# A Systematic Literature Review of Reliable Provisioning for Virtual Network Function Chaining
## 6 Conclusions  
Network Function Virtualization (NFV) enables telecommunications service providers to reduce their costs while providing more flexible solutions. The diversity that the NFV offers by deploying the Virtual Network Functions instead of the dedicated hardware devices allows for a reduction in operational expenditure (OpEx) and capital expenditure (CapEx). Network services are deployed as Service Function Chains (SFCs) in this infrastructure where each SFC includes a set of VNFs. Although the software-based infrastructure results in a cost-efficient and more flexible approach, the failure of a single or multiple VNFs utilizing the computing and network resource usage are among critical issues. In this study, we reviewed relevant research papers on reliable provisioning for VNF chaining through the Systematic Literature Review (SLR) protocol. We categorized the proposed algorithms based on the considered strategy, evaluation approaches, failure type, and occurrence of the failure and studied the advantages and disadvantages of each category. The most considered strategy for a reliable provisioning in NFV is the protection schemes, where the higher availability of a service is achieved by using more resources. In addition, many algorithms only consider one type of a failure or a single failure through the network, which is not a realistic scenario. Moreover, evaluation of the algorithms in different simulation settings is not possible and a common assessment setting is required for precise evaluation. Therefore, there is still a demand for a reliable, realistic, scalable, and cost-efficient provisioning algorithm for VNF placement in real-life scenarios.  
\begin{table}
\begin{tabular}{l l} \hline \hline
**Attribute** & **Related RQ** \\ \hline Reliable Provisioning & 1 \\ \hline Protection Scheme & 1, 2 \\ \hline Recovery Plan & 1, 2 \\ \hline Simulation Comparison Criteria & 1 \\ \hline Network Topology & 1 \\ \hline Number of VNFs & 1 \\ \hline Simulation Platform & 1 \\ \hline Failure Type & 2 \\ \hline Link Failure & 2 \\ \hline VNF Failure & 2 \\ \hline Single Failure & 2 \\ \hline \hline \end{tabular}
\end{table}
Table 5: Classification and contribution to review.  
**Author Contributions:** Conceptualization, M.S.G.; methodology, M.S.G. and V.P.; software, M.S.G., V.P. and L.D.L.; validation, M.S.G., V.P. and L.D.L.; formal analysis, M.S.G. and V.P.; investigation, M.S.G., V.P. and L.D.L.; resources, M.S.G., L.D.L. and V.P.; data curation, M.S.G. and L.D.L.; writing--original draft preparation, M.S.G. and L.D.L; writing--review and editing, M.S.G. and V.P.; visualization, L.D.L. and V.P.; supervision, M.S.G. and V.P.; project administration, M.S.G. and V.P.; funding acquisition, V.P. All authors have read and agreed to the published version of the manuscript.  
This work was supported by Mitacs through the Mitacs Accelerate program.  
**Data Availability Statement:** Not applicable.  
**Acknowledgments:** We are grateful to Mitacs and its partner Ciena for creating this opportunity. We extend our gratitude to [PERSON] and Computer Science department at Dawson College and special thanks to [PERSON], DawsonAI Project Lead whose support made this research possible.  
**Conflicts of Interest:** The authors declare no conflict of interest.