No relevant resource is found in the selected language.

This site uses cookies. By continuing to browse the site you are agreeing to our use of cookies. Read our privacy policy>Search


To have a better experience, please upgrade your IE browser.


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.
Rate and give feedback:
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 User VLANs Fail to Receive Multicast Packets (IGMP snooping)

Users in User VLANs Fail to Receive Multicast Packets (IGMP snooping)

Common Causes

This fault is commonly caused by one of the following:

  • The upstream link or downstream link of the AR100&AR120&AR150&AR160&AR200&AR1200&AR2200&AR3200&AR3600 is broken because the hardware (such as board, fiber, and network cable) is faulty.
  • The Layer 2 multicast configuration of the system or the user VLAN is incorrect, for example, IGMP snooping is not enabled.
  • The Layer 2 multicast configurations on the AR100&AR120&AR150&AR160&AR200&AR1200&AR2200&AR3200&AR3600 conflict, for example, the configuration of disabling dynamic multicast entry learning on interface, multicast group policy, interface prompt leave and igmp-snooping require-router-alert.
  • The number of Layer 2 multicast entries on the AR100&AR120&AR150&AR160&AR200&AR1200&AR2200&AR3200&AR3600 reaches the upper limit.

Troubleshooting Flowchart

After the Layer 2 multicast is configured, multicast traffic cannot be transmitted to users.

The troubleshooting roadmap is as follows:
  • Check whether link failure occurs.
  • Check whether the configurations are incorrect or conflict.
  • Check whether the number of multicast entries exceeds the upper limit.

Figure 20-1 shows the troubleshooting flowchart.

Figure 20-1  Troubleshooting flowchart for Layer 2 multicast

Troubleshooting Procedure


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


  1. Check that the upstream and downstream links are Up.

    Run the display interface brief command in the system view to check whether the Layer 2 multicast service interfaces are in Up state.

    • If the interface status is Administratively Down, run the undo shutdown command in the interface view to enable the interface.

    • If the physical status of the interfaces is Down, check the upstream and downstream physical links.

    • If the physical status and protocol status of the interfaces are Up, go to step 2.

  2. Check whether IGMP snooping is enabled globally and in a VLAN.

    Run the display current-configuration command in the system view to check the configuration. If the output information contains igmp-snooping enable, global IGMP snooping is enabled.

    Run the display igmp-snooping configuration command in the VLAN view to check the IGMP snooping configuration of the VLAN.

    • If the command output does not contain igmp-snooping enable, run the igmp-snooping enable command in the system view and VLAN view to enable IGMP snooping.
    • If IGMP snooping has been enabled globally and in the VLAN, go to step 3.
  3. Check whether the multicast configurations conflict.

    Check whether the following configurations exist on the device:

    • Disabling dynamic learning of multicast entries on user interfaces or VLANs

      If the dynamic learning of router interfaces is disabled in a VLAN, the VLAN does not listen to IGMP Query messages. As a result, no multicast router port is generated. Run the igmp-snooping router-learning command in the VLAN view to enable the dynamic learning of router interfaces in the VLAN.

    • Prompt leave of member interfaces

      The fast leave function can be enabled in a VLAN only when each interface in the VLAN is connected to one host. If a member interface is connected to multiple hosts, the AR100&AR120&AR150&AR160&AR200&AR1200&AR2200&AR3200&AR3600 immediately deletes the forwarding entry of the member interface after receiving an IGMP Leave message from the member interface without sending a Group-Specific Query message.

      Run the undo igmp-snooping prompt-leave command in the VLAN view to disable the fast leave of member interfaces.

    • igmp-snooping require-router-alert

      If igmp-snooping require-router-alert has been configured, the AR100&AR120&AR150&AR160&AR200&AR1200&AR2200&AR3200&AR3600 checks the Options field in IGMP packets, and discards the packets that do not contain the Options field.

      Run the undo igmp-snooping require-router-alert command in the VLAN view to cancel the igmp-snooping require-router-alert configuration. The AR100&AR120&AR150&AR160&AR200&AR1200&AR2200&AR3200&AR3600 will not check the Options field in IGMP packets.

    • Multicast group policy

      The multicast group policy limits the multicast groups that the hosts on a VLAN can join. You can run the display igmp-snooping configuration command in the VLAN view to verify the configuration of multicast group policy. If ACL is configured, verify the ACL configuration.

    • If any configurations conflict, delete the configurations.
    • If no configurations conflict, go to step 4.
  4. Collect the following information and contact technical support personnel.
    • Results of the preceding troubleshooting procedure

    • Configuration files, log files, and alarm files of the devices

Updated: 2019-05-10

Document ID: EDOC1000079719

Views: 454259

Downloads: 4316

Average rating:
This Document Applies to these Products
Related Documents
Related Version
Previous Next