Multicast boundary filtering - filter auto RP
When filtering Multicast traffic, it is possible to filter group to RP mapping information that is sent by Auto RP. This can be done using the filter-autorp keyword on the command like so:
R2(config)#interface GigabitEthernet 0/2 R2(config-if)#ip multicast boundary FILTER_AUTO_RP filter-autorp
where FILTER_AUTO_RP is the access list filtering traffic.
Note that an Auto-RP group range announcement is permitted and passed by the boundary only if all addresses in the Auto-RP group range are permitted by the boundary ACL. If any address is not permitted, the entire group range is filtered and removed from the Auto-RP message before the Auto-RP message is forwarded.
Links:
https://networklessons.com/multicast/multicast-boundary-filtering#Filter_Auto_RP