Applications of the leaky bucket throughput characterisation

The continuous state leaky bucket was defined by the ITU-T as a reference policing algorithm operating on a cell flow of an ATM connection. This algorithm can be fully characterised by a so called maximum throughput function. The maximum throughput function shows how efficiently a policing mechanism can protect an ATM network against excess traffic. This characterisation of the leaky bucket turns out to be a useful tool for studying the properties of the leaky bucket analytically. We present several applications: how to choose the parameters of a leaky bucket for policing of the peak cell rate or the sustainable cell rate when upstream cell delay variation has to be taken into account; how two cell flows can be policed efficiently using one leaky bucket; and how to calculate a bound for the cell delay variation tolerance increase introduced by a switch that provides service guarantees, e.g. by using weighted fair queueing.