PIM BSR uses the 224.0.0.13 to send out the advertisement of the BSR and PR. In case there are more than one advertisement of the RP and BSR candidates, we use the priority and IP address criteria to election the primary RP and primary BSR. However, RP election and BSR election criteria is different
RP election consider the lowest priority or the lowest IP address as a primary RP. However, BSP election considers the highest priority or the highest IP address as primary BSR. We can see the RP and BSP by using following commad.
show ip pim rp mapping ( show RP mapping for the multicast groups )
show ip pim bsr-route ( show BSR router )
To change the priority of the RP and BSR, we use the following commands.
RP
ip pim rp-candidate Loopback0 priority 10
BSR
ip pim bsr-candidate Loopback0 0 10
Example :
We configure R1 and R2 to announce themselves as the RP and BSR candidates. R1 has RP priority of 10 and BSR priority of 10. R2 has RP priority of 20 and BSR priority of 0. We expect that R1 will be the primary RP and R2 will be the primary BSR because of the criteria explained above.
Configuration
R1
ip pim bsr-candidate Loopback0 0 10
ip pim rp-candidate Loopback0 priority 10
R2
ip pim bsr-candidate Loopback0 0
ip pim rp-candidate Loopback0 priority 20
!
RP Mapping
R3#sh ip pim rp mapping
PIM Group-to-RP Mappings
Group(s) 224.0.0.0/4
RP 1.1.1.1 (?), v2
Info source: 1.1.1.1 (?), via bootstrap, priority 10, holdtime 150
Uptime: 00:16:29, expires: 00:02:12
RP 2.2.2.2 (?), v2
Info source: 1.1.1.1 (?), via bootstrap, priority 20, holdtime 150
Uptime: 00:16:40, expires: 00:01:56
BSR Router
R2#show ip pim bsr-router
PIMv2 Bootstrap information
BSR address: 1.1.1.1 (?)
Uptime: 00:13:08, BSR Priority: 10, Hash mask length: 0
Expires: 00:01:12
This system is a candidate BSR
Candidate BSR address: 2.2.2.2, priority: 0, hash mask length: 0
Candidate RP: 2.2.2.2(Loopback0)
Holdtime 150 seconds
Advertisement interval 60 seconds
Next advertisement in 00:00:37
Candidate RP priority : 20
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