Data Diode Use Cases: Where One-Way Transfer Earns Its Place in OT

01Key takeaways

1. 01

   A data diode fits any boundary where data must be published outward but no traffic should return through that path.

2. 02

   Strong use cases include OT telemetry export, safety data, video and physical-security feeds, and cloud analytics export.

3. 03

   Cross-domain and high-assurance transfer is the classic diode use case and still one of the most demanding.

4. 04

   The wrong use cases are flows that need a conversation: remote control, interactive maintenance, or two-way protocols.

5. 05

   Matching the diode to a genuinely one-way data flow is the whole game; force-fitting it creates fragile workarounds.

02When one-way transfer is the right shape

Every good data diode use case shares one property: the protected side needs to send data out, and the receiving side has no legitimate reason to send anything back through that boundary. If that is true, a diode turns the requirement into an enforced physical fact.

If it is not true, no amount of engineering around the diode will make a two-way workflow comfortable. The first question for any candidate use case is therefore the simplest: does this flow need a conversation, or only a publication?

The test for a diode use case: data goes out, nothing needs to come back through the same path.

03OT telemetry and event export

The most common use case is exporting telemetry from a plant network to enterprise systems: production metrics, alarms, events and status. Business systems need to see what is happening, but they have no operational reason to send traffic into the plant.

A diode lets the metrics flow to reporting, dashboards and analytics while removing the inbound path that an attacker would otherwise target. The enterprise gets visibility; the plant keeps a boundary with no way back in.

04Safety and SIS data out

Safety instrumented systems and other high-consequence equipment often need to be observed without being touched. Their state, alarms and diagnostics are valuable to engineers and managers, but inbound connectivity to a safety system is exactly what should not exist.

One-way export of safety data preserves the observation while enforcing the rule that the safety function cannot be reached or altered through the monitoring path.

05CCTV and physical-security export

Video surveillance and physical-access systems frequently sit in sensitive environments yet need to feed monitoring stations or recording platforms elsewhere. The feed must leave; the cameras and controllers should not be reachable from the viewing side.

A diode carries the video and event stream one way, so a compromise of the monitoring network cannot pivot into the camera or access-control infrastructure.

06Cross-domain and high-assurance transfer

The classic diode use case is moving data between security domains of different trust levels, for example from a high-assurance network to a lower one. Here the one-way guarantee is not a convenience but a requirement, and it is often subject to formal evaluation.

These deployments demand the most from the surrounding gateway: rigorous content handling, strong assurance of direction, and provable accounting of what crossed. The diode is the foundation, but the assurance case is the work.

07Cloud and analytics export

Industrial analytics increasingly lives in the cloud, which means production data must leave the plant to be useful. That is a one-way requirement: the cloud needs the data, not a route into the OT environment.

An AIRGAPNET controlled connectivity pattern can be compared with a diode here, depending on whether the export should be continuously one-way or offline by default and opened on a schedule. Either way the goal is the same: the data reaches the cloud without the cloud reaching the plant.

08Where a data diode is the wrong tool

A diode fails when the flow genuinely needs to be bidirectional. Forcing one-way hardware into a two-way process produces brittle workarounds and frustrated operators.

• Interactive remote maintenance that needs a real session into the asset.
• Remote control or command flows that require acknowledgements and responses.
• Protocols that cannot function without return traffic and cannot be proxied cleanly.
• Cases where the real need is occasional two-way access, which suits time-based disconnection better than a permanent one-way path.

For those, a firewall conduit, a controlled access window, or scheduled disconnection is the better control. The diode is not weaker; it is simply built for a different shape of problem.

09Closing thought

Data diodes earn their place wherever a protected environment must publish data without offering a way back in. Telemetry, safety data, video, cross-domain transfer and cloud export all share that shape, and all benefit from an enforced one-way boundary.

Start from the data flow, not the device. If the honest answer is publication, a diode is excellent. If the honest answer is conversation, choose the control that fits and keep the diode for the boundaries that are truly one-way.

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