Runtime Availability and Service Continuity of Containerized VNF Instances

A Virtual Network Function (VNF) is a software implementation of a network function (e.g., firewall, router, etc.), which can be deployed as Virtual Machines (VM) utilizing the resources of the infrastructure managed by the Network Function Virtualization (NFV) Management and Orchestration (MANO). A VNF can also be containerized to benefit from the lower virtualization overhead of containers. A containerized VNF is composed of one or more Managed Container Infrastructure Objects (MCIO). To design a Network Service (NS) for the NFV framework that satisfies required service availability and continuity requirements, one has first to determine the availability, failure rate, and service disruption of the VNFs composing the NS. These characteristics of a VNF depend on the availability and failure rate of its MCIOs and the underlying infrastructure. Solutions proposed to determine these VNF characteristics at design time, consider the estimated resource availability and failure rate of a given infrastructure. However, resources assigned to VNF instances at runtime can be different in characteristics and/or performance resulting in a difference between the estimated and the actual characteristics of the VNF instances. In addition, scaling and different placements of the MCIO instances at runtime can have similar effects. Therefore, in this paper, we investigate the parameters affecting the availability, failure rate, and service disruption of a containerized VNF instance, considering the internal redundancy of the VNF and the scalability of its instances at runtime. Based on this investigation, we propose analytical models to determine the availability, failure rate, and service disruption of a containerized VNF instance.