Fraunhofer Institut für Integrierte Publikations-und Informationssysteme IPSI

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  • Publication
    On the aggregation of deterministic service flows
    ( 2001)
    Schmitt, J.
    ;
    Karsten, M.
    ;
    Steinmetz, R.
    It is common belief that "flat" Quality of Service (QoS) architectures, e.g. the IETFs Integrated Services architecture (IntServ), are not scalable to large networks, e.g. the global Internet. This is due to the ambitious goal of providing per-flow QoS and the resulting complexity of fine-grained traffic management. One solution to this problem is the aggregation of traffic flows in the core of the network, thus creating a hierarchical resource allocation system. While one might suspect that aggregation leads to allocating more resources for the aggregated flow than for the sum of the separated flows if flow isolation shall be guaranteed deterministically, we show in this article that for IntServ's Guaranteed Service flows this is not necessarily the case even if flow isolation is retained. We compare different approaches to describe the aggregated traffic and analyze their impact on bandwidth consumption and ease of flow management. Furthermore, we perform a thorough numerical evaluation of the derived results with respect to their behavior in response to changes in exogenous parameters like the traffic specifications of the flows or the configuration of the network. Applications of these theoretical insights and numerical evidence could be to use the derived formulae for resource allocation in either a hierarchical IntServ, IntServ over DiffServ (Differentiated Services), or IntServ over ATM (Asynchronous Transfer Mode) network.
  • Publication
    Charging for packet-switched network communication - motivation and overview
    ( 2000)
    Karsten, M.
    ;
    Schmitt, J.
    ;
    Stiller, B.
    ;
    Wolf, L.
    Packet-switched network technology is expected to form the integration layer for future multi-service networks. The trend to integrate voice and data traffic can already be observed in the Internet and is expected to carry on until the full integration of all media types is achieved. At the same time it becomes obvious that the business model employed for current Internet usage is probably not sustainable for the creation of an infrastructure suitable to support a diverse and ever-increasing range of application services. Currently, the Internet provides only a single class of best-effort service and prices are mainly built on flat-fee, access-based schemes. However, the large and increasing differentiation of demand for quality of transmission services creates the necessity to differentiate service provision and, consequently, charging for network communications. In this article, we survey relevant service models and motivate the need for appropriate charging mechanisms. We give an overview on requirements for a charging system, its technical components, and issues for future business models that might by employed by service providers.