Best-Effort Versus Reservations Revisited

In this paper, we walk in the footsteps of the stimulating paper by Lee Breslau and Scott Shenker entitled “Best-effort vs. Reservations: A Simple Comparative Analysis”[1]. In fact, we finally follow their invitation to use their models as a starting point and extend them to reason about the very basic but still very much debated architectural issue whether quality of service (QoS) mechanisms like admission control and service differentiation are necessary or if overprovisioning with a single service class does the job just as well at lower system complexity. We analytically compare two QoS systems: a QoS system using admission control and a reservation mechanism that can guarantee bandwidth for flows respectively offers service differentiation based on priority queueing for two service classes and a system with no admission control and a single best-effort service class.