Concept Guide

Table Of Contents
Overriding Bootstrap Router Updates
PIM-SM routers must 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.
Use the following command if you have configured a static RP for a group. If you do not use the override option with the
following command, the RPs advertised in the BSR updates take precedence over any statically configured RPs.
Use the override option to use statically configured RP instead of the longest prefix match of the configured group
address associated with a dynamic RP.
{ip | ipv6} pim rp-address address {group-address group-address mask} [override]
To display the assigned RP for a group, use the show {ip | ipv6} pim rp [mapping | group-address] command
from EXEC privilege mode.
Following is an example of show ip pim rp command output:
DellEMC#show ip pim rp
Group RP
225.0.1.40 165.87.50.5
226.1.1.1 165.87.50.5
Following is an example of show ipv6 pim rp command output:
DellEMC#show ipv6 pim rp
Group RP
ff0e::225:1:2:1 14::1
ff0e::225:1:2:2 14::1
ff0e::226:1:2:1 14::1
ff0e::226:1:2:2 14::1
To display the assigned RP for a group range (group-to-RP mapping), use the show {ip | ipv6} pim rp mapping
command in EXEC privilege mode.
Following is an example of show ip pim rp mapping command output:
DellEMC#show ip pim rp mapping
PIM Group-to-RP Mappings
Group(s): 224.0.0.0/4, Static
RP: 165.87.50.5, v2
Following is an example of show ipv6 pim rp mapping command output:
Dell#show ipv6 pim rp mapping
PIM Group-to-RP Mappings
Group(s): ff00::/8, Static
RP: 2001:100::1, v2
Dell#
Configuring a Designated Router
Multiple PIM-SM routers might be connected to a single local area network (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 IPv4 or IPv6 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 IPv4 or IPv6 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 | ipv6} pim dr-priority priority-value
Change the interval at which a router sends hello messages.
688
PIM Sparse-Mode (PIM-SM)