In many standard fast roaming
scenarios, establishing communications with the network can take 100 to 150 milliseconds,
which is an acceptable delay for some activities such as web browsing, but which can result
in a very noticeable interruption in service during a Wi-Fi VoIP phone call or video
conference.
In July 2004, the IEEE formed a Fast Roaming Task Force to begin work on the
802.11r fast roaming standard for wireless networking. The goal of 802.11r is to improve
handoff times between access points. The final product will be known as Fast BSS
Transition. Motorola will extend its support to include this new standard, as it does for all
other key standards. However, optimized roaming must be enabled today.
To meet this need now, Motorola has employed a unique fast roaming capability in its
WPA2-compatible products that improves the roaming latency of WPA2. This feature,
Opportunistic PMK Caching, has gained the support of such leading supplicant providers
as Microsoft and Funk Software. While PMK Caching and pre-authentication enable fast
Understanding and Achieving Next-Generation Wireless Security 142
roaming within the WPA2 standard and are supported by Motorola, Opportunistic PMK
Caching takes a big step beyond these techniques.
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