H3C Technologies H3C S12500-X Series Switches - Manual (Page 166)

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Figure 52 SPT building in IPv6 PIM-SSM
As shown in Figure 31 , Host B and Host C are receivers. They send MLDv2 report messages to their DRs
to express their interest in the multicast information that the IPv6 multicast source S sends to the IPv6
multicast group G.
After receiving a report message, the DR first checks whether the group address in the message is in the
IPv6 SSM group range and does the following:
• If the group address is in the IPv6 SSM group range, the IPv6 PIM-SSM service is provided.
The DR sends a subscribe message toward the IPv6 multicast source. All routers along the path
from the DR to the IPv6 multicast source create an (S, G) entry so as to build an SPT. The SPT is
rooted at the IPv6 multicast source and has the receivers as its leaves.
• If the group address is not in the IPv6 SSM group range, the IPv6 PIM-SM service is provided.
The receiver-side DR sends a (*, G) join message to the RP, and the IPv6 multicast source registers
with the source-side DR.
In IPv6 PIM-SSM, the term "channel" refers to an IPv6 multicast group, and the term "subscribe message"
refers to a join message.
IPv6 PIM support for VPNs
To support IPv6 PIM for VPNs, a multicast router that runs IPv6 PIM maintains an independent set of IPv6
PIM neighbor table, IPv6 multicast routing table, BSR information, and RP-set information for each VPN.
After receiving an IPv6 multicast data packet, the multicast router checks for the VPN to which the IPv6
data packet belongs, and then forwards the IPv6 packet according to the IPv6 multicast routing table for
that VPN or creates an IPv6 multicast routing entry for that VPN.
Protocols and standards
• RFC 3973, Protocol Independent Multicast-Dense Mode (PIM-DM): Protocol Specification(Revised)
• RFC 4601, Protocol Independent Multicast-Sparse Mode (PIM-SM): Protocol Specification (Revised)
• RFC 3956, Embedding the Rendezvous Point (RP) Address in an IPv6 Multicast Address