Execution environment for integrated real-time systems based on software-defined networking

Today there exists a wide range of industrial systems that are based on federated
architectures, which means that the each computing node in the system is exclusively
assigned to one function. Due to the increasing computing capability of a single
processor and the increasing amount of computing processors on a single platform,
extensive research on integrating multiple functions with different criticality levels
on a shared platform was carried out. For example, in the avionic domain, the
development trend has moved from federated to integrated architectures. The ARINC
653 standard was released, which defines the execution environment for hosting
several avionic software functions within a single computing node. ARINC 653 was
successfully implemented (e.g., Airbus A380) and achieved its primary goals (cost
and weight reduction, enabling modular certification).

However, the existing execution environments based on an integrated architecture
support only static system configurations. In specific domains like the railway
industry, dynamic system adaptation is required during runtime, which affects both
the application execution environment and the data communication mechanisms. In
this dissertation, our focus is on an execution environment based on an integrated
architecture, which guarantees the safe integration of mixed-criticality applications
and also addresses the system reconfiguration problem.

In order to close the research gap, we introduce an execution environment for
integrated real-time applications by leveraging the Software-Defined Networking
(SDN) paradigm. We extend the temporal and spatial isolation mechanisms from the
application layer to the execution environment, so that the integrated applications
share the computing node without interference. For the data communication of
the integrated applications, we propose a virtual switch supporting temporal and
spatial isolation between data flows and leverage the SDN paradigm to address the
reconfiguration requirements of data flows. Besides, we also address the controlled
import and export of messages between data flows in the proposed virtual switch.
For the deterministic communication requirements of hard real-time applications, we
propose a virtual switch that is IEEE 802.1Qbv and IEEE 802.1Qci capable according
to the Time Sensitive Networking (TSN) standard, in order to close the research gap
of virtual switching guaranteeing bounded delay with low jitter in an integrated
architecture.

In the proof-of-concept implementations, we demonstrate the non-interference
between applications in the execution environment by fault injection. In our virtual
switch demonstrators, we evaluate the fundamental isolation mechanisms and determinism
of message switching, while measuring the caused overhead for message
transmission as well as controlled data exchange, where the measured overhead in
the proposed virtual switch is less than 10 μs.