This thesis describes the approach in designing and implementing a driver marking network traffic for quality of service provision. In the beginning distinct technologies usable for the driver development are discussed and compared to each other while the most suiting candidate is chosen for driver development. Next the thesis discusses the design of the driver according to specification and depicts a list of more specific requirements affecting the driver design itself. The focus point in design is the least possible impact on network traffic performance and the running system itself. In addition to the driver an application programming interface usable from user mode is designed and so the system as a whole ensures the marking of network traffic entirely. In the end the created driver architecture is described and the application programming interface is described in terms of use.