HP 6125XLG Ip Multicast Configuration Manual page 290

RPT building
Figure 89 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 is forwarded 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
multicast receivers.
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. 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.
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 89, the process of building an RPT is as follows:
DR
280
Host A
Receiver
DR
Host B
Receiver
Host C