3Com S7902E, Configuration Manual

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Figure 1-7 Building an SPT in IPv6 PIM-SSM
As shown in Figure 1-7 , Hosts B and C are IPv6 multicast information receivers. They send an MLDv2
report message to the respective DRs to announce that they are interested in the information of the
specific IPv6 multicast source S and that sent to the IPv6 multicast group G.
The DR that has received the report first checks whether the IPv6 group address in this message falls in
the IPv6 SSM group range:
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If so, the IPv6 PIM-SSM model is built: the DR sends a channel subscription message hop by hop
toward the IPv6 multicast source S. An (S, G) entry is created on all routers on the path from the
DR to the source. Thus, an SPT is built in the network, with the source S as its root and receivers as
its leaves. This SPT is the transmission channel in IPv6 PIM-SSM.
z
If not, the IPv6 PIM-SM process is followed: the DR needs to send a (*, G) join message to the RP,
and an IPv6 multicast source registration process is needed.
In IPv6 PIM-SSM, the “channel” concept is used to refer to an IPv6 multicast group, and the “channel
subscription” concept is used to refer to a join message.
Protocols and Standards
IPv6 PIM–related specifications are as follows:
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RFC 4601: Protocol Independent Multicast-Sparse Mode (PIM-SM): Protocol Specification
(Revised)
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RFC 3973: Protocol Independent Multicast-Dense Mode(PIM-DM):Protocol Specification(Revised)
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RFC 3956: Embedding the Rendezvous Point (RP) Address in an IPv6 Multicast Address
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RFC 4607: Source-Specific Multicast for IP
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RFC 5059: Bootstrap Router (BSR) Mechanism for Protocol Independent Multicast (PIM)
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draft-ietf-ssm-overview-05: An Overview of Source-Specific Multicast (SSM)