F3726, F3211, F3174, R5135, R3816-HP Firewalls and UTM Devices Appendix Protocol Reference-6PW100

Each admin-scope zone serves specific multicast groups, of which the multicast group addresses

are valid only within the local zone. The multicast groups of different admin-scoped zones might

have intersections. All the multicast groups other than those of the admin-scoped zones are served

by the global-scoped zone.

Figure 59 Relationship in view of multicast group address ranges

As shown in Figure 59, 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

the multicast groups that are not covered by the admin-scoped zones 1 and 2, that is, G−G1−G2

in this case.

PIM-SSM overview

The SSM model and the ASM model are opposites. Presently, 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 relationship 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.

The working 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."

Admin-scope 3

G3 address

Admin-scope 2

G2 address

Admin-scope 1

G1 address

Global-scope

−G1−G2 address