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Application & OT Security · Foundational

Purdue Model

The Purdue Enterprise Reference Architecture, a layered model that segments industrial networks from physical processes up to enterprise IT.

Definition

Levels are commonly described as Level 0 (physical process: sensors and actuators), Level 1 (basic control: PLCs, RTUs), Level 2 (supervisory control: HMIs, SCADA), Level 3 (site operations: historians, MES), an industrial DMZ (often called Level 3.5) and Levels 4-5 (enterprise IT and internet). Traffic should not pass directly between IT and control levels.

Example

An organization places a jump server and replica historian in the Level 3.5 DMZ between plant and corporate networks.

Exam tip

Know the level contents; the IDMZ (3.5) separates IT from OT.

Related terms