What if the very backbone of your industrial operation - the fibre optics connecting your most critical assets - is also its most exposed and forgotten attack surface?
Why Your Most Expensive Machinery is Only as Reliable as Its Weakest Network Link
For decades, the conversation around industrial networks has been dominated by one metric: bandwidth. But on the factory floor, in the electrical substation, or along the railway line, raw speed is a hollow victory if a single, mistimed data packet can halt production, trigger a safety shutdown, or endanger lives.
The true benchmark of industrial networking is not speed, but certainty. It’s the guarantee that a critical control signal will arrive at its destination not just quickly, but precisely on time, every time. This is the world of deterministic networking, and fibre optics are its indispensable physical backbone.
This guide moves beyond the simplistic sales pitches to explore the core engineering principles that separate a functional fibre network from a resilient, secure, and deterministic industrial nervous system. We will dismantle dangerous myths, expose hidden vulnerabilities, and detail the architectures and technologies - from Time-Sensitive Networking (TSN) to Parallel Redundancy Protocol (PRP) - that define modern operational technology (OT).
In the IT world, network performance is measured in megabytes per second and latency is an inconvenience. In the OT world, latency variance - known as jitter - is the enemy. A network can have immense bandwidth, but if jitter is uncontrolled, it destabilizes the finely tuned control loops that govern machinery, robots, and processes.
These are not failures of speed, but failures of predictability.
TSN is a set of IEEE standards that transforms standard Ethernet into a deterministic, time-aware network. It acts like a traffic management system for your data, creating scheduled "green light" windows for time-critical traffic while allowing best-effort data (like file transfers or video streams) to use the remaining capacity.
Fibre optics are the ideal physical medium for TSN. Their inherent immunity to electromagnetic interference (EMI) ensures that the precise timing of these scheduled packets is not corrupted by electrical noise from motors, drives, or power lines. The consistent signal propagation in fibre eliminates the variable latency that can occur in copper cables under different environmental conditions.
Ultimately, achieving determinism is an end-to-end engineering challenge. It requires every component - from Westermo and Welotec switches managing the TSN queues to ProSoft and ATOP gateways providing precise protocol translation - to be selected and configured with timing guarantees in mind. The goal isn't more bandwidth; it's unwavering predictability that keeps industrial systems synchronized, safe, and efficient.
A pervasive and dangerous assumption plagues industrial security: "Our network is on fibre, so it can't be tapped." This misconception breeds complacency, leaving critical control networks exposed to sophisticated physical-layer attacks.
While it's true that fibre does not radiate electromagnetic signals like copper, making it immune to passive eavesdropping, it is far from impervious. The physical cable itself, and the devices that connect to it, present a tangible attack surface.
These threats are particularly insidious because they operate below the level of IP packets. They target the physical and data link layers, where conventional IT cybersecurity tools have no visibility.
True fibre security requires a layered defence strategy that moves from presumption to proof:
By combining these measures, fibre transitions from a presumed security asset into a demonstrably secure industrial backbone.
Industrial networks are often a complex tapestry of modern managed switches and legacy, simple devices. It is these simple devices - unmanaged media converters, patch panels, and switches - that frequently form the most vulnerable, yet overlooked, attack surface.
They are the "plumbing" of the network: essential, ubiquitous, and considered too basic to be a threat. This perceived innocence is what makes them so dangerous. They bridge critical control segments yet typically offer no authentication, no logging, no segmentation, and no security features.
When you compound these issues with default credentials on managed devices, outdated firmware, or counterfeit components, this foundational infrastructure becomes a silent enabler of compromise.
Securing these components delivers one of the highest returns on investment for your overall cybersecurity posture.
By hardening this hidden layer, you transform the weakest parts of your network into its most defensible assets.
The reliability of your entire industrial operation can depend on the integrity of a single, fragile strand of glass. Traditional monitoring is binary: the link is either "up" or "down." It only alerts you when it's already too late, during a costly outage.
AI-driven monitoring transforms this reactive approach into a predictive and proactive intelligence system. By continuously analysing optical performance data in real-time, machine learning algorithms can detect minute changes that are invisible to human operators or threshold-based systems.
Vendors like Welotec, Westermo, and ProSoft are now integrating edge-enabled AI capabilities directly into their industrial networking equipment. This allows for local processing of data, ensuring real-time response and operational resilience even if the connection to a central cloud is lost.
The result is a self-monitoring fibre infrastructure that not only forecasts its own maintenance needs but also stands guard against physical intrusion.
A fundamental conflict has long existed in industrial networking: the need for cybersecurity versus the need for deterministic performance. Engineers rightly fear that adding encryption could introduce the very latency and jitter that will break their real-time control loops.
In a motion control system or a power grid protection relay, processing delays of even a few milliseconds from software-based encryption can be catastrophic. This perceived trade-off has left many critical fibre networks running in the clear, vulnerable to data manipulation and interception.
The solution lies in using the right type of encryption, implemented in the right way:
This approach allows for a "secure by design" deterministic network. Control traffic can be encrypted without compromising the scheduled delivery guarantees of TSN.
Not all data is equally critical. A balanced security policy might involve:
By strategically applying hardware-accelerated, layer-2 encryption, engineers can finally achieve both security and determinism, enabling safe and reliable IT/OT convergence.
In critical infrastructure, network redundancy isn't a feature - it's a requirement for safety and availability. However, traditional redundancy protocols like Spanning Tree Protocol (STP) have recovery times measured in seconds, an eternity for automated systems. A sub-second network outage can cause a manufacturing cell to fault, a generator to trip, or a conveyor system to jam.
The new standard is zero-recovery networking, where redundancy is active and simultaneous, ensuring that a single fault has no perceptible impact on control systems.
Fibre optics are the enabling physical medium for these architectures. Their high bandwidth, deterministic latency, and noise immunity make them ideal for building the redundant, long-distance rings required by PRP and HSR.
Vendors like Westermo and ATOP offer a range of switches and other devices designed specifically for these protocols, supporting dual-homed devices that eliminate single points of failure.
The choice of protocol depends on the criticality of the application. For the most demanding environments - power substation automation, safety systems, high-speed manufacturing - PRP and HSR are becoming the de facto standard.
Many industrial sites contain a mix of modern Ethernet-based devices and legacy serial equipment (e.g., PLCs with RS-232/422/485, DH+, or Modbus RTU). These legacy systems often hold critical process data but represent a significant challenge for IIoT integration and security.
The solution lies in intelligent protocol gateways. Devices from suppliers like ProSoft Technology and ATOP act as secure bridges, translating between legacy serial protocols and modern TCP/IP, often with built-in firewall capabilities. Instead of a risky "rip-and-replace" strategy, these gateways allow for a phased modernization, enabling data from legacy controllers to be securely brought into IT/OT analytics platforms without compromising the stability or security of the original control loop.
The most advanced encryption and AI monitoring can be undone by a single human oversight. A technician plugging an untested laptop into a control network port, a contractor leaving a patch panel unlocked, or an engineer using default passwords on a new device - these actions create immediate and severe risks.
A robust fibre security strategy must include a continuous Human Factor programme:
Fibre networks don't always fail catastrophically; they often degrade slowly. Understanding the "three killers" is essential for maintaining network health.
Proactive, scheduled testing with the right tools is the only way to catch this silent degradation before it leads to a operational crisis.
Here are just some answers to key questions.
Noise immunity ensures the signal's integrity, but it doesn't control its timing. Determinism (via TSN) manages when the signal arrives. In synchronized multi-axis robotics or power grid protection, a noise-free signal that arrives a millisecond late is just as useless as a corrupted one.
While complex, the threat is real for critical infrastructure. More importantly, the "inherently secure" myth leads to complacency in other areas, like unsecured media converters and patch panels. A holistic security strategy addresses both sophisticated and simple attack vectors.
An unmanaged converter is a transparent, dumb device. A managed converter can enforce security policies: it can be configured with VLANs to isolate traffic, have unused ports disabled, and provide logs of link status and data rates, offering visibility and control.
Modern AI monitoring systems from industrial vendors are designed to integrate via APIs or standard protocols like SNMP. They can feed alerts and health scores directly into your existing SCADA, Historian, or Network Operations Center (NOC) dashboard, providing context without requiring a separate silo of information.
It depends on your hardware. MACsec requires support in the network switches and, ideally, hardware acceleration. A network audit will determine if your current infrastructure can support it or if an upgrade to certified switches (e.g., from Westermo) is necessary.
Choose PRP (or HSR) when your control application cannot tolerate any packet loss during a failure event - common in power utility protection schemes and high-speed safety systems. If your system can handle a brief (sub-200ms) interruption, a Fibre Ring with RSTP is a more cost-effective solution.
Yes, securely. Using an industrial protocol gateway from a vendor like ProSoft or ATOP, you can translate the Modbus RTU traffic to Modbus TCP/IP or MQTT. The key is to use a gateway with a built-in firewall to filter traffic and to segment the legacy devices on their own VLAN.
Begin by measuring the Bit Error Rate (BER) on the affected links. A high BER is a key indicator of underlying physical problems. Then, use an OTDR to check for abnormal attenuation events (microbends, bad splices) and ensure all connectors are perfectly clean. This "silent degradation" is a classic symptom of the "three killers."
The principles outlined here - from deterministic timing and layered security to predictive monitoring and zero-recovery architectures - are not isolated technical features. They are the interconnected layers of a modern industrial fibre strategy. Addressing them requires a fundamental shift from viewing the network as passive cabling to treating it as an active, intelligent, and critical asset.
The knowledge, technology, and industrial-grade components from leading suppliers like Westermo, Welotec, ProSoft, and ATOP exist today to engineer this level of certainty. The time to move beyond legacy thinking and inherent assumptions is now.
Mastering these concepts is an ongoing process. Subscribe to the Link & Layer | Smart Learning Hub to receive exclusive, in-depth content that breaks down each of these pillars. We provide the actionable insights, vendor-neutral guidance, and strategic frameworks you need to transform your industrial network from a source of risk into a foundation of competitive advantage.
The integrity of your industrial fibre network is not a niche technical concern; it is the bedrock of your operational resilience and cybersecurity posture. The journey from a vulnerable, forgotten backbone to a secure, monitored, and high-performance asset requires a deliberate strategy, blending physical-layer expertise with modern cybersecurity principles.
The insights in this guide provide the map, but the journey is yours to start. For a deeper dive into the technical specifics, our specialist team has developed a series of detailed implementation guides and configuration templates.
Subscribe to the Link & Layer | Smart Learning Hub to receive our exclusive "Industrial Fibre Hardening Checklist," a comprehensive asset register template, and detailed technical briefs on implementing MACsec and PRP in multi-vendor environments.
Don't let your most critical asset remain your greatest vulnerability. Contact a Throughput Technologies specialist today for a no-obligation assessment of your industrial network backbone.
In industrial networks, determinism - not raw speed - ensures reliability. Predictable timing, low jitter, and synchronized control loops, supported by TSN and fibre optics, prevent safety incidents and maintain operational continuity.
Fibre isn’t inherently secure; physical attacks, rogue transceivers, and insecure media converters threaten industrial networks. True protection requires controlled access, continuous monitoring, and trusted hardware with layered security measures.
Unmanaged media converters, patch panels, and switches silently expose industrial networks to attack. Simple, overlooked devices create hidden vulnerabilities - securing them with trusted hardware and monitoring transforms weak points into strong defences.