Administrator Guide

with the greatest priority value is the DR. If the priority value is the same for two routers, then the router with the greatest IP address is
the DR. By default, the DR priority value is 192, so the IP address determines the DR.
• Assign a DR priority value.
INTERFACE mode
ip pim dr-priority priority-value
• Change the interval at which a router sends hello messages.
INTERFACE mode
ip pim query-interval seconds
• Display the current value of these parameter.
EXEC Privilege mode
show ip pim interface
Electing an RP using the BSR Mechanism
Every PIM router within a domain must map a particular multicast group address to the same RP. The group-to-RP mapping may be
statically or dynamically configured. RFC 5059 specifies a dynamic, self-configuring method called the Bootstrap Router (BSR)
mechanism, by which an RP is elected from a pool of RP candidates (C-RPs).
Some routers within the domain are configured to be C-RPs. Other routers are configured to be Bootstrap Router candidates (C-BSRs);
one router is elected the BSR for the domain and the BSR is responsible for forwarding BSM containing RP-set information to other
routers.
The RP election process is as follows:
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.
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
PIM Sparse-Mode (PIM-SM)
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