Cisco WS-C3750-48PS-S Software Configuration Manual page 819

Chapter 36 Configuring IP Multicast Routing
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
Step 3
access-list access-list-number {deny |
permit} source [source-wildcard]
Step 4 end
Step 5
show running-config
Step 6 copy running-config startup-config
To remove a filter on incoming RP announcement messages, use the no ip pim rp-announce-filter
rp-list access-list-number [group-list access-list-number] global configuration command.
78-16180-02
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.
Create a standard access list, repeating the command as many times as
necessary.
• For access-list-number, enter the access list number specified in
Step 2.
The deny keyword denies access if the conditions are matched.
•
The permit keyword permits access if the conditions are matched.
Create an access list that specifies from which routers and
•
multilayer switches the mapping agent accepts candidate RP
announcements (rp-list ACL).
Create an access list that specifies the range of multicast groups
•
from which to accept or deny (group-list ACL).
For source, enter the multicast group address range for which the
•
RP should be used.
(Optional) For source-wildcard, enter the wildcard bits in dotted
•
decimal notation to be applied to the source. Place ones in the bit
positions that you want to ignore.
Recall that the access list is always terminated by an implicit deny
statement for everything.
Return to privileged EXEC mode.
Verify your entries.
(Optional) Save your entries in the configuration file.
Catalyst 3750 Switch Software Configuration Guide
Configuring IP Multicast Routing
36-17