Troubleshoot IGMPv3 Backwards Compatibility
If you configure the switch to operate in v2-v3 compatibility mode, the switch supports all IGMPv2 and v3 messages. The switch parses the group address of the messages. If the group address is out of SSM range and it is a v3 message, the switch drops the message. If it is a v2 message, IGMP snoop processes handle the message.
To troubleshoot issues with the IGMPv3 backwards compatibility feature, perform the following procedure.
Procedure
Example
Display the configured SSM static channels and display the configured SSM group range:
Switch:1#show ip igmp ssm-map ================================================================================ Igmp Ssm Channel - GlobalRouter ================================================================================ GROUP SOURCE MODE ACTIVE STATUS -------------------------------------------------------------------------------- 233.252.0.1 192.0.2.200 dynamic false enabled 233.252.0.2 192.0.2.200 dynamic false enabled 233.252.0.3 192.0.2.200 dynamic false enabled 233.252.0.4 192.0.2.200 dynamic false enabled 233.252.0.5 192.0.2.200 dynamic false enabled 233.252.0.6 192.0.2.200 dynamic false enabled 233.252.0.7 192.0.2.200 dynamic false enabled 233.252.0.8 192.0.2.200 dynamic false enabled 233.252.0.9 192.0.2.200 dynamic false enabled 233.252.0.10 192.0.2.200 dynamic false enabled 10 out of 10 entries displayed
Switch:1#show ip igmp ssm ========================================================================================== Igmp Ssm Global - GlobalRouter ========================================================================================== DYNAMIC LEARNING SSM GROUP RANGE ------------------------------------------------------------------------------------------ enable 232.0.0.0/255.0.0.0