Explanation/Reference:
Explanation:
Any Source Multicast (ASM) provides discovery of multicast sources. It builds a shared tree between

sources and receivers of a multicast group and supports switching over to a source tree when a new receiver is added to a group. ASM mode requires that you configure an RP.
Single Source Multicast (SSM) builds a source tree originating at the designated router on the LAN

segment that receives a request to join a multicast source. SSM mode does not require you to configure RPs. Source discovery must be accomplished through other means.
Bidirectional shared trees (Bidir) build a shared tree between sources and receivers of a multicast

group but do not support switching over to a source tree when a new receiver is added to a group. Bidir mode requires that you configure an RP. Bidir forwarding does not require source discovery because only the shared tree is used.
Reference: https://www.cisco.com/c/en/us/td/docs/switches/datacenter/sw/5_x/nx-os/multicast/ configuration/guide/n7k_multic_cli_5x/pim.html