Though 802.1X can provide secure authentication for networks, it adds another step to the wireless connection process. This isn’t good for clients that must be able to roam around a building, going from one access point to another. However, you can fine-tune the Pairwise Master Key (PMK) and preauthentication settings via the Windows XP Registry to make roaming better:
Hive: HKEY_LOCAL_MACHINE
Key: \SOFTWARE\Microsoft\EAPOL\Parameters\General\Global
Name: PMKCacheMode
Value: 0 (disabled), 1 (enabled)
Turns PMK caching on and off.
Name: PMKCacheTTL
Value: 5-1440
Number of minutes to keep PMK entries cached, up to 1440 (24 hours).
Name: PMKCacheSize
Value: 1-255
Maximum number of PMK entries that can be cached.
Name: PreAuthMode
Value: 0 (disabled), 1 (enabled)
Whether or not the client should try preauthentication.
Name: PreAuthThrottle
Value: 1-16
Number of top preferred wireless access points that the client will try preauthentication with, based on the order of networks provided by the wireless adapter.