Best-E ort versus Reservations: A Simple Comparative Analysis

Using a simple analytical model, this paper addresses the following question: Should the Internet retain its best-e ort-only architecture, or should it adopt one that is reservation-capable? We characterize the di erences between reservation-capable and best-e ort-only networks in terms of application performance and total welfare. Our analysis does not yield a de nitive answer to the question we pose, since it would necessarily depend on unknowable factors such as the future cost of network bandwidth and the nature of the future tra c load. However, our model does reveal some interesting phenomena. First, in some circumstances, the amount of incremental bandwidth needed to make a best-e ortonly network perform as well as a reservation capable one diverges as capacity increases. Second, in some circumstances reservation-capable networks retain signi cant advantages over best-e ort-only networks, no matter how cheap bandwidth becomes. Lastly, we nd bounds on the maximum performance advantage a reservation-capable network can achieve over beste ort architectures.