QoSmplementing Cisco Quality of Service (QOS) v2.0 Student Guide Version 2.0 2004 KnowledgeNet.com, nc. All Rights Reserved. KNOWLEDGENET is a registered trademark; and the K DESGN and THE BEST OF A NEW BREED are trademarks of KnowledgeNet.com, nc. All other trademarks are the property of their respective companies. Copyright 2004, KnowledgeNet.com, nc. All rights reserved. mplementing Cisco Quality of Service (QOS) v2.0 iMODULE 1 - INTRODUCTION TO IP QOS 1-1 Overview 1-1 Module Objectives 1-2 Outline 1-2LESSON ONE: THE NEED FOR QOS 1-3 Overview 1-3 Objectives 1-4 Outline 1-5 Converged Networks 1-6 Converged Networks Quality ssues 1-8 Available Bandwidth 1-10 End-to-End Delay 1-12 Packet Loss 1-17 Summary 1-19 Quiz 1-20LESSON TWO: UNDERSTANDING QOS 1-23 Overview 1-23 Objectives 1-23 Outline 1-24 QoS Defined 1-25 QoS for Converged Networks 1-26 QoS Requirements 1-27 QoS Traffic Classes 1-31 QoS Policy 1-32 Summary 1-35 Quiz 1-36LESSON THREE: IMPLEMENTING IP QOS 1-39 Overview 1-39 Objectives 1-39 Outline 1-41 Methods for mplementing QoS Policy 1-42 Legacy CL 1-43 Modular QoS CL 1-44 AutoQoS 1-45 QoS mplementation Methods Compared 1-46 QoS Policy Manager 1-47 Network Management MBs for Monitoring QoS 1-49 MBs for Managing QoS 1-50 Summary 1-53 Quiz 1-54MODULE ASSESSMENT 1-57 Overview 1-57 Quiz: ntroduction to P QoS 1-58 Module Assessment Answer Key 1-61MODULE SUMMARY 1-63MODULE 2 - THE BUILDING BLOCKS OF IP QOS 2-1 Overview 2-1 Module Objectives 2-2 Outline 2-2LESSON ONE: MODELS FOR IMPLEMENTING QOS 2-3ii mplementing Cisco Quality of Service (QOS) v2.0 Copyright 2003, KnowledgeNet.com, nc. 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Overview 2-3 Objectives 2-4 Outline 2-5 QoS Models 2-6 Best-Effort Model 2-7 ntegrated Services Model 2-9 Differentiated Services Model 2-14 Summary 2-17 Quiz 2-18LESSON TWO: THE DIFFERENTIATED SERVICES MODEL 2-21 Overview 2-21 Objectives 2-21 Outline 2-22 Differentiated Services Model 2-23 DSCP Encoding 2-25 Per-Hop Behaviors 2-26 Backward Compatibility Using the Class Selector 2-31 Summary 2-32 Quiz 2-33LESSON THREE: IP QOS MECHANISMS 2-37 Overview 2-37 Objectives 2-37 Outline 2-38 QoS Mechanisms 2-39 Classification 2-40 Marking 2-42 Congestion Management 2-43 Congestion Avoidance 2-45 Policing and Shaping 2-46 Compression 2-48 Link Fragmentation and nterleaving 2-49 Applying QoS to nput and Output nterfaces 2-50 Summary 2-51 Quiz 2-52LESSON FOUR: CASE STUDY: QOS MECHANISMS 2-55 Overview 2-55 Objectives 2-55 Outline 2-56 Review Customer QoS Requirements 2-58 dentify QoS Service Class Requirements 2-60 dentify Network Locations Where QoS Mechanisms Should Be Applied 2-61 Present Your Solution 2-64LESSON FIVE: CASE STUDY: THE LIFE OF A PACKET 2-69 Overview 2-69 Objectives 2-69 Outline 2-70 Overview 2-71 Life of a High-Priority (VoP) Packet 2-72 Life of a Low-Priority (FTP) Packet 2-81 Summary 2-91MODULE ASSESSMENT 2-93 Overview 2-93 Quiz: The Building Blocks of P QoS 2-94 Module Assessment Answer Key 2-97Copyright 2004, KnowledgeNet.com, nc. All rights reserved. mplementing Cisco Quality of Service (QOS) v2.0 iiiMODULE SUMMARY 2-99MODULE 3 - INTRODUCTION TO MODULAR QOS CLI AND AUTOQOS 3-1 Overview 3-1 Module Objectives 3-2 Outline 3-2LESSON ONE: INTRODUCING MODULAR QOS CLI 3-3 Overview 3-3 Objectives 3-3 Outline 3-4 Modular QoS CL 3-5 Modular QoS CL Components 3-6 Class Maps 3-7 Configuring and Monitoring Class Maps 3-9 Policy Maps 3-13 Configuring and Monitoring Policy Maps 3-14 Service Policy 3-21 Attaching Service Policies to nterfaces 3-22 Summary 3-24 Quiz 3-25LESSON TWO: INTRODUCING AUTOQOS 3-29 Overview 3-29 Objectives 3-30 Outline 3-30 AutoQoS 3-31 AutoQoS: Router Platforms 3-35 AutoQoS: Switch Platforms 3-36 Configuring AutoQoS 3-38 Monitoring AutoQoS 3-47 Automation with Cisco AutoQoS 3-53 Summary 3-54 Quiz 3-56MODULE ASSESSMENT 3-59 Overview 3-59 Quiz: ntroduction to Modular QoS CL and AutoQoS 3-60 Module Assessment Answer Key 3-62MODULE SUMMARY 3-63MODULE 4 - CLASSIFICATION AND MARKING 4-1 Overview 4-1 Module Objectives 4-2 Outline 4-2LESSON ONE: CLASSIFICATION AND MARKING OVERVIEW 4-3 Overview 4-3 Objectives 4-4 Outline 4-5 Classification 4-6 Marking 4-7 Classification and Marking at the Link Layer 4-8 Classification and Marking at the Network Layer 4-13iv mplementing Cisco Quality of Service (QOS) v2.0 Copyright 2003, KnowledgeNet.com, nc. 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Mapping CoS to Network Layer QoS 4-14 QoS Service Class Defined 4-16 mplementing a QoS Policy Using a QoS Service Class 4-18 Trust Boundaries 4-21 Summary 4-23 Quiz 4-24LESSON TWO: CASE STUDY: CLASSIFICATION AND MARKING 4-27 Overview 4-27 Objectives 4-27 Outline 4-28 Review Customer QoS Requirements 4-30 dentify QoS Service Class Requirements 4-34 dentify Network Locations Where Classification and Marking Should be Applied 4-36 Present Your Solution 4-39LESSON THREE: USING MQC FOR CLASSIFICATION 4-41 Overview 4-41 Objectives 4-42 Outline 4-43 MQC Classification Options 4-44 Configuring Classification with MQC 4-46 Configuring Classification Using nput nterface 4-49 Configuring Classification Using CoS 4-50 Configuring Classification Using Access Lists 4-51 Configuring Classification Using P Precedence 4-53 Configuring Classification Using DSCP 4-54 Configuring Classification Using a UDP Port Range 4-58 Monitoring Class Maps 4-59 Summary 4-60 Quiz 4-61LESSON FOUR: USING MQC FOR CLASS-BASED MARKING 4-65 Overview 4-65 Objectives 4-66 Outline 4-67 Class-Based Marking Overview 4-68 MQC Marking Options 4-69 Configuring Class-Based Marking 4-70 Configuring Class-Based Marking 4-72 Configuring P Precedence Marking 4-73 Configuring P DSCP Marking 4-74 Monitoring Class-Based Marking 4-75 Summary 4-78 Quiz 4-79LESSON FIVE: USING NBAR FOR CLASSIFICATION 4-83 Overview 4-83 Objectives 4-84 Outline 4-85 Network Based Application Recognition 4-86 NBAR Application Support 4-88 Packet Description Language Module 4-92 Protocol Discovery 4-93 Configuring and Monitoring Protocol Discovery 4-95 Configuring NBAR for Static Protocols 4-97 Configuring NBAR for Stateful Protocols 4-100 Summary 4-105Copyright 2004, KnowledgeNet.com, nc. All rights reserved. mplementing Cisco Quality of Service (QOS) v2.0 v Quiz 4-106LESSON SIX: CONFIGURING QOS PRE-CLASSIFY 4-109 Overview 4-109 Objectives 4-110 Outline 4-111 mplementing QoS with Pre-Classification 4-112 QoS Pre-Classify Applications 4-113 QoS Pre-Classify Deployment Options 4-117 Configuring QoS Pre-Classify 4-119 Monitoring QoS Pre-Classify 4-122 Summary 4-124 Quiz 4-125LESSON SEVEN: CONFIGURING QOS POLICY PROPAGATION THROUGH BGP 4-127 Overview 4-127 Objectives 4-127 Outline 4-128 QoS Policy Propagation Through BGP 4-129 P QoS and BGP nteraction 4-131 Cisco Express Forwarding 4-132 QPPB Configuration Tasks 4-136 Summary 4-150 Quiz 4-151LESSON EIGHT: CONFIGURING LAN CLASSIFICATION AND MARKING 4-153 Overview 4-153 Objectives 4-154 Outline 4-154 LAN Classification and Marking 4-155 QoS Trust Boundaries 4-156 LAN Classification and Marking Platforms 4-159 Configuring LAN-Based Classification and Marking 4-171 Monitoring LAN-Based Classification and Marking 4-186 Summary 4-188 Quiz 4-189MODULE ASSESSMENT 4-191 Overview 4-191 Quiz: Classification and Marking 4-192 Module Assessment Answer Key 4-194MODULE SUMMARY 4-195MODULE 5 - CONGESTION MANAGEMENT 5-1 Overview 5-1 Module Objectives 5-2 Outline 5-2LESSON ONE: INTRODUCTION TO QUEUING 5-3 Overview 5-3 Objectives 5-3 Outline 5-4 Congestion and Queuing 5-5 Queuing Algorithms 5-8 FFO 5-9vi mplementing Cisco Quality of Service (QOS) v2.0 Copyright 2003, KnowledgeNet.com, nc. 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Priority Queuing 5-10 Round Robin 5-11 Weighted Round Robin 5-12 Deficit Round Robin 5-14 Summary 5-15 Quiz 5-16LESSON TWO: QUEUING IMPLEMENTATIONS 5-19 Overview 5-19 Objectives 5-19 Outline 5-20 Queuing Components 5-21 Hardware Queue (TxQ) Size 5-24 Congestion on Software nterfaces 5-26 Queuing mplementations in Cisco O 5-27 Summary 5-28 Quiz 5-29LESSON THREE: FIFO AND WFQ 5-31 Overview 5-31 Objectives 5-31 Outline 5-32 FFO Queuing 5-33 Weighted Fair Queuing 5-35 WFQ Classification 5-38 WFQ nsertion and Drop Policy 5-41 WFQ Scheduling 5-43 Benefits and Drawbacks of WFQ 5-51 Configuring WFQ 5-52 Monitoring WF 5-55 Summary 5-57 Quiz 5-58LESSON FOUR: CBWFQ AND LLQ 5-61 Overview 5-61 Objectives 5-62 Outline 5-63 CBWFQ and LLQ 5-64 CBWFQ 5-65 CBWFQ Architecture 5-66 CBWFQ Benefits 5-72 Configuring and Monitoring CBWFQ 5-73 LLQ 5-78 LLQ Architecture 5-80 LLQ Benefits 5-81 Configuring and Monitoring LLQ 5-82 Summary 5-88 Quiz 5-89LESSON FIVE: LAN CONGESTION MANAGEMENT 5-93 Overview 5-93 Objectives 5-93 Outline 5-94 Queuing on Catalyst Switches 5-95 Weighted Round Robin 5-101 Configuring PQ on Catalyst 2950 Switches 5-103 Configuring WRR on Catalyst 2950 Switches 5-104 Monitoring Queuing on Catalyst 2950 Switches 5-106 Summary 5-109Copyright 2004, KnowledgeNet.com, nc. All rights reserved. mplementing Cisco Quality of Service (QOS) v2.0 vii Quiz 5-111MODULE ASSESSMENT 5-115 Overview 5-115 Quiz: Congestion Management 5-116 Module Assessment Answer Key 5-119MODULE SUMMARY 5-121MODULE 6 - CONGESTION AVOIDANCE 6-1 Overview 6-1 Module Objectives 6-2 Outline 6-2LESSON ONE: INTRODUCTION TO CONGESTION AVOIDANCE 6-3 Overview 6-3 Objectives 6-3 Outline 6-4 Behavior of TCP Senders and Receivers 6-5 Congestion and TCP 6-7 Managing nterface Congestion with Tail Drop 6-9 Tail-Drop Limitations 6-10 Summary 6-13 Quiz 6-14LESSON TWO: INTRODUCTION TO RED 6-17 Overview 6-17 Objectives 6-17 Outline 6-18 Random Early Detection 6-19 RED Profiles 6-20 RED Modes 6-22 TCP Traffic Before and After RED 6-23 Applying Congestion Avoidance 6-25 Summary 6-26 Quiz 6-27LESSON THREE: CONFIGURING CLASS-BASED WEIGHTED RED 6-31 Overview 6-31 Objectives 6-31 Outline 6-32 Weighted Random Early Detection 6-33 WRED Profiles 6-37 Configuring CB-WRED 6-42 Configuring DSCP-Based CB-WRED 6-49 Monitoring CB-WRED 6-54 Summary 6-55 Quiz 6-56LESSON FOUR: CASE STUDY: WRED TRAFFIC PROFILES 6-61 Overview 6-61 Objectives 6-61 Outline 6-62 Review Customer QoS Requirements 6-64 dentify QoS Service Class Requirements 6-65 Create WRED Traffic Profiles 6-66 Present Your Solution 6-70viii mplementing Cisco Quality of Service (QOS) v2.0 Copyright 2003, KnowledgeNet.com, nc. 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LESSON FIVE: CONFIGURING EXPLICIT CONGESTION NOTIFICATION 6-73 Overview 6-73 Objectives 6-73 Outline 6-74 Explicit Congestion Notification 6-75 ECN Field Defined 6-76 ECN and WRED 6-77 Configuring ECN-Enabled WRED 6-79 Monitoring ECN-Enabled WRED 6-80 Summary 6-83 Quiz 6-84MODULE ASSESSMENT 6-87 Overview 6-87 Quiz: Congestion Avoidance 6-88 Module Assessment Answer Key 6-93MODULE SUMMARY 6-95MODULE 7 - TRAFFIC POLICING AND SHAPING 7-1 Overview 7-1 Module Objectives 7-2 Outline 7-2LESSON ONE: TRAFFIC POLICING AND TRAFFIC SHAPING OVERVIEW 7-3 Overview 7-3 Objectives 7-4 Outline 7-5 Traffic Policing and Shaping Overview 7-6 Why Use Traffic Conditioners? 7-7 Policing vs. Shaping 7-11 Measuring Traffic Rates 7-12 Single Token Bucket Class-Based Policing 7-14 Dual Token Bucket Class-Based Policing 7-15 Dual-Rate Token Bucket Class-Based Policing 7-18 Class-Based Traffic Shaping 7-21 Cisco OS Traffic Policing and Shaping Mechanisms 7-22 Applying Traffic Conditioners 7-24 Summary 7-25 Quiz 7-26LESSON TWO: CONFIGURING CLASS-BASED POLICING 7-29 Overview 7-29 Objectives 7-30 Outline 7-31 Class-Based Policing Overview 7-32 Configuring Single-Rate Class-Based Policing 7-34 Configuring Dual-Rate Class-Based Policing 7-38 Configuring Percentage-Based Class-Based Policing 7-40 Monitoring Class-Based Policing 7-42 Summary 7-43 Quiz 7-44LESSON THREE: CONFIGURING CLASS-BASED SHAPING 7-47 Overview 7-47 Objectives 7-47 Outline 7-48Copyright 2004, KnowledgeNet.com, nc. All rights reserved. mplementing Cisco Quality of Service (QOS) v2.0 ix Class-Based Shaping Overview 7-49 Traffic Shaping Methods 7-50 Configuring Class-Based Shaping 7-51 Monitoring Class-Based Shaping 7-57 Summary 7-59 Quiz 7-60LESSON FOUR: CONFIGURING CLASS-BASED SHAPING ON FRAME RELAY INTERFACES 7-63 Overview 7-63 Objectives 7-63 Outline 7-64 Frame Relay Refresher 7-65 Frame Relay Congestion Control 7-66 Frame Relay Congestion Adaptation 7-67 FECN to BECN Propagation 7-68 Configuring Frame Relay Adaptive Class-Based Shaping 7-69 Monitoring Class-Based Shaping with FR Adaptation 7-71 Summary 7-72 Quiz 7-73MODULE ASSESSMENT 7-77 Overview 7-77 Quiz: Traffic Policing and Shaping 7-78 Module Assessment Answer Key 7-80MODULE SUMMARY 7-83MODULE 8 - LINK EFFICIENCY MECHANISMS 8-1 Overview 8-1 Module Objectives 8-2 Outline 8-2LESSON ONE: LINK EFFICIENCY MECHANISMS OVERVIEW 8-3 Overview 8-3 Objectives 8-4 Outline 8-4 Link Efficiency Mechanisms Overview 8-5 L2 Payload Compression 8-8 Header Compression 8-10 Large Packets Freeze Out Voice on Slow WAN Links 8-13 Link Fragmentation and nterleaving 8-15 Applying Link Efficiency Mechanisms 8-16 Summary 8-17 Quiz 8-18LESSON TWO: CLASS-BASED HEADER COMPRESSION 8-21 Overview 8-21 Objectives 8-22 Outline 8-22 Header Compression Overview 8-23 Class-Based TCP Header Compression 8-25 Class-Based RTP Header Compression 8-28 Configuring Class-Based Header Compression 8-31 Monitoring Class-Based Header Compression 8-34 Summary 8-35 Quiz 8-36x mplementing Cisco Quality of Service (QOS) v2.0 Copyright 2003, KnowledgeNet.com, nc. 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LESSON THREE: LINK FRAGMENTATION AND INTERLEAVING 8-39 Overview 8-39 Objectives 8-40 Outline 8-40 Fragmentation Options 8-41 Serialization Delay and Fragment Sizing 8-42 Configuring MLP with nterleaving 8-44 Monitoring MLP with nterleaving 8-47 FRF.12 Frame Relay Fragmentation 8-49 Configuring FRF.12 Frame Relay Fragmentation 8-51 Monitoring FRF.12 Frame Relay Fragmentation 8-53 Summary 8-55 Quiz 8-56MODULE ASSESSMENT 8-59 Overview 8-59 Quiz: Link Efficiency Mechanisms 8-60 Module Assessment Answer Key 8-63MODULE SUMMARY 8-65MODULE 9 - QOS BEST PRACTICES 9-1 Overview 9-1 Module Objectives 9-2 Outline 9-2LESSON ONE: TRAFFIC CLASSIFICATION BEST PRACTICES 9-3 Overview 9-3 Objectives 9-3 Outline 9-4 QoS Best Practices 9-5 Voice/Video/Data QoS Requirements 9-10 QoS Requirements Summary 9-17 Traffic Classification 9-18 Enterprise to Service Provider QoS Class Mapping 9-24 Summary 9-27 Quiz 9-28LESSON TWO: CASE STUDY: DEPLOYING END-TO-END QOS 9-33 Overview 9-33 Objectives 9-34 Outline 9-34 QoS Service Level Agreements 9-35 Deploying End-to-End QoS Case Study ntroduction 9-41 Enterprise Campus QoS mplementations 9-43 WAN Edge (CE/PE) QoS mplementations 9-52 Service Provider Backbone QoS mplementations 9-63 Summary 9-71 Quiz 9-73MODULE ASSESSMENT 9-77 Overview 9-77 Quiz: ntroduction to P QoS 9-78 Module Assessment Answer Key 9-82MODULE SUMMARY 9-83Copyright 2004, KnowledgeNet.com, nc. All rights reserved. mplementing Cisco Quality of Service (QOS) v2.0 xiQOSCourse ntroduction OverviewImplementing Cisco Quality of Service (QOS) v2.0 provides students with in-depth knowledge oI IP quality oI service (QoS) requirements, conceptual models such as Best EIIort, Integrated Services (IntServ) and DiIIerentiated Services (DiIIServ), and the implementation oI IP QoS on Cisco IOS platIorms. The curriculum covers the theory oI IP QoS, design issues, and conIiguration oI various QoS mechanisms to Iacilitate the creation oI eIIective administrative policies providing QoS. Case studies and lab exercises included in the course help students apply the concepts that are mastered in individual modules to real-liIe scenarios. The course also gives students design and usage rules Ior various advanced IP QoS Ieatures and the integration oI IP QoS with underlying Layer 2 QoS mechanisms, allowing them to design and implement eIIicient, optimal, and trouble-Iree multiservice networks. 2 mplementing Cisco Quality of Service (QOS) v2.0 Copyright 2003, Cisco Systems, nc. Course GoaI and Objectives This section describes the course goal and objectives. Upon completing this course, you will be able to meet these objectives: Explain the need to implement QoS and explain methods Ior implementing and managing QoSIdentiIy and describe diIIerent models used Ior ensuring QoS in a network and explain key IP QoS mechanisms used to implement the models Explain the use oI MQC and AutoQoS to implement QoS on the network ClassiIy and mark network traIIic to implement a policy deIining QoS requirements Use Cisco QoS queuing mechanisms to manage network congestion Use Cisco QoS congestion avoidance mechanisms to reduce the eIIects oI congestion on the network Use Cisco QoS traIIic policing and traIIic shaping mechanisms to eIIectively limit the rate oI network traIIic Use Cisco link eIIiciency mechanisms to improve the bandwidth eIIiciency oI low-speed WAN linksCorrectly select the most appropriate QoS mechanisms Ior providing QoS using Cisco 'best practices in service provider and enterprise networks 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-4Course GoaI"To identify, describe, and correctIy impIement the appropriate QoSmechanisms required to create an effective administrative poIicy providing QoS."Implementing Cisco Quality of Service (QOS)Copyright 2003, Cisco Systems, nc. Course ntroduction 3 Course OutIine The outline lists the modules included in this course. 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-5Course OutIine Introduction to IP QoS The BuiIding BIocks of IP QoS Introduction to ModuIar QoS CLI and AutoQoS CIassification and Marking Congestion Management Congestion Avoidance Traffic PoIicing and Shaping Link Efficiency Mechanisms QoS Best Practices4 mplementing Cisco Quality of Service (QOS) v2.0 Copyright 2003, Cisco Systems, nc. Cisco Certifications This topic discusses Cisco career certiIications and paths. Cisco provides three levels oI general career certiIications Ior IT proIessionals with several diIIerent tracks to meet individual needs. Cisco also provides Iocused Cisco QualiIied Specialist (CQS) certiIications Ior designated areas such as cable communications, voice, and security. There are many paths to Cisco certiIication, but only one requirementpassing one or more exams demonstrating knowledge and skill. For details, go to http://www.cisco.com/go/certiIications. 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-6Cisco CertificationsCopyright 2003, Cisco Systems, nc. Course ntroduction 5 Learner SkiIIs and KnowIedge This topic lists the course prerequisites. To beneIit Iully Irom this lesson, you must have these prerequisite skills and knowledge: Completion oI the Interconnecting Cisco Networking Devices (ICND) course or Cisco CCNA certiIication. 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-7Prerequisite Learner SkiIIs and KnowIedgeInterconnecting Cisco Networking Devices (ICND) orCisco Certified Networking Associate (CCNA)Interconnecting Cisco Networking Devices (ICND) orCisco Certified Networking Associate (CCNA)Implementing Cisco Quality of Service (QOS)Implementing Cisco Quality of Service (QOS)6 mplementing Cisco Quality of Service (QOS) v2.0 Copyright 2003, Cisco Systems, nc. Learner ResponsibiIities This topic discusses the responsibilities oI the learners. To take Iull advantage oI the inIormation presented in this course, you must have completed the prerequisite requirements. In class, you are expected to participate in all lesson exercises and assessments. In addition, you are encouraged to ask any questions relevant to the course materials. II you have pertinent inIormation or questions concerning Iuture Cisco product releases and product Ieatures, please discuss these topics during breaks or aIter class. The instructor will answer your questions or direct you to an appropriate inIormation source. 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-8Learner ResponsibiIities CompIeteprerequisites IntroduceyourseIf Ask questionsCopyright 2003, Cisco Systems, nc. Course ntroduction 7 GeneraI Administration This topic lists the administrative issues Ior the course. The instructor will discuss these administrative issues: Sign-in process Starting and anticipated ending times oI each class day Class breaks and lunch Iacilities Appropriate attire during class Materials that you can expect to receive during class What to do in the event oI an emergency Location oI the rest rooms How to send and receive telephone and Iax messages 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-9GeneraI AdministrationCIass-ReIated Sign-in sheet Length and times Break and Iunchroom Iocations AttireFaciIities-ReIated Course materiaIs Site emergency procedures Rest rooms TeIephones/faxes8 mplementing Cisco Quality of Service (QOS) v2.0 Copyright 2003, Cisco Systems, nc. Course FIowThis topic covers the suggested Ilow oI the course materials. The schedule reIlects the recommended structure Ior this course. This structure allows enough time Ior the instructor to present the course inIormation and Ior you to work through the laboratory exercises. The exact timing oI the subject materials and labs depends on the pace oI your speciIic class. 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-10Course FIowCongestion Management (Cont.)CourseIntroductionIntroduction to IP QoSBuiIding BIocks of IP QoSTraffic PoIicing and ShapingLunchIntroduction to ModuIar QoSCLI and AutoQoS (Cont.)Congestion AvoidanceLink EfficiencyMechanismsAMPMCongestion ManagementQoS Best PracticesDay 1 Day 2 Day 3 Day 4 Day 5BuiIding BIocks of IP QoS (Cont.)Introduction to MModuIarQoS CLI and AutoQoSCIassification and Marking CIassification and Marking (Cont.)CIassification and Marking (Cont.)Copyright 2003, Cisco Systems, nc. Course ntroduction 9 Icons and SymboIs This topic shows the Cisco icons and symbols used in this course. 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-11Cisco Icons and SymboIsRouterTerminaI Server100BaseTHubWorkgroup Switch:CoIor/SubduedNetwork CIoud,WhitePCNetwork CIoud,Standard CoIorCameraPC/VideoIP Phone10 mplementing Cisco Quality of Service (QOS) v2.0 Copyright 2003, Cisco Systems, nc. Learner Introductions This is the point in the course where you introduce yourselI. Prepare to share the Iollowing inIormation: Your name Your company II you have most or all oI the prerequisite skills A proIile oI your experience What you would like to learn Irom this course 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-12Learner Introductions Your name Your company SkiIIs and knowIedge Brief history ObjectiveCopyright 2003, Cisco Systems, nc. Course ntroduction 11 Course EvaIuationsCisco relies on customer Ieedback to make improvements and guide business decisions. Your valuable input will help shape Iuture Cisco learning products and program oIIerings. On the Iirst and Iinal days oI class, your instructor will provide the Iollowing inIormation needed to Iill out the evaluation: Course acronym (printea on stuaent kit siae label) Course version number (printea on stuaent kit siae label) Cisco Learning Partner ID # Instructor ID # Course ID # (for courses registerea in Cisco Learning Locator) Please use this inIormation to complete a brieI (approximately 10 minutes) online evaluation concerning your instructor and the course materials in the student kit. To access the evaluation, go to http://www.cisco.com/go/clpevals.AIter the completed survey has been submitted, you will be able to access links to a variety oI Cisco resources, including inIormation on the Cisco Career CertiIication programs and Iuture Cisco Networkers events. II you encounter any diIIiculties accessing the course evaluation URL or submitting your evaluation, please contact Cisco via email at clpevalssupportexternal.cisco.com. 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-13Course EvaIuations12 mplementing Cisco Quality of Service (QOS) v2.0 Copyright 2003, Cisco Systems, nc. ModuIe 1 ntroduction to P QoS OverviewAs user applications continue to drive network growth and evolution, demands to support diIIerent types oI traIIic is also increasing. DiIIerent types oI applications with diIIering network requirements create a need Ior administrative policies mandating how individual applications are to be treated by the network. Network traIIic Irom business-critical applications must be protected Irom other types oI traIIic. Requests Irom business-critical and delay-sensitive applications must be serviced with priority. The employment and enIorcement oI quality oI service (QoS) policies within a network plays an essential role in enabling network administrators and architects to meet networked application demands. QoS is a crucial element oI any administrative policy that mandates how to handle application traIIic on a network. This module introduces the concept oI QoS, explains key issues oI networked applications, and describes diIIerent methods Ior implementing QoS. 1-2 mplementing Cisco Quality of Service (QOS) v2.0 Copyright 2003, Cisco Systems, nc. ModuIe Objectives Upon completing this module, you will be able to explain the need to implement QoS and explain methods Ior implementing and managing QoS. ModuIe OutIine The outline lists the components oI this module. 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-1-3ModuIe Objectives Identify probIems that couId Iead to poor quaIity of service and expIain how the probIems might be resoIved Define the term QoS and identify and expIain the key steps to impIementing QoS on a converged network List and describe methods for impIementing QoS 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-1-4ModuIe OutIine The Need for QoS Understanding QoS ImpIementing IP QoSThe Need for QoS OverviewA communications network Iorms the backbone oI any successIul organization. These networks transport a multitude oI applications and data, including high-quality video and delay-sensitive data such as real-time voice. Bandwidth-intensive applications stretch network capabilities and resources, but also complement, add value, and enhance every business process. Networks must provide secure, predictable, measurable, and sometimes guaranteed services. Achieving the required QoS by managing delay, delay variation (jitter), bandwidth, and packet loss parameters on a network becomes the secret to a successIul end-to-end business solution. QoS is the set oI techniques used to manage network resources. ReIevanceWith the emergence oI networks incorporating many types oI traIIic with diIIerent requirements, QoS has become an essential component oI networking. As more converged networks are implemented, QoS becomes more important. 1-4 mplementing Cisco Quality of Service (QOS) v2.0 Copyright 2003, Cisco Systems, nc. ObjectivesUpon completing this lesson, you will be able to identiIy problems that could lead to poor quality oI service and explain how the problems might be resolved. This includes being able to meet these objectives: Describe a converged IP network supporting voice, video, and data traIIic IdentiIy the Iour key quality issues with converged networks Explain how a lack oI bandwidth can cause quality problems and ways to resolve those problems Explain how end-to-end delay can cause quality problems and ways to resolve those problems Explain how packet loss can cause quality problems and ways to resolve those problems Learner SkiIIs and KnowIedge To beneIit Iully Irom this lesson, you must have these prerequisite skills and knowledge: Basic knowledge oI internetworking with TCP/IP concepts Copyright 2003, Cisco Systems, nc. ntroduction to P QoS 1-5 OutIineThe outline lists the topics included in this lesson. 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-1-3OutIine Overview Converged Networks Converged Networks QuaIity Issues AvaiIabIe Bandwidth End-to-End DeIay Packet Loss Summary Quiz1-6 mplementing Cisco Quality of Service (QOS) v2.0 Copyright 2003, Cisco Systems, nc. Converged Networks This topic explains why QoS was not important beIore networks converged. BeIore networks converged, network engineering Iocused on connectivity. The rates at which data came onto the network resulted in bursty data Ilows. Data, arriving in packets, tried to grab as much bandwidth as it could at any given time. The access was very egalitariana Iirst-come, Iirst-served basis. Whoever arrived Iirst got the bandwidth. As a result oI this somewhat anarchic way oI attacking the network, the data rate is adaptive to network conditions. The protocols that have been developed have adapted to the bursty nature oI data networks, and brieI outages are survivable. For example, iI retrieving e-mail, a delay oI a Iew seconds is generally not noticeable. A delay oI minutes is annoying, but not serious. Traditional networks also had requirements Ior applications such as data, video, and systems network architecture (SNA). Since each application had diIIerent traIIic characteristics and requirements, network designers deployed nonintegrated networks designed Ior carrying a speciIic type oI traIIic: data network, SNA network, voice network, and video network. 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-1-4Before Converged NetworksTraditionaI data traffic characteristics: Bursty data fIow First-come, first-served access MostIy not time sensitive - deIays OK Brief outages are survivabIeCopyright 2003, Cisco Systems, nc. ntroduction to P QoS 1-7 The Iigure illustrates a converged network in which voice, video, and data traIIic use the same network Iacilities. Merging these diIIerent traIIic streams with dramatically diIIering requirements can lead to a number oI problems. Although packets carrying voice traIIic are typically very small, they cannot tolerate delay and delay variation as they traverse the network. Voices will break up and words will become incomprehensible. On the other hand, packets carrying Iile transIer data are typically large and can survive delays and drops. It is possible to retransmit part oI a dropped (data) Iile, but it is not Ieasible to retransmit a part oI a (voice) conversation. The constant, but small packet voice Ilow competes with bursty data Ilows. Unless some mechanism mediates the overall Ilow, voice quality will be severely compromised at times oI network congestion. The critical voice traIIic must get priority. Voice and video traIIic are very time sensitive. They cannot be delayed and they cannot be dropped or the resulting quality oI voice and video will suIIer.And, Iinally, converged networks cannot Iail. While a Iile transIer or e-mail packet can wait until the network recovers, voice and video packets cannot. Even a brieI network outage on a converged network can seriously disrupt business operations. 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-1-5After Converged NetworksConverged traffic characteristics: Constant smaII packet voice fIow competes with bursty data fIow CriticaI traffic must get priority Voice and video are time sensitive Brief outages not acceptabIe1-8 mplementing Cisco Quality of Service (QOS) v2.0 Copyright 2003, Cisco Systems, nc. Converged Networks QuaIity Issues This topic describes the basic quality issues presented by converged networks. With inadequate preparation oI the network, voice transmission is choppy or unintelligible. Gaps in speech are particularly troublesome where pieces oI speech are interspersed with silence, and speech literally disappears. In voice-mail systems this silence is a problem. For example, you dial 68614. In a situation where the gaps in speech are actually gaps in the tone, 68614 becomes 6688661144, because the gaps in speech are perceived as pauses in the touch tones.Poor caller interactivity is the consequence oI delay. It causes two problemsecho and talker overlap.Echo is caused by the signal reIlecting the speaker voice Irom the Iar-end telephone equipment back into the speaker ear. Talker overlap is caused when one-way delay becomes greater than 250 ms. When this occurs, one talker steps in on the speech oI the other talker resulting in a 'walkie-talkie call mode. Disconnected calls are the worst cases: II there are long gaps in speech, the parties will hang up; iI there are signaling problems, the calls are disconnected. Such events are completely unacceptable in the voice world yet are quite common Ior an inadequately prepared data network that is attempting to carry voice. Multimedia streams, such as those used in IP telephony or videoconIerencing, may be extremely sensitive to delivery delays and create unique QoS demands on the underlying networks that carry them. When packets are delivered using the 'best-eIIort delivery model, they may not arrive in order, in a timely manner, or at all. The result is unclear pictures, jerky and slow movement, and sound that is out oI synchronization with the image. 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-1-6Converged Networks:QuaIity Issues TeIephone CaII: "I cannot understand you; your voice is breaking up." TeIeconferencing: "The picture is very jerky. Voice not synchronized." Brokerage House: "I needed that information two hours ago. Where is it?" CaII Center: "PIease hoId whiIe my screen refreshes."Copyright 2003, Cisco Systems, nc. ntroduction to P QoS 1-9 The Iour big problems Iacing converged enterprise networks are bandwidth capacity, delay (both Iixed and variable), variation oI delay (also called jitter), and packet loss.Large graphic Iiles, multimedia uses, and increasing use Ior voice and video cause bandwidth capacity problems over data networks. Delay is the time it takes Ior a packet to reach the receiving endpoint aIter being transmitted Irom the sending endpoint. This time is termed the 'end-to-end delay, and consists oI two components: Iixed network delay and variable network delay. Jitter is the delta, or diIIerence, in the total end-to-end delay values oI two voice packets in the voice Ilow.Two types oI Iixed delay are serialization and propagation delays. Serialization is the process oI placing bits on the circuit. The higher the circuit speed, the less time it takes to place the bits on the circuit. ThereIore, the higher the speed oI the link, the less serialization delay is incurred. Propagation delay is the time it takes Ior Irames to transit the physical media. Processing delay is a type oI variable delay, and is the time required by a networking device to look up the route, change the header, and complete other switching tasks. In some cases, the packet also must be manipulated. For example, the encapsulation type or the hop count must be changed. Each oI these steps can contribute to the processing delay. Loss oI packets is usually caused by congestion in the WAN, resulting in speech dropouts or a stutter eIIect iI the play-out side tries to accommodate by repeating previous packets. 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-1-7Converged Networks:QuaIity Issues (Cont.) Lack of bandwidth: muItipIe fIows compete for a Iimited amount of bandwidth End-to-end deIay (fixed and variabIe): packetshave to traverse many network devices and Iinks that add up to the overaII deIay Variation of deIay (jitter): sometimes there is a Iot of other traffic, which resuIts in more deIay Packet Loss: packets may have to be dropped when a Iink is congestedvideo Lacking Proper QoS1-10 mplementing Cisco Quality of Service (QOS) v2.0 Copyright 2003, Cisco Systems, nc. AvaiIabIe Bandwidth This topic explains how a lack oI bandwidth can adversely impact QoS in a network and describes ways to eIIectively increase bandwidth on a link. The example illustrates an empty network with Iour hops between a server and a client. Each hop is using diIIerent media with a diIIerent bandwidth. The maximum available bandwidth is equal to the bandwidth oI the slowest link. The calculation oI the available bandwidth, however, is much more complex in cases where multiple Ilows are traversing the network. The calculation oI the available bandwidth in the illustration is a rough approximation. 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-1-8Lack of Bandwidth Maximum avaiIabIe bandwidth equaIs the bandwidth of the weakest Iink. MuItipIe fIows are competing for the same bandwidth resuIting inmuch Iess bandwidth being avaiIabIe to one singIe appIication.Bandwidth max= min (10 Mbps, 256 kbps, 512 kbps, 100 Mbps) = 256kbpsBandwidth avaiI = bandwidth max / fIowsBad voice Due to Lack of BW Copyright 2003, Cisco Systems, nc. ntroduction to P QoS 1-11 The best approach is to increase the link capacity to accommodate all applications and users, with some extra bandwidth to spare. Although this solution sounds simple, it brings a high cost in terms oI the expense and time it takes to implement. Very oIten there are also technological limitations Ior upgrading to a higher bandwidth. Another option is to classiIy traIIic into QoS classes and prioritize it according to importance. (Voice and business-critical traIIic should get suIIicient bandwidth to support their application requirements, voice should get prioritized Iorwarding, and the least important traIIic should get whatever unallocated bandwidth is remaining.) A wide variety oI mechanisms are available in Cisco IOS QoS soItware that provide bandwidth guarantees: Priority queuing (PQ) or custom queuing (CQ) ModiIied deIicit round robin (MDRR) (on Cisco 12000 series routers) Distributed type oI service (ToS)-based and QoS group-based weighted Iair queuing (WFQ) (on Cisco 7 00 series routers) Class-based weighted Iair queuing (CBWFQ) Low-latency queuing (LLQ) Optimizing link usage by compressing the payload oI Irames (virtually) increases the link bandwidth. Compression, on the other hand, also increases delay because oI the complexity oI compression algorithms. Using hardware compression can accelerate packet payload compressions. Stacker and Predictor are two compression algorithms that are available in Cisco IOS soItware. Another link eIIiciency mechanism is header compression. This mechanism is especially eIIective in networks where most packets carry small amounts oI data (that is, where payload-to-header ratio is small). Typical examples oI header compression are TCP header compression and Real-Time Transport Protocol (RTP) header compression. 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-1-14Ways to Increase AvaiIabIe Bandwidth1-12 mplementing Cisco Quality of Service (QOS) v2.0 Copyright 2003, Cisco Systems, nc. End-to-End DeIay This topic explains how end-to-end delay can adversely impact QoS in a network and describes ways to eIIectively reduce delay. This Iigure illustrates the impact a network has on the end-to-end delay oI packets going Irom one end to the other. Each hop in the network adds to the overall delay because oI these Iactors: Propagation delay is caused by the speed oI light traveling in the media; Ior example, the speed oI light traveling in Iiber optics or copper media. Serialization delay is the time it takes to clock all the bits in a packet onto the wire. This is a Iixed value that is a Iunction oI the link bandwidth.There are processing and queuing delays within a router, which can be caused by a wide variety oI conditions. Propagation delay is generally ignored but it can be signiIicant; Ior example, about 40 ms coast-to-coast, over optical. Internet Control Message Protocol (ICMP) echo (ping) is one way to measure the round-trip time oI IP packets in a network. 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-1-15End-to-End DeIay End-to-end deIay equaIs a sum of aII propagation, processing and queuing deIays in the path. In best-effort networks, propagation deIay is fixed, processing and queuing deIays are unpredictabIe.DeIay = P1 + Q1 + P2 + Q2 + P3 + Q3 + P4 = X msBad voice Due toDelay variationCopyright 2003, Cisco Systems, nc. ntroduction to P QoS 1-13 ExampIe: Effects of DeIay A customer has a router in New York and a router in San Francisco, each connected by a 128-kbps WAN link. The customer sends a 66-byte voice Irame across the link. To transmit the Irame (528 bits) it will take 4.125 ms to clock out (serialization delay). However, the last bit will not arrive until 40 ms it clocks out (propagation delay). The total delay equals 44.125 ms. Now, change the circuit to a T1. To transmit the Irame (528 bits) it will take 0.344 ms to clock out (serialization delay). However, the last bit will not arrive until 40 ms aIter transmission (propagation delay) Ior a total delay oI 40.344 ms. In this case, the signiIicant Iactor is propagation delay. In the same situationbut Ior a link between Seattle and San Franciscoserialization delay remains the same and propagation delay drops to around 6 ms, making 528 bits take 10.125 (128-kbps link) and 6.344 (T1 link).As is evident, you must take both serialization and propagation delays into account. 1-14 mplementing Cisco Quality of Service (QOS) v2.0 Copyright 2003, Cisco Systems, nc. There are Iour kinds oI delay: Processing Delay: The time it takes Ior a router to take the packet Irom an input interIace and put it into the output queue oI the output interIace. The processing delay depends on various Iactors, such as: CPU speed CPU utilization IP switching mode Router architecture ConIigured Ieatures on both input and output interIace Queuing Delay: The time a packet resides in the output queue oI a router. It depends on the number and sizes oI packets already in the queue and on the bandwidth oI the interIace. It also depends on the queuing mechanism. Serialization Delay: The time it takes to place a Irame on the physical medium Ior transport.Propagation Delay: The time it takes to transmit a packet. (This usually depends on the type oI media interIace.) 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-1-18Processing and Queuing DeIay Processing DeIay: The time it takes for a router to take the packet from an input interface, examine it, and put it into the output queue of the output interface Queuing DeIay: The time a packets resides in the output queue of a router SeriaIization DeIay: The time it takes to pIace the "bits on the wire" Propagation DeIay: The time it takes to transmit a packetCopyright 2003, Cisco Systems, nc. ntroduction to P QoS 1-15 Assuming that a router is powerIul enough to make a Iorwarding decision in negligible time, it can be said that most processing, queuing, and serialization delay is inIluenced by the Iollowing Iactors:Average length oI the queue Average length oI packets in the queue Link bandwidth There are several approaches to accelerate packet dispatching oI delay-sensitive Ilows: Increase link capacity: SuIIicient bandwidth causes queues to shrink, making sure packets do not have to wait long beIore they can be transmitted. Additionally, more bandwidth reduces serialization time. On the other hand, this might be an unrealistic approach because oI the costs associated with the upgrade. Prioritize delay-sensitive packets: This is a more cost-eIIective approach. There are a wide variety oI queuing mechanisms available in Cisco IOS soItware that have pre-emptive queuing capabilities, Ior example: PQ CQ Strict-priority or alternate priority queuing within the MDRR (on Cisco 12000 series routers) LLQ Compress payload: Payload compression reduces the size oI packets and, thereIore, virtually increases link bandwidth. Additionally, compressed packets are smaller and need less time to be transmitted. On the other hand, compression uses complex algorithms that take time and add to the delay. This approach is, thereIore, not used to provide low-delay propagation oI packets. 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-1-24Ways to Reduce DeIay1-16 mplementing Cisco Quality of Service (QOS) v2.0 Copyright 2003, Cisco Systems, nc. Header compression: Header compression is not as CPU-intensive as payload compression and can be used in combination with other mechanisms to reduce delay. It is especially useIul Ior voice packets that have a bad payload-to-header ratio, which is improved by reducing the header oI the packet (RTP header compression). By minimizing delay, jitter is also reduced (delay is more predictable). Copyright 2003, Cisco Systems, nc. ntroduction to P QoS 1-17 Packet Loss This topic explains how packet loss can adversely impact QoS in a network and describes ways to manage packet loss so that QoS is not aIIected. The usual packet loss occurs when routers run out oI buIIer space Ior a particular interIace (output queue). The Iigure illustrates a Iull interIace output queue, which causes newly arriving packets to be dropped. The term used Ior such drops is simply 'output drop or 'tail-drop (packets are dropped at the tail oI the queue). Routers might also drop packets Ior other (less common) reasons, Ior example: Input queue drop: Main CPU is congested and cannot process packets (the input queue is Iull).Ignore: Router ran out oI buIIer space. Overrun: CPU is congested and cannot assign a Iree buIIer to the new packet. Frame errors: Hardware-detected error in a Iramecyclic redundancy check (CRC), runt, giant. 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-1-25Packet Loss TaiI-drops occur when the output queue is fuII. These are common drops, which happen when a Iink is congested. Many other types of drops exist, usuaIIy the resuIt of router congestion, that are uncommon and may require a hardware upgrade (input drop, ignore, overrun, frame errors).Bad voice Due to Packet Loss1-18 mplementing Cisco Quality of Service (QOS) v2.0 Copyright 2003, Cisco Systems, nc. Packet loss is usually the result oI congestion on an interIace. Most applications that use TCP experience slowdown because TCP adjusts to the network resources. (Dropped TCP segments cause TCP sessions to reduce their window sizes.) There are some other applications that do not use TCP and cannot handle drops (Iragile Ilows). The Iollowing approaches can be taken to prevent drops oI sensitive applications: Increased link capacity to ease or prevent congestion. Guarantee enough bandwidth and increase buIIer space to accommodate bursts oI Iragile applications. There are several mechanisms available in Cisco IOS QoS soItware that can guarantee bandwidth and provide prioritized Iorwarding to drop-sensitive applications, Ior example: PQ CQ MDDR (on Cisco 12000 series routers) IP RTP prioritization CBWFQ LLQ Prevent congestion by dropping other packets beIore congestion occurs. Weighted random early detection (WRED) can be used to start dropping other packets beIore congestion occurs.There are some other mechanisms that can also be used to prevent congestion:TraIIic shaping delays packets instead oI dropping them (generic traIIic shaping |GTS|, Frame Relay traIIic shaping |FRTS|, and class-based shaping). TraIIic policing can limit the rate oI less important packets to provide better service to drop-sensitive packets (committed access rate |CAR| and class-based policing). 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-1-30Ways to Prevent Packet LossCopyright 2003, Cisco Systems, nc. ntroduction to P QoS 1-19 SummaryThis topic summarizes the key points discussed in this lesson. ReferencesFor additional inIormation, reIer to this resource: To learn more about QoS, reIer to 'Cisco IOS Quality oI Service (QoS) at the Iollowing URL: http://www.cisco.com/warp/public/732/Tech/qos/ 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-1-31Summary Converged networks create new requirements for managing network traffic. Converged networks suffer from different quaIity issues incIuding Iack of adequate bandwidth, end-to-end and variabIe deIay, and Iost packets. Networks experience different types of deIay incIuding processing deIay, queuing deIay, seriaIization deIay, and propagation deIay. Many technoIogies exist today that can overcome the probIems presented by Iack of bandwidth, deIay, variabIe deIay, and packet Ioss.1-20 mplementing Cisco Quality of Service (QOS) v2.0 Copyright 2003, Cisco Systems, nc. QuizUse the practice items here to review what you learned in this lesson. The correct answers are Iound in the Quiz Answer Key. Q1) Which three types oI traIIic can typically tolerate packets being dropped? (Choose three.)A) Iile transIers B) voice C) e-mail D) HTTP Q2) Which three oI the Iollowing are key quality issues speciIically Ior converged networks? (Choose three.) A) lack oI bandwidth B) end-to-end delay C) variable delay D) propagation delay Q3) The maximum bandwidth available between two points is . A) the bandwidth oI the slowest link B) the bandwidth oI the Iastest link C) the average bandwidth across the links D) the average oI the slowest and Iastest links Q4) What are three ways to reduce delay Ior time-sensitive packets in a network? (Choose three.)A) compress headers B) Iorward the most important packets Iirst C) upgrade bandwidth on the links D) aggressively drop packets Q5) Which is the most common drop to occur when a link is congested? A) tail drop B) input drop C) overrun drop D) no buIIer drop Copyright 2003, Cisco Systems, nc. ntroduction to P QoS 1-21 Quiz Answer Key Q1) A, C, D ReIates to: Converged Networks Q2) A, B, C ReIates to: Converged Networks Quality ssues Q3) AReIates to: Available Bandwidth Q4) A, B, C ReIates to: End-to-End Delay Q5) AReIates to: Packet Loss 1-22 mplementing Cisco Quality of Service (QOS) v2.0 Copyright 2003, Cisco Systems, nc. Understanding QoS OverviewThe basic concepts and key terminology oI QoS are explained in this lesson. The three key steps involved in implementing a QoS policy are described. ReIevanceTo understand the more technical aspects oI network QoS, it is Iirst important to understand the basic concepts oI QoS and to be able to deIine some key QoS terms. ObjectivesUpon completing this lesson, you will be able to deIine the term QoS and identiIy and explain the key steps to implementing QoS on a converged network. This includes being able to meet these objectives: DeIine the term 'QoS with respect to traIIic in a network List and explain the key steps involved in implementing a QoS policy on a network Explain the QoS requirements oI the common types oI network applications DeIine the term 'QoS service policy DeIine the term 'QoS policy Learner SkiIIs and KnowIedge To beneIit Iully Irom this lesson, you must have these prerequisite skills and knowledge: Basic knowledge oI internetworking with TCP/IP concepts 1-24 mplementing Cisco Quality of Service (QOS) v2.0 Copyright 2003, Cisco Systems, nc. OutIineThe outline lists the topics included in this lesson. 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-1-3OutIine Overview QoS Defined QoS for Converged Networks QoS Requirements QoS Traffic CIasses QoS PoIicy Summary QuizCopyright 2003, Cisco Systems, nc. ntroduction to P QoS 1-25 QoS Defined This topic deIines the term 'QoS. QoS is the ability oI the network to provide better or 'special service to selected users and applications to the detriment oI other users and applications. Cisco IOS QoS Ieatures enable network administrators to control and predictably service a variety oI networked applications and traIIic types, thus allowing network managers to take advantage oI a new generation oI media-rich and mission-critical applications.The goal oI QoS is to provide better and more predictable network service by providing dedicated bandwidth, controlled jitter and latency, and improved loss characteristics. QoS achieves these goals by providing tools Ior managing network congestion, shaping network traIIic, using expensive wide-area links more eIIiciently, and setting traIIic policies across the network. QoS oIIers intelligent network services that, when correctly applied, help to provide consistent, predictable perIormance. 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-1-4QoS Defined1-26 mplementing Cisco Quality of Service (QOS) v2.0 Copyright 2003, Cisco Systems, nc. QoS for Converged Networks This topic describes the three steps necessary Ior implementing QoS on a network. There are three basic steps involved in implementing QoS on a network: Step 1 IdentiIy traIIic and its requirements. Study the network to determine the type oI traIIic running on the network and then determine the QoS requirements Ior the diIIerent types oI traIIic. Step 2 Group the traIIic into classes with similar QoS requirements. In the example below, Iour classes oI traIIic could be deIined: voice, high priority, low priority, andbrowser.Step 3 DeIine QoS policies that will meet the QoS requirements Ior each traIIic class. ExampIe: Three Steps to ImpIementing QoS on a Network In a typical network, voice will always require absolute minimal delay. Some data associated with key applications will require very low delay (transaction-based data used in airline reservations or online banking applications). Other types oI data can tolerate a great deal oI delay (Iile transIers and e-mail). Nonbusiness network surIing can also be delayed or even prohibited.A one-to-one mapping between traIIic classes and QoS policies need not be made. For example, three QoS policies could be implemented to meet the requirements oI the Iour traIIic classes deIined above: Assign to voice traIIic: Assign to high-priority traIIic Assign to both the low priority and browser traIIic 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-1-5QoS for Converged NetworksCopyright 2003, Cisco Systems, nc. ntroduction to P QoS 1-27 QoS Requirements This topic explains how traIIic is identiIied on a network and describes elemental QoS requirements. The Iirst step in implementing QoS is identiIying the traIIic on the network and determining QoS requirements Ior the traIIic. Determine users QoS problems. Measure the traIIic on the network during congested periods. Conduct CPU utilization assessment on each oI their network devices during busy periods to determine where problems might be occurring. Determine the business model, business goals, and obtain a list oI business requirements. This will help you deIine the number oI classes and determine the business requirements Ior each traIIic class. DeIine the service levels required by diIIerent traIIic classes in terms oI response time and availability. What is the impact on business iI a transaction is delayed by two or three seconds? Can Iile transIers wait until the network is quiescent? 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-1-6Step 1: Identify Traffic and Its Requirements Network audit Identify traffic on the network Business audit Determine how each type of traffic is important for business Service IeveIs required Determine required response time1-28 mplementing Cisco Quality of Service (QOS) v2.0 Copyright 2003, Cisco Systems, nc. Voice traIIic has extremely stringent QoS requirements. Voice traIIic generally generates a smooth demand on bandwidth and has minimal impact on other traIIic as long as it is managed. While voice packets are typically small (60 to 120 bytes), they cannot tolerate delay or drops. The result oI delays and drops are poorand oIten unacceptablevoice quality. Because drops cannot be tolerated, User Datagram Protocol (UDP) is used to package voice packets because TCP retransmit capabilities have no value. Voice packets can tolerate no more than a 15-ms delay (one-way requirement) and less than 1 percent packet loss.A typical voice call will require 17 to 106 kbps oI guaranteed priority bandwidth plus an additional 150 bps per call Ior voice-control traIIic. Multiplying these bandwidth requirements times the maximum number oI calls expected during the busiest time period will provide an indication oI the overall bandwidth required Ior voice traIIic. 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-1-7 Latency < 150 ms* Jitter < 30 ms* Loss < 1%* 17-106 kbps guaranteed priority bandwidth per caII 150 bps (+ Layer 2 overhead) guaranteed bandwidth for voice-controI traffic per caII*one-way requirementsQoS Traffic Requirements:Voice---Copyright 2003, Cisco Systems, nc. ntroduction to P QoS 1-29 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-1-8QoS Requirements:Videoconferencing Latency < 150 ms Jitter < 30 ms Loss < 1% Minimum priority bandwidth guarantee required is: Video-Stream + 20% For exampIe, a 384 kbps stream wouId require 460 kbps of priority bandwidth*one-way requirements---VideoconIerencing applications also have very stringent QoS requirements very similar to voice.But videoconIerencing traIIic is oIten bursty and greedy in nature and, as a result, can impact other traIIic. ThereIore, it is important to understand the videoconIerencing requirements Ior a network and to provision careIully Ior it. The minimum bandwidth Ior a videoconIerencing stream would require the actual bandwidth oI the stream (dependent upon the type oI videoconIerencing codec being used) plus some overhead. For example, a 384-kbps video stream would actually require a total oI 460 kbps oI priority bandwidth. 1-30 mplementing Cisco Quality of Service (QOS) v2.0 Copyright 2003, Cisco Systems, nc. The QoS requirements Ior data traIIic vary greatly. DiIIerent applications (Ior example, a human resources application versus an automated teller machine application) may make greatly diIIerent demands on the network. Even diIIerent versions oI the same application may have varying network traIIic characteristics. While data traIIic can demonstrate either smooth or bursty characteristics depending upon the application, data traIIic diIIers Irom voice and video in terms oI delay and drop sensitivity. Almost all data applications can tolerate some delay and generally can tolerate high drop rates.Because data traIIic can tolerate drops, the retransmit capabilities oI TCP become important and, as a result, many data applications use TCP. In enterprise networks, important (business-critical) applications are usually easy to identiIy. Most applications can be identiIied based on TCP or UDP port numbers. Some applications use dynamic port numbers that, to some extent, make classiIications more diIIicult. Cisco IOS soItware supports network-based application recognition (NBAR), which can be used to recognize dynamic port applications. It is recommended that data traIIic be classiIied into no more than Iour to Iive-classes as described in the graphic above. There will still remain additional classes Ior voice and video. 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-1-9QoS Traffic Requirements:Data Different appIications have different traffic characteristics Different versions of the same appIication can have different traffic characteristics CIassify data into reIative-priority modeI with no more than four- tofive-cIasses: Mission-CriticaI Apps: LocaIIy defined criticaI appIications TransactionaI: Interactive traffic, preferred data service Best-Effort: Internet, e-maiI, unspecified traffic Less-Than-Best-Effort(Scavenger): Napster/Kazaa, peer-to-peer appIicationsCopyright 2003, Cisco Systems, nc. ntroduction to P QoS 1-31 QoS Traffic CIasses This topic explains how to divide traIIic into traIIic classes. AIter the majority oI network traIIic has been identiIied and measured, use the business requirements to deIine traIIic classes. Because oI its stringent QoS requirements, voice traIIic will almost always exist in a class by itselI. Cisco has developed speciIic QoS mechanisms such as LLQ that ensure that voice always receives priority treatment over all other traIIic. AIter the applications with the most critical requirements have been deIined, the remaining traIIic classes are deIined using the business requirements. ExampIe: Traffic CIassification A typical enterprise might deIine Iive traIIic classes as: Voice: Absolute priority Ior Voice over IP (VoIP) traIIic Mission critical: Small set oI locally deIined critical business applications Transactional: Database access, transaction services, interactive traIIic, preIerred data servicesBest effort: Internet, e-mail Scavenger (less-than-best-effort): Napster/Kazaa and other point-to-point applications 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-1-10Step 2: Divide Traffic into CIasses1-32 mplementing Cisco Quality of Service (QOS) v2.0 Copyright 2003, Cisco Systems, nc. QoS PoIicy This topic describes how to deIine QoS policies aIter traIIic classes have been deIined. Finally, deIine a QoS policy Ior each traIIic class. DeIining a QoS policy involves: Setting a minimum bandwidth guarantee Setting a maximum bandwidth limit Assigning priorities to each class Using QoS technologies, such as advanced queuing, to manage congestion ExampIe: Defining QoS PoIicies Using the traIIic classes previously deIined, QoS policies could be determined as:Voice: Minimum bandwidth 1 Mbps. Use QoS marking to mark voice packets as priority 5; use LLQ to always give voice priority. Mission critical: Minimum bandwidth 1 Mbps. Use QoS marking to mark critical data packets as priority 4; use CBWFQ to prioritize critical class traIIic Ilows. Best effort: Maximum bandwidth 500 kbps. Use QoS marking to mark these data packets as priority 2; use CBWFQ to prioritize best-eIIort traIIic Ilows that are below mission-critical and voice. Scavenger: Maximum bandwidth 100 kbps. Use QoS marking to mark less-than-best-eIIort (scavenger) data packets as priority 0; use weighted random early detection (WRED) to drop these packets whenever the network has a propensity Ior congestion. 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-1-11Step 3: Define PoIicies for Each Traffic CIass Set minimum bandwidth guarantee Set maximum bandwidth Iimits Assign priorities to each cIass Manage congestionCopyright 2003, Cisco Systems, nc. ntroduction to P QoS 1-33 A QoS policy is a network-wide deIinition oI the speciIic levels oI QoS assigned to diIIerent classes oI network traIIic. Having a QoS policy is just as important in a converged network as a security policy. A written and public QoS policy allows users to understand and negotiate Ior QoS in the network. 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-1-12QoS PoIicyA network-wide definition of the specific IeveIs of quaIity of service assigned to different cIasses of network traffic1-34 mplementing Cisco Quality of Service (QOS) v2.0 Copyright 2003, Cisco Systems, nc. The graphic illustrates how a QoS policy could be deIined Ior a network. Enterprise Resource Planning (ERP) applications have a high QoS priority and must be available all the time. Video applications are guaranteed 100 kbps oI bandwidth, but can operate only between the hours oI 9:00 a.m. to 5:00 p.m. on weekdays. Voice traIIic is guaranteed less than 150 ms delay in each direction but limited to the hours oI 9:00 a.m. to 5:00 p.m. on weekdays; toll calls are completely restricted to avoid personal long-distance calls. 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-1-13QoS PoIicy (Cont.)AIign Network Resources with Business PrioritiesCopyright 2003, Cisco Systems, nc. ntroduction to P QoS 1-35 SummaryThis topic summarizes the key points discussed in this lesson. ReferencesFor additional inIormation, reIer to this resource: For more inIormation on QoS, reIer to 'Implementing Quality oI Service at the Iollowing URL:http://www.cisco.com/en/US/partner/tech/tk543/tk757/technologieswhitepaper09186a008017I93b.shtml 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-1-14Summary QoS is the abiIity of the network to provide better or "speciaI" service to users/appIications. BuiIding QoS requires three steps: identify requirements, cIassify network traffic, and define network-wide poIicies for quaIity. Voice, video, and data have very different QoSrequirements to run effectiveIy on a network. A QoS poIicy is a network-wide definition of the specific IeveIs of QoS assigned to cIasses of network traffic.1-36 mplementing Cisco Quality of Service (QOS) v2.0 Copyright 2003, Cisco Systems, nc. QuizUse the practice items here to review what you learned in this lesson. The correct answers are Iound in the Quiz Answer Key. Q1) Quality oI Service is deIined as 'the ability oI the network to. A) improve the quality oI voice transmission B) oIIer end-to-end circuits with preIerred priority C) provide special services to user and applications D) consistently move priority packets to the Iront oI queues Q2) Which three oI the Iollowing represent the three steps to implementing Quality oI Service in converged networks? (Choose three.) A) deIine QoS policies B) divide traIIic into classes C) identiIy traIIic and its requirements D) interview users to determine problems Q3) Which three oI the Iollowing represent characteristics oI voice traIIic? (Choose three.) A) drop sensitive B) smooth, constant Ilow C) benign, does not aIIect other traIIic D) relies on TCP to handle packet loss Q4) Which type oI application typically uses TCP Ior a transport protocol? A) data B) voice C) video D) videoconIerencing Q5) Which three oI the Iollowing does QoS policy involve? (Choose three.) A) assigning priorities to each class B) setting a maximum bandwidth limit C) setting a minimum bandwidth guarantee D) combining traIIic classes to go under one policy Copyright 2003, Cisco Systems, nc. ntroduction to P QoS 1-37 Quiz Answer Key Q1) CReIates to: QoS Defined Q2) A, B, C ReIates to: QoS for Converged Networks Q3) A. B, C ReIates to: QoS Requirements Q4) AReIates to: QoS Requirements Q5) A, B, C ReIates to: QoS Policy 1-38 mplementing Cisco Quality of Service (QOS) v2.0 Copyright 2003, Cisco Systems, nc. mplementing P QoS OverviewCisco recommends using either the Modular QoS command-line interIace (MQC) or Cisco AutoQoS Ior implementing QoS in a network. The MQC oIIers a highly modular way to Iine-tune a network. AutoQoS oIIers an automated method Ior almost instantly incorporating consistent voice QoS in a network oI routers and switches. In addition, CiscoWorks QoS Policy Manager (QPM) provides centralized QoS design, administration, and traIIic monitoring that scales to large QoS deployments. ReIevanceIt is very important to understand the diIIerent ways to implement QoS in a network. There are tradeoIIs regarding the use oI the MQC versus AutoQoS in implementing QoS and knowing the diIIerences between MQC and AutoQoS can help a network administrator save time and resources.1-40 mplementing Cisco Quality of Service (QOS) v2.0 Copyright 2003, Cisco Systems, nc. ObjectivesUpon completing this lesson, you will be able to list and describe methods Ior implementing QoS. This includes being able to meet these objectives: List and describe methods Ior conIiguring and monitoring QoS on a network Explain at a high level, the CLI (nonmodularized) method oI conIiguring QoS Explain at a high level, the MQC method oI conIiguring QoS Explain at a high level, the AutoQoS method oI conIiguring QoS IdentiIy and explain the advantages and disadvantages oI using each oI the methods oI implementing QoS on a network Explain how QPM can be used to manage QoS policies on a network Explain the purpose oI a MIB and how it is used with QPM to monitor network Explain how the QoS MIBs can be used with QPM to monitor QoS on a network Learner SkiIIs and KnowIedge To beneIit Iully Irom this lesson, you must have these prerequisite skills and knowledge: Basic understanding oI the Cisco IOS command-line interIace (CLI) Copyright 2003, Cisco Systems, nc. ntroduction to P QoS 1-41 OutIineThe outline lists the topics included in this lesson. 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-1-3OutIine Overview Methods for ImpIementing QoS PoIicy Legacy CLI ModuIar QoS CLI AutoQoS QoS ImpIementation Methods Compared QoS PoIicy Manager Network Management MIBs for Monitoring QoS MIBs for Managing QoS Summary Quiz1-42 mplementing Cisco Quality of Service (QOS) v2.0 Copyright 2003, Cisco Systems, nc. Methods for ImpIementing QoS PoIicy This topic describes Iour diIIerent methods Ior implementing and managing a QoS policy. Just a Iew years ago, the only way to implement QoS in a network was by using the CLI to individually conIigure QoS policies at each interIace. This was a time-consuming, tiresome, and error-prone task involving cutting and pasting conIigurations Irom one interIace to another. Cisco introduced the MQC in order to simpliIy QoS conIiguration by making conIigurations modular. Using MQC, QoS can be conIigured in a building block approach using a single module repeatedly to apply policy to multiple interIaces. Cisco AutoQoS represents innovative technology that simpliIies the challenges oI network administration by reducing QoS complexity, deployment time, and cost in enterprise networks. Cisco AutoQoS incorporates value-added intelligence in Cisco IOS soItware and Cisco Catalyst soItware to provision and assist in the management oI large-scale QoS deployments. The Iirst phase oI Cisco AutoQoS oIIers straightIorward capabilities to automate VoIP deployments Ior customers who want to deploy IP telephony but lack the expertise and staIIing to plan and deploy IP QoS and IP services. Customers can more easily provision and manage successIul QoS deployments by using Cisco AutoQoS together with CiscoWorks QPM. Cisco AutoQoS provides QoS provisioning Ior individual routers and switches, simpliIying deployment and reducing human error. CiscoWorks QPM provides centralized QoS design, administration, and traIIic monitoring that scales to large QoS deployments. 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-1-4Methods for ImpIementing QoS PoIicy CLI MQC AutoQoS QPMCopyright 2003, Cisco Systems, nc. ntroduction to P QoS 1-43 Legacy CLI This topic describes the CLI method Ior implementing QoS. At one time, CLI was the only way to implement QoS in a network. It was a painstaking task involving copying one interIace conIiguration and then pasting it into other interIace conIigurations. It took a lot oI time and patience. The CLI method was nonmodularthere was no way to separate the classiIication oI traIIic Irom the actual deIinition oI policy. Network administrators had to do both on every interIace. The Iigure illustrates an example oI the complex conIiguration tasks involved in using CLI. While CLI is not recommended Ior implementing QoS policy, it is still used to Iine-tune QoS implementations that have been generated using the Cisco AutoQoS macro. 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-1-5ImpIementing QoS with CLI TraditionaI method NonmoduIar Cannot separate traffic cIassification from poIicy definitions Used to augment, fine-tune newer AutoQos methodinterface serial 0/0ip address 10.1.61.1 255.255.255.0ip tcp header~compression iphc~formatload~interval 30custom~queue~list 1ppp multilinkppp multilink fragment~delay 10ppp multilink interleavemultilink~group 1ip rtp header~compression iphc~format!interface serial0/1bandwidth 256no ip addressencapsulation pppno ip mroute~cacheload~interval 30no fair~queueppp multilinkmultilink~group 1interface serial 0/0ip address 10.1.61.1 255.255.255.0ip tcp header~compression iphc~formatload~interval 30custom~queue~list 1ppp multilinkppp multilink fragment~delay 10ppp multilink interleavemultilink~group 1ip rtp header~compression iphc~format!interface serial0/1bandwidth 256no ip addressencapsulation pppno ip mroute~cacheload~interval 30no fair~queueppp multilinkmultilink~group 11-44 mplementing Cisco Quality of Service (QOS) v2.0 Copyright 2003, Cisco Systems, nc. ModuIar QoS CLI This topic describes the MQC method Ior implementing QoS. The MQC is a CLI structure that allows users to create traIIic polices and then attach these polices to interIaces. A traIIic policy contains one or more traIIic classes and one or more QoS Ieatures. A traIIic class is used to classiIy traIIic; the QoS Ieatures in the traIIic policy determine how to treat the classiIied traIIic. The MQC oIIers signiIicant advantages over the legacy CLI method Ior implementing QoS. By using MQC, a network administrator can signiIicantly reduce the time and eIIort it takes to conIigure QoS on a complex network. Rather than conIiguring 'raw CLI commands interIace by interIace, the administrator develops a uniIorm set oI traIIic classes and QoS policies, which can be applied on interIaces. The use oI the MQC allows the separation oI traIIic classiIication Irom the deIinition oI QoS policy. This enables easier initial QoS implementation and maintenance as new traIIic classes emerge and QoS policies Ior the network evolve. 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-1-6ImpIementing QoS with MQC A command syntax for configuring QoS poIicy Reduces configuration steps and time Configure poIicy, not "raw" per-interface commands Uniform CLI across major Cisco IOS pIatforms Uniform CLI structure for aII QoS features Separates cIassification engine from the poIicyclass~map VoIP~RTPmatch access~group 100class~map VoIP~Controlmatch access~group 101!policy~map QoS~Policyclass VoIP~RTPpriority 100class VoIP~Controlbandwidth 8class class~defaultfair~queue!interface serial 0/0service~policy output QoS~Policy!access~list 100 permit ip any any precedence 5access~list 100 permit ip any any dscp efaccess~list 101 permit tcp any host 10.1.10.20 range 2000 2002access~list 101 permit tcp any host 10.1.10.20 range 11000 11999class~map VoIP~RTPmatch access~group 100class~map VoIP~Controlmatch access~group 101!policy~map QoS~Policyclass VoIP~RTPpriority 100class VoIP~Controlbandwidth 8class class~defaultfair~queue!interface serial 0/0service~policy output QoS~Policy!access~list 100 permit ip any any precedence 5access~list 100 permit ip any any dscp efaccess~list 101 permit tcp any host 10.1.10.20 range 2000 2002access~list 101 permit tcp any host 10.1.10.20 range 11000 11999Copyright 2003, Cisco Systems, nc. ntroduction to P QoS 1-45 AutoQoSThis topic describes the use oI Cisco AutoQos Ior implementing QoS in a network. 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-1-7ImpIementing QoS with AutoQoS LAN & WAN-routers and switches One command enabIes Cisco QoS for VoIP on a given port/interface/PVCUsing Cisco AutoQos, network administrators can implement the QoS Ieatures that are required Ior VoIP traIIic without an in-depth knowledge oI the Iollowing underlying technologies: PPPFrame Relay ATMService policies Link eIIiciency mechanisms, such as link Iragmentation and interleaving (LFI) The AutoQoS VoIP Ieature simpliIies QoS implementation and speeds up the provisioning oI QoS technology over a Cisco network. It also reduces human error and lowers training costs. With the AutoQoS VoIP Ieature, one command (the command) enables QoS Ior VoIP traIIic across every Cisco router and switch. Network administrators can also use existing Cisco IOS commands to modiIy the conIigurations that are automatically generated by the AutoQoS VoIP Ieature in case the deIault AutoQoS conIiguration is not suIIicient. CiscoWorks QPM can be used in conjunction with the AutoQoS VoIP Ieature to provide a centralized, web-based tool to cost eIIectively manage and monitor network-wide QoS policies. The AutoQoS VoIP Ieature, together with CiscoWorks QPM, eases QoS implementation, provisioning, and management. Note: Cisco AutoQoS was introduced in the 12.2(15)T Cisco OS software release. 1-46 mplementing Cisco Quality of Service (QOS) v2.0 Copyright 2003, Cisco Systems, nc. QoS ImpIementation Methods Compared This topic compares the diIIerent methods Ior implementing QoS. The three methods Ior conIiguring QoS on a network are the legacy CLI method, the MQC method, and Cisco AutoQoS. Cisco recommends the use oI the MQC and Cisco AutoQoS Ior implementing QoS. While MQC is much easier to use than CLI, AutoQoS can simpliIy the conIiguration oI QoS. As a result, the Iastest implementation possible can usually be accomplished with AutoQoS. MQC oIIers excellent modularity and the ability to Iine-tune complex networks. AutoQoS oIIers the Iastest way to implement QoS, but has limited Iine-tuning capabilities. When an AutoQoS conIiguration has been generated, it is necessary to use CLI commands to Iine-tune an AutoQoS conIiguration iI necessary. (On most networks Iine-tuning will not be necessary Ior AutoQoS.) 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-1-8Comparing Methods for ImpIementing QoSCopyright 2003, Cisco Systems, nc. ntroduction to P QoS 1-47 QoS PoIicy Manager This topic describes the use oI the QPM Ior managing QoS on a network. CiscoWorks QPM provides a scalable platIorm Ior deIining, applying, and monitoring QoS policy on a system-wide basis Ior Cisco devices, including routers and switches. QPM enables you to baseline proIile network traIIic, create QoS policies at an abstract level, control the deployment oI policies, and then monitor QoS to veriIy intended results. As a centralized tool QPM is used to monitor and provision QoS Ior groups oI interIaces and devices.QPM provides a web-based intuitive user interIace to deIine QoS policies and translates those policies into the device CLI commands. QPM lets you analyze traIIic throughput by application or service class. This analysis leverages that inIormation to conIigure QoS policies to diIIerentiate traIIic and deIine the QoS Iunctions that are applied to each type oI traIIic Ilow. By simpliIying QoS policy deIinition and deployment, QPM makes it easier Ior you to create and manage end-to-end diIIerentiated services in your network, thus making more eIIicient and economical use oI your existing network resources. For example, you can deploy policies that ensure that your mission-critical applications always get the bandwidth required to run your business. 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-1-9QoS PoIicy ManagerSuite of management functions aIIow networkadministrators to fuIIy Ieverage the Cisco inteIIigent IP infrastructure, enabIe network-wide QoS for voice, and obtain precise, easy to understand QoS information with monitoring and reporting. Voice QoS ready devices DepIoyment audit Device overwrite report Voice QoS ready devices DepIoyment audit Device overwrite report Device QoS TroubIeshooting Device QoS TroubIeshooting Recommendations via wizards, tempIates Verification Customize Recommendations via wizards, tempIates Verification CustomizeReporting Monitoring Provisioning1-48 mplementing Cisco Quality of Service (QOS) v2.0 Copyright 2003, Cisco Systems, nc. Customers can more easily provision and manage successIul QoS deployments using Cisco AutoQoS together with QPM. Cisco AutoQoS provides QoS provisioning Ior individual routers and switches, simpliIying deployment and reducing human error. CiscoWorks QPM provides centralized QoS design, administration, and traIIic monitoring that scales to large QoS deployments. 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-1-10Cisco AutoQoS with CiscoWorks QPMUse AutoQoS to configure each switch or router.Use QPM to manage network-wide QoS for muItipIe devices.Copyright 2003, Cisco Systems, nc. ntroduction to P QoS 1-49 Network Management MIBs for Monitoring QoS This topic describes the key Management InIormation Bases (MIBs) that are used in managing QoS implementations. An MIB is a Simple Network Management Protocol (SNMP) structure that describes the particular device being monitored. Cisco provides many standards-based MIBs Ior use in monitoring the status oI devices on a network. Advanced network management products, such as CiscoWorks QPM, use these MIBs to generate statistics on the perIormance oI the network. Specialized QoS MIBs enable QPM to graphically display key QoS inIormation to aid in the management oI QoS policies on the network.Note: See the Cisco Network Management Toolkit for MBs at http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-1-11Network Management MIBs for Monitoring QoS MIB: Management Information Base An SNMP structure that describes the particuIar device being monitored1-50 mplementing Cisco Quality of Service (QOS) v2.0 Copyright 2003, Cisco Systems, nc. MIBs for Managing QoS This topic describes the key MIBs that are used Ior managing QoS policy on a network. The Class-Based QoS MIB (CBQoSMIB) provides read access to QoS conIigurations. This MIB also provides QoS statistics inIormation based on the MQC, including inIormation regarding class map and policy map parameters. This CBQoSMIB actually contains two MIBs: Cisco Class-Based QoS MIB and Cisco Class-Based QoS Capability MIB. 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-1-12CIass-Based QoS MIB (CBQoSMIB) Provides read access to configuration and statisticaI information for MQC-based QoS poIicies Provides MQC configuration information and appIication statistics Provides CBQoS statistics on a per-poIicy/per-interface or PVC basis AIIows monitoring of pre- and post-poIicy bit rates on a deviceCopyright 2003, Cisco Systems, nc. ntroduction to P QoS 1-51 CiscoWorks QPM uses the inIormation collected in the class-based MIB to build a number oI reports showing the eIIect oI QoS policies on the network. These reports can graphically illustrate the overall input traIIic Ilow divided by traIIic class, the traIIic that was actually sent, and the traIIic that was dropped because oI QoS policy enIorcement. In the Reports tab Ior QPM, under Historical Reports, it is possible to create graphs, some oI which include: 'Matching TraIIic Per Class Prior to QoS Actions graphs that display the traIIic that matched each policy group Iilters, beIore any policy actions were perIormed 'Matching TraIIic Per Class After QoS Actions graphs that display the traIIic that matched each policy group Iilters and was transmitted (not dropped) by the conIigured QoS policies 'Matching TraIIic Per Class Discaraea by QoS Drop Actions graphs that display the traIIic that matched each policy group Iilters and was dropped (not transmitted) by QoS policy drop actions 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-1-13QPM: Monitoring and Reporting with CBQoSMIB1-52 mplementing Cisco Quality of Service (QOS) v2.0 Copyright 2003, Cisco Systems, nc. Another important MIB that is used Ior monitoring QoS is the Cisco NBAR Protocol Discovery MIB (CNPD MIB). Using the inIormation collected by this MIB, it is possible to collect detailed protocol and application-level network utilization statistics. Note: CNPD MB is discussed further in the module Classification and Marking when NBAR is explained. 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-1-14Cisco NBAR ProtocoI Discovery MIB NBAR protocoI discovery statistics onIy avaiIabIe on the configured device Provides abiIity to retrieve statistics via SNMP into a centraI performance monitoring systemCopyright 2003, Cisco Systems, nc. ntroduction to P QoS 1-53 SummaryThis topic summarizes the key points discussed in this lesson. ReferencesFor additional inIormation, reIer to these resources: For more inIormation on QPM, reIer to 'Introduction to QPM at the Iollowing URL: http://www.cisco.com/en/US/products/sw/cscowork/ps2064/productsuserguidechapter09186a00800e0a00.htmlFor more inIormation on Cisco MIBs, reIer to 'Cisco Network Management Toolkit Ior MIBs at the Iollowing URL: http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml 2003, Cisco Systems, Inc. AII rights reserved. QOS v2.0-1-15Summary There are four different methods for impIementingQoS: CLI, MQC, AutoQoS, and QPM. CLI QoS configurations can be compIex and in many cases requires Iearning different syntax for different QoS mechanisms. MQC separates the cIassification of network traffic from the definition of the QoS poIicy. AutoQoS is used to automaticaIIy impIement a set of QoS poIicies on a router or switch. QPM can be used with the two QoS MIBs (CBQoSMIB and CNPD-MIB) to provide enhanced monitoring of network QoS.1-54 mplementing Cisco Quality of Service (QOS) v2.0 Copyright 2003, Cisco Systems, nc. QuizUse the practice items here to review what you learned in this lesson. The correct answers are Iound in the Quiz Answer Key. Q1) Which three methods are used to implement QoS policy? (Choose three.) A) AutoQoS B) QoS CLI Manager C) QoS Policy Manager D) Command-Line InterIace Q2) Which oI the Iollowing is a major advantage oI MQC? A) capability to generate QoS CLI code automatically B) ability to separate classiIication Irom policy deIinition C) capability to do Iine-tuning with 'raw CLI commands D) ability to automatically recognize new classes oI traIIic Q3) Which three oI the Iollowing are advantages oI Cisco AutoQoS over other methods Ior implementing QoS? (Choose three.) A) reduces human error B) lowers training costs C) increases consistency D) works Ior all situations Q4) Which three oI the Iollowing are Ieatures oI QPM? (Choose three.) A) baseline proIile network traIIic B) control deployment oI policies C) create QoS policies at an abstract level D) auto alert users oI QoS policy violation Q5) MIB is an acronym Ior. A) Management Interrupt Block B) Management InIormation Base C) Management InIormation Block D) Management Implementation Block Copyright 2003, Cisco Systems, nc. ntroduction to P QoS 1-55 Q6) Using the Class-Based QoS MIB with QPM, it is possible to create which two oI the Iollowing? (Choose two.) A) AutoQoS Macro EIIiciency Analysis B) matching TraIIic Per Class After QoS Actions C) matching TraIIic Per Class Prior to QoS Actions D) matching TraIIic by AutoQoS Generated Classes 1-56 mplementing Cisco Quality of Service (QOS) v2.0 Copyright 2003, Cisco Systems, nc. Quiz Answer Key Q1) A, C, D ReIates to: Methods for mplementing QoS Policy Q2) BReIates to: Modular QoS CL Q3) A, B, C ReIates to: AutoQoSQ4) A, B, C ReIates to: QoS Policy Manager Q5) BReIates to: Network Management MBs for Monitoring QoS Q6) B, C ReIates to: MBs for Managing QoS Module Assessment OverviewUse this assessment to test what you learned in this module. The correct answers and solutions are Iound in the Module Assessment Answer Key. 1-58 mplementing Cisco Quality of Service (QOS) v2.0 Copyright 2003, Cisco Systems, nc. Quiz: Introduction to IP QoS Complete the Quiz to assess what you have learned in the module. ObjectivesThis activity tests your knowledge on how to meet these objectives: IdentiIy problems that could lead to poor QoS and explain how the problems might be resolvedDeIine the term QoS and identiIy and explain the key steps to implementing QoS on a converged network List and describe methods Ior implementing QoS InstructionsComplete these steps: Step 1 Answer all questions in this quiz by selecting the best answer(s) to each question. Step 2 VeriIy your results against the answer key located at the end oI this section. Step 3 Review the topics in this module that relate to the questions that you answered incorrectly. Q1) Which oI the Iollowing terms is used to describe the time it takes to actually transmit a packet on a link (put bits on the wire)? A) encoding delay B) processing delay C) serialization delay D) transmission delay Q2) What is the 'best solution Ior reducing delay on a link? A) compress data and headers B) drop low priority packets early C) increase the bandwidth oI the link D) incorporate advanced queuing technologies Q3) Which three oI the Iollowing are characteristics oI converged network traIIic? (Choose three.)A) constant small packet Ilow B) time-sensitive packets C) brieI outages are unacceptable D) bursty small packet Ilow Copyright 2003, Cisco Systems, nc. ntroduction to P QoS 1-59 Q4) How much one-way delay can a voice packet tolerate? A) 15 ms B) 150 ms C) 300 ms D) 200 ms Q5) Which transport layer protocol is used Ior voice traIIic? A) UDP B) TCP C) XNS D) HTTP Q6) Which three oI the Iollowing represent components in the deIinition oI a QoS policy? (Choose three.) A) user validated B) network-wide C) speciIic levels oI quality oI service D) diIIerent classes oI network traIIic Q7) How are QoS implementations generated using AutoQoS Iine-tuned? A) command-line interIace B) Modular QoS CLI C) QoS AutoTune D) QoS Policy Manager Q8) Which three oI the Iollowing are advantages oI using MQC? (Choose three.) A) reduction in time to conIigure a complex policy B) ability to apply one policy to multiple interIaces C) separation oI classiIication Irom policy deIinition D) automatic generation oI CLI commands Irom M