Huawei Quidway S3900 Series Operation Manual page 417

Operation Manual – Multicast Protocol
Quidway S3900 Series Ethernet Switches-Release 1510
Collecting the Advertisement messages sent by the Candidate-RP (C-RP) in the
network.
Selecting part of the C-RP information to constitute the RP-set, namely, the
mapping database between the multicast group and RP.
Advertising the RP-set to the whole network in order that all the router (including
DR) in the network knows the position of RP.
One or more candidate BSRs must be configured in a PIM domain. Through the
auto-election, the candidate BSRs elect a BSR which is responsible for collecting and
advertising RP information. The auto-election among candidate BSRs is described in
the following section:
Specify a PIM-SM-enabled interface when configuring a router as a candidate
BSR.
Each candidate BSR considers itself as the BSR of the PIM-SM and uses the IP
address of the specified interface as the BSR address to send Bootstrap
messages.
When the candidate BSR receives Bootstrap messages from other routers, it will
compare the BSR address in the received Bootstrap message with its own BSR
address in priority and IP address. When the priority is the same, the candidate
BSR with a higher IP address is considered to be better. If the former is better, the
candidate BSR will replace its own BSR address with the new BSR address and
does not consider itself as BSR any more. Otherwise, the candidate BSR will keep
its own BSR address and continue to consider itself as BSR.
The positions of RPs and BSRs in the network are as shown in Figure 7-4:
Figure 7-4 Diagram for the communication between RPs and BSRs
Only one BSR can be elected in a network or management domain, while multiple
candidate BSRs (C-BSR) can be configured. In this case, once the BSR fails, other
C-RP
BSR message
C-RP advertisement
Huawei Technologies Proprietary
BSR
C-RP
C-BSR
C-RP
7-7
Chapter 7 PIM Configuration