OT Network Architecture
Definition
The overall structural design of an operational technology network — its organization into functional zones, the conduits connecting them, and the segmentation separating them — typically based on the layered Purdue Model reference architecture.
Key Points
- Typically organized around the Purdue Model's layered zones, from enterprise IT at the top through DMZ, supervisory control, and basic control layers down to the physical process at the bottom
- Segments the network into zones based on function and criticality rather than treating OT as a single flat network, limiting how far a compromise or fault in one zone can propagate to others
- Conduits — the defined, controlled connections between zones — are where security controls (firewalls, monitoring, access control) are concentrated, since traffic must pass through these specific chokepoints rather than flowing freely between zones
- Architecture decisions made at design time directly shape what's achievable later — a flat, unsegmented legacy OT network is far more difficult and disruptive to retrofit with proper segmentation than one designed with zones and conduits from the outset
- Modern OT network architecture increasingly needs to account for connectivity patterns the classic Purdue Model didn't originally anticipate — cloud connectivity, remote access, and IoT sensor integration all require deliberate architectural accommodation rather than being layered on as an afterthought
Concept
Rather than treating an industrial site's technology environment as a single flat network, OT network architecture organizes it into distinct zones by function and criticality — enterprise IT, a DMZ buffer, supervisory control systems, basic process control, and the physical process itself — connected through defined conduits where security and monitoring controls can be concentrated, rather than allowing traffic to flow unrestricted across the entire environment.
Explainer
The architectural discipline of zones and conduits exists specifically to bound the consequences of any single compromise or fault — a well-architected OT network limits how far a problem originating in one zone can propagate, while a flat, unsegmented network offers no such containment, letting an incident anywhere potentially reach everywhere. This is why architecture decisions made early in an OT environment's design carry outsized long-term consequences: retrofitting proper zone segmentation onto a legacy flat network is a disruptive, costly undertaking precisely because it means re-architecting live production infrastructure, while building the segmentation in from the start costs comparatively little extra at design time. For CE verticals, OT network architecture quality is the structural foundation everything else in an organization's OT security posture depends on — asset inventory, patch management, visibility, and secure remote access all function within whatever zone and conduit structure the underlying architecture provides, making architectural investment a leverage point that improves the effectiveness of every other OT security practice built on top of it.
Cite this entry
OT Network Architecture. ConnectedEarth Knowledge Base. https://connectedearth.space/knowledge-base/ot-network-architecture/ (updated 13 September 2026).