VoIP Performance Management and Optimization
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VoIP Performance Management and Optimization

4.0 1
by Adeel Ahmed, Habib Madani, Talal Siddiqui

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ISBN-10: 1587055287

ISBN-13: 9781587055287

Pub. Date: 08/13/2010

Publisher: Cisco Press

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


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

Product Details

Cisco Press
Publication date:
Networking Technology: IP Communications Series
Product dimensions:
7.50(w) x 9.20(h) x 1.20(d)

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


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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VoIP Performance Management and Optimization 4 out of 5 based on 0 ratings. 1 reviews.
Boudville More than 1 year ago
If you know anything about the Internet Protocol, then meeting VoIP for the first time can be a surprise. While laypersons might complain about low VoIP sound quality, the very fact that you can often still carry on a conversation in real time using it is quite impressive, given the unreliable underlying IP. But as VoIP has become popular, expectations have rise and thus the need for comprehensive metrics of performance. Leading to KPI, which the book explains in detail. It is a set of metrics for which software exists that measure it in real time (or as close to it as possible) and then to display results in some visually clear manner for the sysop. The visuals let the sysop's wetware (ie. brain) see if outages exist, or if some quality metric is decreasing. To some extent these can be subjective performance issues if there is no outright network failure. A key idea is for proactive monitoring, where the sysop in a Network Operations Centre can use a fault management system for diagnosis. The text discusses how to do fault isolation, especially in the common case where your network has several switches, gateways and subnets. For a sysop, the examples in chapters 7 and 8 may be the most valuable portions of the text, as they deal with those sometime difficult scenarios. You can use the examples to guide how you might reduce down your network problems to a given piece of equipment or subnet. In some respects, the diagnosis for VoIP problems is harder than for generic IP traffic, or indeed for streaming video. Bottleneck problems in the latter are less jarring than having a VoIP conversation repeatedly "time out" and the different KPI metrics explore various dimensions of possible problems. You can also see that Cisco offers a sophisticated VoIP dashboard and associated debugging facilities, as evidenced by Appendices C and D.