YANG Data Model for supporting multipath IGMP/MLD proxies

The ability to support multiple upstream interfaces in IGMP/MLD proxies necessitates configuring different upstream interfaces for specific multicast channels or sessions. [RFC9398] defined YANG Data Model for Internet Group Management Protocol (IGMP) and Multicast Listener Discovery (MLD) Proxy Devices. Building on that foundation, this document proposes an augmentation of thet model for the support of multiple upstream interfaces in IGMP/MLD proxies.