Quality of service provisioning in network function virtualization: a survey

Network function virtualization (NFV) is a promising paradigm for network service provisioning which decouples the network functions from the physical infrastructure, allowing to deploy the virtualized network functions (VNF) as modular software components over commodity servers. In this architecture, service function chaining (SFC) creates an application-specific network overlay which determines the placement and ordering of network functions in a specific service delivery chain. The diverse choices for VNF placement over physical hardware, scheduling of VNF instances to run over the servers and design of optimal chaining mechanisms for traffic steering in the network have direct consequences on the quality-of-service (QoS) perceived by the network users. Previous surveys have focused on categorizing and evaluating various aspects of SFC, NFV and SDN. Due to the tight coupling of QoS provisioning with NFV problems, our work aims primarily at complementing the existing surveys in the sense that we review and classify the state-of-art research efforts in NFV design and implementation from the perspective of QoS provisioning. Our survey provides a closer look at the design space of QoS-related NFV solutions and sheds light on the open research topics in relevance with QoS-based SFC. We also present a case study to evaluate the performance of some recent VNF placement algorithms.