Typical industrial network architecture designs

Industrial network architectures as we see them implemented today didn't just fall out of the sky. They evolved over time from standalone devices or small collections of connected proprietary devices, using proprietary communication media and proprietary protocols to communicate. Before we look how to design for security, let's first take a quick scroll through the history of automation and controls and see how things came about.

Evolution from standalone islands of automation

When, back in the late 1960s, Programmable Logic Controllers or PLCs first started replacing the racks of relays, timers, and actuators that used to run the controls and automation process, they weren't much more than that: a replacement for those racks of relays, timers, and actuators (controls). They were a very compact and sophisticated replacement for those controls, though, allowing the owner to make changes without having to rewire half...