HP 4800G Series Configuration Manual page 876

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Router A and Router B are MSDP peers on common multicast routers. Such MSDP peers just forward

received SA messages.

In a PIM-SM network running the BSR mechanism, the RP is dynamically elected from C-RPs. To

enhance network robustness, a PIM-SM network typically has more than one C-RP. As the RP election

result is unpredictable, MSDP peering relationships should be built among all C-RPs so that the winner

C-RP is always on the "MSDP interconnection map", while loser C-RPs will assume the role of common

PIM-SM routers on the "MSDP interconnection map".

Implementing inter-domain multicast delivery by leveraging MSDP peers

learned the existence of Source through multicast source registration. If RPs in PIM-SM 2 and PIM-SM

3 also wish to know the specific location of Source so that receiver hosts can receive multicast traffic

originated from it, MSDP peering relationships should be established between RP 1 and RP 3 and

between RP 3 and RP 2 respectively.

Figure 1-2 MSDP peering relationships

Multicast packets

Join message

The process of implementing inter-domain multicast delivery by leveraging MSDP peers is as follows:

When the multicast source in PIM-SM 1 sends the first multicast packet to multicast group G, DR 1

encapsulates the multicast data within a register message and sends the register message to RP 1.

Then, RP 1 gets aware of the information related to the multicast source.

As the source-side RP, RP 1 creates SA messages and periodically sends the SA messages to its

MSDP peer. An SA message contains the source address (S), the multicast group address (G),

and the address of the RP which has created this SA message (namely RP 1).

1-2, an active source (Source) exists in the domain PIM-SM 1, and RP 1 has

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