My office has a VoIP system. It’s…small business solution…Vonage…not happy with it, because…calls…punctuated…gaps of silence…call is like a strobe light. The other party…talking, but…no idea that I can’t hear the full conversation.

It’s very frustrating, and given that we don’t run a very sophisticated network in our small office, we don’t have good tools to diagnose the exact problem. We’ve tuned things as best as we can, but we still suffer from lost packets and poor quality calls at times. And I suspect we aren’t alone in our misery.

As Denise Dubie pointed out a few months ago, network managers are struggling with how to manage the performance of VoIP. She cited a Network Instruments customer survey in which one-third of the 275 respondents say they don’t have the ability to monitor VoIP performance. The top concerns of those surveyed are: being able to monitor the QoS of the VoIP application, ensuring reliability of VoIP applications to perform under heavy use, and ensuring the network can adequately handle the added VoIP traffic.

To get some advice on successful VoIP implementations, I talked with Ivan McDuffie, an area engineering manager with NEC Unified Solutions. His company provides customized solutions for networking and communications, and McDuffie has been involved in many of the customer engagements for VoIP installation. He holds several technical credentials, including Cisco Certified Network Professional, Cisco Certified Design Professional, and Certified Network Instruments Administrator, giving him a good foundation for understanding the challenges that VoIP poses to a network.

His top advice for anyone considering a VoIP installation: Do your groundwork to ensure that the network is fully ready to support the added traffic of VoIP before you begin the implementation.

For the past 10 months, McDuffie has been using a GigaStor retrospective network analysis appliance from Network Instruments to conduct his network assessments. In a typical implementation, he might use VoIP management tools from NetIQ to generate VoIP calls and use GigaStor and its related monitoring tool Observer to capture, view and analyze the traffic.

One of the reasons McDuffie likes the GigaStor and Observer tools is that they are not VoIP-specific; rather, they are all-purpose networking monitoring tools. Having analysis tools that monitor both VoIP and overall network traffic is very helpful during the deployment phases of VoIP. In the predeployment stage, the tools help McDuffie track bandwidth utilization parameters that identify bottlenecks and specific points of contention on the network. During the deployment, VoIP traffic is generally segmented to its own VLAN; Observer then provides extensive metrics on the performance of each VLAN.

Linda Musthaler is a principal analyst with Essential Solutions Corporation.