R3303-HP HSR6800 Routers IP Multicast Configuration Guide

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• At the receiver side:
a. A receiver host initiates an MLD report to announce that it is joining an IPv6 multicast group.
b. After receiving the MLD report, the receiver-side DR resolves the RP address embedded in the
IPv6 multicast address and sends a join message to the RP.
• At the IPv6 multicast source side:
c. The IPv6 multicast source sends IPv6 multicast traffic to the IPv6 multicast group.
d. The source-side DR resolves the RP address embedded in the IPv6 multicast address, and sends
a register message to the RP.
RPT building
Figure 92 RPT building in an IPv6 PIM-SM domain
As shown in Figure 92, the process of building an RPT is as follows:
1. When a receiver joins the IPv6 multicast group G, it uses an MLD report message to inform the
directly connected DR.
2. After getting the IPv6 multicast group G's receiver information, the DR sends a join message, which
is forwarded to the RP that corresponds to the multicast group.
3. The routers along the path from the DR to the RP form an RPT branch. Each router on this branch
generates a (*, G) entry in its forwarding table. The asterisk means any IPv6 multicast source. The
RP is the root of the RPT, and the DRs are the leaves of the RPT.
The IPv6 multicast data addressed to the IPv6 multicast group G flows through the RP, reaches the
corresponding DR along the established RPT, and finally is delivered to the receiver.
When a receiver is no longer interested in the IPv6 multicast data addressed to the multicast group G, the
directly connected DR sends a prune message, which goes hop-by-hop along the RPT to the RP.
After receiving the prune message, the upstream node deletes the interface connected with this
downstream node from the outgoing interface list and examines whether it has receivers for that IPv6
multicast group. If not, the router continues to forward the prune message to its upstream router.
Multicast source registration
The purpose of IPv6 multicast source registration will inform the RP about the existence of the IPv6
multicast source.
Source
Server
Host A
Host B
Host C
Receiver
Receiver
IPv6 multicast packets
RPT
Join message
RP DR
DR