Explanation/Reference:
Auto-RP
Automatic route processing (Auto-RP) is a feature that automates the distribution of group-to-RP mappings in a PIM network. This feature has these benefits:
It is easy to use multiple RPs within a network to serve different group ranges.
It allows load splitting among different RPs.
It facilitates the arrangement of RPs according to the location of group participants.
It avoids inconsistent, manual RP configurations that might cause connectivity problems.
Multiple RPs can be used to serve different group ranges or to serve as hot backups for each other. To ensure that Auto-RP functions, configure routers as candidate RPs so that they can announce their interest in operating as an RP for certain group ranges. Additionally, a router must be designated as an RP-mapping agent that receives the RP-announcement messages from the candidate RPs, and arbitrates conflicts. The RP-mapping agent sends the consistent group-to-RP mappings to all remaining routers.
Thus, all routers automatically determine which RP to use for the groups they support auto-rp candidate-rp To configure a router as a Protocol Independent Multicast (PIM) rendezvous point (RP) candidate that sends messages to the well-known CISCO-RP-ANNOUNCE multicast group (224.0.1.39), use the auto-rp candidate-rp command in PIM configuration mode. To return to the default behavior, use the no form of this command.
auto-rp candidate-rp type interface-path-id scope ttl-value [ group-list access-list- name ] [ interval seconds ] [bidir] no auto-rp candidate-rp type interface-path-id scope ttl-value [ group-list access- list-name ] [ interval seconds ] [bidir]