Cisco 3845 - Security Bundle Router Software Manual page 760

Configuring IP Multicast Routing
To accept all RPs advertised with Auto-RP and reject all other RPs by default, use the ip pim accept-rp
auto-rp global configuration command. This procedure is optional.
If all interfaces are in sparse mode, use a default-configured RP to support the two well-known
groups 224.0.1.39 and 224.0.1.40. Auto-RP uses 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 RP must be configured as follows:
Switch(config)# ip pim accept-rp 172.10.20.1 1
Switch(config)# access-list 1 permit 224.0.1.39
Switch(config)# access-list 1 permit 224.0.1.40
Filtering Incoming RP Announcement Messages
You can add configuration commands to the mapping agents to prevent a maliciously configured router
from masquerading as a candidate RP and causing problems.
Beginning in privileged EXEC mode, follow these steps to filter incoming RP announcement messages.
This procedure is optional.
Command
Step 1
configure terminal
Step 2
ip pim rp-announce-filter rp-list
access-list-number group-list
access-list-number
Cisco ME 3800X and 3600X Switch Software Configuration Guide
33-26
Purpose
Enter global configuration mode.
Filter incoming RP announcement messages.
Enter this command on each mapping agent in the network. Without
this command, all incoming RP-announce messages are accepted by
default.
For rp-list access-list-number, configure an access list of candidate RP
addresses that, if permitted, is accepted for the group ranges supplied
in the group-list access-list-number variable. If this variable is
omitted, the filter applies to all multicast groups.
If more than one mapping agent is used, the filters must be consistent
across all mapping agents to ensure that no conflicts occur in the
Group-to-RP mapping information.
Chapter 33 Configuring IP Multicast Routing
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