Changing the IGMP Version

By default, the routing device runs IGMPv2. Routing devices running different versions of IGMP negotiate the lowest common version of IGMP that is supported by hosts on their subnet and operate in that version.

To enable SSM functionality, you must configure version 3 on the host and the host’s directly connected routing device. If a source address is specified in a multicast group that is statically configured, the version must be set to IGMPv3.

Note: If a static multicast group is configured with the source address defined and the IGMP version is configured to be version 2, the source is ignored and only the group is added. In this case the join is treated as an IGMPv2 group join.

To change to IGMPv3 (for source-specific multicast [SSM] functionality), include the version statement:

You can include this statement at the following hierarchy levels:

• [edit protocols igmp interface interface-name]
• [edit logical-systems logical-system-name protocols igmp interface interface-name]

If you configure the IGMP version setting at the individual interface hierarchy level, it overrides configuring the IGMP version using the interface statement and specifying the all option.

Note: If you have already configured the routing device to use IGMP version 1 (IGMPv1) and then configure it to use IGMPv2, the routing device continues to use IGMPv1 for up to 6 minutes and then uses IGMPv2.