GWMP is a GateWay Messaging Protocol used by LoRa packet forwarders to typically talk to a LoRaWAN Network Server (LNS).
On the ThingsIX Network, the GWMP can be used to send packets to the ThingsIX forwarder.
On the Helium's Network, the GWMP is used to send packets to a Helium gateway rs.
This program, gwmp-mux, allows for a single packet forwarder connection to be multiplexed out to one or more potential hosts. As such, a single gateway can connect to multiple LNSs. For example the above gateway-rs and forwarder an be used on the same gateway.