Quality of Service: Where are We?

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. In this paper we give an overview about the terms, issues and trends in the provisioning of QoS whereby we concentrate on principles and architectural aspects. We briefly describe the fundamental steps followed by systems offering QoS and review the IntServ work evolving in the Internet as an example for a prominent QoS model. Furthermore, past, actual, and future issues are discussed which we consider to be important..