Managed or Unmanaged – Which Ethernet Switch in Public Transport?
18 May, 2021

Ethernet switches are the backbone of digital transformation of public transport vehicles. They connect all onboard devices to form a network and ensure that data is transmitted to the right places. Depending on the specifics of the network, managed or unmanaged switches can be used. In this article, we highlight useful applications in buses and trains.

What are the Characteristics of Unmanaged Switches for Public Transport?

General features of unmanaged switches for buses and trains

On board of buses and trains, unmanaged switches fulfill basic functions of intermediaries between all devices. Based on the MAC addresses 🛈🛈 The MAC address (Media-Access-Control-Address) is the hardware address of a device in a network. of the connected nodes, the Ethernet switch forwards data packets within the network. In this way, it ensures communication between the nodes.

Unmanaged switches are neither visible nor addressable in the IP network. As plug-and-play devices, they are characterized by quick installation that requires no configuration and equally simple device replacement.

Unmanaged topologies in vehicles

Line or star topologies are suitable for coupling several unmanaged switches in a network. A ring topology leads to a loop with unmanaged devices and thus to an endless duplication of data packets. This means that communication between the nodes is not guaranteed.

PoE budget management in unmanaged vehicle networks

For unmanaged switches with Power over Ethernet function, the allocation of the PoE budget 🛈🛈 The PoE budget is the total PoE power that the switch can provide for all ports. depends on the respective PoE class of the end subscriber. Each end user has its own fixed PoE class, which determines the power requirements per switch port in an unmanaged network.

PoE classes according to IEEE 802.3at Power requirement at switch port
0 15 W
1 4 W
2 8 W
3 15 W
4 30 W

Application areas of unmanaged switches in public transport

Unmanaged switches find application in small, simple onboard networks to which they add additional ports. In such networks, intelligent management functions such as data control and diagnostics are handled by another suitable network device. Example: In a network of multiple cameras connected using unmanaged switches, the video recorder typically takes over network control.

In general, unmanaged switches are very well suited for simple stand-alone solutions in public transport vehicles. Subsystems consisting purely of video, ticketing or passenger counting devices are among the possible applications. Unmanaged networks are also used for retrofits 🛈🛈 Retrofit refers to the modernization or expansion of existing installations or systems. of subsystems, as far as another onboard instance (e.g. router or board computer) can control the network.

An example for an IP network in a public transport bus with unmanaged switches

Unmanaged switches are used in public transport vehicles to implement simple stand-alone solutions. Network management is handled by another suitable device such as the router.


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  • 8-10 Ports
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  • Fast Ethernet or Gigabit
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What are the Characteristics of Managed Switches for Public Transport?

General features of Ethernet Switches for Buses and Trains

In addition to their basic functions, managed switches have a number of intelligent features. As the name suggests, they enable management – i.e. administration, configuration, and monitoring of the network. Each switch is visible as a network member in the vehicle via its own IP address and can be addressed and configured via a web, JSON or USB interface.

Managed switches enable modern network infrastructures consisting of shared networks. Sensitive data from all subsystems such as passenger WLAN, ticketing, video surveillance, passenger information and other systems flow through the same network without any conflicts. The intelligent functionalities of managed switches ensure data separation and security.

An example for an IP network with managed switches on board of a public transport vehicle

Managed switches can also be used to implement sophisticated onboard networks, as data traffic can be selectively controlled and segmented. Such IP networks are characterized by a high level of fail-safety.


Data separation with virtual networks in vehicles

Managed switches have a VLAN function that enables them to segment communication within a shared network and prevent unauthorized access. The VLAN is used when there are different subsystems in the vehicle, such as payment and/or video surveillance systems. In shared networks, managed switches monitor and control all traffic.

Other advantages of managed switches in public transport

The use of managed switches in public transport vehicles opens up possibilities that go beyond the basic functions of Ethernet switches:

  • Individual setting of the operating parameters of the network connections (IP addresses, PoE budget)
  • Adapt configurations during operation
  • Realization of a fail-safe, highly available network using ring topologies
  • Traffic control and prioritization
  • Create virtual networks (VLANs) for segmentation purposes
  • Output diagnostic data about the health of the network
  • Enable and accelerate troubleshooting

Managed topologies in vehicles

In addition to simple line and star topologies, managed switches also enable the creation of complex ring topologies in public transport vehicles. Ring topologies ensure high resilience through network redundancy.

PoE budget management in managed vehicle networks

Managed switches with PoE allow the available power to be set individually for each port. This ensures optimal utilization of the available PoE budget.

Managed, Unmanaged or a Combination of Both Switch Types for Public Transport?

Which Ethernet switch type is right for your case depends entirely on the requirements of your onboard network. Are there simple subsystems and isolated solutions to be connected or do you need a complex network infrastructure consisting of different systems and device types? Is there an onboard network participant that has management capabilities itself and sufficient capacity to control the network? Is separation of data streams required and does the (outage) security of the network play an important role? Does your team have the necessary skills and resources to take care of the switch configuration?

Also consider other aspects such as possible changing future requirements for the onboard network or the performance of your current networks.

Managed and unmanaged Ethernet switches are part of a comprehensive communications network and should not be viewed as individual components. That’s why we at TRONTEQ see it as our obligation to assist you with decision support and best practices. As your partner, we can help you optimize the data flow in your onboard network and reduce the complexity of the installation. We are here to help you with any questions you may have about choosing the right switch.

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2GE + 8FE Managed M12 PoE Gigabit Ethernet Switch

  • 8-16 Ports
  • With/without PoE
  • Fast Ethernet or Gigabit
  • Push-pull connectors
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Related Topics

Our products are fundamental for the digitalization in public transport. ROQSTAR M12 Ethernet Switches provide the network infrastructure for e-ticketing, passenger counting systems (PCS), dynamic passenger information (DPI) and closed-circuit television (CCTV).


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