<p>An important aspect of development and research in the field of computer networking systems is evaluation. Through evaluation, performance and behavior of software and protocols over a network can be determined. A network emulator is one of several tools available to accomplish this.</p><p>In this thesis, the network emulator Dummynet is described, as well as its extension KauNet. KauNet extends Dummynet by introducing pattern-driven emulation. A pattern defines specific points at which to apply a certain computer network characteristic or behavior. The use of patterns allow an increased control and repeatability of an emulation. Repeating a test with an identical configuration and the same pattern will yield identical results.</p><p>The goal of the project was to add a new functionality to KauNet. The new functionality consists of a notification system capable of passing information from KauNet to external observers. By adding this new functionality, emulation statistics can be available for the observers immediately when occurring. Another example of information that can be forwarded, is simulated cross-layer information. For KauNet to know when and what information to send, a new type of pattern has been created, called trigger pattern. Trigger patterns behave similarly to the existing patterns, sharing the same structure and processing in KauNet. Through the use of trigger patterns, events may be raised at specific points. The notification system may then be used to pass the event information.</p><p>This thesis describes the evaluation, design and implementation of the trigger patterns and notification system in KauNet. Finally, it concludes with a verification of the new trigger functionality in a usage example.</p><p> </p>

An important aspect of development and research in the field of computer networking systems is evaluation. Through evaluation, performance and behavior of software and protocols over a network can be determined. A network emulator is one of several tools available to accomplish this. In this thesis, the network emulator Dummynet is described, as well as its extension KauNet. KauNet extends Dummynet by introducing pattern-driven emulation. A pattern defines specific points at which to apply a certain computer network characteristic or behavior. The use of patterns allow an increased control and repeatability of an emulation. Repeating a test with an identical configuration and the same pattern will yield identical results. The goal of the project was to add a new functionality to KauNet. The new functionality consists of a notification system capable of passing information from KauNet to external observers. By adding this new functionality, emulation statistics can be available for the observers immediately when occurring. Another example of information that can be forwarded, is simulated cross-layer information. For KauNet to know when and what information to send, a new type of pattern has been created, called trigger pattern. Trigger patterns behave similarly to the existing patterns, sharing the same structure and processing in KauNet. Through the use of trigger patterns, events may be raised at specific points. The notification system may then be used to pass the event information. This thesis describes the evaluation, design and implementation of the trigger patterns and notification system in KauNet. Finally, it concludes with a verification of the new trigger functionality in a usage example.

Quality of Service is major factor for a successful business in modern and future network services. A minimum level of services is assured indulging quality of Experience for modern real time communication introducing user satisfaction with perceived service quality. Traffic engineering can be applied to provide better services to maintain or enhance user satisfaction through reactive and preventive traffic control mechanisms. Preventive traffic control can be more effective to manage the network resources through admission control, scheduling, policing and traffic shaping mechanisms maintaining a minimum level before it get worse and affect user perception. Accuracy, dynamicity, uniformity and reproducibility are objectives of vast research in network traffic. Real time tests, simulation and network emulation are applied to test uniformity, accuracy, reproducibility and dynamicity. Network Emulation is performed over experimental network to test real time application, protocol and traffic parameters. DummyNet is a network emulator and traffic shaper which allows nondeterministic placement of packet losses, delays and bandwidth changes. KauNet shaper is a network emulator which creates traffic patterns and applies these patterns for exact deterministic placement of bit-errors, packet losses, delay changes and bandwidth changes. An evaluation of KauNet with different patterns for packet losses, delay changes and bandwidth changes on emulated environment is part of this work. The main motivation for this work is to check the possibility to delay and drop the packets of a transfer/session in the same way as it has happened before (during the observation period). This goal is achieved to some extent using KauNet but some issues with pattern repetitions are still needed to be solved to get better results. The idea of history and trace-based traffic shaping using KauNet is given to make this possibility a reality.