Cisco IOS Cookbook, 2nd Edition

Configuring Basic Multicast Functionality with PIM-DM

Problem

You want to pass multicast traffic through the router.

Solution

In a small network with few routers and relatively light multicast application bandwidth requirements, the easiest way to implement multicast routing is to use PIM-DM. This example shows the configurations for two routers that are connected through a Serial connection, both with FastEthernet interfaces to represent the LAN connections. It is important to enable multicast routing on all interfaces that connect to other multicast-enabled routers or to multicast user or server segments.

The first router looks like this:

Router1#configure terminal 
Enter configuration commands, one per line.  End with CNTL/Z.
Router1(config)#ip multicast-routing
Router1(config)#interface FastEthernet0/0
Router1(config-if)#ip address 192.168.1.1 255.255.255.0
Router1(config-if)#ip pim dense-mode
Router1(config-if)#exit
Router1(config)#interface Serial1/0
Router1(config-if)#ip address 192.168.2.5 255.255.255.252
Router1(config-if)#ip pim dense-mode
Router1(config-if)#end
Router1#

And the second router looks remarkably similar:

Router2#configure terminal 
Enter configuration commands, one per line.  End with CNTL/Z.
Router2(config)#ip multicast-routing
Router2(config)#interface FastEthernet0/0
Router2(config-if)#ip address 192.168.3.1 255.255.255.0
Router2(config-if)#ip pim dense-mode
Router2(config-if)#exit
Router2(config)#interface Serial1/0
Router2(config-if)#ip address 192.168.2.6 255.255.255.252 ...