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VoIP Performance Management and Optimization

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  • Copyright 2011
  • Dimensions: 7-3/8" x 9-1/8"
  • Edition: 1st
  • eBook (Watermarked)
  • ISBN-10: 0-13-343360-9
  • ISBN-13: 978-0-13-343360-9

VoIP Performance Management and Optimization

A KPI-based approach to managing and optimizing VoIP networks

IP Communications

Adeel Ahmed, CCIE® No. 4574

Habib Madani

Talal Siddiqui, CCIE No. 4280

VoIP Performance Management and Optimization is the first comprehensive, expert guide to managing, monitoring, troubleshooting, and optimizing large VoIP networks. Three leading Cisco VoIP experts bring together state-of-the-art techniques for ensuring that customer service level agreements (SLA) are consistently met or exceeded.

The authors begin by reviewing how VoIP is deployed in enterprise and service provider networks and the performance tradeoffs and challenges associated with each leading VoIP deployment model. Next, they present a comprehensive approach to diagnosing problems in VoIP networks using key performance indicators (KPI) and proactively addressing issues before they impact service.

In this book, you will find a proven tools-based strategy for gauging VoIP network health and maximizing performance and voice quality. You also will learn how to perform trend analysis and use the results for capacity planning and traffic engineering—thereby optimizing your networks for both the short- and long-term.

The authors all work in the Cisco Advanced Services Group.

  • Deploy, manage, monitor, and scale multivendor VoIP networks more effectively
  • Integrate performance data from multiple VoIP network segments and service flows to effectively manage SLAs
  • Use performance counters, call detail records, and call agent trace logs to gauge network health in real time
  • Utilize dashboards to analyze and correlate VoIP metrics, analyze trends, and plan capacity
  • Implement a layered approach to quickly isolate and troubleshoot both localized and systemic problems in VoIP networks
  • Optimize performance in networks where the service provider owns the “last mile” connection
  • Improve performance when VoIP is deployed over publicly shared infrastructure
  • Manage performance in enterprise networks using both centralized and distributed call processing
  • Plan media deployment for the best possible network performance
  • Monitor trends, establish baselines, optimize existing resources, and identify emerging problems
  • Understand and address common voice quality issues

This IP communications book is part of the Cisco Press® Networking Technology Series. IP communications titles from Cisco Press help networking professionals understand voice and IP telephony technologies, plan and design converged networks, and implement network solutions for increased productivity.

Category: Networking: Unified Communications

Covers: Voice over IP Network Management

Table of Contents



Part I VoIP Networks Today

Chapter 1 Voice over IP (VoIP) and Network Management 1

VoIP Technology 2

VoIP Overview 3

    Media Transport Protocol for VoIP—RTP 5

    VoIP Signaling Protocols 8

Common Network Problems in VoIP Networks 9

    Delay/Latency 9

        Propagation Delay 10

        Processing Delay 10

        Serialization/Queuing Delay 11

    Jitter 11

    Packet Loss 12

    Voice Activity Detection (VAD) 13

    Other Issues 13

Common Voice Quality Problems in IP Networks 14

Strategic Importance of VoIP and Management 18

Network Management Methodologies 20

    Telecommunications Management Network 20

    FCAPS Model 21

        Fault Management 21

        Configuration Management 21

        Accounting Management 22

        Performance Management 22

        Security Management 22

    Information Technology Infrastructure Library (ITIL) 23

        Service Strategy 23

        Service Design 24

        Service Transition 25

        Service Operation 26

        Continual Service Improvement 27

    Enhanced Telecom Operations Map (eTOM) 27

Comprehensive Network Management Methodology 28

    Focusing on Performance Metrics 30

Summary 32

Reference 32

Chapter 2 A Metrics-Based Approach for Managing the VoIP Network 33

VoIP Networks Require a Layered Management Approach 34

    Tracking Systemic Performance Issues 37

    Localized Performance Issues 39

    Subjective Performance Issues 39

    Downtime and Impact 40

Proactive Monitoring Concept 41

KPIs 43

    VoIP-Signaling KPIs 44

    VoIP Media KPIs 45

VoIP Network Segments and VoIP Service Flows 46

    Voicemail Segment 46

    Announcement Segment 47

    Voice Termination Point Segment 47

        Voice ONNET Call Leg Segment 47

        Voice OFFNET or PSTN-Bound Segment 47

    PSTN Bearer Traffic Segment 48

Service-Level Agreement (SLA) Management 48

    SBC Trunk Uptime 50

    PSTN/IMT Trunk Uptime 50

    Signaling SS7 Link Uptime 50

    Vendor Accountability 51

    Tools Utilized 51

Summary 52

Reference 52

Part II VoIP Deployment Models

Chapter 3 VoIP Deployment Models in Service Provider Networks 53

Service Provider Voice Implementation Models 54

Residential Applications: Voice over Broadband 55

Small/Medium Business Applications (Voice over T1/E1/PRI/CAS) 58

IP Trunks 59

Session Border Controller (SBC) Models 62

Key Components Used in SBC Models 63

    PSTN Offload 64

    Network Hiding 65

Voice Security in Service Provider Networks 65

    Securing VoIP Network Elements 65

    Securing Call Signaling and the Media 66

Common Issues and Problems When Deploying IP-Based Telephony Services 66

    Convergence-Related Issues 66

    Issues in Media Affecting Quality 67

    Issues in Signaling Affecting the Services and Features 67

    IP Routing–Related Issues 67

    High Availability and Convergence for Business Continuity 68

Summary 68

References 68

Chapter 4 Internet Telephony 69

Internet Telephony Deployment Model 70

    Internet Telephony Network Elements 72

    Internet Telephony Applications 73

        PC-Based Software Voice Applications 73

        ATA-Based Voice Applications 74

    Traffic Profiling 74

    Potential Bottlenecks 75

Wholesale VoIP Solution 75

    Key Network Elements 77

        Media Gateway Controller (MGC) 77

        IP Transfer Point (ITP) 78

        Route Server 78

        Gatekeepers 79

        Application Servers 79

        Element Management Systems (EMS) 79

    Wholesale Voice Applications 80

        Prepaid and Postpaid Calling Solutions 80

        Network Transit and Trunking Applications 82

        Managed Services for Enterprises 83

        Applications and Benefits for Service Providers 83

Common Issues and Problems with Internet Telephony 83

    Last-Mile Connection Bandwidth 84

    End Device/Application-Related Issues 85

    No Customer Service-Level Agreements (SLA) 86

    Issues with Emergency Calls (E911) 86

    Security Issues 87

Summary 88

References 88

Chapter 5 VoIP Deployment Models in Enterprise Networks 89

Unified Communication Solution Components in Enterprise Networks 90

    Unified Communications Manager/CallManager 90

    Voice Gateways 91

    Gatekeepers 92

    Session Border Controller 93

    Messaging Application 94

    Rich Media Applications 95

        Cisco Unified MeetingPlace and WebEx 95

        Cisco Unified Presence 95

        Cisco Emergency Responder 96

        Cisco Unified Contact Center 97

        Cisco Unified Application Environment 97

Common Enterprise Deployment Models 97

    Centralized Call Processing 98

    Distributed Call Processing 100

    Hybrid Models 102

Common Issues and Problems 104

    Convergence-Related Issues 104

    Issues Affecting Media Quality 105

    Voice-Signaling Protocol Impairments 106

    Voice Security in Enterprise Converged Networks 106

Summary 107

References 107

Part III Performance and Optimization of VoIP Networks

Chapter 6 Managing VoIP Networks 109

Requirements for Enabling Voice in IP Networks 109

    Network Readiness Assessment 110

        Network Design 110

        Network Infrastructure Services 112

        Network Links 113

        Hardware and Software Considerations 114

        Power and Environment 115

    Auditing for VoIP Network Readiness 116

        Analyzing Configurations, Versions, and Topology 117

        Synthetic Traffic Tests 118

    Managing Network Capacity Requirements 118

        Voice Traffic Engineering Theory 119

        Example of Estimating Capacity Requirements 119

        Monitoring Network Resources 122

    An Audit for Gauging the Current VoIP Network Utilization 122

        Device Utilization 123

        Link Utilization 124

    Measurements for Network Transmission Loss Plan 124

Effectively Monitoring the Network 127

    Discovery—Complete Picture 128

        Seed Devices for Network Discovery 129

        Cisco Discovery Protocol (CDP) Discovery 129

        Routing Table Discovery 130

        ARP Discovery 130

        Routing Protocol—OSPF Discovery 130

        Ping Sweep Discovery 130

        Seed Files 131

    Voice Quality Metrics 131

        MOS or K-factor 132

        PSQM 132

        PESQ 133

    Approaches to Measure Jitter, Latency, and Packet Loss in the IP Network 133

        Using Call Detail Records for Voice Quality Metrics 133

        Using IP-SLA and RTTMON for Voice Quality Metrics 134

        Using Cisco NetFlow for Measuring Voice Quality Metrics 135

        Round-Trip Delay Measurement 136

        Voice Jitter/Frame Slip Measurements 137

        Measurement of Effective Bandwidth 137

        Voice Band Gain Measurement 137

        Silence Noise level Measurement 138

        Voice Clipping 138

        Echo Measurements 138

    Voice-Signaling Protocol Impairments in IP Networks 139

How to Effectively Poll the Network 140

    Polling Strategy 141

    Key Alarms and Events Monitoring 143

    SNMP Configuration and Setting 143

        Basic Configuration 144

        SNMP Trap Settings 144

        Traps Use Case BTS 10200 Cisco Softswitch 144

    Standard Polling Intervals and Traps 145

        Scenario 1: Phones Unregistering from Unified CM and Reregistering to SRST Router Because of WAN Link Outage 145

        Scenario 2: Phones Unregistering from the Unified CM and Reregistering to the SRST Router Because of WAN Congestion 146

        Using eXtensible Markup Language (XML) for Polling and Extraction of Key Information 147

        XML Overview 148

        XML APIs 149

Using the Syslog/Trace Logs for Deep Analysis 150

Alarm and Event Audit and Correlation 151

Effectively Monitoring the PSTN Bearer Traffic 153

QoS in VoIP Networks 155

    Defining a QoS Methodology 155

        Differentiated Services (Diff Serv) for Applying QoS 155

        Using Bandwidth/Resource Reservation and Call Admission Control (CAC) for Providing QoS 157

    Managing QoS 157

        PacketCable Use Case 159

Trouble Ticketing (TT) Systems 162

    Identifying and Streamlining the Categories of Trouble Tickets 162

    Correlating the TT to the Service Uptime 162

Summary 163

References 164

Chapter 7 Performance Analysis and Fault Isolation 167

Proactive Monitoring Through Performance Counters 168

    Classification of Performance Counters 168

        Network Device KPIs 168

        Functional- or Services-Based Grouping of KPIs 169

        Fault Isolation–Based Grouping of KPIs 173

        Protocol-Based Grouping of KPIs 174

        SLA Tracking Through KPIs 175

        Equipment-Based Grouping of KPIs 177

    Collection 177

    Alarm Processing 178

    Correlation 179

        Simple Correlation 180

        Advanced Correlation 180

        Complex Correlations 181

    Recommendations for VoIP-Centric Network Management Framework 182

Performance Analysis from a Transit Network Perspective 183

    Signaling Protocol Transport Optimization 184

        Enterprise Networks 184

    Cisco IOS QoS Recommended SNMP Polling Guidelines 187

        Case Study of Link Congestions 187

        SP Networks 194

    Performance Data in an Enterprise VoIP Environment 197

        CPU Status 198

        Physical Memory 198

        Hard Disk Status 199

        High Utilization of Disk Space 199

        Virtual Memory 199

        Number of Active Phones 200

        Gateway Registration (MGCP) 200

        Gatekeeper Registration (H.323 RAS) 200

        Calls in Progress 201

        Calls Active 201

        Calls Attempted 202

        Calls Completed 202

        PRI Channels Active 203

        Conferencing/Transcoding DSP’s Depletion 203

        Available Bandwidth of a Location (CAC) 204

    Recommendations for Categorizing Performance Measurements 204

Enterprise Case Study—Analyzing Network Performance 206

    CPU Rate and Critical Processes 206

    Rate of Active Calls 207

        Tracking Trunk Utilization for PSTN Access 208

        Trend Analysis Best Practices 211

Performance Analysis from Call Agent Perspective 211

    Performance Analysis for VoIP Call Traffic 211

    Performance Analysis for a PSTN Network (PSTN Trunk and SS7 Signaling) 215

    Performance Analysis for an SIP Network 217

    Performance Tracking for a Session Border Controller (SBC) 218

    Performance Information Through the Call Detail Records (CDR) 219

    Performance Enhancement Schemes and Their Effect on VoIP Network Monitoring 220

        Effect of DNS Caching 220

        Server Load Balancing 220

        Firewall 220

        Optimizing the SBC 221

Performance Analysis from a DOCSIS Network 221

    VoIP Endpoints 222

    DOCSIS/DQoS 224

    CPU Impact/Link Utilization 226

Trace Log Monitoring on Softswitch and Network Devices 229

    Analyzing and Correlating Syslog Messages 230

    Log Files Management 231

        Security 231

        Storage Location (Local Versus Remote) and Archiving Logs 233

Tools and Scripts 234

    Tools for Monitoring an Enterprise VoIP Network 234

        Cisco Unified Operations Manager (CUOM) 234

        Cisco Unified Service Manager 236

        Cisco Unified Service Statistics Manager 237

    Tools for Monitoring Service Provider VoIP Networks 239

        IXIA’s IxRave Solution 239

        IxRave Case Study—Voice Assurance for Cable Networks 240

    Tools for Monitoring DOCSIS Networks—VoIP Dashboard 242

    Tools for Monitoring VoIP Network Health Through Protocols 244

    Tools for Analyzing Call Detail Records 246

        SP CDR Report Scenario 246

        Customizing CDR Reporting for Effective Monitoring 247

    Dashboard Views for the VoIP Network 247

Software Maintenance 248

    Software Release Management 249

    Software Lifecycle Management 249

    Software Resiliency 251

    Periodic Auditing of a VoIP Network 251

Summary 254

References 254

Chapter 8 Trend Analysis and Optimization 257

Trend Analysis Through Key Metrics 258

    Dashboard as a Profiling Tool 259

        Network Utilization and Efficiency 260

        Safeguarding Network Resources from Potential Security Threats 261

    Dashboard for Trunk Resources Utilization 265

        Feedback for Change Control 266

    Profiling in an SP VoIP Network 271

    Profiling in an Enterprise VoIP Network 277

        Balancing the Device Load on CUCM Cluster Nodes 278

        Maximizing Trunk Capacity and Avoiding Call Blocking 280

Call Detail Record–Based Trend Analysis 283

    Benchmarking 283

        Verifying VoIP Network Resources Capacity 284

    SLA Conformance 286

        Monitoring for Service Availability 286

        Normal Versus Abnormal Termination Profiling: Categorizing and Correlating the Call Termination Code 288

        Monitoring for Service Quality 289

    Verifying Toll Savings (On-net Versus Off-net Profiling) 289

    Detecting Toll Frauds 291

Resource Optimization and Capacity Planning 291

Network Resource Utilization and Optimization 291

Capacity Planning and Upgrade Strategies 296

Managing Subscriber Growth Impact by Using Trend Analysis 298

        UC Manager Cluster Capacity 298

        Network Bandwidth and Transcoding DSPs 299

        Considerations for Adding Trunk Capacity 302

Summary 302

References 302

Part IV Appendixes

Appendix A Scripts and Tools for Monitoring and Troubleshooting VoIP Networks 305

Appendix B Detailed Call Flows 331

Appendix C VoIP Dashboard 367

Appendix D Debugs, Traces, and Logs 373

9781587055287    TOC    7/1/2010

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