Dimensioning Links for IP Telephony

Abstract. Packet loss is an important parameter for dimensioning net-work links or traffic classes carrying IP telephony traffic. We present a model based on the Markov modulated Poisson process (MMPP) which calculates packet loss probabilities for a set of superpositioned voice input sources and link properties. We do not introduce another new model to the community, rather try and verify one of the existing models via exten-sive simulation and a real world implementation. A plethora of excellent research on queuing theory is still in the domain of ATM researchers, hence we attempt to highlight their validity to the IP (Telephony) com-munity. Packet level simulations show reasonable correspondence with the pre-dictions of the model. Our main contribution is the verification of the MMPP model with measurements in a laboratory environment. The loss rates predicted by the model are in general close to the measured loss rates and the loss rates obtained by simulation. The general conclusion is that the MMPP-based model is a tool well suited for dimensioning links carrying packetised voice in a system with limited buffer space.