OT network

An OT network is the communication infrastructure that connects operational technology systems used to monitor and control physical processes in industrial environments. It typically links devices such as PLCs, DCS controllers, SCADA systems, HMIs, sensors, actuators, and industrial robots, and is distinct from the corporate IT network that supports business applications.

In manufacturing, the OT network carries time-sensitive control signals, status data, and process measurements between shop-floor equipment and supervisory systems. It often uses industrial fieldbuses and real-time Ethernet protocols, and may connect through gateways to higher-level systems such as MES, historians, and edge or cloud services.

Key characteristics of an OT network

• Process-focused: Designed to support reliable and deterministic control of physical equipment and production processes.
• Real-time behavior: Often requires predictable latency and high availability, especially for safety and control functions.
• Use of industrial protocols: Commonly relies on protocols such as Modbus, PROFINET, EtherNet/IP, OPC UA, and various fieldbuses.
• Integration with IT: Frequently segmented and connected to IT networks via firewalls, DMZs, and secure gateways to exchange data with ERP, MES, quality, and analytics systems.
• Long-lived assets: Includes equipment with long lifecycles, meaning legacy systems and mixed generations of technology often share the same network.

Security and regulated manufacturing context

In regulated manufacturing environments, the OT network is a critical part of the overall cybersecurity posture. It commonly falls within the scope of information security and industrial control system security programs.

Organizations may align OT network security with standards and frameworks, such as ISO 27001 for information security management, ISO 27002 for security controls, and industrial control system guidance. Typical practices include network segmentation, access control, monitoring of industrial protocols, and controlled connectivity between OT and IT networks.

Operational role in manufacturing systems

From an operational perspective, the OT network:

• Connects field devices to controllers and supervisory systems for continuous process control.
• Provides data to MES, batch systems, historians, and quality systems for traceability, deviation analysis, and compliance reporting.
• Supports remote diagnostics, maintenance, and firmware updates for production equipment, subject to access controls and change management.

Common confusion

• OT network vs IT network: An IT network supports business applications (email, ERP, office tools, file services), while an OT network supports industrial control and automation. In modern plants they are interconnected but typically segmented for security and reliability.
• OT network vs OT systems: The OT network is the communication layer. OT systems include the hardware and software (PLCs, SCADA, HMIs, sensors) that use that network to perform control and monitoring.

Relation to supplier and control standards

When assessing suppliers that provide equipment or services connected to an OT network, organizations may request evidence of how information security and control standards are applied to that environment. This can include how specific security controls and good practices are implemented to protect industrial assets, interfaces to corporate IT, and any remote access paths into the OT network.