Taking advantage of ATM services and tariffs: the importance oftransport layer dynamic rate adaptation

Modern network services provided by frame relay (FR) or asynchronous transfer mode (ATM) networks show a wide variety of service characteristics and related quality of service, which amounts to a tremendous diversity of tariff structures. One of the network provider's objectives is to maximize the chargeable utilization of the network. This is intended to be achieved by a traffic contract on a per-connection basis. The network service user's interest is, of course, to minimize the cost for usage of the service. This can be achieved by traffic-contract-conformant behavior. In order to avoid (chargeable) injection of data that will be lost due to congestion in the network, the user has to adapt to the congestion state of the network by interpreting the congestion information provided by the network service. If the network user is logically mapped to the lowest end-to-end layer (i.e., the transport layer), the adaptive behavior has to be realized by adaptive rate control in this layer. This article analyzes the upcoming network services and their tariffs, demonstrates the advantage of rate control by a congestion avoidance algorithm, and the applicability of this concept to the telemetry and scientific data distribution applications of the European Space Agency (ESA)