Stateful:
When stateful failover is enabled, the active unit continually passes per-connection state information to the standby unit. After a failover occurs, the same connection information is available at the new active unit. Supported end-user applications are not required to reconnect to keep the same communication session.
The state information passed to the standby unit includes these:
The NAT translation table
The TCP connection states
The UDP connection states
The ARP table
The Layer 2 bridge table (when it runs in the transparent firewall mode)
The HTTP connection states (if HTTP replication is enabled)
The ISAKMP and IPSec SA table
The GTP PDP connection database
The information that is not passed to the standby unit when stateful failover is enabled includes these:
The HTTP connection table (unless HTTP replication is enabled)
The user authentication (uauth) table
The routing tables
State information for security service modules
