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Best-Effort versus Reservations: A Simple Comparative Analysis
Lee Breslau and Scott Shenker (Xerox PARC)
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.
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