Why does the interface status display ERROR DOWN(link-flap)?

Latest reply: Apr 17, 2018 03:39:42 2553 1 0 0

Q: Why does the interface status display ERROR DOWN(link-flap)? How do I restore the interface to the Up state?


A
: If the interface status displays ERROR DOWN(link-flap), the interface has link flapping protection enabled and has frequently alternated between Up and Down states. By default, if an interface alternates between Up and Down states five times within 10 seconds, the device shuts down the interface and records the interface status as ERROR DOWN(link-flap). If the device detects frequent Up/Down state changes on an interface, the device shuts down the interface to prevent frequent network topology changes, or triggers an active/standby link switchover if there is a standby link to ensure uninterrupted service transmission.


NOTE:

By default, link flapping protection is enabled on CE series switches in V100R002C00 with the patch V100R002SPH006 loaded as well as V100R003C00 and later versions.

You can run the display interface command to view the interface status.


<HUAWEI> display interface 10GE 1/0/1 10GE1/0/1 current state : ERROR DOWN(link-flap) (ifindex: 5)
Line protocol current state : DOWN 
 ---- More ---- 


If an interface is in ERROR DOWN(link-flap) state, you are advised to perform the following operations:


  • Check historical alarms. If many Up/Down alarms of the interface were generated for a long time, the interface status is unstable. You are advised to check whether the optical modules and optical fibers on the local and remote interfaces are normal.


  • Restore the interface to Up state. By default, an interface in ERROR DOWN state does not automatically go Up. Run the shutdown and undo shutdown commands to manually enable the interface. In V200R002C50 and later versions, you can remove and reinstall the transmission medium on an optical interface to manually restore the interface to Up state. If an interface is not in Error-Down state, run the error-down auto-recovery cause link-flap interval interval-value command to configure the interface to automatically go Up when it is in ERROR DOWN(link-flap) state.


To disable the device from detecting Up/Down events on an interface, you can perform either of the following operations:


  • Disable link flapping detection on the interface. To disable link flapping detection on an interface, enter the interface view first.

a) In V100R002C00 and earlier versions, run the undo port link-flap trigger error-down command to disable link flapping detection.


b) In V100R002C00 with the patch V100R002SPH006 loaded as well as V100R003C00 and later versions, run the port link-flap threshold 0 command to disable link flapping detection.


NOTE:

If link flapping detection is disabled on an interface, the system does not detect faults caused by link flapping on the interface in real time. Exercise caution when deciding to perform this operation.


  • Adjust the link flapping detection threshold. If the network adapter of a server disconnects intermittently during server startup, the device may incorrectly determine the interface status. You can run the port link-flap { interval interval-value threshold threshold-value | interval interval-value | threshold threshold-value } command to increase the link flapping detection threshold.

You can also find the answer in Interface Management in FAQs.


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WoodWood
Created Apr 17, 2018 03:39:42 Helpful(0) Helpful(0)

:)
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