Dimensioning Token Bucket Policers For Various Voice-over Ip Applications Using Real-Scenario Measurements

Abstract

Due to its stringent QoS requirements, VoIP applications pose great challenges to network planners and network operators. It is essential that the network be dimensioned appropriately and that traffic-engineering methodologies be deployed. In order for traffic-engineering mechanisms to work properly, the characteristics ofthe sources have to be known. Only then it is possible to keep up QoS by either reserving appropriate bandwidth shares or performing call admission control based on allocated capacities. In this paper, we characterize traffic traces, generated by various VoIP applications in different situations, and derive the required service rate for individual traffic flows. Although in most cases VoIP sources send out fairly steady packet streams, there are situations where software-based clients emit rather bursty traffic, resulting in unreasonably high bandwidth needs. To save the integrity ofall active flows from ill-behaving traffic, we deploy traffic policers per each flow and determine the appropriate traffic parameters ofthe policer. On the basis ofthe bursty traffic flows, we investigate the effects that traffic parameters have on the bandwidth demand and discuss trade-off possibilities in order to reduce it.