31.4.6 IPv6 PIM-SM operation when using MLDv2

IPv6 PIM-SM operation is as follows when the multicast distribution server (source address S1) sends multicast packets to multicast group G1, and hosts join the group via MLDv2:

1. Hosts send an MLDv2 Report (G1, S1) message as a request for joining the multicast group.

2. Switches receiving the MLDv2 Report (G1, S1) send a PIM-Join message that includes the group address (G1) to the rendezvous point over the shortest path.

3. The rendezvous point receiving the PIM-Join message learns about the existence of the group. A delivery tree from the sender via the rendezvous point is formed so that multicast packets can be delivered from the sender network to each group member via the rendezvous point.

4. The shortest path from the sender to each group member is determined by using the existing unicast routing information (PIM-Join messages are sent to the sender over the shortest path to the sender to form a shortest-path delivery tree).

5. Switches receiving multicast packets sent by multicast distribution server S1 bound for group G1 forward the multicast packets based on the shortest path delivery tree.

   Figure 31-16: Outline of IPv6 PIM-SM Operation When Using MLDv2