[Trouble shooting]How to Check the Fault If a Switch interface Is Down(Err-down)?

Hi, community!

When you run the display interface gx/x/x command to check that the interface status is Down, you need to rectify the fault and restore the interface.

The electrical interface status is Down.

1. Check whether the “shutdown” command exists on the interface. If yes, run the “undo shutdown” command.       

2. Run the “display interface gx/x/x” command to check the interface status. If both the physical layer status and protocol layer status are Down, Check the physical layer status first.

current state: Indicates the physical layer status.

protocol current state: Indicates the protocol layer status.

3. Check the physical layer as follows:

1). The network cable is faulty. Replace the network cable.

2). Check whether the “undo shutdown” command is run on the interface of the peer device.

3). The interface on the peer device is faulty.

The optical interface status is Down.

4. Check whether the interface mode has been switched to the optical interface mode.

5. Check whether the optical module is completely inserted into the device.

6. Check whether the optical module is Huawei-certified.

1). The optical module has "HUAWEI" on its surface.

2). All of the following conditions are met:

After the display elabel command is run on the device, the date displayed in the Manufactured field is later than July 1, 2013.

Run the display version command on the device. The command output shows that the software version is V200R001C00 or later.

After the display transceiver command is run on the device, the Vendor Name field of the module is displayed as HUAWEI.

7. Try to cross-connect the fiber again.

8. Check whether the optical module is damaged.

9. Check whether the optical module parameters at both ends are consistent.

<HUAWEI> display transceiver interface GigabitEthernet 2/0/3 verbose

GigabitEthernet2/0/3 transceiver information:

-------------------------------------------------------------

Common information:

Transceiver Type:1000_BASE_SX_SFP // Optical module model

Connector Type:LC

Wavelength(nm):850                // Optical module wavelength

Transfer Distance(m):500(50um),300(62.5um) // Transmission distance of the optical module

Digital Diagnostic Monitoring:YES

Vendor Name: HUAWEI

Vendor Part Number:02315204

Ordering Name:

10. Check whether the optical module rate matches the interface rate. The following link is used to query the mapping between optical modules and device interfaces.

https://info.support.huawei.com/network/infofinder/openHardwarePage?domain=0&module=1&lang=zh#

11. If the physical status of the interface is error-down, check the following operations:

(Protected port) DOWN: An interface is added to an interface protection group and set to be a protected interface. To add an interface to an interface protection group and set the interface to be a protected interface, run the port protect-group and protect-group member commands.

Administratively down: The administrator has run the shutdown command on the interface.

TRIGGER DOWN (BFD): When BFD detects a fault, the physical status of the interface becomes Down according to the OAM association.

TRIGGER DOWN (3AH): When 3AH detects a fault, the physical status of the interface becomes Down according to the OAM association.

TRIGGER DOWN (1AG): When 1AG detects a fault, the physical status of the interface becomes Down according to the OAM association.

ERROR DOWN(auto-defend): When the interface receives packets from an attack source, the physical status of the interface becomes Down.

ERROR DOWN(efm-threshold-event): When the number of error frames, error codes, or error frame seconds of EFM OAM detected by the interface reaches or exceeds the threshold within a set period, the physical status of the interface becomes Down according to the OAM association.

ERROR DOWN(efm-remote-failure): When EFM detects a remote failure, the physical status of the interface becomes Down according to the OAM association.

ERROR DOWN(bpdu-protection): If an edge interface receives RST BPDUs after BPDU protection is enabled, the physical status of the edge interface becomes Down.

ERROR DOWN(error-statistics): If the system detects that the number of error packets received by the interface exceeds the threshold, the physical status of the interface becomes Down.

ERROR DOWN(transceiver-power-low): If the system detects that the optical power of the interface falls below the configured lower alarm threshold, the physical status of the interface becomes Down.

ERROR DOWN(port-security): When the number of learned MAC address entries reaches the limit, the interface changes to Down.

ERROR DOWN(mac-address-flapping): When the learned MAC address flaps, the interface changes to Down.

ERROR DOWN(dhcp-packet-overspeed): When the DHCP packet rate of the interface exceeds the threshold, the physical status of the associated interface becomes Down.

ERROR DOWN(link-flap): When the link flaps, the physical status of the associated interface becomes Down.

ERROR DOWN(data-integrity-error): The chip memory identifier has a data integrity error and the physical status of the interface becomes Down.

LOOPBACK-DETECT DOWN: The interface goes Down due to loopback detection.

UP(E-TRUNK-DOWN): The Eth-Trunk interface goes Down because of E-Trunk negotiation.