Single client, Multiple server, sockets sharing the same port.

Since datagrams are connectionless, it should be easy to share the same port. Just be sure to label it as a shareable port when establishing the socket. As for using the same socket, well, you should be able to do that based on the connectionless premise, since you essentially open the socket and wait for data (usually the datagram will contain information regarding source, but you can easily enough just receive data from multiple sources).

Edit: You only need a shareable port if there's multiple applications using it. If there's only one application, you don't need that although it's usually easier to work with in Linux due to socket timeouts being somewhat unpredictable.