Session availability is supported when fast failover is enabled and when “Synchronize System Configuration” is selected. For more information, see Configuring Fast Failover and Enabling Session Availability.
In session availability, mobile user devices are able to retain their IP address. In addition, the mobile user device does not have to have to re-associate after the failover. These characteristics ensure that the failover is achieved within 5 seconds, which is fast enough to maintain the mobile user‘s session.
Note
In session availability, the fast failover is achieved within 5 seconds only if there is at least one client device (mobile unit) associated to the AP. In the absence of any client device, the AP takes more time to failover since there is no need to preserve the user session.The authentication state is not preserved during fast failover. If a WLAN (Wireless Local Area Network) Service requires authentication, the client device must re-authenticate. However, in such a case, the session availability is not guaranteed because authentication may require additional time during which the user session may be disrupted.
Session availability is not supported in a WLAN Service that uses Captive Portal (CP) authentication.
Session availability does not support user-specific filters as these filters are not shared between the primary and secondary controller.