Managing Failures and Service Quality in the Context of NFV

In the context of network function virtualization (NFV), virtual network functions (VNF) are the building blocks of network services (NS). VNFs are usually distributed applications composed of VNF components (VNFC). A VNFC instance is the actual consumer of resources and it is realized as a virtual machine (VM). Service availability of an NS is one of its important characteristics which has been expansively investigated in the literature. Fault tolerance is the main mechanism used to guarantee service availability. Fault tolerance relies on VNF redundancy and failover operation. It reduces the service outages when a complete failure of a VNF happens. However, complete failures are less frequent than partial failures in which only some VNFC instances of a VNF fail. Partial failures can cause service degradation and annoy tenants who usually expect a guaranteed service quality. To handle partial failures, the failover mechanism may not be ideal since it can cause a complete service outage. We, therefore, propose a solution to determine the redundancy of VNFs to guarantee the required quality of service for an NS and avoid service degradation below a defined level. We propose a framework that includes an architecture and operations to guarantee service quality and avoid potential service outage.