Explicitly specifying backup interfaces without traffic thresholds
For the primary and backup interfaces to operate in strict active/standby mode, do not specify the traffic thresholds on the primary interface. If the traffic thresholds are configured, the interfaces will operate in load sharing mode.
You can assign priority to backup interfaces. When the primary interface fails, the backup interfaces are activated in descending order of priority, with the highest-priority interface activated first. If two backup interfaces have the same priority, the one configured first has preference.
To prevent link flapping from causing frequent interface switchovers, you can configure the following switchover delay timers:
Up delay timer—Number of seconds that the primary or backup interface must wait before it can come up.
Down delay timer—Number of seconds that the active primary or backup interface must wait before it is set to down state.
When the link of the active interface fails, the interface state does not change immediately. Instead, a down delay timer starts. If the link recovers before the timer expires, the interface state does not change. If the link is still down when the timer expires, the interface state changes to down.
To configure strict active/standby interface backup for a primary interface:
Step | Command | Remarks |
|---|---|---|
1. Enter system view. | system-view | N/A |
2. Enter interface view. | interface interface-type interface-number | This interface must be the primary interface. |
3. Specify a backup interface. | backup interface interface-type interface-number [ priority ] | By default, an interface does not have any backup interfaces. Repeat this command to specify up to three backup interfaces for the interface. |
4. Set the switchover delay timers. | backup timer delay up-delay down-delay | By default, the up and down delay timers are both 5 seconds. |