public void PingServer(string ip)
{
      int timeout = 2000;
      Ping ping = new Ping();
      PingOptions options = new PingOptions();
      AutoResetEvent waiter = new AutoResetEvent(false);
      string data = "AAA";
      byte[] dataBuffer = Encoding.ASCII.GetBytes(data);

      options.DontFragment = true;
      options.Ttl = 32;

            ping.PingCompleted += (sender, eventArgs) =>
            {
                this.Invoke((MethodInvoker)delegate
                {
                     setDelegate(eventArgs.UserInfo.Status(ip).ToString());
                });
            };

     ping.SendAsync(ip, timeout, dataBuffer, options, waiter);
    //waiter.WaitOne();
}