The default is approx 30 seconds, however this is configurable based on the Link Control settings. These settings are used by our Vector Routing algorithm to determine when a link is down.
When a failover does occur the appliance will reset its routing tables and interface queues in order to make sure that traffic only routes out the active links.
During this process any existing real-time applications will require a reset or restart in order to continue the live stream. Some applications are able to do this automatically without end-user knowledge, others must be restarted manually by the end-user.
In either case the application will begin operating over the active link with little if any interruption.