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Recovering an Interface From ERROR DOWN State

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Recovering an Interface From ERROR DOWN State

Recovering an Interface From ERROR DOWN State


You may find that a physical interface on a switch is in ERROR DOWN state, and want to figure out why the interface is in such a state and how to restore the interface. This document describes the ERROR DOWN state and how to restore an interface in this state.


This document applies to S series switches in V200R001C00 and later versions. The down-cause field value varies depending on the version and product model.

Cause Description

In any view of the interconnected two devices, run the display interface interface-type interface-number command to check the current running status and statistics of the specified interface. The current state field displays ERROR DOWN(down-cause). The following uses ERROR DOWN(as-not-ready) as an example.

<HUAWEI> display interface gigabitethernet 0/0/12
GigabitEthernet0/0/12 current state : ERROR DOWN(as-not-ready)
Line protocol current state : DOWN
Switch Port, Link-type : access(negotiated),
PVID :1, TPID : 8100(Hex), The Maximum Frame Length is 9216
IP Sending Frames' Format is PKTFMT_ETHNT_2, Hardware address is 000b-0974-a475 
Last physical up time: 2013-08-10 21:09:51 
Last physical down time : 2013-08-10 21:10:51
Current system time: 2013-08-10 21:15:06
Speed : 1000,   Loopback: NONE
Duplex: FULL,   Negotiation: ENABLE

Recovery Measure

If the current state field displays ERROR DOWN (down-cause), check whether the interface is shut down because of error events. You need to rectify the fault according to the down-cause field. The following table lists common values of the down-cause field.

Value of the down-cause Field



When the device negotiates to the AS mode, its interface status becomes Down and then becomes Up after services in the service profiles have been delivered.


After the auto-defend action command is used to configure actions against attack sources, the interface that receives attack packets is shut down to prevent the device from attacks.


On an STP-enabled network, after BPDU protection is configured on edge interfaces of a switch, the switch sets the physical status of the edge interface that receives BPDUs to Down to block services on this interface if the switch is attacked by forged BPDUs.


When the efm trigger error-down command associates a remote fault event with the current interface of a switch, the switch sets the protocol status of the interface to Down to interrupt all services on the interface if EFM detects the critical-event, dying-gasp, link-fault, or timeout fault event.


When link monitoring is configured for an interface on a link, the link is considered unavailable if the number of errored frames, errored codes, or errored frame seconds detected by the interface reaches or exceeds the threshold within a specified period. You can associate an EFM crossing event with the current interface. The system then sets the administrative status of the interface to Down. In this manner, all services on the interface are interrupted.


When an Ethernet interface configured with a backup link receives error packets, faults such as service packet loss occur. To ensure nonstop service transmission, when the number of received error packets reaches the alarm threshold, the interface is shut down and services are switched to the backup link.


An interface receives Runts error packets if the optical fiber, network cable, or optical module is removed and reinstalled, the shutdown or undo shutdown command is executed, or Runts packets are forwarded on the network. To avoid worse impact on the device or services, the device counts the number of Runts error packets received by an interface within 1 minute, and shuts down the interface if the number reaches the alarm threshold 5.


Cable faults or active/standby switchovers will cause an interface to frequently alternate between Up and Down. You can configure link flapping protection on interfaces. When the switch receives an interface Up/Down message, it checks the number of interface flappings and interval. If the number of interface flappings within the specified period reaches the configured limit, the switch shuts down the interface.


After the storm control action is configured as error-down on an interface, the interface is shut down when the average rate of received broadcast, multicast, and unknown unicast packets is larger than the specified limit within the interval for detecting storms.


When interface security is configured on a switch, the MAC addresses learned by the switch become secure dynamic MAC addresses. If the port-security protect-action command sets the security protection action to shutdown on an interface, the interface is shut down when the number of secure MAC addresses learned by the interface exceeds the upper limit or static MAC address flapping is detected after static MAC address detection is enabled.


When MAC address flapping occurs on a user network because of loops, you can configure a loop prevention action for the switch to perform when MAC address flapping occurs. After the MAC address flapping action is configured on an interface, if the switch detects MAC address flapping on the interface, it sets the physical status of the interface to Down.


When the optical power of an Ethernet optical interface configured with a backup link is reduced, faults such as packet loss occur. To ensure normal service operation, the interface is triggered to transit to the Error-Down state and services are switched immediately if the optical power is lower than the lower alarm threshold.


After the switch runs for a long time, the chip memory identifier has a data integrity error.

You can recover an interface from the ERROR DOWN state using either of the following measures:

  • Manual recovery

    Run the shutdown and undo shutdown commands or run the restart command in the interface view to restart the interface.

  • Automatic recovery

    Run the error-down auto-recovery cause down-cause interval interval-value command in the system view to enable an interface in ERROR DOWN state due to the cause indicated by the down-cause field to go Up and set the automatic recovery delay.

    For example, the current state field is displayed as ERROR DOWN(auto-defend) for GE0/0/1. You can run the following command to enable the interface to go Up after 30 seconds.

    <HUAWEI> error-down auto-recovery cause auto-defend interval 30

    When the interface is in Up state, you can then check the services to figure out why the interface enters the ERROR DOWN state for rectifying the fault.

Manual recovery or automatic recovery can only temporarily restore an interface in ERROR DOWN state. You need to troubleshoot the services to rectify the fault that causes the interface to enter the ERROR DOWN state. Otherwise, even if the interface recovers from the ERROR DOWN state, it will enter this state again unless the fault is rectified.

Related Information

For details about troubleshooting an ethernet interface in physically down state, refer to Huawei S Series Campus Switches Troubleshooting Guide--Troubleshooting: Ethernet Interface Physically Down.

Updated: 2019-07-23

Document ID: EDOC1100088108

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