Multicast data is forwarded normally. After Multicast Listener Discovery (MLD) snooping is configured, users cannot receive multicast data.
If the MLD snooping version configured on the switch is earlier than that running on user hosts, the switch only forwards MLD Report messages to router ports and does not generate group member ports and forwarding entries.
Run the display mld-snooping configuration command to check the MLD snooping configuration. If the MLD snooping version configured on the switch is earlier than that running on user hosts, run the mld-snooping version version command to set the same MLD version as user hosts.
If the general query interval on the local switch is smaller than that of the upstream MLD querier or MLD snooping device, the local switch may incorrectly age out some MLD snooping entries that are still in use. As a result, multicast packets matching these entries cannot be forwarded.
Run the display mld-snooping command to check MLD snooping parameters. If the general query interval on the local switch is smaller than the general query interval on the upstream MLD querier or MLD snooping device, run the mld-snooping query-interval query-interval command to increase the interval. It is recommended that the upstream and downstream devices use the same general query interval.
On Huawei fixed switches, the default values of the MLD general query interval and MLD snooping general query interval are both 125 seconds.
Fast leave can be configured in a VLAN only when each interface in the VLAN is connected to only one host. If an interface is connected to multiple hosts and fast leave is configured in the VLAN to which the interface belongs, the switch does not send Query message and immediately deletes the forwarding entries of the interface after receiving an MLD Done message from the interface. This causes traffic forwarding interruption.
Run the display mld-snooping configuration command to check the configuration. If the command output contains mld-snooping prompt-leave, run the undo mld-snooping prompt-leave command in the VLAN view to disable the fast leave function.
If the switch is configured to check Router-Alert option, the switch checks for the Router-Alert option in MLD packets and discards packets without the option.
Run the display mld-snooping configuration command to check the configuration. If the command output contains mld-snooping require-router-alert, run the undo mld-snooping require-router-alert command in the VLAN view to delete the configuration.
The multicast group policy limits the multicast groups that the hosts in a VLAN can join. Run the display mld-snooping configuration command to verify the multicast group policy configuration. If IPv6 access control list (ACL6) rules are configured, run the display acl ipv6 command to check whether ACL6 rules are correctly configured.
The Layer 2 multicast filtering functions filters UDP packets from certain VLANs. This causes interruption in Layer 2 multicast traffic forwarding.
Run the undo multicast-source-deny vlan command in the interface view to disable the Layer 2 multicast filtering function.