White Papers

1. C-BSRs flood their candidacy throughout the domain in a BSM. Each message contains a BSR priority value, and the C-BSR
with the highest priority value becomes the BSR.
2. Each C-RP unicasts periodic Candidate-RP-Advertisements to the BSR. Each message contains an RP priority value and the
group ranges for which it is a C-RP.
3. The BSR collects the most efficient group-to-RP mappings and periodically updates it to all PIM routes in the network.
4. The BSR floods the RP-Set throughout the domain periodically in case new C-RPs are announced, or an RP failure occurs.
Constraints
1. When a multicast group range is removed from the ACL group list, the E-BSR sends the advertisements to the group with
hold-time as 0 only when the C-RP timer expires. Till the timer expires, the C-RP will act as a RP for that multicast group.
2. In E-BSR, if the C-RP advertisements are not in synchronization with the standby, first few BCM C-RP advertisement might
not have the complete list of RP mappings. Due to this, there is a possibility of RP mapping timeout and momentary traffic
loss in the network.
3. If you configure a secondary VLT peer as an E-BSR and in case of ICL flap or failover, the VLT lag will be down resulting a
BSM timeout in the PIM domain and a new BSR will be elected. Hence, it is recommended to configure the primary VLT peer
as E-BSR.
NOTE: BSR configuration in the multicast topology should ensure that secondary VLT node is not selected as E-BSR. If
selected as E-BSR during ICL flap or VLT failover, traffic disruption will be reported.
To enable BSR election for IPv4 or IPv6, perform the following steps:
1. Enter the following IPv4 or IPv6 command to make a PIM router a BSR candidate:
CONFIGURATION
ip pim bsr-candidate
ipv6 pim bsr-candidate
2. Enter the following IPv4 or IPv6 command to make a PIM router a RP candidate:
CONFIGURATION
ip pim rp-candidate
ipv6 pim rp-candidate
3. Display IPv4 or IPv6 Bootstrap Router information.
EXEC Privilege
show ip pim bsr-router
Example:
DellEMC# show ip pim bsr-router
PIMv2 Bootstrap information
This system is the Bootstrap Router (v2)
BSR address: 7.7.7.7 (?)
BSR Priority: 0, Hash mask length: 30
Next bootstrap message in 00:00:08
This system is a candidate BSR
Candidate BSR address: 7.7.7.7, priority: 0, hash mask length: 30
DellEMC#
show ipv6 pim bsr-router
Example:
DellEMC#show ipv6 pim bsr-router
PIMv2 Bootstrap information
BSR address: 200::1 (?)
BSR Priority: 0, Hash mask length: 126
Expires: 00:01:43
This system is a candidate BSR
Candidate BSR address: 100::1, priority: 0, hash mask length: 126
Next Cand_RP_advertisement in 00:00:25
RP: 100::1(Lo 0)
DellEMC#
652
PIM Source-Specific Mode (PIM-SSM)