GOTCHAS REMAIN
Despite all the performance and other benefits of 802.11n, there are still questions about reliability, performance, legacy devices, integration into the existing wire-centric infrastructure, and market dynamics.
RF remains a black art, and although MIMO makes Wi-Fi more reliable, it's still no guarantee that interference won't interrupt. For starters, good planning is required, perhaps using a tool such as Cisco's Spectrum Expert (formerly Cognio), which identifies possible sources of interference. There are also architectural approaches to address the reliability problem. Meru's newest 802.11n access point, the AP400, was designed for robustness. Its four built-in radios can operate simultaneously, on different channels; interference on one channel or band doesn't prevent a client from roaming to another radio. Another approach, used by Ruckus Wireless and Xirrus, is to employ directional antennas. These approaches are still considered a bit unconventional, but they're worth watching.
If aggregate performance is a key issue, legacy clients that operate only in 802.11b mode may need to be replaced or upgraded. That's not always possible with older Vo-Fi handsets, portable scanners, and other application-specific devices. In these cases, moving nonlegacy clients to the 5-GHz band, where there's great channel selection and support for multiple 40-MHz channels, may be prudent. That way, the legacy clients won't impact the peak-performance capabilities of the 802.11n-capable gear.
The challenge of consistent network management between wired and wireless networks is also vexing. Even Cisco, which leads in market share in both segments, doesn't have a management interface between both platforms. As HP points out, enterprises aren't eager to layer on a different set of intrusion-detection and -prevention systems, security, and network-access control tools for the wireless environment. For now, you will need different sets of tools for managing wired and wireless networks, so for organizations that do both, back-end support costs will rise, not fall.
Illustration by Nick Rotondo
Continue to the sidebars:
Rollout: AirWave's WLAN Management Suite Put To The Test,
Copper Costs Lots Of Pretty Pennies
and
Voice Is A Bump On Road To Wireless
Continue to the story:
Building Better Branch-Office Wireless