Industrial Switch

What is an Industrial Switch?

An industrial switch is a network switch built specifically for industrial environments: it connects PLCs, HMIs, IO modules and servers over Ethernet and keeps working reliably under extreme temperatures, vibration, dust and electromagnetic interference (EMI). Where an office switch sits in an air-conditioned server room, an industrial switch is mounted on a DIN rail in a control cabinet next to variable-frequency drives, in a pumping station or in a substation. It also supports industrial redundancy protocols and management functions that an office switch often lacks.

Industrial switches form the core of the Control Network and the Supervisory Network: if the switch fails, communication between control system and process stops, however good the rest of the installation is.

🧠 How does an industrial switch work?

Technically, an industrial switch works like any Ethernet switch, but with a number of functions that make the difference in OT:

1. Forwarding frames at Layer 2 - the switch learns which MAC addresses sit behind which port and forwards each frame only to the right port (Layer 2 of the OSI model). A Layer 3 switch can also route between VLANs, but it does not replace a firewall.
2. Logical separation with VLANs - one physical network is divided into separate broadcast domains, for example for control, cameras and engineering. This is how the switch helps put segmentation and the zones of the zones and conduits model into practice.
3. Priority for process traffic - with QoS, time-critical protocols such as ProfiNET and IP take precedence over, say, camera streams or backup traffic.
4. Redundancy - ring protocols such as MRP and DLR, the topology-independent RSTP, or seamless redundancy with PRP and HSR, keep communication going after a cable break or a failed switch.
5. Management and diagnostics - through a web interface, CLI or SNMPv3, an administrator reads port status, error counters and alarms; many switches send events to Syslog and have an alarm relay that a PLC can read.

🔄 How does it differ from an office switch?

The difference lies mainly in the hardware and in the protocols the switch supports:

Fanless also means there is no fan drawing dust and moisture into the unit. The alarm relay switches when, for example, one of the two power inputs or a link fails, so the PLC can pass this on and the fault becomes immediately visible in the SCADA system.

🔁 Which redundancy protocols does an industrial switch support?

A common rule of thumb says industrial networks “recover within 50 ms”, but that depends heavily on the protocol:

For a PROFINET installation, MRP with the 200 ms profile is the usual choice. Set the watchdog time of the O longer than 200 ms, otherwise the I/O device reports a communication fault while the ring reconfigures. For IRT applications that cannot tolerate any interruption, PROFINET also offers MRPD, in which frames are sent through the ring twice. In substations based on IEC 61850, PRP and HSR are common, because protection relays must not see any interruption at all. Read more about ring topologies under Ring Redundancy, and about fast recovery of networks in general under Redundancy.

🏭 Where are industrial switches used?

• Factories and machine building - the Control Network with PLCs, drives and I/O, often with MRP or DLR rings per production line.
• Process industry - redundant backbones between the control room and field cabinets, using fibre over longer distances.
• Water and infrastructure - pumping stations, wastewater treatment plants, tunnels and locks, often in outdoor cabinets with large temperature swings.
• Energy - substations, where switches must meet IEC 61850-3 and IEEE 1613 (EMC immunity, temperature, vibration) and pass on Precision Time Protocol for time synchronisation.
• Rail and transport - switches for rolling stock under EN 50155 and for trackside equipment under EN 50121-4.

Increasingly, TSN is added for deterministic, real-time traffic over a shared network, along with Power over Ethernet (IEEE 802.3af/at/bt) for cameras, Wi-Fi access points and sensors.

🧭 How do you choose an industrial switch?

Start with the requirements of the installation, not with the brand. These steps help:

1. Define the environment - temperature inside the cabinet (sunlight on an outdoor cabinet can push the internal temperature far above ambient), vibration, humidity and any ATEX zones.
2. Choose managed or unmanaged - see the table below. For anything related to production, a managed switch is the norm.
3. Choose the redundancy protocol - matched to the fieldbus protocol: MRP for PROFINET, DLR for EtherNet/IP, PRP/HSR in substations.
4. Count ports and media - copper or fibre (SFP slots), number of ports now and in ten years, PoE budget.
5. Check protocol support - PROFINET or EtherNet/IP conformance, IGMP snooping for multicast traffic, PTP where time synchronisation is needed.
6. Assess the security - certification to IEC 62443-4-2 at the required security level, how long the vendor will supply firmware updates, and a policy for vulnerability disclosure.

There are also “lite managed” or “smart” switches with a limited feature set, such as VLANs and PROFINET diagnostics only; they suit smaller machine networks.

🔐 How do you secure an industrial switch?

A switch sits in the middle of the network, which makes it both a target and an important security tool. An unconfigured switch is a way in for an insider or for malware spreading laterally. Key measures:

• Hardening - change default passwords, disable unused ports, replace Telnet and HTTP with SSH and HTTPS, and allow management only from a dedicated management VLAN.
• Port Security and 802.1X - only known devices may use a port; 802.1X requires authentication before a device gets network access.
• ACLs on Layer 3 switches - restrict traffic between VLANs, in addition to an industrial firewall between zones.
• SNMPv3 instead of SNMPv1/v2c, because the older versions send community strings unencrypted.
• Monitoring - copy traffic through a SPAN port or a TAP to a system for network monitoring and anomaly detection, and forward logs to a SIEM.
• Patch management - track switch firmware in the asset inventory and follow vulnerabilities; industrial switches appear regularly in security advisories.

In the EU, a switch as a product falls under the Cyber Resilience Act: routers, internet modems and switches are listed in Annex III as important products of Class I. The obligation to report actively exploited vulnerabilities applies from 11 September 2026 and the full requirements from 11 December 2027. Organisations within the scope of NIS2 (in the Netherlands the Cyberbeveiligingswet) must also take appropriate measures in their own networks, and the switch is a core component of those.

❓ Frequently asked questions

How much does an industrial switch cost compared with an office switch?

An industrial switch typically costs several times more per port than an office switch, because it has a wider temperature range, dual power inputs, more robust components and industrial protocols. In return, it often stays in service for ten years or more. Downtime of a production line caused by a failed switch usually costs more than the price difference.

Can I use an office switch in a control cabinet?

Using an office switch in a control cabinet is not recommended, because the cabinet temperature quickly exceeds the range of 0 to about 40 °C and its EMC immunity is not designed for drives and switching loads. It also lacks a 24 V DC supply, DIN-rail mounting and industrial redundancy protocols. Use an industrial switch in control cabinets instead.

Does an industrial switch always need a ring protocol?

An industrial switch does not always need a ring protocol, but redundancy is strongly advised for any network segment whose failure would stop production. The protocol usually follows from the fieldbus protocol: MRP for PROFINET, DLR for EtherNet/IP and PRP or HSR in substations. For a single machine with a short service life, a star configuration may be sufficient.

What is a Layer 3 industrial switch?

A Layer 3 industrial switch can route IP traffic between VLANs or subnets in addition to forwarding frames. This is useful in a backbone with several production lines, and with ACLs such a switch can restrict traffic between VLANs. An industrial firewall is still needed at the boundary between security zones, because it can inspect traffic at protocol and application level.

What does IEC 62443-4-2 mean for an industrial switch?

IEC 62443-4-2 defines the technical security requirements for components of an industrial automation system, such as authentication, authorisation, logging and secure updates. An industrial switch certified to this standard at, for example, security level 2 demonstrably provides the corresponding functions. Several manufacturers have their industrial switches certified against it.

Why are industrial switches often fanless?

An industrial switch is often fanless because a fan is a moving part that wears and fails, and because it draws dust, moisture and dirt into the enclosure. Passive cooling through a finned metal housing therefore increases reliability. You do still need to leave enough space around the switch in the cabinet for heat dissipation.

📌 In summary

An industrial switch is a robust, usually managed network switch that connects PLCs, HMIs and servers in OT networks and keeps working through heat, cold, vibration and electromagnetic interference. With VLANs, QoS, redundancy protocols such as MRP, DLR and PRP, and a hardened configuration in line with IEC 62443, it forms the foundation of reliable and secure industrial automation.