private MulticastSocket createSocket() throws IOException {
  MulticastSocket sock=new MulticastSocket(mcastPort);
  sock.setLoopbackMode(false);
  if (sockItf != null)   sock.setInterface(sockItf);
  if (sock.getLoopbackMode())   U.warn(log,"Loopback mode is disabled which prevents nodes on the same machine from discovering " + "each other.");
  sock.joinGroup(mcastGrp);
  if (ttl != -1)   sock.setTimeToLive(ttl);
  return sock;
}

private MulticastSocket createSocket ( ) throws IOException { MulticastSocket sock = new MulticastSocket ( mcastPort ) ; sock . setLoopbackMode ( false ) ; if ( sockItf != null ) sock . setInterface ( sockItf ) ; if ( sock . getLoopbackMode ( ) ) U . warn ( log , "Loopback mode is disabled which prevents nodes on the same machine from discovering " + "each other." ) ; sock . joinGroup ( mcastGrp ) ; if ( ttl != - 1 ) sock . setTimeToLive ( ttl ) ; return sock ; }
creates multicast socket and joins multicast group .
