11n is no silver bullet
These users are all adopting or evaluating 802.11n, which promises five to six times more throughput than existing 802.11abg WLANs. The additional capacity will be very welcome, but all agree that 11n won't eliminate the need for careful, thoughtful, end-to-end capacity planning.
"It guarantees faster speeds, but it doesn't prevent one bandwidth hog from taking most of that," says Hanset. "I'd like to have a 'fair-share' mechanism in the WLAN, so that can't happen, especially in high-density areas."
Hanset also cautioned that 11n throughput can be dramatically affected by inadequate upstream links and, in the University of Tennessee's case, power injectors. Tests showed an Aruba 11n access point delivering 80M to 90Mbps, but 160Mbps with a gigabit connection and gigabit-capable power injectors," he says.
In many migrations, enterprises simply are replacing existing 11abg access points with 11n devices. But if the 11n products are making use of the 5GHz frequency, because there are more channels and less radio noise, some tweaking will be needed, warns Brandeis' John Turner. That's because 5GHz signals don't propagate as well as those in the 2.4GHz band.
"We've seen where we've installed an 11n access point and expected great performance in the 5GHz band," he says. "But you walk behind two walls and your signal vanishes. It's not dead-simple."