For dedicated networks at railway companies, maximum availability of mission-critical data and reliable transmission are top priorities. Historically, this was an area for SDH networks. However, the growing number of applications such as video surveillance, LAN coupling, or connecting WiFi hotspots, increasingly requires Ethernet/IP technologies.

Due to the strong demand for more and more bandwidth, in public communications networks migration to Ethernet/IP is already at a very advanced stage. On the other hand, operators of communications networks at railway companies, or power or water utilities, are still holding back.

Where high bandwidth is important, it’s increasingly frequently lower-cost, packet-based networks that dominate. KEYMILE is a leading technology supplier of communications solutions in access and transmission systems and has long-standing, in-depth experience. In terms of dedicated networks, the company has defined three scenarios.

1. SDH networks plus Ethernet over SDH: today, established SDH technology is primarily used in dedicated networks belonging to railway companies and utilities which require maximum availability of mission-critical data.

Typical applications are connecting axle counters, signal boxes and tunnel monitoring. As the new terminal equipment often has just one Ethernet interface, network operators have to transmit Ethernet data streams using Ethernet over SDH (EoS) via the SDH networks.

2. SDH network and Ethernet networks at the same time: in addition to their SDH networks, a number of companies have set up Ethernet/IP-based networks. These networks function independently from one another. The traditional services run via SDH.

The new applications, like video surveillance, advertising displays on platforms, or LAN coupling, use Ethernet/IP. However, separate networks make management more complex.

3. Solely Ethernet networks: these are suitable for areas where data traffic is mostly packet-based. Should circuit-switched data transmission be required nevertheless, network operators can implement it using the CESoP function (Circuit Emulation Services over Packet).

The long-term objective is to create a standardised, integrated data network on an Ethernet/IP basis for all data communications. As a result, network operators can avoid parallel networks and isolated solutions.

"The conflict when developing dedicated networks is how to provide compatibility with existing systems and integrate new applications as well. In this case, the key issue is migrating from traditional circuit-switched to packet-based transmission, but retaining the availability and reliability of data transmission", comments Klaus Pollak, Head of Consulting & Projects at KEYMILE in Hanover.

"Even if the trend towards Ethernet/IP is clear, it will still take a while before all networks have switched to Ethernet/IP. Therefore, it’s even more important to use future-proof, flexible access and transmission platforms that provide native TDM and Ethernet/IP technology from one single system, allowing seamless migration."