HP MSR2003 Configuration Manual page 296

Figure 91 RPT building at the receiver side
As shown in Figure 91, the process for building a receiver-side RPT is the same as the process for building
an RPT in IPv6 PIM-SM:
1. When a receiver wants to join the IPv6 multicast group G, it uses an MLD message to inform the
directly connected router.
2. After receiving the message, the router sends a join message, which is forwarded hop by hop to
the RP for the IPv6 multicast group.
3. The routers along the path from the receiver's directly connected router to the RP form an RPT
branch. Each router on this branch adds a (*, G) entry to its forwarding table.
When a receiver wants to leave the IPv6 multicast group G, the directly connected router sends a prune
message. The prune message goes hop by hop along the reverse direction of the RPT to the RP. After
receiving the prune message, an upstream node removes the interface that connects to the downstream
node from the outgoing interface list. It also checks whether it still has receivers for that IPv6 multicast
group. If not, the router continues to forward the prune message to its upstream router.
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