Changing the IGMP Version

Changing the IGMP Version
Several settings can be tweaked in the router to enhance or change performance. The majority
of them are beyond the scope of this chapter. However, in this section, we discuss one important
feature: changing the IGMP version. It is important that you understand and know how to perform
this change because of the compatibility issues between IGMP versions.
To put it simply, the IGMP version that runs on the hosts must also run on the router. Cisco
routers use IGMPv2 by default and do not auto-detect the IGMP version that the host is using.
The command to change from IGMPv2 to IGMPv1, or vice versa, is ip igmp version (2 | 1).
Because the IGMP version needs to match only on the subnet, the command must be entered on
the interface that connects to the subnet housing the IGMPv1 hosts. The other interfaces on the
router can remain on IGMPv2.