Backup line configuration 1. After the main link goes Down, enable the ISDN line 1. Configure the backup line (in the interface mode of the main interface): Router(config-if)# backup interface 2. Configure the backup delay (in the interface mode of the main interface): Router(config-if)# backup delay {enable-delay|never} {disable-delay|never} Among them: enable-delay indicates the time interval for initiating backup after the main interface goes Down; disable-delay indicates the time interval for shutting down the backup link after the primary link is restored. 2. When the load of the main link reaches the set value, enable the backup link for simultaneous transmission. 1. Configure the backup line (in the interface mode of the main interface): Router(config-if)# backup interface 2. Configure load parameters (in the interface mode of the main interface):
