Multicast Between PIM-SM Domains Within an AS Using MSDP

When a multicast source and its receivers are located in different PIM-SM domains of the same AS, you can configure MSDP peers on the RPs to implement inter-domain multicast.

Figure 1 PIM-SM inter-domain multicast in an AS

As shown in Figure 1, RPs of two PIM-SM domains set up a peer relationship to learn multicast source information from each other.