VoIP performance: more than a bandwidth issue

Typically, IT managers will try to solve degradation in performance by boosting bandwidth. However, unlike data networks, VoIP performance problems generally are not bandwidth or throughput issues. For example, packet loss and out-of-sequence packets — issues network managers have not had to worry about with data networks — are in fact the cause of 50 per cent of the quality of service (QoS) problems with VoIP systems. Latency is typically responsible for the other 50 per cent.

VoIP management challenges can also escalate as the system expands beyond initial deployment to additional users. For many, adding voice to the IP network adds a new level of complexity that current troubleshooting processes and monitoring tools may not be equipped to handle.

What network managers need for VoIP management today are tools that provide a clear view into the network at all locations — from the edge to the core — to ensure predictable, consistent performance for all applications traveling across the LAN and WAN. These tools must be able to detail how much bandwidth specific applications use and when; provide root-cause analyses for network slowdowns and outages; measure QoS performance in the routers and carrier networks; determine how policy affects QoS; and analyze network performance both in the main office and in branch offices.

This ultimately means having tools on hand that offer both network and VoIP specific analytics that measure traffic flow and volumes, signal degradation and packet analysis, among other critical data. These tools can deliver significant value to VoIP lifecycle management — from pre-deployment to ongoing maintenance to future planning.

In pre-deployment, for example, tools can be used to verify if a drop is active; the phone can receive power from the switch and is able to communicate properly with network servers; the switch port is configured properly; and/or if the infrastructure is capable of sending PoE (Power over Ethernet) to each phone.

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During deployment, managers can monitor transmissions between IP phones and the VoIP network to verify if IP phones are working correctly during boot-up and initialization; monitor and measure call setup time and verify voice quality (such as jitter and dropped packets are within acceptable levels); and obtain QoS metrics.

For ongoing monitoring and management, testing requirements include regular performance measurements to ensure QoS standards are being met; capturing and decoding of packets for analysis and isolating problems and troubleshooting; evaluating link status; measuring VoIP impact on network performance; and creating protocol growth charts to determine when and where bandwidth will be required.

Troubleshooting tools can help managers perform detailed diagnostics to assess communication details between IP phones and call servers, as well as generate real-time QoS analysis of calls over VoIP VLANs or within a central link to identify single/multiple user problems, isolate the direction of degradation, and discover configuration problems.

For growth planning, analysis tools support capacity planning information by showing VoIP traffic volume rate growth and calculate performance baselines.

It is evident that the unique nature of VoIP networks and the associated QoS requirements require a more comprehensive approach to network management that looks beyond traditional bandwidth concerns. As we witness the rapid growth in VoIP adoption and deployment, there is an equally compelling need for effective analysis and troubleshooting tools that address both VoIP and network-specific issues.

QuickLink: 066113

–Brad Masterson is product manager for Fluke Networks Canada and can be reached atbrad.masterson@flukenet

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