Providing bandwidth guarantees over a best-effort network: call-admission and pricing

This paper introduces a framework for answering questions regarding the conditions on the network load that allow a best-effort network like the Internet to support connections of given duration that require a certain quality of service. Such quality of service is expressed in terms of the percentage of time the bandwidth allocated to a connection may drop below a certain level or the maximum allowable delay in placing the call through the network waiting for more favorable loading conditions. The call-acceptance conditions, which depend on the behavior of the system over the lifetime of accepted calls, are thus based on transient models for the congestion (instead of looking at the average behavior) and attempt to exploit the time-scales of the fluctuations of the number of connections competing for bandwidth. Extensions of the model consider the case of dynamic pricing which allows connections that pay more to get larger shares of the bandwidth, and investigate the trade-off between quality of service, the size of the acceptance region, and the charge to be paid by the connection. Under this framework we introduce an option contract that reduces the risk of quality disruption, if a user has a fixed budget at his disposal, and calculate its price. One potential use of this methodology is towards developing a simple admission control mechanism for placing voice calls through an IP network, where the decisions can be taken by edge devices