802.11k and 802.11r are both standards designed to create a more seamless roaming experience for wireless clients. This is particularly useful for VoIP or other applications where long roaming times can result in a very noticeable impact on performance.
Why does roaming occur?
A wireless client will decide to roam to a new access point (AP) when it detects a better signal from that AP than the one it is currently associated with. This behavior is normal, particularly when devices are moving around within an environment, such as laptops, tablets, and mobile phones.
Why do clients sometimes experience service interruptions when roaming?
When a client roams to a new AP it needs to establish an association/authentication relationship with that AP. In situations where the APs are acting independently of each other, this whole process must occur each time the client moves to a new AP. Without the inclusion of standards like 802.11k and 802.11r, the client will disconnect from it's existing AP before connecting to the new one. This results in a period of time where the client has no network access. This can be manifested in the form of packet loss, dropped calls, or other negative performance.
How do 802.11k and 802.11r help?
Both standards take different measures to reduce the time required for a client to roam between APs in the same network, and thus reduce the impact of roaming on performance.
- 802.11k reduces the time required to roam by allowing the client to more quickly determine which AP it should roam to next and how. The Cisco Meraki AP the client is currently connected to will provide it with information regarding neighboring APs and their channels. This way when the client is ready to roam, it has a better idea of where it will be roaming to.
- 802.11r uses Fast Basic Service Set Transition (FT) to allow encryption keys to be stored on all of the APs in a network. This way, a client doesn't need to perform the complete authentication process to a backend server every time it roams to a new AP within the network. Thus avoiding a significant amount of latency that would have previously delayed network connectivity.
Configuring 802.11r in Dashboard
This feature can be enabled from the Configure > Access control page under either Network access > 802.11r (old page version) or Security > 802.11r (new page version). If this option does not appear, a firmware update may be required. 802.11r is also not available while using NAT mode or Layer 3 roaming.
Note: 802.11r is intended for use on SSIDs that use enterprise authentication methods.
Fast Transition (FT) 802.11r roaming is not supported between Meraki MR55/MR45 and any other MR Access Point (AP) running version 25.x or lower. If you have a mixed deployment with MR55/MR45 and any other model of Meraki APs and 802.11r is either set as enabled or adaptive on any of the SSIDs configuration ensure all your APs are running version 26.4 or higher.
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