delay, Jitter, and Loss……Page 800
Traffic Characteristics of Voice, Video, and Data……Page 801
QoS Tools……Page 807
Differentiated Services……Page 808
Integrated Services……Page 809
Classification and Marking Concepts……Page 814
CAR, PBR, and CB Marking……Page 815
Queuing Concepts……Page 821
CBWFQ and LLQ……Page 822
Comparing Queuing Options……Page 823
Conceptual Questions……Page 824
Priority Queuing and Custom Queuing……Page 825
WFQ……Page 826
CBWFQ, LLQ, IP RTP Priority……Page 827
Comparing Queuing Tool Options……Page 829
Shaping and Policing Concepts……Page 831
Shaping with FRTS, GTS, DTS, and CB Shaping……Page 832
Shaping and Policing Concepts……Page 833
Traffic Shaping……Page 835
Traffic-Policing Tools……Page 837
WRED……Page 838
FRED……Page 839
Congestion-Avoidance Concepts and Random Early Detection (RED)……Page 840
Weighted RED (WRED)……Page 841
Flow-Based WRED (FRED)……Page 843
Compression……Page 844
Link Fragmentation and Interleave……Page 845
Compression Tools……Page 846
LFI Tools……Page 848
Call Admission Control Concepts……Page 852
Local-Based CAC……Page 853
Measurement-Based CAC……Page 854
Resources-Based CAC……Page 855
QoS Design……Page 856
QoS Management……Page 857
QoS Design……Page 859
LAN QoS Concepts……Page 862
Catalyst 6500 Series of Switches……Page 863
Catalyst 4500/4000 Series of Switches……Page 864
Catalyst 3550/3524 Series of Switches……Page 865
Foundation Topics……Page 869
QPPB Route Marking: Step 1……Page 874
QPPB Per-Packet Marking: Step 2……Page 875
QPPB Sample Configuration……Page 877
QPPB: The Hidden Details……Page 879
QPPB Summary……Page 881
Flow-Based dWFQ……Page 899
ToS-Based dWFQ……Page 902
Distributed QoS Group–Based WFQ……Page 905
Summary: dWFQ Options……Page 907
MDRR Configuration……Page 912