Session failover
Whether it is a device or link failover, session failover occurs for forwarded TCP
traffic except for the virus scanned sessions that are in progress, VPN sessions, UDP, ICMP,
multicast, and broadcast sessions and proxy traffic.
Device normally maintains session information for TCP traffic which is not passing through proxy service. Hence, in case of failover, the device which takes over will take care of all the sessions (TCP session not passing through proxy application). The entire process is transparent for the end users.