Article

Wi-Fi client variation obstructs wireless LAN performance management

Shamus McGillicuddy

As Microsoft's IT organization transitions its 15,000-access point, 450-controller wireless LAN to 802.11n technology, it faces an unexpected concern – managing Wi-Fi client performance.

The lack of hardware and software standards and uniformity among Wi-Fi client devices poses an ongoing challenge to network engineers who want to manage and monitor wireless LAN performance and end-user experience. Each Wi-Fi client, from laptops to smart devices, interacts with wireless LAN infrastructure differently, making it difficult to predict and monitor how it performs on the network.

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In Microsoft's case, the company has client devices running a wide variety of Wi-Fi chipsets, from Intel, Broadcom, Atheros and others. Predicting how those various Wi-Fi clients will perform with voice, video and other real-time applications is a challenge for Victoria Poncini, wireless LAN architect for Microsoft's IT organization

That variability in Wi-Fi clients stems from the fact that manufacturers have a high degree of latitude in designing Wi-Fi devices. The Wi-Fi Alliance, which creates WLAN standards, focuses on certification of interoperability for 802.11 technologies but not necessarily on standardizing Wi-Fi client devices. So a laptop from one manufacturer may instantly try to roam from one access point (AP) to another as soon as it senses variations in signal strength, while another manufacturer's laptop may decline to roam to another AP until it loses contact with the first one.

"I was talking to one vendor who has a customer that is a hospital," said Craig Mathias, principal with consultancy and testing house Farpoint Group. "They get new releases for [Wi-Fi] drivers for clients all the time. Sometimes the drivers are installed automatically. They're not sure how that's going to affect performance overall. Do these things work? Are new bugs introduced?"

The industry doesn't have a good handle on what a wireless LAN end-user device should look like, Mathias said.

"There's no client in the [IEEE 802.11] standard. End-user nodes decide things like how they're going to roam and when they're going to roam," he said. "There's no way to do centralized control, but that's what we ultimately need. Absent being able to precisely control the client, you want at least to know what's going on."

Client-based wireless LAN performance management

Until now, vendors have focused their wireless LAN performance management efforts on the infrastructure of things – not the client. Companies like Ruckus Wireless have pioneered dynamic technologies like beam-forming to help APs choose the best path to deliver a strong RF signal to a client. Other vendors, such as Cisco Systems, Aruba Networks and Motorola's Air Defense, offer RF analysis features that help wireless LAN infrastructure automatically detect and work around sources of RF interference.

But Veriwave, a vendor of wireless assessment tools, turned that focus on client-side performance with its new WaveDeploy wireless LAN lifecycle assessment tool. Rather than assessing RF signal quality within a given environment, WaveDeploy examines client-side performance, relying on software agents deployed on individual Wi-Fi clients to assess performance and user experience.

According to Eran Karoly, Veriwave's vice president of marketing, these software agents send data they collect from Wi-Fi clients to a test application running on a network engineer's laptop, which generates analyses and reports of how client devices perform on the network.

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"WaveDeploy can find reasons for why the network is not working," Karoly said. "We can find that the capacity of the network has been exceeded because the quality of service profile associated with a particular client is misconfigured. Or we can discover whether another client in the vicinity is misbehaving and not allowing a client to access the network."

Poncini is using WaveDeploy to gain visibility into the performance of Wi-Fi clients on the Microsoft WLAN despite their variability.

"You can load this software onto clients and use the WaveDeploy software with the client to go around and test voice, video, multicast applications and data applications," she said. "It provides you with a report on how the performance of your current infrastructure would look given that client's abilities."

Previously, understanding Wi-Fi client performance was "pretty much trial and error -- just kind of running different clients and trying to troubleshoot issues with different client performance on the network," Poncini said. "It was very cumbersome, with lots of back and forth with end users."

"Even though we can't necessarily mitigate all the client issues," she said, "we can come to a better infrastructure deployment that actually works for most clients."

Let us know what you think about the story; email: Shamus McGillicuddy, News Editor


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