An engineer is designing a PIM Anycast RP solution between two data centers.

MSDP should be enabled between the Anycast RP routers using separate unique loopback interfaces. In a PIM Anycast RP design, multiple RPs share the same RP address so multicast routers can reach the topologically closest RP through normal unicast routing. That shared RP address gives redundancy and load sharing, but it also creates a source-discovery problem: a source registered to RP1 must be known by RP2 so receivers using RP2 can join the same multicast stream. Cisco Anycast RP designs solve this by running MSDP between the RPs. The MSDP peerings should use unique loopback addresses, not the shared Anycast RP address, because each router must have an individually reachable identity for the MSDP session. Extending the RP subnet at Layer 2 between data centers is unnecessary and poor design. Using the configured Anycast RP address for MSDP creates ambiguity because both routers advertise the same address. Doing nothing would leave each RP aware only of locally registered sources. Reference topics: Anycast RP, MSDP, PIM sparse mode, source-active exchange, multicast RP redundancy.