Facilitating Bi-Directional PIM communication between hosts in different multicast domains. A first rendezvous point (RP) router contained in a first multicast domain receives a first control packet. The first control packet includes a first multicast destination address G1. In response to receiving the first control packet, the first RP router generates a second control packet. This second control packet includes a second multicast destination address G2, wherein the second multicast destination address G2 is distinct from the first multicast IP address G1. After the second control packet is generated, the first RP router transmitting the second control packet toward a second RP router contained in a second multicast domain. The second control packet initiates a distribution tree building process between the first and second RP routers. This distribution tree can be used to transmit multicast data packets between the first and second RP routers. For example, first RP router encapsulates multicast data packets it receives from sources in the first RP router's domain. The first RP router then transmits the encapsulated packets to the second RP via the distribution tree. The second RP router receives the encapsulated packets. The second RP router decapsulates the packets to produce the multicast data packets, which are subsequently distributed to hosts within the second RP router's domain.