A VNF-as-a-Service Design Through Micro-Services Disassembling the IMS

With the evolution of Telco systems towards 5G, new requirements emerge for delivering services. Network services are expected to be designed to allow greater flexibility. In order to cope with the new users' requirements, Telcos should rethink their complex and monolithic network architectures into more agile architectures. Adoption of NFV as well as micro-services patterns are opportunities promising such an evolution. However, to gain in flexibility, it is crucial to satisfy structural requirements for the design of VNFs as services. We present in this paper an approach for designing VNF-as-a-Service. With this approach, we define design requirements for the service architecture and the service logic of VNFs. As Telcos have adopted IMS as the de facto platform for service delivery in 3G and even 4G systems, it is interesting to study its evolution for 5G towards a microservices-based architecture with an optimal design. Therefore, we consider IMS as a case of study to illustrate the proposed approach. We present new functional entities for IMS-as-a-Service through a functional decomposition of legacy network functions. We have developed and implemented IMS-as-a-Service with respect to the proposed requirements. We consider a service scenario where we focus on authentication and authorization procedures. We evaluate the involved microservices comparing to the state-of-the-art. Finally, we discuss our results and highlight the advantages of our approach.