There is quite a few examples to RECEIVE multicast messages with a spcific network interface (NIC, e.g. eth0, 127.0.0.1 etc). However, there is few discussion/examples about how to SEND multicast (UDP) messages to a specific interface, e.g. local loop (127.0.0.1) instead of eth0 by default.There is quite a few examples to RECEIVE multic