Reference Guide

PIM Sparse-Mode (PIM-SM) | 675
Override Bootstrap Router Updates
PIM-SM routers need to know the address of the RP for each group for which they have (*,G) entry. This
address is obtained automatically through the bootstrap router (BSR) mechanism or a static RP
configuration.
If you have configured a static RP for a group, use the option
override with the command ip pim rp-address
to override bootstrap router updates with your static RP configuration. If you do not use this option, the
RPs advertised in the BSR updates take precedence over any statically configured RPs.
Display the assigned RP for a group using the command
show ip pim rp from EXEC privilege mode, as
shown in Figure 30-6.
Figure 30-6. Displaying the Rendezvous Point for a Multicast Group
Display the assigned RP for a group range (group-to-RP mapping) using the command show ip pim rp
mapping command in EXEC privilege mode
Figure 30-7. Display the Rendezvous Point for a Multicast Group Range
Configure a Designated Router
Multiple PIM-SM routers might be connected to a single LAN segment. One of these routers is elected to
act on behalf of directly connected hosts. This router is the Designated Router (DR).
The DR is elected using hello messages. Each PIM router learns about its neighbors by periodically
sending a hello message out of each PIM-enabled interface. Hello messages contain the IP address of the
interface out of which it is sent and a DR priority value. The router 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 using the command
ip pim dr-priority priority-value from INTERFACE
mode.
• Change the interval at which a router sends hello messages using the command
ip pim query-interval
seconds from INTERFACE mode.
• Display the current value of these parameter using the command
show ip pim interface EXEC Privilege
mode.
FTOS#show ip pim rp
Group RP
225.0.1.40 165.87.50.5
226.1.1.1 165.87.50.5
FTOS#show ip pim rp mapping
PIM Group-to-RP Mappings
Group(s): 224.0.0.0/4, Static
RP: 165.87.50.5, v2