This read-write enumerated integer controls whether all existing multicast groups' traffic is sent out this interface regardless of other group-membership parameters, with disable meaning the interface follows normal group-membership-based forwarding instead. An admin enables this on an interface where every downstream device needs every multicast stream, such as a monitoring aggregation port. For example, enabling ipMulticastInterfaceSendAll on a port feeding a network recorder ensures it receives every multicast group's traffic without needing individual IGMP joins.