title: Do I need a PORT when joining a multicast group or just the IP?
body: <p>I would like to learn that once and for all. What is the procedure to connect a multicast socket? I know you have to bind to a local interface (do you need IP and port for that?) then I know you have to join a group (do you need IP:PORT for the address you want to join and the network interface again!!!??) and then finally you can leave the group.</p>
  
  <p>Can someone with experience clarify what is the whole of those many addresses? I will list below:</p>
  
  <ul>
  <li>BindAddress (IP:PORT)</li>
  <li>NetworkAddress (IP:PORT)</li>
  <li>MulticastAddress (IP:PORT)</li>
  </ul>
  
  <p>Where and what is the multicast <em>group</em> here?</p>