Availability evaluation of the virtualized infrastructure manager in network function virtualization environments

The Network Function Virtualization (NFV) initiative involving the European Telecommunications Standard Institute (ETSI) and a group of telecom companies, started in 2012 aimed at allowing the network operators to deploy a set of services in a reliable, secure and fastway. In fact, just as a physical machine (equipped with operative system, CPU, memory etc.) can be virtualized by exploiting some virtualization frameworks, a network function (e.g. Firewall, IDS, Load Balancer etc.) can be virtualized by exploiting standard hardware resources. Considering that one of the main benefits of an NFV infrastructure is its high availability, this paper focuses on the analysis of the Virtualized Infrastructure Manager (VIM), a core element that is implemented through the OpenStack platform and is aimed at managing the whole NFV rchitecture. In the present work, inspired by OpenStack technology, the authors propose and assess aVIM model composed by three main modules namely: (i) the High-Availability Proxy providing a Load Balancer function, (ii) a Database management System typically implemented in MySQL technology and (iii) a set of core modules called Functional Blocks, aimed at providing some functionalities (authentication, disk images storage etc.) for the whole system. The architecture has been assessed by means of the Stochastic Reward Nets (SRN). In particular, the system availability has been evaluated by performing both a steady-state and transient analysis of SRNs in order to obtain the best system configuration with the “five nines” availability requirement