Best-effort versus reservations: a simple comparative analysis

Using a simple analytical model, this paper addresses the following question: Should the Internet retain its best-effort-only architecture, or should it adopt one that is reservation-capable? We characterize the differences between reservation-capable and best-effort-only networks in terms of application performance and total welfare. Our analysis does not yield a definitive 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 traffic load. However, our model does reveal some interesting phenomena. First, in some circumstances, the amount of incremental bandwidth needed to make a best-effort-only network perform as well as a reservation capable one diverges as capacity increases. Second, in some circumstances reservation-capable networks retain significant advantages over best-effort-only networks, no matter how cheap bandwidth becomes. Lastly, we find bounds on the maximum performance advantage a reservation-capable network can achieve over best-effort architectures.