Quality of Service (QoS) in Software Defined Networking (SDN): A survey

Supporting end-to-end Quality of Service (QoS) in existing network architectures is an ongoing problem. Although researchers from both academia and industry have proposed many solutions to solve the QoS limitations of the current networking, many of them either failed or were not implemented. Software Defined Networking (SDN) paradigm has emerged in response to limitations of traditional networking architectures. Its main advantages are the centralized global network view, programmability, and separation of the data plane and control plane. These features have got attention of researchers to improve the QoS provisioning of today's various network applications. In this survey paper, we aim at making a picture of QoS-motivated literature in OpenFlow-enabled SDN networks by comprehensively surveying relevant research studies. We organize the related studies according to the categories that are the most prominent ways in which QoS can benefit from the concept of SDN: Multimedia flows routing mechanisms, inter-domain routing mechanisms, resource reservation mechanisms, queue management and scheduling mechanisms, Quality of Experience (QoE)-aware mechanisms, network monitoring mechanisms, and other QoS-centric mechanisms such as virtualization-based QoS provisioning and QoS policy management etc. In addition, we discuss QoS capabilities of OpenFlow protocol by reviewing its versions along with some well-known, open-source, and community-driven controller projects. Furthermore, we outline the potential challenges and open problems that need to be addressed further for better and complete QoS abilities in SDN/OpenFlow networks and lessons we have learned during preparation of this survey paper.