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AR Router Troubleshooting Guide

This Product Documentation provides guidance for maintaining AR Enterprise Router, covering common information collection and fault diagnostic commands, typical fault troubleshooting guide, and troubleshooting.
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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).
Users in a VLAN Cannot Communicate with Each Other

Users in a VLAN Cannot Communicate with Each Other

This section describes common causes of the communication failure between users in a port-based VLAN, and provides the corresponding troubleshooting flowcharts, troubleshooting procedures, alarms, and logs.

Common Causes

This fault is commonly caused by one of the following:
  • The link between users is faulty.
  • The interfaces connected to the users are shut down manually or the physical interfaces are damaged.
  • The device learns incorrect MAC addresses.
  • Port isolation is configured on the device.
  • Incorrect static Address Resolution Protocol (ARP) entries are configured on the user terminals.
  • Incorrect mappings between interfaces and MAC addresses are configured on the device.
NOTE:

If users in different VLANs cannot communicate with each other, rectify the fault according to the IP Forwarding Troubleshooting.

Troubleshooting Flowchart

Figure 16-1 shows the troubleshooting flowchart.

Figure 16-1  Troubleshooting flowchart for communication failure between users in a port-based VLAN

Troubleshooting Procedure

NOTE:

Saving the results of each troubleshooting step is recommended. If your troubleshooting fails to correct the fault, you will have a record of your actions to provide Huawei technical support personnel.

Procedure

  1. Check that the interfaces connected to the user terminals are in Up state.

    Run the display interface interface-type interface-number command in any view to check the status of the interfaces.

    • If the interface is in Down state, check for the cause and make the interface Up. The following table provides the common causes and troubleshooting methods.

      Cause

      Method

      The interface was manually shut down.

      Run the interface interface-type interface-number command in the system view to enter the interface view, and then run the display this command to check the interface status. If the interface was shut down by using the shutdown command, run the undo shutdown command in the interface view.

      The link fails.

      Replace the cable between the user terminal and the Router.
      NOTE:

      If the user terminal is connected to the Router by using a twisted pair, select a new twisted pair with a proper transmission according to the distance between the user terminal and the Router.

      Duplex modes and speeds of the local and remote interfaces are different.

      Run the speed, duplex, and negotiation auto commands to ensure that the duplex modes and speeds of the interfaces are the same.

      The interface is faulty.

      Connect the devices using other idle interfaces.
    • If the interface is Up, go to 2.

  2. Check whether the IP addresses of user terminals are in the same network segment.

    • If they are in different network segments, change the IP addresses of the user terminals.
    • If they are in the same network segment, go to 3

  3. Check that the MAC address entries on the Router are correct.

    Run the display mac-address command on the Router to check whether the MAC addresses, interfaces, and VLANs in the learned MAC address entries are correct. If the learned MAC address entries are incorrect, run the undo mac-address mac-address vlan vlan-id command on the interface to delete the current entries so that the Router can learn MAC address entries again.

    After the MAC address table is updated, check the MAC address entries again.
    • If the MAC address entries are incorrect, go to 4.
    • If the MAC address entries are correct, go to 5.

  4. Check that the VLAN is properly configured.

    • Check the VLAN configuration according to the following table.

      Check Item

      Method

      The VLAN has been created.

      Run the display vlan vlan-id command in any view to check whether the VLAN has been created. If not, run the vlan command to create the VLAN.

      The interfaces have been added to the VLAN.

      Run the display vlan vlan-id command in any view to check whether the VLAN contains the interfaces. If not, add the interfaces to the VLAN.
      NOTE:

      If the interfaces are located on different devices, add the interfaces connecting the devices to the VLAN.

      • Add an access interface to the VLAN by using either of the following methods:

        NOTE:

        The default type of a router interface is hybrid. To change the interface type to access, run the port link-type Access command in the interface view.

        1. Run the port default vlan command in the interface view.
        2. Run the port command in the VLAN view.
      • Add a trunk interface to the VLAN.

        NOTE:

        The default type of a router interface is hybrid. To change the interface type to trunk, run the port link-type trunk command in the interface view.

        Run the port trunk allow-pass vlan command in the interface view.

      • Add a hybrid interface to the VLAN by using either of the following methods:

        NOTE:

        The default type of a router interface is hybrid. To change the interface type to hybrid, run the port link-type Hybrid command in the interface view.

        1. Run the port hybrid tagged vlan command in the interface view.
        2. Run the port hybrid untagged vlan command in the interface view.

      Connections between interfaces and user terminals are correct.

      Check the connections between interfaces and user terminals according to the network plan. If any user terminal is connected to an incorrect interface, connect it to the correct interface.

      After the preceding operations:
      • If the MAC address entries are correct, go to 5.
      • If the MAC address entries are incorrect, go to 7.

  5. Check whether port isolation is configured.

    Run the interface interface-type interface-number command in the system view to enter the interface view, and then run the display this command to check whether port isolation is configured on the interface.
    • If port isolation is configured, run the undo port-isolate enable command on the interface to disable port isolation.
    • If port isolation is not configured, go to 6.

  6. Check whether correct static Address Resolution Protocol (ARP) entries are configured on the user terminals.

    • If the static ARP entries are incorrect, modify them.
    • If the static ARP entries are correct, go to 7.

  7. Collect the following information and contact technical support personnel.

    • Results of the preceding troubleshooting procedure

    • Configuration file, log file, and alarm file of the AR100&AR120&AR150&AR160&AR200&AR1200&AR2200&AR3200&AR3600

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Updated: 2019-05-10

Document ID: EDOC1000079719

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