PIM-SM Overview 343
Configuring Candidate-BSRs
In a PIM domain, one or more candidate BSRs should be configured. A BSR (Bootstrap
Router) is elected among candidate BSRs. The BSR takes charge of collecting and
advertising RP information.
The automatic election among candidate BSRs operates as follows:
■ One interface which has started PIM-SM must be specified when configuring the
router as the candidate BSR.
■ At first, each candidate BSR considers itself as the BSR of the PIM-SM domain, and
sends a Bootstrap message by taking the IP address of the interface as the BSR
address.
■ When receiving Bootstrap messages from other routers, the candidate BSR will
compare the BSR address of the newly received Bootstrap message with that of
itself. Comparison standards include priority and IP address. The bigger IP address
is considered better when the priority is the same. If the new BSR address is better,
the candidate BSR will replace its BSR address and stop regarding itself as the BSR.
Otherwise, the candidate BSR will keep its BSR address and continue to regard
itself as the BSR.
Perform the following configuration in PIM view.
Candidate-BSRs should be configured on the routers in the network backbone. By
default, no BSR is set. The default priority is 0.
One Switch can only be configured with one candidate-BSR. When a candidate-BSR is
configured on another interface, it will replace the previous configuration.
Configuring Candidate-RPs
In PIM-SM, the shared tree built by the multicast routing data is rooted at the RP.
There is a mapping from a multicast group to an RP. A multicast group can be
mapped to an RP. Different groups can be mapped to one RP.
Perform the following configuration in PIM view.
When configuring RP, if the range of the served multicast group is not specified, the
RP will serve all multicast groups. Otherwise, the range of the served multicast group
is the multicast group in the specified range. 3Com recommends that you configure
Candidate RP on the backbone router.
Table 353 Configuring candidate-BSRs
Operation Command
Configure a candidate-BSR c-bsr interface-type interface_number
hash_mask_len [ priority ]
Remove the candidate-BSR
configured
undo c-bsr
Table 354 Configuring candidate-RPs
Operation Command
Configure a candidate-RP c-rp interface_type interface_number [
group-policy acl_number | priority priority_value
]*
Remove the candidate-RP
configured
undo c-rp { interface_type interface_number | all
}
