Reference points to better understand IT/OT convergence

For decades, IT and OT evolved separately — different cultures, priorities and lifecycles. IT favors flexibility, frequent updates and connectivity. OT favors stability, availability and operational continuity.

Convergence shifts that balance. Field systems are now connected to enterprise networks, cloud platforms and analytics tools. This connectivity brings visibility — but it also exposes systems that were never designed to be connected.

Managing this convergence well means understanding both worlds: their constraints, dependencies and respective priorities — before designing, connecting or securing anything.

Does this sound familiar? Let's talk →

Modernizing an OT system is not the same as modernizing an IT system. In IT, a poorly planned migration causes inconvenience. In OT, it can stop a production line, interrupt a critical service or create a risk to personnel safety.

Before any intervention, it is essential to understand: what are the real dependencies of the system? What maintenance windows are available? What are the impacts of an interruption, even a brief one? Is the target system compatible with existing real-time constraints?

Controlled modernization means evolving without destabilizing — by sequencing changes, documenting each step and involving field teams from the start.

Does this sound familiar? Let's talk →

OT encompasses all computing systems that interact directly with the physical world — well beyond traditional factories and control rooms.

A smart thermostat, an access control system, a networked surveillance camera, a pressure sensor on a pipeline, a railway signaling controller, a maritime navigation system — all are OT.

What sets them apart from IT: an interruption is not just an inconvenience. It can have direct physical, operational or safety consequences.

In OT environments, cybersecurity must never take priority over machine safety or the physical safety of personnel. These two priorities are non-negotiable — any cybersecurity measure that compromises them is a poor measure, regardless of its technical justification. This is why OT requires a fundamentally different approach from IT.

Does this sound familiar? Let's talk →

You cannot secure what you do not know. In IT/OT environments, flows are often poorly documented or unknown — communications between controllers, supplier access, interfaces with enterprise systems, legacy protocols.

Documenting flows means mapping who talks to whom, on which protocol, with what level of access and for what purpose. It means identifying implicit dependencies, uncontrolled access and communication paths that should never have existed.

It also means inventorying field assets — equipment, controllers, sensors, gateways — to avoid shadow OT: systems present on the network, operational, but unknown to the responsible team. An unregistered asset is an unsupervised, unmaintained and unsecured asset.

This documentation becomes the foundation for everything: network segmentation, access controls, incident response, audits and architecture evolution. Without it, every decision rests on assumptions — not facts.

Does this sound familiar? Let's talk →

IT/OT frameworks are tools — not recipes. NIST SP 800-82 covers OT system security. The Purdue model structures the levels of an IT/OT architecture. ISA/IEC 62443 addresses security for industrial automation systems. ITSG (Canada) provides guidance applicable to sensitive systems in the Canadian context.

But no framework knows your environment, your field constraints, your legacy systems or your operational priorities. Applied mechanically, they can lead to poorly adapted decisions — or even counterproductive ones.

The RĒSUNIX approach uses these frameworks as reference points, not checklists — adapting them to the real context of each mandate. Other sector-specific or regulatory frameworks may also apply depending on client needs.

Does this sound familiar? Let's talk →

One of the greatest challenges of IT/OT convergence is not technical — it is human. IT and OT teams have different cultures, priorities and vocabularies. What is obvious to an automation engineer is not obvious to a network administrator, and vice versa.

Training at RĒSUNIX is not a standard course. It is built around real needs: who needs to understand what, to make which decisions, in which operational context.

The goal is concrete — IT teams understand field constraints, OT teams understand cyber challenges, and management has a shared view of risks and priorities. A shared language is the foundation of an architecture that holds over time.

Does this sound familiar? Let's talk →