5. Compatibility with IGMPv1 Hosts

5. Compatibility with IGMPv1 Hosts

An IGMPv2 host may be placed on a subnet where there are hosts that have not yet been upgraded to IGMPv2. The following requirement applies:

The host MUST allow its Membership Report to be suppressed by either a Version 1 Membership Report or a Version 2 Membership Report.

An IGMPv2 router may be placed on a subnet where there are hosts that have not yet been upgraded to IGMPv2. The following requirements apply:

If a router receives a Version 1 Membership Report, it MUST set a timer to note that there are version 1 hosts present which are members of the group for which it heard the report. This timer should be the same as the [Group Membership Interval].

If there are version 1 hosts present for a particular group, a router MUST ignore any Leave Group messages that it receives for that group.