Ethernet switches are fundamental building blocks in modern industrial networks. They connect PLCs, HMIs, SCADA systems, variable speed drives, remote I/O, industrial computers, access points, gateways and other Ethernet-enabled devices.
One of the first choices when specifying a switch is whether the application needs a managed or unmanaged model.
An unmanaged switch can be exactly the right choice for a simple network. A managed switch provides considerably more visibility and control, but those additional capabilities only create value when the network or application requires them.
This guide explains the practical differences and the information purchasing and technical teams should consider before ordering an industrial Ethernet switch.
What Does an Ethernet Switch Do?
An Ethernet switch connects devices on a local Ethernet network and forwards traffic between its ports.
In an industrial environment, connected devices can include:
- PLCs
- HMIs
- SCADA servers and workstations
- Variable speed drives
- Remote I/O
- Industrial gateways
- Energy meters
- Industrial computers
- Wireless access points
- Serial device servers
- Other industrial Ethernet equipment
The switch becomes part of the communications infrastructure that allows these devices to exchange data.
What Is an Unmanaged Ethernet Switch?
An unmanaged switch is designed to provide basic Ethernet connectivity without requiring network configuration for normal operation.
Devices are connected to the ports and the switch automatically forwards Ethernet traffic according to its internal switching functions.
Unmanaged switches are often suitable where the network is small, simple and does not require advanced monitoring, segmentation or redundancy features.
What Is a Managed Ethernet Switch?
A managed switch provides configurable network functions in addition to basic Ethernet switching.
Depending on the model, these can include:
- VLANs
- Spanning Tree protocols
- Ring or redundancy technologies
- SNMP monitoring
- Port mirroring
- Quality of Service
- Multicast management
- Port security
- Traffic statistics
- Alarm and event functions
- Link aggregation
- Configuration backup
- Network management and diagnostic functions
Feature sets differ significantly between switch families, so the word 'managed' does not guarantee that every managed switch supports every function.
Managed vs Unmanaged at a Glance
| Requirement | Unmanaged Switch | Managed Switch |
|---|---|---|
| Basic Ethernet connectivity | Yes | Yes |
| Configuration required for basic use | Usually no | Usually yes for advanced functions |
| VLAN support | Generally no | Common |
| Network monitoring | Limited | Common |
| Port mirroring | Generally no | Common |
| Redundancy protocols | Limited or model-specific | Common on industrial models |
| SNMP | Generally no | Common |
| Traffic prioritisation | Limited | Often available |
| Configuration complexity | Low | Higher |
These are general distinctions. Always verify the actual product specification.
When Is an Unmanaged Switch a Good Choice?
An unmanaged industrial switch can be appropriate where the requirement is simply to connect a small number of devices on a straightforward local network.
Examples can include:
- A small standalone machine
- A simple PLC and HMI connection
- A few Ethernet devices inside one control panel
- A small local monitoring network
- An application where network segmentation and remote diagnostics are not required
The simplicity of an unmanaged switch can be an advantage. There is less configuration to maintain and fewer network settings to alter accidentally.
When Should You Consider a Managed Switch?
A managed switch becomes increasingly useful as the network becomes larger, more critical or more complex.
Typical reasons include:
- Separating traffic using VLANs
- Monitoring switch and port status remotely
- Implementing redundant network paths
- Troubleshooting communications with port mirroring
- Managing multicast traffic
- Prioritising selected traffic
- Applying network access controls
- Integrating switch alarms into a monitoring system
- Collecting network statistics
- Managing fibre and copper uplinks across a larger architecture
What Is a VLAN?
A Virtual Local Area Network, or VLAN, allows a managed Ethernet infrastructure to logically separate network traffic even when devices share physical switching equipment.
For example, an industrial site might use separate VLANs for automation devices and management traffic according to the network design.
VLANs can improve organisation, traffic control and segmentation, but incorrect VLAN configuration can also prevent devices from communicating.
VLAN design should therefore be planned as part of the network architecture rather than enabled simply because the switch supports it.
What Is Spanning Tree?
Ethernet networks can experience serious problems if redundant physical links create uncontrolled switching loops.
Spanning Tree Protocol and related variants such as Rapid Spanning Tree Protocol can help manage redundant Layer 2 paths by preventing loops while allowing an alternate path to become active when network conditions change.
Support and behaviour vary by switch, and industrial networks may also use manufacturer-specific or specialised redundancy technologies.
Industrial Ring Networks
Ring topologies are common in industrial environments because they can provide an alternate communications path if a link is interrupted.
However, simply connecting switches in a physical ring does not automatically create a safe redundant network. The switches and network configuration must support an appropriate redundancy mechanism.
Different industrial switch manufacturers offer various ring and redundancy technologies with different recovery characteristics and compatibility requirements.
If ring redundancy is required, include that requirement in the RFQ rather than ordering switches based only on port count.
What Is SNMP?
Simple Network Management Protocol, or SNMP, is commonly used to monitor and manage network equipment.
On compatible managed switches, SNMP can provide information such as:
- Port status
- Traffic counters
- Device status
- Errors
- Environmental or power information where supported
This information can be integrated into suitable network management platforms.
SNMP versions and security capabilities differ between products, so requirements should be specified where relevant.
What Is Port Mirroring?
Port mirroring allows traffic from one or more switch ports to be copied to another port for analysis.
This can be extremely useful when troubleshooting industrial communications because a technician can connect a suitable diagnostic tool to the mirror port and inspect relevant network traffic without physically inserting equipment into the communication path.
Port mirroring is one example of a managed-switch feature that may have little value during normal operation but can save substantial troubleshooting time when a network problem occurs.
What Is Quality of Service?
Quality of Service, commonly abbreviated QoS, provides mechanisms for classifying and prioritising network traffic.
In networks carrying different types of traffic, appropriate QoS configuration can help ensure that selected traffic receives the required forwarding priority.
The actual benefit depends on network design, traffic patterns and the industrial protocols being used.
Multicast Traffic and IGMP Snooping
Some industrial Ethernet protocols and applications use multicast traffic.
Without appropriate management, multicast traffic can be forwarded more broadly than necessary and consume bandwidth on ports that do not require it.
Managed switches may support features such as IGMP snooping to manage multicast forwarding more intelligently.
If the automation network uses multicast-intensive protocols, switch capability should be considered as part of the network design.
What Is PoE?
Power over Ethernet, or PoE, allows compatible network devices to receive both data and electrical power through Ethernet cabling.
Typical PoE-powered devices can include:
- Wireless access points
- VoIP equipment
- Selected industrial devices
A switch with PoE ports must have sufficient power capacity for the connected devices.
Do not specify a PoE switch only by the number of PoE ports. Check the supported PoE standard, per-port power capability and the switch's total PoE power budget.
Understanding PoE Power Budget
A switch might physically provide eight PoE-capable ports but not necessarily supply the maximum possible power to all eight simultaneously.
The total power available to powered devices is commonly referred to as the PoE budget.
When selecting a PoE switch, calculate or estimate the maximum power required by all connected devices and compare this with the switch specification, while allowing for the design requirements of the installation.
Copper Ethernet Ports
Industrial switches commonly provide RJ45 copper Ethernet ports.
When specifying copper ports, consider:
- Required port count
- 10/100 Mbps, Gigabit or higher speed requirements
- PoE requirements
- Cable distance
- Connector and environmental requirements
- Network architecture
Standard Ethernet copper link distance limitations and cabling requirements still apply. Where distance, electromagnetic conditions or site layout make copper unsuitable, fibre may be preferable.
Fibre Ports and SFP Slots
Many industrial switches provide fibre connectivity through fixed optical ports or SFP slots.
An SFP slot accepts a compatible Small Form-factor Pluggable transceiver, allowing the switch to use an appropriate optical interface.
When selecting SFPs, specify:
- Required data rate
- Single-mode or multimode fibre
- Required wavelength
- Connector type
- Link distance
- Switch compatibility
Do not assume that every SFP module is supported by every switch.
Why Fibre Is Useful in Industrial Networks
Fibre optic links can provide advantages for longer distances and electrically challenging environments.
Because optical fibre does not conduct electrical current, it can also help provide electrical separation between network locations.
Fibre is frequently used between control rooms, buildings, substations, plant areas and remote infrastructure where copper Ethernet would be unsuitable or exceed normal link distance limits.
DIN Rail vs Rack Mount
Industrial Ethernet switches are available in different physical formats.
DIN rail switches are common inside control panels, kiosks and industrial enclosures.
Rack-mount switches are common in network cabinets, control rooms and larger infrastructure installations.
Mounting style should be specified together with power, port and environmental requirements.
Power Supply Requirements
Industrial switches often accept DC power supplies commonly used in control panels, while other models may use AC input or support redundant power inputs.
Check:
- Input voltage range
- Power consumption
- Redundant input support
- PoE power requirements
- Connector type
- Whether a power supply is included or must be sourced separately
A switch should not be ordered without confirming how it will be powered.
Redundant Power Inputs
Many industrial switches provide two DC power inputs so the switch can be connected to redundant power sources.
This can improve availability where the surrounding electrical design actually provides independent power paths.
Two terminals on a switch do not by themselves create a redundant power system. The upstream power architecture must also be designed appropriately.
Operating Temperature
Industrial switches may be installed in environments far outside a typical air-conditioned office.
Temperature requirements can be particularly important in outdoor cabinets, plant rooms, mining environments and unconditioned control panels.
Check the manufacturer's specified operating range and any derating or installation requirements.
Industrial Switch vs Ordinary Office Switch
An industrial switch is not defined merely by its appearance or DIN rail clip.
Depending on the product, industrial models can provide characteristics such as:
- Wider operating temperature ranges
- DC industrial power inputs
- Redundant power inputs
- DIN rail mounting
- More robust mechanical construction
- Industrial EMC performance
- Alarm relay outputs
- Fibre uplinks
- Industrial redundancy functions
- Approvals for specific environments
The required level of industrialisation depends on the application. A climate-controlled control room and an outdoor roadside cabinet do not impose the same requirements.
Does Every Industrial Network Need a Managed Switch?
No.
A small standalone machine with a PLC, HMI and one Ethernet device may not gain meaningful value from advanced management functions.
Using an unmanaged industrial switch can be entirely appropriate where the architecture is simple and there is no requirement for segmentation, redundancy or detailed network diagnostics.
Conversely, using unmanaged switches throughout a large critical network can make troubleshooting, segmentation and resilience considerably more difficult.
The switch should match the network requirement rather than being selected according to the assumption that managed is always better.
Cybersecurity Considerations
Managed switches can provide useful network control features, but purchasing a managed switch does not automatically make an industrial network secure.
Industrial cybersecurity requires an appropriate architecture that can include:
- Network segmentation
- Controlled remote access
- Secure configuration
- Access management
- Firewalls
- Patch and firmware management
- Monitoring
- Backup of device configurations
- Physical security
Unused services and ports should be managed according to the site's cybersecurity requirements and manufacturer guidance.
Common Switch Selection Mistakes
A request for an '8-port industrial switch' leaves many important questions unanswered.
Common mistakes include:
- Not specifying managed or unmanaged
- Not specifying Ethernet speed
- Forgetting fibre uplinks
- Ordering the wrong SFP type
- Not checking SFP compatibility
- Ignoring the PoE power budget
- Not specifying the input voltage
- Assuming the power supply is included
- Ignoring operating temperature
- Not identifying redundancy requirements
- Assuming every managed switch supports the required industrial protocol features
- Ordering a commercial switch for an unsuitable industrial environment
Replacing an Existing Industrial Switch
When replacing a failed or obsolete switch, provide the exact manufacturer and model number if possible.
Also record:
- Number of active copper ports
- Port speeds
- Fibre ports or installed SFP modules
- PoE devices
- Power supply arrangement
- Managed features currently in use
- VLAN configuration
- Redundancy configuration
- Mounting arrangement
- Operating environment
If the existing switch is managed, a configuration backup can be important. Replacing the hardware without recreating the required network configuration can leave the system unable to communicate correctly.
A Practical Planning Checklist
When requesting a switch quotation, provide as much of the following as possible:
- Managed or unmanaged: ___
- Copper port count: ___
- Required Ethernet speed: ___
- PoE required: yes or no
- PoE device count and power requirements: ___
- Fibre ports or SFP slots: ___
- Single-mode or multimode fibre: ___
- Fibre link distance: ___
- Required redundancy: ___
- VLAN support required: yes or no
- SNMP or monitoring requirements: ___
- Input voltage: ___
- Redundant power required: yes or no
- Mounting: DIN rail or rack mount
- Operating temperature: ___
- Installation environment: ___
- Existing switch model if replacing: ___
- Quantity: ___
If you are unsure about some of these requirements, provide the network application, connected devices and photographs or model information from the existing installation where possible.
For replacement equipment, include the existing manufacturer and model number together with details of the connected devices, fibre links, PoE requirements and any managed network features currently in use.
Technical Note
This article provides general industrial networking information. Network topology, redundancy, cybersecurity, VLAN design, multicast management, fibre selection and switch configuration must be assessed for the specific installation. Manufacturer documentation, applicable standards and site procedures take precedence, and critical network design or configuration should be undertaken or verified by appropriately competent personnel.
Related catalogue examples: Industrial Networking. For an equipment enquiry, contact Softcore Group Industrial Solutions at info@softcoregroup.co.za.