The Project

Our client, a global bank headquartered in Europe, migrated to a new Voice over IP (VoIP) managed service across their global VoIP footprint of 8 sites and 4000 handsets. Following the upgrade, users started reporting intermittent call quality issues. There were several pain points:

1 High impact service deterioration. Poor VoIP quality had affected several high-profile calls, increasing the pressure on the IT organisation to resolve the issues quickly and effectively.

1 A lack of transparency and visibility. Ambiguity and confusion as to whether the root cause was due to the VoIP system or the supporting network infrastructure.

1 Inadequate tool capability. The service provider was unable to determine the root cause of problems using their existing tools that focused on faults and availability monitoring

The client then decided to try a more holistic monitoring solution. They selected CorvilNet for its ability to integrate network, infrastructure and service provider performance visibility with an understanding of the demands for voice, video, web, storage and database applications.

The Solution

A Corvil CNE-6300 appliance was deployed in each data center, bundled with Corvil’s Operational Performance Monitoring software. The solution configuration included:

1 Base Network Performance Monitoring appliance, including packet capture and comprehensive network analytics out of the box.

1 An Enterprise Application decoder pack, with support for VoIP media and control protocols including H.225, H.245 and SIP signalling, plus RTP, RTCP and RSVP. Auto-discovery of VoIP traffic and full application layer visibility of control traffic and media traffic.

1 Corvil Lens, providing intuitive real-time monitoring of VoIP performance by gatekeeper and site, plus a network view showing MPLS network traffic, broken down by class of service between each site.

The Project

Voice over IP (VoIP) Monitoring

Challenges

• Highexposure–outagesandpoorquality are immediately noticed

• Sharedinfrastructureaffectsquality and complicates analysis

• Intermittentproblems–rootcausehard to determine

• Scale–thousandsofhandsets,dozens of sites

Why Corvil

• SingleplatformforVoIPandregulartraffic–control&media,networkand application

• Trustedindependentmonitoringto hold VoIP and network service providers to account

• Rapidtroubleshooting–completecapture with details of call quality, control traffic and the network context

• Always-onone-waylatencyandloss measurements, plus interframe jitter and shaper-detection, backed up with 100% packet capture

• Scalability–distributedsystem,processing millions of packets and business messages per second, with zero impact on the infrastructure

Benefits

• Holdserviceproviderstoaccountand improve their responsiveness when issues occur

• Rapidproblemresolution–abilityto identify the root cause of issues to the VoIP application-layer or to the network

• HolisticOperationalPerformanceMonitoring solution supporting VoIP plus web, storage, database and network services

• Increasedefficiencyandgreaterconsensus between departments, including the causes of network and application performance issues

• Quantifiablecostbenefitanalysis–target infrastructure upgrades with accurate performance baselining and trending

Monitoring Voice over IP

Figure 1: Corvil VoIP monitoring rollout comprised a Corvil CNE-6300 appliance in each gatekeeper site, monitoring control and media traffic between sites globally, including the latency and loss point to point across the service provider.

PSTN

Gatekeeper

Data Centre

Branch

Branch

Branch

Corvil 6300 VoIP Other Apps

ServiCe ProviDer

Corvil Lens for real-time voiP monitoring and alerting

1 Flexible monitoring hierarchy, for

example summarized by gatekeeper

and by site with per-element

breakdown.

2 MOS quality metrics.

3 Monitor gaps in media traffic at any

point in the network, plus compare to

service provider packet loss.

4 Monitor Jitter based on RTP

inter-frame variation, and compare

to point-to-point latency variation.

Click through from Lens to query

per-packet metrics and details of

control traffic flow.

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This solution provided:

1 A single platform with full decode and visibility of application flows including VoIP control and media traffic, plus web services, storage and database protocols and network management protocols.

1 Full network analysis, including microburst, top talkers, listeners, conversations, TCP metrics, packet capture and export, etc.

1 Long term reporting for performance-aware capacity planning and trending.

1 Efficient workflows for moving from an intuitive high level performance view of the entire installation to the right level of detail for effective troubleshooting.

The VoIP team could monitor performance from each data center to each site, and swiftly rank by any of the measured metrics, including:

1 Call quality metrics such as MOS (mean opinion score) and internal/external R factors

1 Inter-packet jitter and missing RTP packets as reported by receiving handsets

1 Inter-packet jitter and missing RTP packets as measured in the network

1 Point to point latency, jitter and loss between sites across the service provider cloud

The team could also access the complete flow of control traffic, search for individual gatekeepers, handsets, and calls, and see the complete network context.

Ranking by jitter, the team quickly saw that call quality degradation was associated with two particular gatekeepers, which were introducing excessive jitter. With integrated network monitoring they could compare the jitter at different points, to confirm that the network was not the source: the jitter was present in the traffic leaving the gatekeeper, before accessing the WAN. They generated detailed gatekeeper reports and used these to follow up with the VoIP service provider. With this information, the problem was quickly identified as a bug and resolved with a software upgrade from the service provider. Ongoing monitoring confirmed the problem was fixed.

Additionally, they discovered a misconfigured router at one site was marking streaming video traffic with the priority “Expedited Forwarding” EF label. This resulted in uncontrolled drops accessing the service provider cloud whenever the video traffic was active. With Corvil they quickly identified this problem and used Corvil bandwidth sizing to achieve the required quality levels.

Benefits

Monitor all traffic, not one application in isolation Monitoring VoIP on its own will not resolve problems when those problems are caused by VoIP interaction with other traffic at key network nodes.

early Warning Get real-time alerts on deteriorating performance such as increasing levels of jitter and loss, before they have a significant impact on perceived call quality.

Microvisibility VoIP performance depends on events measured in milliseconds. Unlike flow-based and call-based monitoring tools, CorvilNet gives you a direct view of the short timescale behaviour of networks and applications, letting you see and understand the microburst events that cause jitter and packet loss.

Service Provider SLA Management Visibility of the latency and loss of every VoIP packet across the WAN, allows service provider issues to be immediately detected and authoritatively confirmed. Multi-class SLAs can be monitored and enforced.

rapid root Cause Analysis and Troubleshooting With combined application and network views performance issues are quickly detected. All troubleshooting teams use the same high-integrity dataset, improving collaboration and time-to-resolve. WAN issues can be authoritatively identified, improving responsiveness of Service Provider support.

Single Platform Serves Multiple Teams Customized dashboards for each team, showing both live and historical data. For example, the VoIP team can view call quality while the network team monitors packet latency and loss and service-provider SLAs. This allows teams to operate independently and yet still collaborate efficiently.

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