As you can see, the iPad completes the roam in 8.5ms, the time it takes to complete the 802.11 authentication and reassociation; no full 802.1X authentication, RADIUS TLS session resumption, or even 4-way handshake are required! This is the result of support for the Wi-Fi Alliance Voice-Enterprise certification on both the WLAN and client. In the tests that were captured, the WLAN was configured for WPA2-Enterprise with 802.1X authentication and dynamic keying. The initial client association resulted in a full 802.1X authentication with the RADIUS server, followed by fast roams as shown above.
Roaming with 802.11r (Fast BSS Transition) is noticeably faster than other proprietary fast-roaming methods (OKC/PKC) and it's also faster than roaming on a Pre-Shared Key (PSK) WLAN. This is because the 4-Way Handshake exchange can be eliminated by embedding the key derivation material (ANonce, SNonce, MIC, and GTK) within the Fast Transition Information Element inside the 802.11 Authentication and Reassociation frames. There is also a Mobility Domain IE that comes into play to distinguish boundaries between different WLANs (since key material must be exchanged between APs on the backend, two separate WLANs cannot facilitate fast roaming).
via WiFi News by WiFiNovation | Scoop.it More READ
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