Fortinet 50B 用户手册

The modem interface can work in one of two modes:

• redundant mode
• stand alone mode

The redundant modem interface serves as a backup to the Ethernet interface. If 
that Ethernet interface disconnects from its network, the modem automatically 
dials the configured dial-up account(s). When the modem connects to a dial-up 
account, the FortiGate unit routes IP packets normally destined for the selected 
Ethernet interface to the modem interface. During this time, the unit pings the 
Ethernet connection to check when it is back online.

When the Ethernet interface can connect to its network again, the FortiGate unit 
disconnects the modem interface and switches back to the Ethernet interface.

For the FortiGate unit to switch from an Ethernet interface to the modem you must 
select the name of the interface in the modem configuration and configure a ping 
server for that interface. You must also configure firewall policies for connections 
between the modem interface and other FortiGate interfaces.

In stand alone mode, you manually connect the modem to a dial-up account. The 
modem interface operates as the primary connection to the Internet. The 
FortiGate unit routes traffic through the modem interface, which remains 
permanently connected to the dial-up account.

If the connection to the dial-up account fails, the FortiGate unit modem 
automatically redials the number. The modem redials the ISP number based on 
the amount of times specified by the redial limit, or until it connects to a dial-up 
account.