class VirtualNetworkFilter implements IFloodlightModule, IVirtualNetworkService, IOFMessageListener, IDeviceListener {

    @Override
    public Command receive(IOFSwitch sw, OFMessage msg, FloodlightContext cntx) {
        switch (msg.getType()) {
            case PACKET_IN:
                return processPacketIn(sw, (OFPacketIn)msg, cntx);
            default:
            	break;
        }
        log.warn("Received unexpected message {}", msg);
        return Command.CONTINUE;
    }

}