TAKING ADVANTAGE OF ATM SERVICES AND TARIFFS - THE IMPORTANCE OF TRANSPORT LAYER DYNAMIC ROLE ADAPTATION

Modern network services provided by frame relay (FR) or asynchronous t ransfer mode (ATM) networks show a wide variety of service characteris tics and related quality of service, which amounts to a tremendous div ersity of tariff structures. One of the network provider's objectives is to maximize the chargeable utilization of the network. This is inte nded to be achieved by a traffic contract on a per-connection basis. T he network service user's interest is, of course, to minimize the cost for usage of the service. This can be achieved by traffic-contract-co nformant behavior. In order to avoid (chargeable) injection of data th at will be lost due to congestion in the network, the user has to adap t to the congestion state of the network by interpreting the congestio n information provided by the network service. If the network user is logically mapped to the lowest end-to-end layer (i.e., the transport l ayer), the adaptive behavior has to be realized by adaptive rate contr ol in this layer. This article analyzes the upcoming network services and their tariffs, demonstrates the advantage of rate control by a con gestion avoidance algorithm, and the applicability of this concept to the telemetry and scientific data distribution applications of the Eur opean Space Agency (ESA).