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Troubleshooting Guide

CloudEngine 16800, 12800, 12800E, 8800, 7800, 6800, and 5800 Series Switches

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Huawei uses machine translation combined with human proofreading to translate this document to different languages in order to help you better understand the content of this document. Note: Even the most advanced machine translation cannot match the quality of professional translators. Huawei shall not bear any responsibility for translation accuracy and it is recommended that you refer to the English document (a link for which has been provided).
A MAC Address Flapping Alarm Is Generated on a Device and VM Services Cannot Be Accessed

A MAC Address Flapping Alarm Is Generated on a Device and VM Services Cannot Be Accessed

Problem Description

On the VXLAN network shown in Figure 19-2, a MAC address flapping alarm is generated on a device, and VM services cannot be accessed.
Figure 19-6 VXLAN networking

Root Cause

The MAC address of a VM conflicts with that of the VXLAN gateway.


Perform the following steps to locate and rectify the fault:

  1. Determine the device where MAC address flapping occurs based on alarm information.
  2. Check the MAC address table on the device to determine the MAC address of the VM.
    <HUAWEI> display mac-address
    Flags: * - Backup  
           # - forwarding logical interface, operations cannot be performed based 
               on the interface.
    BD   : bridge-domain   Age : dynamic MAC learned time in seconds
    MAC Address    VLAN/VSI/BD   Learned-From        Type                Age
    00e0-fc00-0001 -/-/100            evn                   -
    0000-0000-0002 -/-/100            evn                   -
    Total items: 2  
  3. Check whether a MAC address flapping record exists.
    Run the display mac-address flapping command to check MAC address flapping records. The following command output shows that MAC address 00e0-fc00-0001 flaps.
    <HUAWEI> display mac-address flapping
    MAC Address Flapping Configurations :
      Flapping detection          : Enable
      Aging  time(s)              : 300
      Quit-VLAN Recover time(m)   : --
      Exclude VLAN-list           : --
      Security level              : Middle
      Exclude BD-list             : --
    S: start time    E: end time    (D): error down
    Time         : S:2018-10-24 15:46:04           E:2018-10-24 15:47:32         
    VLAN/BD      : -/100
    MAC Address  : 00e0-fc00-0001 
    Original-Port: Eth-Trunk1.3                  
    Move-Ports   : Eth-Trunk10.2                   
    MoveNum      : 1348   
    Total items on slot 1: 1

    If a large number of MAC address flapping records are generated, a loop may occur. Remove newly added cables or shut down the corresponding interfaces.

  4. Check the MAC address of a VBDIF interface.
    Run the display interface vbdif 100 command to check the MAC address of VBDIF 100. The following command output shows that the MAC address of VBDIF 100 is 00e0-fc00-0001. It is confirmed that the VM's MAC address conflicts with the gateway's MAC address, causing a service access exception on the server.
    <HUAWEI> display interface vbdif 100
    Vbdif100 current state : UP (ifindex: 149)
    Line protocol current state : UP 
    Last line protocol up time : 2018-10-24 15:55:30
    Route Port,The Maximum Transmit Unit is 1500
    Internet Address is
    IP Sending Frames' Format is PKTFMT_ETHNT_2, Hardware address is 00e0-fc00-0001
    Current system time: 2018-10-24 15:55:32
  5. Change the MAC address of the VM or gateway to ensure that no MAC address conflict exists on the network. If the gateway is not used, you are advised to delete the corresponding VBDIF interface.
    <HUAWEI> system-view  
    [~HUAWEI] undo interface vbdif 100
    [*HUAWEI] commit
  6. Run the display mac-address flapping command again to check MAC address flapping records. If the number of MAC address flapping times does not increase and VM services can be accessed, the fault is rectified.
Updated: 2020-01-07

Document ID: EDOC1000060766

Views: 616579

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