For example, if the client has an active connection that is transferring a file via FTP protocol,
when the fail occurs, the file copying continues uninterrupted via the standby unit that has assumed an active role.
The state link interface is used to pass the state of all established connections from the active unit to the standby device. The
information that is passed to the standby unit in a stateful failover setup includes the following:
NAT translation table
TCP connection states
UDP connection states
The ARP entries
The Layer 2 bridge table when running in transparent firewall mode
The HTTP connection states (if HTTP replication is enabled)
The Internet Security Association and Key Management Protocol (ISAKMP) and IPsec SA table
The connection database for GPRS Tunneling Protocol (GTP) Packet Data Protocol (PDP)
The exception to information that is not passed to the standby unit in a stateful failover setup is the following:
The HTTP connection table (unless HTTP replication is enabled)
The user authentication (uauth) table
The routing tables
Multicast traffic information
State information for Security Service Cards
There are three options for configuring a state link when configuring failover:
1.
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