Users Guide

Group Address Interface Mode Uptime Expires Last Reporter
239.0.0.2 Vlan 300 IGMPv2-Compat 00:00:36 Never 10.11.3.2
Member Ports: Te 1/1
R1(conf)#do show ip igmp ssm-map 239.0.0.2
SSM Map Information
Group : 239.0.0.2
Source(s) : 10.11.5.2
R1(conf)#do show ip igmp groups detail
Interface Vlan 300
Group 239.0.0.2
Uptime 00:00:01
Expires Never
Router mode IGMPv2-Compat
Last reporter 10.11.3.2
Last reporter mode IGMPv2
Last report received Join
Group source list
Source address Uptime Expires
10.11.5.2 00:00:01 Never
Interface Vlan 400
Group 239.0.0.1
Uptime 00:00:05
Expires Never
Router mode INCLUDE
Last reporter 10.11.4.2
Last reporter mode INCLUDE
Last report received ALLOW
Group source list
Source address Uptime Expires
10.11.5.2 00:00:05 00:02:04
Member Ports: Te 1/2
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.
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.
PIM Source-Specific Mode (PIM-SSM) 695