Modern networks (e.g. MPLS), which are nowadays used in the provider and enterprise environment, have the ability to classify and prioritise IP flow of traffic depending on the classes. In larger networks the realisation of a QoS concept is demanding and complex. In particular it?s nearly impossible for customers to check the configuration within a provider network. The question arises if the customer is actually getting the capacity and implementation he demands. At this point our thesis begins. With our software it should become possible to scrutinise the settings of the provider by generating exact defined traffic on a WAN-Link and to check if the processing is handled properly according to the customer?s requests. The main focus of our work was the generation of packets and to insert them with an exact timing into the network as well as to capture the filtered packets at the receiver. The analysis and interpretation of the received data was processed theoretically and not integrated into the software. The main tool for our software development was WinPcap, an architecture for packet capture and network analysis for the Win32 platforms. In addition considerations in terms of barriers between sender and receiver had to be made. For instance, it might occur that a firewall is located in-between. Another problem was caused by the operating system that may react with messages to received data. Therefore we developed and implemented a mechanism, which prevents this behaviour. Additionally an ARP was built in for the address resolution of the sender and receiver. Software which is developed based on our programmes could be used in different areas of network analysis.