Controller-based, pervasive wireless LANs are quickly become a standard feature of enterprise networks, according to a new study by BT North America.

And nearly one-third of enterprises are migrating to the high-throughput draft 802.11n WLAN standard within the next 12 months. The study's authors say that rate of adoption for a not-yet-ratified standard is unprecedented, indicating that 11n benefits are urgently needed by a significant number of enterprise sites. But half of the respondents still say there's no rush, and no plans to make that move.

The Web-based survey was completed by IT professionals from 226 companies. Forty-three percent of those companies had 1,000 or less IT employees; 28 percent had 1,000 to 10,000; and one-quarter had more than 10,000.

Thirty-nine percent of the survey respondents said they have controller-based WLAN architectures, and 22 percent more are either actively migrating to that or plan to. The trend is most pronounced in larger companies, according to Rick Blum, director of strategic marketing for the BT consulting group, and author of the study.

But controller solutions can become very expensive for companies with lots of branch offices or remote locations. One start-up, Aerohive, has eliminated the controller as a separate box: It's offering a distributed WLAN architecture that still permits centralized management.

The main enterprise driver for WLANs is making employees mobile, increasing collaboration and/or improving productivity, says Greg Taylor, practice lead for BT's WLAN consulting practice. Sixty-one percent of the sample listed these as "very important."

Taylor says there is little formally published literature on improved efficiencies, but some create internal studies in an attempt to document improvements. But measuring in hard dollars is rare, he says. "It's more about the whole feature set associated with wireless LANs," he says.

That's often coupled with a desire to deploy a secure wireless infrastructure to pre-empt unauthorized and vulnerable rogue WLAN deployments within the enterprise.

But those "softer" criteria also make it likely that WLAN expansions or upgrades may be sidelined in favor of higher priority projects, such as data center virtualization, which demonstrate hard-dollar cost justification, both men agreed.

The shift to 11n is under way for about one-third of the sample. Another 20 percent said they plan to adopt 11n starting 12 months or more from now. "The migration to 11n plays into the laptop [technology] refresh cycle," Taylor says. As new laptops with integrated 11n chipsets show up in the enterprise, "that adds to the justification for migrating the WLAN to 11n," he says. The typical enterprise refresh cycle is two to five years, according to Taylor.

The BT consultants say they see customers most often adopting the draft 11n infrastructure in brand-new construction, where it's matched with a high-capacity wired infrastructure. "You need gigabit switches and 10-gig backbones on the wired side," Taylor says. "The mixed -11abg and 11n mode will provide minimal gains."

Some see 11n as providing the bandwidth and quality that will allow WLANs to finally sever the Ethernet cable for most clients connecting to the LAN.

Enterprise IT is focused on clear priorities in terms of what BT calls "advanced WLAN features." Forty percent have secure, controlled guest access, and 30 percent will have it in the next year; 41 percent have centralized WLAN management and/or wireless intrusion prevention, and 34 percent plan to within 12 months.

But adoption of heavily touted features like VoIP, real-time location services, and fixed-mobile convergence (being able to shift voice calls on the fly between cellular and Wi-Fi networks) is slow: Nearly half to two-thirds of respondents have no plans to implement these capabilities.

BT consultants see a lot of wireless VoIP trials, with mobile VoIP phones, but relatively few of them are moving yet to full-scale deployments. One common application: making use of wireless VoIP for internal IT staff and tech support. The trials have shown very mixed results, because a WLAN originally designed for data can yield poor voice quality for wireless calls, according to Taylor.

Both consultants agree that one of the most persistent challenges facing enterprise WLANs is the wireless client: provisioning, administering, securing and managing. Some clients, for example, may not support a given 802.1x supplicant for certificate-based authentication, or may support it erratically. A well-thought-out system of user tech support is a key element in this, with both technicians and users having the training needed for secure, efficient wireless connectivity.