307
Figure 89
RPT building at the receiver side
As shown in
, the process for building a receiver-side RPT is similar to that for building an RPT
in IPv6 PIM-SM:
1.
When a receiver joins IPv6 multicast group G, it uses an MLD message to inform the directly
connected router.
2.
After getting the receiver information, the router sends a join message, which is forwarded
hop-by-hop to the RP of the IPv6 multicast group.
3.
The routers along the path from the receiver's directly connected router to the RP form an RPT
branch, and each router on this branch adds a (*, G) entry to its forwarding table. The * means
any IPv6 multicast source.
When a receiver is no longer interested in the multicast data addressed to IPv6 multicast group G, the
directly connected router sends a prune message, which goes hop-by-hop along the reverse direction of
the RPT to the RP. After receiving the prune message, each upstream node deletes the interface connected
with the downstream node from the outgoing interface list and examines whether it has receivers in that
IPv6 multicast group. If not, the router continues to forward the prune message to its upstream router.
