On traffic characteristics and bandwidth requirements of voice over IP applications

Voice over IP (VoIP) services will play an important role in future IP networks, promising cost savings and new revenue sources to operators and service providers. To provide quality of service guarantees, certain mechanisms need to be implemented which support predictable packet handling, bandwidth allocation, and call admission control. In order to configure these mechanisms, a solid understanding of VoIP traffic characteristics and its respective bandwidth requirements is necessary. In this paper, we characterize traffic traces generated by various VoIP applications. According to the H.323 standard, the characteristics are described by means of token bucket parameters, which are then used to derive the required service rates for individual traffic flows. While in most cases sources send out fairly steady packet streams, there are situations where software based clients emit rather bursty traffic resulting in unreasonably high bandwidth needs. On basis of these traffic flows, we investigate the effects that token bucket parameters have on the bandwidth demand and discuss tradeoff possibilities in order to reduce it.