The Ethernet Switch and its Role in Buses and Trains
22 Apr, 2021

Ethernet switches are a central link in digital IP networks in public transport vehicles. They operate on the basis of the standard Ethernet protocol and are used to connect onboard devices such as ticket validators, cameras and board computers in buses, subways and streetcars. In the following, we will discuss the special features of switches for public transport.

Network infrastructures in public transport vehicles should be secure and stable to ensure error-free communication of the onboard devices. In this context, the Ethernet switch assumes the function of a “control center” for distributing and, if necessary, combining data streams. Based on individual IP addresses, Ethernet switches can distinguish under which connection (port) which devices are connected. This ensures the correct forwarding of data or Ethernet frames to the correct recipient.

Switches for public transport vehicles differ in terms of external features such as design, number and type of Ethernet ports. Other significant qualitative differences arise in the type of power supply and configuration options.

Physical Features of Ethernet Switches for Buses and Trains


Basically, switches can be found in many areas such as data centers, industrial and home networks. Even though they are functionally the same devices, they differ significantly in their physical characteristics. For example, Ethernet switches developed specifically for public transport stand out due to their lightweight, compact and at the same time robust design. These features have proven to be particularly advantageous due to tight spaces and the increased vibrations in public transport vehicles.

Connection types

In addition, switches for use in public transport vehicles may have other types of connections. Instead of the common RJ45 connectors that have become established for networks, many public transport companies rely on Ethernet switches with M12 sockets. The latter have proven to be better suited to the special conditions of vibration, shock, extreme temperatures and temperature fluctuations in buses and trains. A stable connection ensures a secure and uninterrupted connection to other onboard devices.

Power supply to onboard devices 

Each individual subscriber within an onboard network must be supplied with power. Transport operators have two options to choose from for this:

  1. Connect each device separately to the power grid.
  2. Make use of Power over Ethernet (PoE) technology and use the switch as a power source. In this case, end devices with up to 30W of power can be supplied directly via the network cable. The data transmission runs in parallel with the power transmission without any interference. This type of power supply eliminates the need for additional cables in favor of easier installation and maintenance.

    Switches that have PoE technology are marked as such. At TRONTEQ, all devices are available both with and without PoE.

Qualitative Features of Ethernet Switches

Management capabilities

To keep better track of the onboard network, some switches have additional features beyond just connecting Ethernet devices. Such switches are referred to as “managed.” Using managed switches in the topology of a network allows the integration of intelligent functions such as management, configuration, monitoring and troubleshooting of network problems – all remotely via a web browser user interface or API access.

No management capabilities are offered by the unmanaged switches, which simply allow connected devices to communicate with each other. They add additional ports to the network, but do not offer any intelligent features. Since unmanaged switches are not configurable, they are also quicker to get up and running – all you have to do is plug them in and they perform their functions. If remote maintenance and diagnostics are covered by other network participants, unmanaged switches are used.

Transmission speed

Ethernet connections differ in their transmission speed. While Fast Ethernet switches offer up to 100 Mbit/s, Gigabit Ethernet ports are capable of transmitting up to 1000 Mbit/s. To illustrate this, let’s take the following example: You can download an HD movie at 100 Mbit/s in about 9 minutes; at 1000 Mbit/s, on the other hand, it takes less than a minute. The bandwidth required by onboard devices in public transport vehicles is an important criterion when choosing the right switch.

What Distinguishes a Network Switch from a Router?

Like other devices in buses and trains, routers are also participants in a network connected by switches. They are used to network the vehicle with the outside world by establishing an Internet connection and ensuring that all onboard devices connected to the switches can be reached via radio. Routers are indispensable when it comes to exchanging data between the vehicle and the control center or other vehicles.

At a Glance

As intermediaries within IP networks, Ethernet switches fulfill essential functions for the digitization of public transport vehicles. Switches developed specifically for transportation are generally more compact and robust in design and feature shock-proof M12 connectors. Fast Ethernet and Gigabit ports enable the creation of data-intensive network architectures. Beyond their pure connectivity functions, switches can power connected devices using PoE. In addition, the use of intelligent managed switches brings practical additional features such as remote control of the entire network.


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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