code: @Override
  	public Destination createDestination(final IndividualAddress remote,
  		final boolean connectionOriented, final boolean keepAlive, final boolean verifyMode)
  	{
  		if (detached)
  			throw new IllegalStateException("TL detached");
  		synchronized (proxies) {
  			if (proxies.containsKey(remote))
  				throw new KNXIllegalArgumentException("destination already created: " + remote);
  			final AggregatorProxy p = new AggregatorProxy(this);
  			final Destination d = new Destination(p, remote, connectionOriented, keepAlive, verifyMode);
  			proxies.put(remote, p);
  			logger.trace("created {} destination for {}", (connectionOriented ? "co" : "cl"), remote);
  			return d;
  		}
  	}
docs: {@inheritDoc} Only one destination can be created per remote address. If a
  destination with the supplied remote address already exists for this transport
  layer, a {@link KNXIllegalArgumentException} is thrown.<br>
  A transport layer can only handle one connection per destination, because it can't
  distinguish incoming messages between more than one connection.