As manufacturers and critical infrastructure operators face increasing regulatory scrutiny under frameworks like CMMC, NIS2, and IEC 62443, one strategy consistently proves both technically sound and compliance-enabling: network segmentation.

But in operational technology (OT), segmentation is not as simple as carving VLANs or dropping a firewall between zones.
It’s about creating defensible, compliant, and auditable boundaries of trust — without breaking production or triggering downtime.

Unlike IT networks, where users and applications can be centrally authenticated and patched, OT environments host legacy controllers, HMIs, and PLCs designed before cybersecurity was a concern.
These devices often lack encryption or password protection, can’t support endpoint agents or certificates, and must operate continuously — 24/7, with no patch windows allowed.

For these reasons, compliance frameworks explicitly call out segmentation as a compensating control.
Under CMMC, such systems are categorized as Specialized Assets — requiring isolation and monitoring rather than direct hardening.
Under IEC 62443, segmentation is essential to define “Zones” and “Conduits” for security level enforcement.

Segmentation transforms a flat network into a structured environment where risks are contained, traffic is observable, and compliance evidence can be generated automatically.

Traditional segmentation in OT relied on VLANs or static firewalls — methods that are brittle, complex, and difficult to audit.
VLANs collapse under multi-vendor deployments, and every rule change introduces operational risk.

Modern segmentation replaces these static boundaries with software-defined enclaves — isolated communication domains that define who and what can talk, at what layer, and under which policy.

Trout’s approach to segmentation, for example, uses software-defined DMZs (“micro-DMZs”) in front of each critical asset, turning every PLC, HMI, or historian into its own protected zone.

Each enclave:

• Authenticates both endpoints and services.

• Inspects and logs communications in real time.

• Enforces least-privilege communication policies (who can talk to whom, and how).

This architecture can be deployed incrementally, allowing teams to move from a flat to a zero-trust segmented network with no downtime — a key enabler for compliance readiness.

Segmentation directly supports core requirements across compliance frameworks:

Access Control (AC) — Enclaves enforce least-privilege communication per device or user.
System & Communication Protection (SC) — Traffic is restricted by policy, and monitored for anomalies.
Audit & Accountability (AU) — Each enclave generates its own telemetry for traceability.
Incident Response (IR) — Segmented zones contain breaches, limiting propagation.
Risk Assessment (RA) — Segmentation defines clear asset boundaries for scoping and risk scoring.

Because Trout’s enclaves operate at the network edge, they provide a ready-to-audit architecture — where every policy, flow, and control aligns naturally with compliance evidence.

Consider a manufacturing site running ten legacy CNC machines, each with unencrypted controllers.
Encrypting or patching these controllers isn’t feasible.

By placing each controller inside a Trout Access Gate enclave, the organization can:

• Limit communications to approved engineering workstations.

• Log all Modbus or SMB traffic for compliance evidence.

• Prevent lateral movement even if one machine is compromised.

• Demonstrate compensating controls under CMMC Level 2 or IEC 62443 SL2.

Instead of expensive network redesigns, segmentation delivers measurable compliance progress — fast.

Network segmentation is no longer a best practice — it’s a compliance accelerator.
In OT environments, where many assets can’t be secured directly, segmentation provides the control plane for trust, enabling organizations to:

• Contain legacy risks,

• Simplify audits, and

• Prove compliance — without halting production.