HP FlexNetwork 7500 Series Configuration Manual page 108

As shown in
messages) to the BSR. An advertisement message contains the address of the advertising C-RP
and the multicast group range to which it is designated. The BSR collects these advertisement
messages and organizes the C-RP information into an RP-set, which is a database of mappings
between multicast groups and RPs. The BSR encapsulates the RP-set information in the bootstrap
messages (BSMs) and floods the BSMs to the entire PIM-SM domain.
Figure 37 Information exchange between C-RPs and BSR
Based on the information in the RP-set, all routers on the network can select an RP for a specific
multicast group based on the following rules:
The C-RP that is designated to the smallest group range wins.
1.
If the C-RPs are designated to the same group ranges, the C-RP with the highest priority wins.
2.
If the C-RPs have the same priority, the C-RP with the largest hash value wins. The hash value
3.
is calculated through the hash algorithm.
If the C-RPs have the same hash value, the C-RP with the highest IP address wins.
4.
RPT building
Figure 38 RPT building in a PIM-SM domain
Source
Server
Figure 37, each C-RP periodically unicasts its advertisement messages (C-RP-Adv
RP
RPT
Join message
Multicast packets
DR
98
Host A
Receiver
DR
Host B
Receiver
Host C