Overprovisioning or Rightprovisioning?



The two main alternatives for achieving high QoS on the public internet are (i) admission control and (ii) capacity overprovisioning. In the study of these alternatives the implicit (and sometimes explicit) message is that ideally, QoS issues should be dealt with by means of sophisticated admission control (AC) algorithms, and only because of their complexity providers fall on the simpler, perhaps more cost effective, yet "wasteful" solution of capacity overprovisioning (CO) (see e.g. Olifer and Olifer [Wiley and Sons, 2005], Parekh [IWQoS'2003], Milbrandt et al. [J.Comm. 2007]). In the present survey we observe that these two alternatives are far from being mutually exclusive. Rather, for data critical applications, a substantial amount of "overprovisioning" is in fact a fundamental step of any safe and acceptable solution to QoS and resiliency requirements. We observe from examples in real life that in many cases large amounts of overprovisioning are already silently deployed within the internet domain and that in some restricted network settings they have become accepted practice even in the academic literature. Then we survey the main techniques currently in use to compute the provisioning capacities required in a resilient high QoS network.

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