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Configuring IP Multicast Routing
Configuring Auto-RP
IPC-408
Cisco IOS IP Configuration Guide
Find a router whose connectivity is not likely to be interrupted and assign it the role of RP-mapping
agent. All routers within time-to-live (TTL) number of hops from the source router receive the Auto-RP
discovery messages. To assign the role of RP mapping agent in that router, use the following command
in global configuration mode:
Verifying the Group-to-RP Mapping
To learn if the group-to-RP mapping has arrived, use the following command in EXEC mode on the
designated routers:
Starting to Use IP Multicast
Use your IP multicast application software to start joining and sending to a group.
Preventing Join Messages to False RPs
Note the ip pim accept-rp global configuration commands previously configured throughout the
network. If the ip pim accept-rp command is not configured on any router, this problem can be
addressed later. In those routers already configured with the ip pim accept-rp command, you must
specify the command again to accept the newly advertised RP.
To accept all RPs advertised with Auto-RP and reject all other RPs by default, use the ip pim accept-rp
auto-rp command.
If all interfaces are in sparse mode, a default RP is configured to support the two well-known groups
224.0.1.39 and 224.0.1.40. Auto-RP relies on these two well-known groups to collect and distribute
RP-mapping information. When this is the case and the ip pim accept-rp auto-rp command is
configured, another ip pim accept-rp command accepting the default RP must be configured, as follows:
ip pim accept-rp <default RP address> 1
access-list 1 permit 224.0.1.39
access-list 1 permit 224.0.1.40
Filtering Incoming RP Announcement Messages
To filter incoming RP announcement messages, use the following command in global configuration
mode:
Command Purpose
Router(config)# ip pim send-rp-discovery scope
ttl-value
Assigns the RP mapping agent.
Command Purpose
Router# show ip pim rp [mapping | metric]
[rp-address]
Displays active RPs that are cached with associated multicast
routing entries. Information learned by configuration or Auto-RP.
Command Purpose
Router(config)# ip pim rp-announce-filter rp-list
access-list group-list access-list
Filters incoming RP announcement messages.