Cisco Systems 78-11741-02 manual Filtering Incoming RP Announcement Messages, IPC-408

Configuring IP Multicast Routing

Configuring Auto-RP

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:

Command	Purpose
Router(config)# ip pim send-rp-discovery scope	Assigns the RP mapping agent.
ttl-value

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:

Command	Purpose
Router# show ip pim rp [mapping metric]	Displays active RPs that are cached with associated multicast
[rp-address]	routing entries. Information learned by configuration or Auto-RP.

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-rpglobal configuration commands previously configured throughout the network. If the ip pim accept-rpcommand is not configured on any router, this problem can be addressed later. In those routers already configured with the ip pim accept-rpcommand, 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-rpauto-rpcommand.

If all interfaces are in sparse mode, a default RP is configured to support the two well-known groups

224.0.1.39and 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-rpauto-rpcommand is configured, another ip pim accept-rpcommand 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 rp-announce-filter rp-list		Filters incoming RP announcement messages.
access-list group-listaccess-list
	Cisco IOS IP Configuration Guide

IPC-408