The 802.11n ripple effect

Deploying 802.11n requires infrastructure tweaks in an enterprise

As wireless LAN products based on the draft of the IEEE 802.11n specification continue to emerge, enterprise network managers have to take care. You can't just go and drop 802.11n access points into your network and expect everything to work flawlessly.

That's the upshot of a new white paper by Paul DeBeasi of the Burton Group, posted on the Wi-Fi Alliance's Web site, that goes into all of the considerations for 802.11n in the enterprise.

For example, the paper points out that older 802.11 access points can sometimes come close to the Power over Ethernet (PoE) maximum of 15.4 watts. Newer 802.11n access points are likely to require more power - so now you have to think about using a wall outlet for power instead of the single cable supporting both power and Ethernet signals.

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As wireless LAN products based on the draft of the IEEE 802.11n specification continue to emerge, enterprise network managers have to take care. You can't just go and drop 802.11n access points into your network and expect everything to work flawlessly.

That's the upshot of a new white paper by Paul DeBeasi of the Burton Group, posted on the Wi-Fi Alliance's Web site, that goes into all of the considerations for 802.11n in the enterprise.

For example, the paper points out that older 802.11 access points can sometimes come close to the Power over Ethernet (PoE) maximum of 15.4 watts. Newer 802.11n access points are likely to require more power - so now you have to think about using a wall outlet for power instead of the single cable supporting both power and Ethernet signals.

Alternatively, some vendors will offer multiple Ethernet connections on their access points, so those access points may be powered by more than one PoE connection. Or you may find the access points cutting throughput to stay within the PoE limit. Other options include support for the emerging PoE Plus, which is still under development.

The higher speed offered by 802.11n means you need higher-speed connections on the wired side of the access points. The specification is designed to exceed 100Mbps - which means you can't use a Fast Ethernet connection to backhaul the traffic to the wired network. New access points will have to use Gigabit Ethernet instead.

That means upgrading any wiring-closet switches to have Gigabit Ethernet ports facing the access points.

The report says that WLAN controllers that forward data will be backhauling traffic from hundreds of 802.11n access points, so those controllers are each going to need several Gigabit Ethernet connections.

Whether or not you actually deploy 802.11n, the Burton Group paper says you will have to update any wireless intrusion-detection systems, because older systems won't be able to recognize 802.11n access points. (Compare WLAN Security products)

For more details, take a look at the useful white paper, which is free (it requires a painless registration with the Wi-Fi Alliance that grants immediate access).

Read more about lans & wans in Network World's LANs & WANs section.