Survey on QoS management of VoIP

In this paper, we present a survey on management mechanisms used for ensuring the quality of services (QoS) for voice-over IP (VoIP) applications. We first address the motivations of QoS management for VoIP. We then partition the system into two management planes, data plane and control plane, and describe mechanisms in each plane respectively. In data plane, we cover several important techniques including packet classifier, buffer management, scheduling, loss recovery, and error concealment. In control plane, we describe admission control, resource provisioning, traffic engineering, and connection management etc. As we will see, admission control plays a critical role in QoS for VoIP. Thus, we will discuss methodologies used in admission control in detail. Specifically, we examine parameter-based and measurement-based admission control algorithms, and their use in VoIP. Finally, we discuss limitations of current technologies and future research issues in providing QoS to VoIP applications.