c# UDP 组播

 IPEndPoint endPoint = new IPEndPoint(IPAddress.Any, 111);

            Socket s = new Socket(endPoint.Address.AddressFamily,
                SocketType.Dgram,
                ProtocolType.Udp);
            //// Creates an IPEndPoint to capture the identity of the sending host.
            //IPEndPoint sender = new IPEndPoint(IPAddress.Parse("230.1.1.1"), 111);
            //EndPoint senderRemote = (EndPoint)sender;

            // Binding is required with ReceiveFrom calls.
            s.Bind(endPoint);
            s.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.AddMembership, new MulticastOption(IPAddress.Parse("230.1.1.1")));
            byte[] msg = new Byte[2506];
            Console.WriteLine("Waiting to receive datagrams from client...");

            // This call blocks. 
            EndPoint ep = (EndPoint)endPoint;
            int count = s.ReceiveFrom(msg, ref ep);