Fast BSS Transition (FT) IEEE 802.11 r support
- 1 General
- 2 Northbound API
- 2.1 OVSDB
- 2.1.1 Wifi_VIF_Config
- 2.1.2 Wifi_VIF_Neighbors
- 2.1 OVSDB
- 3 Southbound API
- 4 Requirements
General
This release introduces support for IEEE 802.11r Fast BSS Transition, a critical feature for enhancing Wi-Fi roaming performance.
Fast BSS Transition (FT) significantly reduces the time and overhead required for client devices to roam between Access Points (APs) within the same network. By allowing devices to pre-authenticate with neighboring APs, it eliminates the need for a full re-authentication process during a handoff. This minimizes connection interruption and latency, ensuring a smoother and more reliable experience for mobile devices.
The OpenSync software stack has been updated to support a broader range of Fast Transition Authentication and Key Management (AKM) suites, including FT-SAE and FT-PSK. This also includes support for modern AKMs that leverage longer cryptographic hashes, which improves security and key derivation robustness.
This enhancement is particularly beneficial for real-time applications like voice calls, video conferencing, and live streaming, as it ensures seamless connectivity as a user moves throughout a Wi-Fi network.
Northbound API
OVSDB
Wifi_VIF_Config
Name | Type | Description |
|---|---|---|
ft_over_ds | bool |
Default: |
ft_pmk_r0_key_lifetime_sec | integer | Lifetime of a PMK-R0 key in seconds.
Default: |
ft_pmk_r1_max_key_lifetime_sec | integer | Maximum lifetime for PMK-R1 key in seconds. Default: |
ft_pmk_r1_push | bool |
Default: |
ft_psk_generate_local | bool |
Default: |
nas_identifier | string | In IEEE 802.11r context NAS Identifier is used as the R0 Key Holder ID (R0KH-ID). It is a string that uniquely identifies BSS in the Mobility Domain. Please note this field is also used for WPAx-Enterprise. |
ft_encr_key | string (64) | Acts as a shared secret for the exchange of FT RxKH keys and association contexts between other BSS and ‘this’ BSS over the Distribution System. It has a fixed length of 64 hexadecimal characters to form 256-bit encryption key. |
wpa_key_mgmt Existing field | set | Field specifying Authorization and Key Management is extended with the following enum variants:
|
Wifi_VIF_Neighbors
This table is used to define neighboring Access Points and is extended with Fast BSS Transition fields by adding following parameters.
Name | Type | Description |
|---|---|---|
ft_enabled | bool |
|
nas_identifier | string | In IEEE 802.11r context NAS Identifier is used as the R0 Key Holder ID (R0KH-ID). This entry allows ‘current’ AP to resolve R0KH-ID potentially coming from Re-association Request to BSSID of the R0KH. |
ft_encr_key | string (64) | Specifies an encryption key expected by a remote BSS that is subject of this table entry. In other words - if ‘current’ AP is about to send RRB PMK-R1 Push frame to ‘this’ BSS - it shall use this key to encrypt it. |
Southbound API
On most platforms configuration for Fast BSS Transition is handled by hostapd and by such it doesn’t require integration with other components. In OpenSync, One Wi-Fi Manager (OWM) translates FT configuration to a correct hostapd configuration file and is responsible for keeping configuration and state in sync.
Important note for Broadcom: Custom patches for hostapd on Broadcom platforms add custom configuration option ft_rrb_lo_sock. RRB exchanges use L2 frames that usually are not forwarded from one BSS to the other on the same platform. This configuration option enables loopback and allow RRB message exchange between BSSes on the same AP.
Requirements
There are no specific requirements for this feature on platforms that use hostapd other than building hostapd with support for IEEE 802.11r.
Other platforms are not supported.