Concept Guide
Mode Count Intvl Prio
Gi 1/3 v2/S 1 30 1
Address : fe80::201:e8ff:fe02:140f
DR : this router
Gi 1/11 v2/S 0 30 1
Address : fe80::201:e8ff:fe02:1417
DR : this router
Dell#
Creating Multicast Boundaries and Domains
A PIM domain is a contiguous set of routers that all implement PIM and are congured to operate within a common boundary dened by
PIM multicast border routers (PMBRs).
PMBRs connect each PIM domain to the rest of the Internet.
Create multicast boundaries and domains by ltering inbound and outbound bootstrap router (BSR) messages per interface. The following
command is applied to the subsequent inbound and outbound updates. Timeout removes existing BSR advertisements.
• Create multicast boundaries and domains by ltering inbound and outbound BSR messages per interface.
ip pim bsr-border
• Remove candidate RP advertisements.
clear ip pim rp-mapping
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 congured. RFC 5059 species a dynamic, self-conguring 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 congured to be C-RPs. Other routers are congured 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 ood 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 ecient group-to-RP mappings and periodically updates it to all PIM routes in the network.
4 The BSR oods 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, rst 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 trac loss in the network.
3 If you congure a secondary VLT peer as an E-BSR and in case of ICL ap 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 congure 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
PIM Sparse-Mode (PIM-SM)
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