Source-Specific Multicast (SSM) requires all IGMP hosts to send IGMPv3 reports, which creates a compatibility issue with IGMPv2 hosts. In particular, reports from an IGMPv2 host contain a Group Multicast Address but do not contain source addresses. The IGMPv3 reports contain both the Group Multicast Address and one or more source addresses. Use the ip igmp ssm-map command and a properly configured prefix list to convert IGMPv2 reports into IGMPv3 reports.
The prefix list filters for the group multicast address. The prefix list is then associated with one or more source addresses. When the ip igmp ssm-map enable command is configured, IGMPv3 reports are sent for IGMPv2 hosts.
This example configures the SSM map at the global configuration level.
device(config)# ip igmp ssm-map enable device(config)# ip igmp ssm-map ssm-map-230-to-232 203.0.0.10 device(config)# ip igmp ssm-map ssm-map-233-to-234 204.0.0.10
This example configures the prefix list for an SSM range.
device(config)# ip prefix-list ssm-map-230-to-232 seq 5 permit 230.0.0.0/8 device(config)# ip prefix-list ssm-map-230-to-232 seq 10 permit 231.0.0.0/8 device(config)# ip prefix-list ssm-map-230-to-232 seq 15 permit 232.0.0.0/8 device(config)# ip prefix-list ssm-map-233-to-234 seq 5 permit 233.0.0.0/8 device(config)# ip prefix-list ssm-map-233-to-234 seq 10 permit 234.0.0.0/8 device(config)# ip prefix-list ssm-map-230-to-232 seq 15 permit 232.0.0.0/8