A MulticastRedundancyGroup represents groups of RPs that use MSDP to form a redundant set. In other words, it is a redundancy group of multicast services that function as a collection of RPs using anycast.

Anycast RP is a useful application of MSDP that configures a multicast sparse mode network to provide for fault tolerance and load sharing within a single multicast domain. Two or more RPs are configured with the same IP address (for example, on loopback interfaces.
Note: The loopback address should be configured as a host address (with an IPv4 mask).

All of the downstream routers are configured so that they know that is the IP address of their local RP.

IP routing automatically selects the topologically closest RP for each source and receiver. Because some sources use only one RP and some receivers a different RP, MSDP enables RPs to exchange information about active sources.

All the RPs are configured to be MSDP peers of each other. Each RP will know about the active sources in the area of the other RP. If any of the RPs fail, IP routing converges and one of the RPs would become the active RP in both areas.