Farpoint Group principal Craig Mathias advises a phased 802.11n deployment approach. Note that most 802.11n vendors support mesh capabilities, which interconnect access points over the air instead of requiring them all to be wired to an Ethernet switch. Turning up some mesh access point connections is one way to get your feet wet with 802.11n ahead of standards, eliminate some cabling and better support aggregate traffic from 54Mbps 802.11g/a access points. From there, Mathias says:

1) Move bandwidth-intensive users and applications to 802.11n in the 5GHz band, which is far less cluttered than the 2.4GHz band used by 802.11g/b networks.

2) Install dual-band, dual-radio access points with one 802.11g radio to avoid disrupting your current environment.

3) Wait to deploy 802.11n in the 2.4GHz band until all clients can be upgraded to avoid sub-optimal performance.

What to ask your wireless LAN vendor about 802.11n

When you issue an RFP for your 802.11n deployment, you will face a variety of architectural arguments from the WLAN vendors. Test these architectures to see which performs best in your environment.

1. If your vendor says it distributes some of the forwarding decisions out to access points to reduce latency and benefit voice calls, ask how security is handled in peer-to-peer sessions.

2. If a system is fully centralized, ask how the architecture avoids bottlenecks at the WLAN controller.

3. If you stay with your current vendor, ask whether you need a new, more powerful controller to handle 802.11n.

4. Most 802.11n architectures require new power-over-Ethernet equipment, while others claim to be able to leverage existing PoE switches. In the latter cases, find out what, if anything, you give up performance-wise for the benefit of retaining your existing equipment.

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