Enabling PMK Caching for Roaming on 802.1X Networks
If you use 802.1X authentication in conjunction with WPA2-Enterprise and have multiple wireless access points (APs), you should ensure Pairwise Master Key (PMK) caching is enabled on the Windows clients. It enables faster roaming, eliminating pre or full 802.1X authentication when roaming to another AP. If PMK caching isn’t supported by the APs, pre-authentication can also be enabled. If supported by the AP, it eliminates having to perform full 802.1X authentication when roaming to another AP.
In previous Windows versions, PMK caching had to be enabled via the registry or group policy. In Windows 7, it can be configured via the Windows GUI: On the Wireless Network Properties dialog, select the Security tab, and then click the Advanced Settings button.