On Temporal Isolation Assessment in Virtualized Railway Signaling as a Service Systems

TL;DR

This paper explores the potential of using general-purpose hypervisors like Xen to enable safe, reliable, and cost-effective virtualization of railway signaling systems, emphasizing the importance of assessing temporal isolation for safety standards.

Contribution

It proposes leveraging real-time hypervisors for railway signaling virtualization and highlights the need for systematic evaluation of temporal isolation for safety certification.

Findings

Preliminary background on virtualization in railway signaling

Identification of issues in assessing temporal isolation

Call for systematic evaluation for safety certification

Abstract

Railway signaling systems provide numerous critical functions at different safety level, to correctly implement the entire transport ecosystem. Today, we are witnessing the increasing use of the cloud and virtualization technologies in such mixed-criticality systems, with the main goal of reducing costs, improving reliability, while providing orchestration capabilities. Unfortunately, virtualization includes several issues for assessing temporal isolation, which is critical for safety-related standards like EN50128. In this short paper, we envision leveraging the real-time flavor of a general-purpose hypervisor, like Xen, to build the Railway Signaling as a Service (RSaaS) systems of the future. We provide a preliminary background, highlighting the need for a systematic evaluation of the temporal isolation to demonstrate the feasibility of using general-purpose hypervisors in the safety-critical context for certification purposes.