In an Auto-RP deployment, which device role collects candidate-RP advertisements and advertises the group-to-RP mappings to all routers?

In an Auto-RP deployment, the Mapping Agent is responsible for collecting candidate-RP advertisements from all Candidate RPs. It then processes these advertisements and advertises the group-to-RP mappings to all other routers in the PIM domain. This allows all routers to discover which RP is responsible for which multicast groups. A Candidate RP is a router configured to offer its services as an RP for specific multicast groups, but it doesn't distribute the mappings. The Bootstrap Router (BSR) is part of PIM Bidirectional (PIM-Bidir) or PIM Sparse Mode (PIM-SM) with BSR, a different RP discovery mechanism, not Auto-RP. "RP only" is not a distinct role in Auto-RP; a router can be an RP, but the Mapping Agent performs the advertisement function.