What Role Does the Network Play for the IBIS-IP / VDV 301 Standard?

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30 Nov, 2023

Digitalization in the transportation sector requires the transfer of ever-increasing amounts of data, pushing the existing serial communication to its limits. As an IP-based data transmission solution, IBIS-IP provides an efficient alternative.

The IBIS-IP standard was developed by working groups under the leadership of the Association of German Transport Companies (VDV) and brings various advantages. These include the transfer of large amounts of data, enabling new functionalities, and improving compatibility between components from different manufacturers within a system. The application areas of IBIS-IP span across various fields.

IBIS-IP Standard and the VDV 301 Documents

IBIS-IP defines general communication rules for IP-based devices for customer information in public transport. As a successor standard to the IBIS vehicle bus, IBIS-IP considers existing functionalities and replaces the master/slave architecture with a modern, service-oriented architecture. This allows for flexible network technology and promotes independence from manufacturers for peripheral devices.

IBIS-IP is divided into chapters in the VDV 301 documents:

VDV 301-1 describes the general system architecture
VDV 301-2 describes the different services
VDV 301-3 describes the network infrastructure.

All documents are publicly accessible in the VDV’s know-how section: https://knowhow.vdv.de/topics/ibis-ip/.

Significance of Ethernet Switches for IBIS-IP

The network infrastructure is essential for implementing IBIS-IP. Without a stable and robust network infrastructure, no IBIS-IP service functions in the vehicle.

Looking closer at the OSI model, it becomes clear why this is the case:

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Ethernet Layers

The Ethernet standard operates across two vital layers: Layer 1 and Layer 2. Layer 1, or the “physical layer,” handles the actual transmission of data using technologies such as optical fiber or copper wire. For instance, signal transmission can happen through twisted pairs (TP).

Layer 2, known as the “data link layer,” ensures a dependable connection. To ensure accuracy in data transmission, information is segmented into blocks called (Ethernet) frames. Additionally, Layer 2 assigns a unique MAC (Media Access Control) address to each network node. These MAC addresses serve as identifiers, allowing devices to be addressed at the Layer 2 level. They are globally unique and are typically physically attached to devices for identification purposes.

If inappropriate cables, connectors, or copper lines are used, communication among participants cannot occur. Employing Ethernet switches with conventional RJ45 connectors can cause sporadic failures due to shocks and vibrations. These downtimes can impact passenger information, video surveillance, and passenger counting systems.

Furthermore, the communication paths within the vehicle’s network need careful consideration. It’s necessary to decide which component manages the network. A practical solution involves a combination of routers and switches. Routers handle communication to and from the vehicle, while switches operate within the vehicle.

For more information on selecting the right switch and tips for a robust and stable network in the vehicle, refer to our additional articles:

Ethernet switches are a crucial part of the network infrastructure in public transport vehicles. They facilitate data communication among participants. Intelligent managed switches can control data traffic in addition to basic data communication and monitor network errors.

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