3com 5500-SI Manual De Usuario

PIM-SM Overview 341

In a PIM-SM network, multiple RPs (candidate-RPs) can be configured. Each 
Candidate-RP (C-RP) is responsible for forwarding multicast packets with the 
destination addresses in a certain range. Configuring multiple C-RPs is to implement 
load balancing of the RP. These C-RPs are equal. All multicast routers calculate the RPs 
corresponding to multicast groups according to the same algorithm after receiving 
the C-RP messages that the BSR advertises.

It should be noted that one RP can serve multiple multicast groups or all multicast 
groups. Each multicast group can only be uniquely correspondent to one RP at a time 
rather than multiple RPs.

The BSR is the management core in a PIM-SM network. Candidate-RPs send 
announcement to the BSR, which is responsible for collecting and advertising the 
information about all candidate-RPs.

It should be noted that there can be only one BSR in a network but you can configure 
multiple candidate-BSRs. In this case, once a BSR fails, you can switch over to another 
BSR. A BSR is elected among the C-BSRs automatically. The C-BSR with the highest 
priority is elected as the BSR. If the priority is the same, the C-BSR with the largest IP 
address is elected as the BSR.

The router that serves as the RP is the core router of multicast routes. If the dynamic 
RP elected by BSR mechanism is invalid for some reason, the static RP can be 
configured to specify RP. As the backup of dynamic RP, static RP improves network 
resilience and enhances the operation and management capability of multicast 
network.

PIM-SM basic configuration includes:

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PIM-SM advanced configuration includes:

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