Maintaining OT Asset Visibility Over Time

OT asset discovery provides a snapshot of what exists in an operational environment at a given moment. Asset visibility, however, is not static. Industrial environments change continually, often in small and incremental ways that are easy to overlook.

Maintaining OT asset visibility over time means ensuring that asset information remains accurate, current, and useful long after an initial discovery exercise has been completed.

This article explains why OT asset discovery should not be treated as a one-off activity, how change typically occurs in OT environments, and how organisations can keep visibility up to date with minimal disruption.

Why OT asset discovery should not be a one-off exercise

A one-time discovery exercise can be valuable, particularly as a starting point. It helps establish what assets exist, where they are located, and how they communicate.

The limitation is that OT environments rarely remain unchanged.

In real operational settings, assets are added, removed, replaced, or modified as part of routine maintenance, upgrades, and operational improvements. Even small changes can affect visibility and risk understanding if they are not captured.

Over time, a static asset inventory begins to drift away from reality. When this happens, decisions based on that information become less reliable. This can affect security planning, incident response, compliance efforts, and operational troubleshooting.

Maintaining visibility is therefore about keeping the asset picture aligned with how the environment actually operates today, not how it looked at a single point in the past.

How change happens in OT environments

Change in OT environments is often gradual rather than disruptive. It may not be driven by large transformation projects, but by many small operational decisions.

Common sources of change include:

• Replacement of failed equipment with newer models
• Temporary connections made permanent over time
• Engineering laptops and contractor devices appearing intermittently
• Firmware or configuration changes that alter communication patterns
• Network segmentation changes to support production requirements

In many environments, these changes are not centrally tracked. Responsibility may be distributed across engineering, maintenance, IT, and third-party suppliers.

It is frequently observed that no single team has full visibility of how the environment has evolved over time. As a result, asset records slowly lose accuracy even though each individual change may have seemed minor at the time.

Periodic vs continuous discovery models

There are two broad approaches to maintaining OT asset visibility: periodic discovery and continuous discovery. Each has advantages and limitations.

Periodic discovery

Periodic discovery involves running asset discovery exercises at defined intervals, such as quarterly or annually.

This approach can work in relatively stable environments where change is infrequent and well controlled. It also allows discovery activities to be planned around maintenance windows and operational constraints.

The main limitation is timing. Changes that occur shortly after a discovery exercise may remain unrecorded for months. During that gap, asset data may already be outdated.

Periodic discovery also tends to create peaks of activity rather than a steady flow of updated information, which can make it harder to integrate asset data into day-to-day decision-making.

Continuous discovery

Continuous discovery focuses on maintaining visibility as assets appear, disappear, or change over time. This is typically achieved through passive monitoring of network traffic rather than repeated scanning.

In many industrial networks, passive methods are better suited to long-term visibility because they observe normal communications without actively interacting with devices.

Continuous discovery can provide earlier awareness of changes, such as new devices appearing or unexpected communication paths forming. It also reduces reliance on scheduled discovery windows.

However, continuous approaches still require governance. Data needs to be reviewed, validated, and maintained, otherwise visibility tools can become sources of unstructured information rather than usable insight.

Managing change without disrupting operations

A common concern is that maintaining asset visibility will interfere with production systems. This concern is understandable in environments where availability and safety are priorities.

In practice, disruption is usually avoided by focusing on methods that align with operational realities.

Key principles include:

• Preferring passive techniques that do not send traffic to OT devices
• Aligning discovery and review activities with existing operational processes
• Avoiding assumptions that IT-style scanning approaches are suitable for OT networks
• Treating asset visibility as an ongoing process rather than a recurring project

In operational environments, visibility is often most effective when it is quietly maintained in the background, rather than introduced as a disruptive activity.

Keeping asset data accurate and usable

Maintaining visibility is not only about detecting change. It is also about ensuring that asset information remains meaningful.

Over time, asset records can become cluttered with outdated entries, duplicate devices, or incomplete data. Without regular review, visibility degrades even if discovery continues.

Effective maintenance typically involves:

• Regular validation of asset relevance
• Clear definitions of what constitutes an OT asset
• Consistent naming and classification conventions
• Processes for handling temporary or transient devices

It is commonly seen that organisations focus heavily on initial discovery but underestimate the effort required to keep data clean and usable over time.

Asset visibility as an operational capability

Maintaining OT asset visibility is best understood as an operational capability rather than a single technical task.

It supports multiple objectives, including security, reliability, compliance, and troubleshooting. When visibility is current, these activities are based on accurate assumptions about the environment.

When visibility is outdated, risk decisions are made with incomplete information.

Keeping asset visibility up to date does not require constant intervention, but it does require ongoing attention. The goal is not perfection, but sustained alignment between recorded assets and the real operational environment.

All OT Asset Discovery Articles