networking - Let two UDP-servers listen on the same port?

Question

I have a client which sends data via UDP-broadcast. (To let's say 127.0.0.255:12345)

Now I want to have multiple servers listening to this data. To do so on a local machine, they need to share the port 12345 for listening.

My question is, if that is possible, if there are any disadvantages and if there could be problems with this approach.

There is one alternative which unfortunately brings with a lot of overhead:
Implement some kind of registration-process. On startup, each server tells the client its port. The client then sends the messages to each port (having to send the data multiple times, some kind of handshaking needs to be implemented...)
Do you know any better alternative?

If that matters:
I'm using C++ with Boost::Asio. The software should be portable (mainly Linux and Windows).

Answer 1

You will have to bind the socket in both processes with the SO_REUSEPORT option. If you don't specify this option in the first process, binding in the second will fail. Likewise, if you specify this option in the first but not the second, binding in the second will fail. This option effectively specifies both a request ("I want to bind to this port even if it's already bound by another process") and a permission ("other processes may bind to this port too").

See section 4.12 of this document for more information.