Over the last years, Quality of Service (QoS) has evolved as a research field to support new application types in general, very often in networked computer systems. The most prominent of these applications are distributed multimedia applications, which transmit and process audiovisual information streams. Due to their real-time nature, any correct processing and transport of these data must take timing aspects into account. The goal of QoS mechanisms is to ensure that the overall presentation of audiovisual data to the user respects these properties in an end-to-end mode.