Concept Guide

Mode Count Intvl Prio
Te 1/3 v2/S 1 30 1
Address : fe80::201:e8ff:fe02:140f
DR : this router
Te 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 congured to operate within a common boundary dened 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 congured. RFC 5059 species a dynamic, self-conguring 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 congured to be C-RPs. Other routers are congured 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 ecient 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 trac loss in the network.
3 If you congure 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 congure 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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