Client State Synchronization

Client state synchronization allows faster client reauthentication in the event of a controller failure by synchronizing PMK Pairwise Master Key. PMK is a shared secret key that is generated after PSK or 802.1X authentication. and Key cache entries between active and standby controllers. When you enable this feature, clients only need to perform a four-way key exchange to reconnect to the network (instead of performing a full authentication to the RADIUS Remote Authentication Dial-In User Service. An Industry-standard network access protocol for remote authentication. It allows authentication, authorization, and accounting of remote users who want to access network resources.  server), dramatically shortening the time required for the client to reconnect.

Feature Guidelines and Limitations

Note the following guidelines and limitations before enabling this feature in your high availability deployment:

• Client state synchronization is supported by AP-500 series access points, or later versions, that support 802.11n 802.11n is a wireless networking standard to improve network throughput over the two previous standards, 802.11a and 802.11g. With 802.11n, there will be a significant increase in the maximum raw data rate from 54 Mbps to 600 Mbps with the use of four spatial streams at a channel width of 40 MHz. and 802.11ac 802.11ac is a wireless networking standard in the 802.11 family that provides high-throughput WLANs on the 5 GHz band..
• The client state synchronization and standby controller over-subscription features are mutually exclusive and cannot be enabled simultaneously. If your deployment uses the standby controller over-subscription feature, the feature must be disabled before enabling state synchronization.