Common Configuration Errors
This section describes common faults caused by incorrect IGMP configurations and provides the troubleshooting procedure.
IGMP Entries Cannot Be Created
Fault Description
Hosts request data of multicast group G after IGMP configuration is complete. However, the last-hop multicast device does not create any IGMP entry.
Procedure
- Check whether the ordered group address is in the range of reserved group addresses (224.0.0.1 to 224.0.0.255). When receiving IGMP Report messages with destination addresses in this range, the device does not generate IGMP entries.
- Run the display interface interface-type interface-number command to check whether the interface directly connected to the host network segment is in Up state.
If the interface is in Down state, check whether the interface is correctly connected, whether the interface has been shut down using the shutdown command, and whether the interface has a correct IP address configured.
- Run the display current-configuration command to check whether multicast routing is enabled.
If the command output does not contain "multicast routing-enable", run the multicast routing-enable command in the system view to enable multicast routing.
- Run the display current-configuration interface interface-type interface-number command to check whether IGMP is enabled on the interface directly connected to the host network segment.
If the command output does not contain "igmp enable", IGMP is not enabled on the interface. Run the igmp enable command in the interface view to enable IGMP.
- Run the display igmp interface interface-type interface-number command to check whether the IGMP configuration on the interface is correct.
- The IGMP version (identified by Current IGMP version in the command output) running on the interface must be later than or the same as the IGMP version running on the hosts.
- If the IGMP group policy field displays an ACL rule, check whether the multicast group address is rejected by the ACL rule. If so, modify the ACL rule to allow the multicast device to receive Report messages of this multicast group.
(S, G) Entries Are Not Generated After IGMP SSM Mapping Is Enabled
Fault Description
The interface is enabled with SSM mapping and IGMP, and is configured with a static SSM mapping policy. After the interface receives IGMPv1 or IGMPv2 Report messages, (S, G) entry doesn't exist in the MFIB table.
Procedure
- Check whether G in the (*, G) Report message is in the SSM group address range.
Run the display this command in the PIM view to check the current configuration. If the command output displays "ssm-policy", the SSM group address range is redefined on the device.
Run the display acl { acl-number | name acl-name | all } command to check the ACL configuration. Ensure that G is in the SSM group address range. By default, the SSM group address range is 232.0.0.0 to 232.255.255.255.
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