HP VPN Firewall Appliances Appendix Protocol Reference

109
Embedded RP
The embedded RP mechanism enables a router to resolve the RP address from an IPv6 multicast address
so that the IPv6 multicast group is mapped to an RP. This RP can take the place of the statically configured
RP or the RP dynamically calculated based on the BSR mechanism. The DR does not need to learn the RP
address beforehand. The specific process is as follows.
• 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:
a. The IPv6 multicast source sends IPv6 multicast data to the IPv6 multicast group.
b. 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 71 RPT building in an IPv6 PIM-SM domain
As shown in Figure 71, 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 hop-by-hop 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 reaches the receiver.
Source
Server
Host A
Host B
Host C
Receiver
Receiver
IPv6 multicast packets
RPT
Join message
RP DR
DR