See your hardware installation manual for the specific slot and port numbers. See your hardware installation manual for the specific slot and port numbers. This command first appeared in Cisco IOS Release 11.0. The interface you define with this command can back up only one other interface. Note Routers support only serial and ISDN backup interfaces.
Access servers support both asynchronous and serial backup interfaces.
To return to the default value, use the no form of this command. Default No threshold is predefined. This command first appeared in Cisco IOS Release 10.0. When the transmitted or received load on the primary line is greater than the value assigned to the enable-threshold argument, the secondary line is enabled. The received load on the primary line plus the received load on the secondary line is less than the value entered for the disable-load argument.