UDP multicast listener must rebind after any IPv4 interface change

[aza...@azarielkley.com]

Greetings,

I have a very basic UDP multicast listener which binds to INADDR_ANY
which joins a multicast group running on a system with a single
ethernet adapter. When I disable the adapter and then re-enable, the
listener no longer receives packet traffic, unlike some other UDP
unicast listeners and TCP listeners.

This may be a well known behavior but I can't find anyone anywhere
discussing the issue. It's a no brainer to simply catch IPv4 network
address change events and restart the multicast listener but I am
uncomfortable not knowing the cause of the behavior, and further why
it is so different from unicast UDP and TCP listeners.