NICT Telefonica This document describes multipath support for Internet Group Management Protocol (IGMP) / Multicast Listener Discovery (MLD) proxy devices. The proposed extension allows IGMP/MLD proxy devices to receive multicast sessions/channels through different upstream interfaces. An upstream interface can be selected on the basis of multiple criteria, such as channel/session IDs and interface priority values. A mechanism for upstream interface takeover that enables switching from an inactive to active upstream interface is also described.