Session Initiation Protocol Proxy in a Role of a Quality of Service Control Application in Software-Defined Networks

This article deals with quality of service (QoS) in internet protocol (IP) telephony by applying software-defined networking (SDN) tools. The authors develop a new design that deterministically classifies real-time protocol (RTP) streams based on data found in session initiation protocol (SIP) using SIP proxy as a mediator, and the concept making this possible is called SDN. Compared to traditional networks, SDN allows us to approach network configuration differently. SDN networks are programmable through software applications running on top of the SDN controller. One of the technologies that might benefit from this concept is IP telephony, which often needs an additional priority management configuration to ensure consistent quality of its real-time media exchange. Typically, a session protocol for real-time communications is SIP, and as such, its infrastructure may be used to classify the traffic in question and take advantage of the centralized approach of SDN networks to distribute the class information across the switching devices. Different approaches and possible applications are discussed in the conclusion. The contribution of this paper lies in the proposal of SDN-based QoS mechanisms. The entire design of the concept was implemented and validated in a laboratory environment. The results clearly demonstrate the efficiency of the proposed approach.