HPE 5820X Series, Руководство по настройке

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132
Figure 50 Relationship in view of multicast group address ranges
In Figure 50 , the admin-scoped zones 1 and 2 have no intersection, but the admin-scoped zone
3 is a subset of the admin-scoped zone 1. The global-scoped zone serves all multicast groups
that are not covered by the admin-scoped zones 1 and 2, that is, G
− G1 − G2 in this case.
PIM-SSM
The ASM model includes the PIM-DM and PIM-SM modes. The SSM model can be implemented by
leveraging part of the PIM-SM technique. It is also called "PIM-SSM."
The SSM model provides a solution for source-specific multicast. It maintains the relationships
between hosts and routers through IGMPv3.
In actual application, part of IGMPv3 or PIM-SM technique is adopted to implement the SSM model.
In the SSM model, receivers locate a multicast source by means of advertisements, consultancy,
and so on. No RP or RPT is required, no source registration process exists, and the MSDP is not
needed for discovering sources in other PIM domains.
In PIM-SSM, the term "channel" refers to a multicast group, and the term "channel subscription"
refers to a join message.
The operating mechanism of PIM-SSM is summarized as follows:
•
Neighbor discovery
•
DR election
•
SPT building
Neighbor discovery
PIM-SSM uses the same neighbor discovery mechanism as in PIM-DM and PIM-SM. See " Neighbor
discovery ."
DR election
PIM-SSM uses the same DR election mechanism as in PIM-SM. See " DR election ."
SPT building
The decision to build an RPT for PIM-SM or an SPT for PIM-SSM depends on whether the multicast
group that the receiver wants to join falls into the SSM group range. The SSM group range reserved
by IANA is 232.0.0.0/8.
Admin-scope 3
G3 address
Admin-scope 2
G2 address
Admin-scope 1
G1 address
Global-scope
G
−
G1
−
G2 address