In the recent past wireless sensor networks have increasingly attracted research interest due to their abilities to perform monitoring tasks. In the ideal case they would allow to be randomly deployed (ad-hoc) wherever they are needed, independent of surrounding terrain. They would constantly adapt to environmental changes and operate without further maintenance while being comparatively cheap. In case of a node failure a wireless sensor network is expected to heal itself by rerouting network traffic and changing network topology, if needed. While al lot of effort has been made to fulfil theses goals, nearly nothing has been done to preserve data integrity in case of unforeseen malfunctions. This work addresses some problems related to networks where distinct roles for each network member is choosen before deployment.