Cisco IOS Cookbook, 2nd Edition

Using IGMP Version 3

Problem

You want to take advantage of the new features in IGMP Version 3.

Solution

Cisco routers use IGMP Version 2 by default. If you want to use IGMP Version 3, and if the end devices on your network support this version, you can enable native v3 support as follows:

Router1#configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Router1(config)#ip multicast-routing
Router1(config)#ip pim ssm default
Router1(config)#interface FastEthernet0/0
Router1(config-if)#ip pim sparse-dense-mode
Router1(config-if)#ip igmp version 3
Router1(config-if)#end
Router1#

Alternatively, if you want to take advantage of Source-Specific Multicast(SSM) features, but your end devices don’t support IGMP Version 3, you can use Cisco’s proprietary IGMP v3lite:

Router1#configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Router1(config)#ip multicast-routing
Router1(config)#ip pim ssm default
Router1(config)#interface FastEthernet0/0
Router1(config-if)#ip pim sparse-dense-mode
Router1(config-if)#ip igmp v3lite
Router1(config-if)#end
Router1#

Discussion

The most useful single feature of IGMP Version 3 is SSM. This allows an end device to specify not only the multicast group that it wishes to receive, but also the multicast source. The range of multicast addresses that may use specific sources is defined in the ip pim ssm global configuration command:

Router1(config)#ip pim ssm default

In this form, the router allows SSM for multicast addresses in ...