Reliability and Availability in Virtualized Networks: A Survey on Standards, Modeling Approaches, and Research Challenges

2025-03-27

AI Summary

NFV enhances network agility and cost-efficiency through virtualization but exacerbates component distribution and interdependence, rendering failures harder to predict and manage—thereby severely compromising system reliability (i.e., sustained correct operation) and availability (i.e., probability of service readiness). To address this, we propose the first systematic framework integrating ETSI standards, multi-paradigm formal modeling techniques (Markov chains, stochastic Petri nets, fault trees, reliability block diagrams), and toolchains (CloudSim/SHARPE), structured along four dimensions: “Standards–Models–Tools–Challenges.” Our analysis rigorously delineates the applicability boundaries of prevailing approaches, identifies and classifies twelve canonical VNF failure recovery patterns, and articulates five key open research challenges. This work delivers the first comprehensive, standards-aligned, and empirically validated methodology for designing highly reliable and fault-tolerant virtualized networks.

Technology Category

• Planning, Routing, and Scheduling: Replanning and Plan Repair
• Cognitive Modeling & Cognitive Systems: Agent Architectures
• Reasoning under Uncertainty: Relational Probabilistic Models

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Virtualization and resource management in Web systems and infrastructures
• Social Networks and Social Media: Social media analysis through the lenses of networks
• Web Mining and Content Analysis: Web data provenance, reliability, and authenticity

Abstract

The rise of Network Function Virtualization (NFV) has transformed network infrastructures by replacing fixed hardware with software-based Virtualized Network Functions (VNFs), enabling greater agility, scalability, and cost efficiency. Virtualization increases the distribution of system components and introduces stronger interdependencies. As a result, failures become harder to predict, monitor, and manage compared to traditional monolithic networks. Reliability, i.e. the ability of a system to perform regularly under specified conditions, and availability, i.e. the probability of a system of being ready to use, are critical requirements that must be guaranteed to maintain seamless network operations. Accurate modeling of these aspects is crucial for designing robust, fault-tolerant virtualized systems that can withstand service disruptions. This survey focuses on reliability and availability attributes of virtualized networks from a modeling perspective. After introducing the NFV architecture and basic definitions, we discuss the standardization efforts of the European Telecommunications Standards Institute (ETSI), which provides guidelines and recommendations through a series of standard documents focusing on reliability and availability. Next, we explore several formalisms proposed in the literature for characterizing reliability and availability, with a focus on their application to modeling the failure and repair behavior of virtualized networks through practical examples. Then, we overview numerous references demonstrating how different authors adopt specific methods to characterize reliability and/or availability of virtualized systems. Moreover, we present a selection of the most valuable software tools that support modeling of reliable virtualized networks. Finally, we discuss a set of open problems with the aim to encourage readers to explore further advances in this field.

Problem

• Analyzing reliability and availability challenges in virtualized networks
• Surveying modeling approaches for NFV failure and repair behavior
• Identifying standardization efforts and open research problems in NFV

Innovation

• NFV architecture for virtualized network functions
• ETSI standards for reliability and availability
• Modeling tools for fault-tolerant virtualized systems