~ How to choose the right Ethernet switch for rugged embedded computers ~
Whether used for on-board entertainment on trains or video feed transmission from military drones, connectivity is becoming an important factor in non-commercial applications. As more embedded systems adopt networked architectures, Ethernet switches play an increasingly crucial role. Martin Frederiksen, managing director of networked embedded systems expert Recab UK, explains how to select Ethernet switches for demanding operating environments.
In today’s interconnected world, the number of devices connected to the internet climbs every day. According to research firm McKinsey, 127 new devices are connected to the internet every second, with billions of devices connected globally. These numbers increase when we consider local area networks (LANs) consisting of connected, critical embedded systems in sectors such as rail, military and defence, industrial and offshore.
Switches are central to the performance of networked architectures, allowing data to be relayed between connected computers and devices, and trafficked out to a larger network via protocols such as Ethernet. Protecting these switches is especially important for critical applications used in harsh environments, on-vehicle networks, both discrete and process manufacturing applications and more.
Ensuring the protection of Ethernet switches in demanding environments requires the switch to be ruggedised. However, before an Ethernet switch can be considered as part of a ruggedised solution, it is worth looking at the role of switches and network requirements. Experience developing rugged embedded systems with Ethernet capabilities shows that designing the network first, and then subsequently ruggedising it and the components, ensures the best solution.
Network technology features
There are several key requirements for network-based applications. These include the ability to establish and manage multiple networks using a single physical device, mirror ports to monitor traffic, daisy chain switches for local network expansion, secure network traffic and ruggedise the network components.
Security is a rather complex area, but a vital one for critical applications. There are two types of network security: virtual security, primarily from software systems and data encryption, and physical security, where components play a role in maintaining data integrity.
An example of network virtual security would be the intruder detection system, which detects potential security breaches, logs information about the possible breach and signals an alert on the console or through the serial port. This is complemented by a network’s encryption standards.
Physical security comes from the ports of specific switches, which is why working with an embedded specialist is invaluable in critical embedded network projects. Small form-factor pluggable (SFP) ports can convert a network’s copper medium into a fibreoptic channel. Because fibreoptic technology is dielectric, the medium is protected against electromagnetic (EM) snooping and other malicious attacks. Fibreoptic channels also boast the benefit of being able to transmit data longer distances, with less signal loss.
A common mixed media application uses copper wire networks for local communication and interfaces with fibreoptic networks for higher-speed applications, network-to-network connectivity and long-distance communication. As such, several manufacturers of small form factor Ethernet switches include a combination of ports on their products.
Whatever solution is chosen must depend on the needs of the project and where the application will be used. For example, a rail application might call for the use of a switch that is specially designed for harsh rolling stock operating environments.
Ruggedisation
In many networked applications, ruggedisation is a critical consideration. This is true for outdoor applications, on-vehicle networks, factory floor applications in both discrete and process manufacturing and more.
For these types of applications, we must consider the environmental conditions. In particular, system designers should note factors such as the operating temperature range, levels of shock and vibration during operation and the quality of the power source. For many critical applications, the size, weight, power and cost (SWaP-C) of networking devices will also be a key consideration.
Selecting off-the-shelf Ethernet switch products for demanding applications requires a clear understanding of the environmental needs and evaluation of each product’s specifications. To thrive in harsh environments, networks must be designed with these needs in mind. For extended temperature operation, that includes everything from PCB layout and part specification to stringent environmental testing to verify performance.
The exact requirements will vary from application to application, so there is no one size fits all approach to switch selection or ruggedisation. Unfortunately for most system designers, it is much more complex than specifying the number of ports or the data speeds required. This is where partnering with an embedded system design specialist is beneficial.
With connectivity playing an ever-more central role in non-commercial applications, it’s important that these considerations are made to ensure effective, lasting embedded system performance. Choosing the wrong switch or failing to fully plan for the operational and environmental requirements, is a costly mistake — but it’s one that can be avoided with planning and forethought.
