In industrial automation, the choice between managed and unmanaged Ethernet switches significantly impacts network performance, security, and scalability. This guide delves into the distinctions between these two types of switches, drawing insights from industry discussions and practical applications.

1. Understanding Managed and Unmanaged Switches

• Unmanaged Switches: These are plug-and-play devices that automatically handle data traffic without user configuration. They are ideal for simple, isolated networks where advanced features are unnecessary.
• Managed Switches: These offer extensive configurability, allowing for network segmentation, traffic prioritization, and enhanced security. They are essential for complex networks requiring detailed control and monitoring.

2. Advantages of Managed Switches

Managed switches provide several benefits that are crucial for complex industrial networks:

• Network Segmentation: Using VLANs, managed switches can isolate different parts of the network, enhancing security and performance.
• Traffic Prioritization: Quality of Service (QoS) settings allow critical data to be prioritized, ensuring timely delivery.
• Enhanced Security: Features like access control lists and port security help protect the network from unauthorized access.
• Remote Monitoring and Management: Protocols like SNMP enable administrators to monitor network performance and troubleshoot issues remotely.

3. When to Use Unmanaged Switches

Unmanaged switches are suitable for simpler applications:

• Isolated Networks: In systems where devices communicate within a closed network, unmanaged switches suffice.
• Cost-Sensitive Projects: They are more affordable and require less technical expertise to deploy.
• Quick Deployment: Their plug-and-play nature allows for rapid setup without configuration.

However, they lack the advanced features necessary for managing complex or critical networks.

4. Practical Applications in Industrial Settings

In industrial environments, the choice between managed and unmanaged switches often depends on the specific application:

• Field-Level Devices: Unmanaged switches are commonly used to connect sensors and actuators within a machine, where the network is isolated and traffic is predictable.
• Plant-Wide Networks: Managed switches are preferred for connecting PLCs, HMIs, and SCADA systems across the plant, where network segmentation and traffic management are critical.
  

This approach balances cost and complexity, using unmanaged switches for simple, isolated networks and managed switches for broader, more complex systems.

5. Making the Right Choice

When deciding between managed and unmanaged switches, consider the following:

• Network Complexity: Use managed switches for complex networks requiring segmentation and traffic control.
• Security Requirements: Managed switches offer advanced security features necessary for protecting critical systems.
• Budget Constraints: For simple, isolated networks, unmanaged switches provide a cost-effective solution.
• Technical Expertise: Managed switches require more technical knowledge to configure and maintain.

6. Troubleshooting Industrial Ethernet Switches: Managed vs. Unmanaged

Diagnosing Unmanaged Switch Issues|
Unmanaged switches offer no configuration or diagnostics, so troubleshooting is mostly physical and observational.
Common Issues and Fixes:

• No Power
  • Ensure the switch is receiving proper voltage (check for a power LED).
  • Verify power supply or adapter functionality.

• No Link/No Communication
  • Check Ethernet cables and connectors for damage or poor seating.
  • Replace cables one at a time to isolate a bad connection.
  • Try swapping ports if one port appears dead.

• Intermittent Connectivity
  • Electromagnetic interference (EMI) may be affecting signal integrity—consider shielded cables.
  • Avoid running cables parallel to power wiring.

• Traffic Overload
  • Unmanaged switches can flood traffic across all ports; if too many devices are broadcasting, performance drops.
  • Reduce the number of devices or use a managed switch to segment traffic.

Diagnosing Managed Switch Issues
Managed switches provide advanced tools like SNMP, port mirroring, and web-based GUIs that aid in diagnostics.
Common Issues and Fixes:

• Misconfigured VLANs
  • Verify that ports are assigned to the correct VLANs.
  • Ensure trunk ports are correctly passing tagged VLAN traffic.

• Spanning Tree Loops
  • Check for network loops—STP (Spanning Tree Protocol) should block redundant paths.
  • View topology through the switch’s interface or CLI.

• Bandwidth Saturation
  • Use the switch’s monitoring tools to inspect port utilization.
  • Identify noisy devices or unnecessary traffic using port mirroring.

• Firmware Bugs
  • Confirm the switch firmware is up to date.
  • Reboot the device if it becomes unresponsive, then schedule a firmware upgrade if needed.

• Access Issues
  • Lost login credentials can be resolved by a physical reset or console port access (check manufacturer guide).
  • Ensure management IP address is reachable and no ACLs are blocking access.

General Troubleshooting Tips

• LED Indicators
  • Use front-panel LEDs as the first diagnostic step—link lights, activity flashes, and power indicators are valuable.

• Loopbacks and Port Tests
  • Use loopback plugs and cable testers to validate physical links.

• Documentation
  • Keep a diagram of the network layout, including IP addresses and VLANs, to quickly isolate issues.

• Use a Laptop Directly
  • Connect directly to the switch with a known-good laptop and Ethernet cable to eliminate upstream issues.

4. When to Upgrade

If you’re constantly running into traffic, interference, or segmentation issues with unmanaged switches, it’s time to consider managed switches. Likewise, if your managed switch’s GUI is sluggish or lacks support for newer features (like Layer 3 routing), an upgrade may be necessary.

FAQ: Managed vs. Unmanaged Ethernet Switches in Industrial Automation

Q: What’s the main difference between a managed and an unmanaged Ethernet switch in an industrial setting?
A: The core difference lies in configurability. An unmanaged switch is plug-and-play with no settings or monitoring features—ideal for simple or isolated networks. A managed switch, however, allows configuration of VLANs, traffic prioritization, and remote monitoring, making it suitable for larger, more complex industrial environments

Q: When should I choose a managed switch over an unmanaged one?
A: Use a managed switch when you need network segmentation (e.g., VLANs), remote diagnostics, higher security, or bandwidth control—especially in plant-wide or SCADA systems. Choose unmanaged only for small, fixed installations where simplicity and cost are priorities (Hirschmann, Phoenix Contact, Red Lion).

Q: Are managed switches harder to install?
A: Yes, managed switches require more setup—assigning IPs, configuring VLANs, enabling protocols like SNMP or STP. However, brands like Allen-Bradley Stratix and Siemens Scalance offer simplified integration with industrial control platforms like Studio 5000 and TIA Portal.

Q: Can I mix managed and unmanaged switches on the same network?
A: Yes, and it’s common practice. For example, unmanaged switches might be used on the machine level to connect sensors, while managed switches handle backbone communications and traffic control at the supervisory level

Q: Will using unmanaged switches compromise network security?
A: In larger networks—yes. Unmanaged switches can’t prevent broadcast storms or unauthorized access. Managed switches provide features like port security and access control lists (ACLs) that are essential in industrial environments with remote access or multiple users