Industrial network integrity

InTech, Oct 2006 by Verhappen, Ian, Byres, Eric

The cause is usually a device that cannot hear its neighbor devices, and depending on the protocol, either sends an interrupt request or misses its turn to transmit.

Of course, once you have identified a problem, it may become necessary to use a variety of tools to determine the source of the problem so you can solve it.

The traditional multimeter still has a role to play, but now it mostly insures sufficient power is available to the device. In the case of the fieldbus protocols, there are a number of tools available that are specific to each protocol.

For example, noise may arise from both internal sources (e.g. bad connectors) and sources external to the network (such as a motor starting). A physical-layer tool can quickly identify these by analyzing either the waveform or another physical characteristic of the network.

There are increasing numbers of these tools on the market for nearly any field network you might choose.

Be aware that in order to analyze, repair, or work on a fieldbus device, the device must be live on the network, or it will not be functioning and communicating in its typical fashion. For this reason, many facilities have a small fieldbus network in their maintenance facility.

If the protocol analyzer does not provide the degree of information required in most cases, it then becomes time to analyze the raw data, which in most cases also requires a high degree of knowledge to interpret.

The tools this person will likely use includes an oscilloscope and Time Domain Reflectometer to isolate the individual packets and area in the network causing the symptoms. The knowledge is what helps convert the data gathered into a solution.

Because the lower layer protocols are the same, troubleshooting of the industrial Ethernet networks uses many of the same tools that work in the IT space.

However, the user must be careful the tools are not invasive or introduce additional loads onto the network for if they do, that could exacerbate the problem and even cause the system to fail.

As well, some management solutions (especially those based on version one of the Simple Network Management Protocol) can become a security issue unless proper attention is paid to the design and implementation of the network and the maintenance procedures.

Borrowed heavily from IT

If a system is not secure, how do you know it is reliable?

Security is comprised of ensuring confidentiality, integrity, and availability.

How do we make sure our system is secure? It certainly is not to ignore the whole cyber security problem and hope it goes away. The IT department is not the enemy; it is a very useful ally.

The answer lies in understanding the industrial control world has already borrowed heavily from the IT world, making technologies such as Windows, TCP/IB and Ethernet our own. Now we need to borrow their security technologies and practices, but modify and use them properly in our world. It also lies in clearly understanding how our assumptions and needs differ from the IT world.