HP FlexFabric 5950 series Configuration Manual page 392

RPT building
Figure 117 RPT building in an IPv6 PIM-SM domain
Source
Server
As shown in
1. When a receiver wants to join the IPv6 multicast group G, it uses an MLD message to inform the
receiver-side DR.
2. After getting the receiver information, the DR sends a join message, which travels hop by hop to
the RP for the IPv6 multicast group.
3. The routers along the path from the DR to the RP form an RPT branch. Each router on this
branch adds to its forwarding table a (*, G) entry, where the asterisk (*) represents any IPv6
multicast source. The RPT is rooted at the RP and has the DR as its leaf.
When the IPv6 multicast data addressed to the IPv6 multicast group G reaches the RP, the RP
forwards the data to the DR along the established RPT. Finally, the DR forwards the IPv6 multicast
data to the receiver hosts.
When a receiver is no longer interested in the IPv6 multicast data addressed to the IPv6 multicast
group G, the receiver-side DR sends a prune message. The prune message goes hop by hop along
the RPT to the RP. After receiving the prune message, the upstream node deletes the interface that
connects to this downstream node from the outgoing interface list. At the same time, the upstream
router checks for the existence of receivers for that IPv6 multicast group. If no receivers for the IPv6
multicast group exist, the router continues to forward the prune message to its upstream router.
IPv6 multicast source registration
The IPv6 multicast source uses the registration process to inform an RP of its presence.
RP
RPT
Join message
IPv6 multicast packets
Figure 117, the process of building an RPT is as follows:
DR
382
Host A
Receiver
DR
Host B
Receiver
Host C