Dependability of Network Services in the Context of NFV: A Taxonomy and State of the Art Classification

In the context of Network Function Virtualization (NFV), Network Services (NS) are realized by interconnecting Virtual Network Functions (VNF) using Virtual Links (VL). Service dependability is an important characteristic of NSs. Service dependability includes service availability, reliability, and continuity attributes. The NFV framework brings new challenges to NS dependability because of the resource-sharing possibility, NS and VNF elasticity, and the dynamicity in the NFV environment. There has been a lot of work on the dependability of NSs in the context of NFV. Existing works address different dependability attributes and use different methods and mechanisms in the proposed solutions. Thus, it is difficult to evaluate and compare these solutions, determine the well-investigated areas, and identify gaps. In this paper, we investigate the state of the art for NS dependability in the context of NFV and survey existing solutions. We define a taxonomy that represents the different aspects of NS dependability and their relations in this context. We analyze 102 papers published in the past 5 years and map them to our proposed taxonomy to understand what is addressed in the proposed solution and how. We identify the gaps and discuss potential future work directions.