(Optional) Configuring an Action to Perform After a Loopback Is Detected
Context
After loopback detection is enabled on an interface, the interface periodically sends detection packets and checks whether loopback packets are received. When a loopback is detected on an interface, the system sets the interface status to loopback, minimizing impact on the system and the entire network.
Procedure
- Configuring an action to perform after a loopback is detected in the system view
- Run loopback-detect action error-down
The action to perform on the interface is set to error-down when a loopback is detected on the interface.
The default action is alarm.
When the system detects a loopback on an interface, the interface enters the Error-Down state and the system sends an alarm to the NMS.
If the action to perform on the interface is alarm, inter-device loopback may suppress loopback detection on other interfaces on the local device. In this situation, set the action to error-down or use STP to prevent loopback.
- Run loopback-detect action error-down
- Configuring an action to perform after a loopback is detected in the interface view
- Run loopback-detect action { error-down | alarm }
The action to perform on the interface is set when a loopback is detected on the interface.
By default, when a loopback is detected on an interface, the action is as follows:- If the loopback-detect action error-down command is not used in the system view, an alarm is generated.
- If the loopback-detect action error-down command is used in the system view, the interface is shut down.
If the loopback-detect action (interface view) and loopback-detect action error-down commands are executed in the interface view and system view respectively, the configuration in the interface view takes effect.
- Run loopback-detect action { error-down | alarm }
Follow-up Procedure
When the action is set to error-down, if a loopback occurs on the interface, the interface enters the Error-Down state. The device records the status of an interface as Error-Down when it detects that a fault occurs. The interface in Error-Down state cannot receive or send packets and the interface indicator is off. You can run the display error-down recovery command to check information about all interfaces in Error-Down state on the device.
Manual (after the interface enters the Error-Down state)
When there are few interfaces in Error-Down state, you can run the shutdown and undo shutdown commands in the interface view or run the restart command to restore the interface.
Auto (before the interface enters the Error-Down state)
If there are many interfaces in Error-Down state, the manual mode brings in heavy workload and the configuration of some interfaces may be ignored. To prevent this problem, run the error-down auto-recovery cause loopback-detect interval interval-value command in the system view to enable an interface in error-down state to go Up and set a recovery delay. You can run the display error-down recovery command to view automatic recovery information about the interface.
This mode is invalid for the interface that has entered the Error-Down state, and is only valid for the interface that enters the Error-Down state after the error-down auto-recovery cause loopback-detect interval interval-value command is used.