Backup line configuration
1. After the main link is 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}
Where: enable-delay indicates the time interval for the backup to be initiated after the main interface is down;
disable-delay indicates the time interval when the backup link is closed after the main link is restored.
2. When the load of the main link reaches the set value, enable the backup link to transmit simultaneously.
1. Configure the backup line (in the interface mode of the main interface):
Router(config-if)# backup interface
2. Configure the load parameters (in the interface mode of the main interface):
Router(config-if)# backup load
Where: x means that when the load of the main link reaches x% of the main link bandwidth, the backup link is enabled;
y means that when the total link load reaches y% of the main link bandwidth, the backup link is closed.
3. You can also use logical interfaces as backup.
4. Use floating-point static routes for backup
By changing the management distance (AD) of the static route, the static routes on the backup link have a higher AD value. In normal state, the main link is routed (because its AD value is low), and the backup link will be automatically enabled when the main link is down.
example:
Main link routing: Ip router 172.16.254.0 255.255.255.0 Serial 0
Backup link routing: Ip router 172.16.254.0 255.255.255.0 Serial 1 20
Notice:
1. When the AD value of the static routes of the two links is set to the same, equal value load balancing of the static routes can be achieved.
2. The default routes for two different exit paths can be backed up like the static route above when their AD values are different; but when their AD values are the same, the so-called "equal value load balancing of the default route" cannot be achieved, and the default route configured first will only take effect.
FW: Note:
1. When the AD value of the static routes of the two links is set to the same, equal value load balancing of the static routes can be achieved.
2. The default routes for two different exit paths can be backed up like the static route above when their AD values are different; but when their AD values are the same, the so-called "equal value load balancing of the default route" cannot be achieved, and the default route configured first will only take effect.
What is the difference between the link and the exit? Can you explain the meaning of the second sentence?
FW: The meaning of the second sentence is: You have two Internet outlets, and you connect to different isp, and you connect to s0 and s1 of your router respectively.
If your configuration is:
ip router 0.0.0.0 0.0.0.0 s0
ip router 0.0.0.0 0.0.0.0 s1
Then, in fact, your Internet exit only uses s0, because the configuration of the second sentence will not take effect. because
ip router 0.0.0.0 0.0.0.0 s0
It is the default route, and it can only be the default route configured first, the following sentence
ip router 0.0.0.0 0.0.0.0 s1
It doesn't work. This is: the so-called "equivalent load balancing of default routes" cannot be achieved.
If your s0 and s1 are connected to the same network segment (172.16.0.0/16), and your configuration is as follows:
ip router 172.16.0.0 255.255.0.0 s0
ip router 172.16.0.0 255.255.0.0 s1
Then when you go to the target network segment 172.16.0.0/27, both s0 and s1 exits will be used, because the above two sentences configure static routes, not default routes. This is called equal value load balancing of static routing.
FW: There is a sentence above that is written incorrectly.
"Then when you reach the target network segment 172.16.0.0/27" should be changed to:
"Then you reach the target network segment 172.16.0.0/16."
FW: Say a few more words
Link: Generally refers to the physical line connected to the router and other devices.
Exit: Generally refers to the network line connected to the entire network or local network and external network. It is often used to refer to the physical lines connected to the internal network and the ISP.
Article entry: csh Editor in charge: csh