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Tips for navigating the evolving wireless LAN landscape

Bulk up on IP addresses, think about subnet roaming, take a close look at 5GHz

By , Network World
June 20, 2011 06:09 AM ET

Network World - The influx of mobile clients is accelerating an IT rethink of wireless LAN design and operations.

"When WLANs were first deployed the attention was on coverage," says David Morton, director of mobile communications at the University of Washington in Seattle. "You didn't spend a lot of time thinking about the number of devices in a given area, apart from a big lecture hall, and you didn't give a lot of thought on how to keep a session alive as you moved from one area to another."

But with mobile Wi-Fi devices more numerous, users typically are connecting, and authenticating, often but briefly to update social networking sites. Much of the resulting Web traffic increase is often video or audio. Social networking and streaming applications can be more or less chatty.

WI-FI EXPLOSION: Wi-Fi client surge forcing fresh wireless LAN thinking

Here's how some IT shops are handling big changes to their wireless LAN environments and what other wireless experts are advocating:

Have enough IP addresses. In just six months, Carnegie Mellon University doubled its address pool. It first added 4,000 new addresses, and then another 4,000 to handle the influx of Wi-Fi clients.

Revisit how your WLAN handles subnet roaming. The new Wi-Fi devices really are mobile, not just portable: Users are on the move streaming music or video, having video chats, or checking social networking sites. There is more real-time communications and interactions.

"If you're roaming across subnets, that's a Layer 3 issue," says Rohit Mehra, director of enterprise communications infrastructure for market researcher IDC. "All WLAN vendors support this and have for years. But the scale and the workload on the WLAN potentially can be higher [with more, and more active, clients]. Enterprises want to look at this and test and design their networks accordingly."

Get more information about your RF environment, and how it's changing, both long-term and day by day. Spectrum monitoring and analysis tools, and more RF experience and expertise by IT staff, will be increasingly important. "Most enterprises don't have good visibility into the Physical Layer [of the WLAN]," says Paul DeBeasi, research vice president for wireless and mobility at Gartner. "They often don't realize how busy the 2.4GHz band really is, for example. [see "Smartphone, tablet Wi-Fi performance varies widely"]

Make Wi-Fi network management a priority. "You don't want to wait until an access point is saturated and you're getting angry calls from users," says Craig Mathias, principal of Farpoint Group, an Ashland, Mass., wireless consultancy, and a Network World blogger. "Become really friendly with your network management console in learning about what's going on in your network."

Be ready for continuous Wi-Fi network "tuning." Some locations will see an influx of users at different times of the day, or an increase in the number of Wi-Fi clients, or both. You may need to add or move access points, change their power settings, make use of directional antennas or other features to control the sizes of the Wi-Fi "cells," to balance users across access points, to minimize interference and to prioritize traffic or applications.

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