To receive multicast traffic, a host must explicitly join a multicast group by sending an IGMP report; then, the traffic is forwarded to that host. In some situations, you might like multicast traffic to be forwarded to a port where a multicast-enabled host is not available (for example, when you test multicast configurations).
Static IGMP emulates a host or router attached to a switch port, so that multicast traffic is forwarded to that port, and the switch sends a proxy join for all the statically configured IGMP groups when an IGMP query is received. You can emulate a host to forward a particular multicast group to a port; and you may emulate a router to forward all multicast groups to a port. Static IGMP is only available with IGMPv2.