Construction Of Spt; Pim Protocol Relationships - HP A6600 Configuration Manual

Construction of SPT

Whether to build an RPT for PIM-SM or an SPT for PIM-SSM depends on whether the multicast group the
receiver will join falls in the SSM group range (SSM group range reserved by IANA is 232.0.0.0/8).
Figure 43 SPT building in PIM-SSM
As shown in
messages to the respective DRs to express their interest in the information of the specific multicast source
S.
After receiving a report message, the DR first determines whether the group address in this message falls
in the SSM group range:
If so, the DR sends a subscribe message for channel subscription hop by hop toward the multicast
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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 PIM-SSM.
If not, the DR follows the PIM-SM process. The DR sends a (*, G) join message to the RP, and a
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multicast source registration process is needed.
In PIM-SSM, the term channel refers to a multicast group, and the term channel subscription refers to a
join message.

PIM protocol relationships

In a PIM network, PIM-DM cannot run together with PIM-SM, BIDIR-PIM, or PIM-SSM. However, PIM-SM,
BIDIR-PIM, and PIM-SSM can run together and the receiver chooses based on the process shown in
44.
Figure 43, Host B and Host C are multicast information receivers. They send IGMPv3 report
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Figure