From flat OT network to secure uptime: open SDN and microsegmentation with OpenFlow

Industrial networks are under increasing pressure. Many OT networks are still flat or only partially segmented. They were historically designed for availability and connectivity, not for control, visibility, and cybersecurity. At the same time, many industrial protocols lack built-in features for authentication, encryption, and authorization. This creates risks such as uncontrolled communication, lateral movement, and disruption of critical production processes.

In this session, we introduce OT Software-Defined Networking as a practical approach to better understand, segment, and protect industrial networks without compromising uptime. The solution is based on OpenFlow: an open standard that decouples central network control from the underlying hardware.

This open architecture reduces dependency on a single vendor and makes it possible to build a future-proof network across various hardware vendors and technologies. This allows asset owners to retain more freedom when designing, expanding, and modernizing their industrial network.

With central SDN control, OT teams gain full insight into:

• which devices are connected to the network;
• which devices are allowed to communicate with each other;
• which protocols are permitted for this.

Based on this, the network can be configured step-by-step according to a deny-by-default model. Only explicitly approved communication is allowed. This creates micro-segmentation down to the device and protocol level, without complex manual firewall rules, extensive VLAN architectures, or re-addressing of existing installations.

During the session, we will demonstrate how OT-SDN can be applied in brownfield environments with limited maintenance windows, high availability requirements, long lifecycles, and equipment from multiple vendors.

The central message is simple: OT cybersecurity is not just about preventing attacks, but above all about protecting uptime. An open, OpenFlow-based SDN architecture combines vendor independence with central control, network visibility, and effective microsegmentation.

Speaker

Thomas Vasen is OT Cybersecurity Manager at HMS Networks and focuses on cybersecurity for Operational Technology. He is ISA/IEC 62443 certified and holds a Product Management Certification (PMC) Level VII.

Thomas has over 25 years of international experience in telecom, cybersecurity, industrial automation, and B2B software services. He is Group Leader of the Security in ICS/OT theme at Cybernode.se and an active member of the HSD Security Delta OT Security Expert Platform.

As an international speaker and trusted advisor, Thomas helps organizations connect OT security, industrial networking, and digital transformation in a practical and future-oriented way.