Cybersecurity of Industrial Systems

2 Architecture and Communication in an Industrial Control System

2.1. Network architecture

Figure 2.1. Typical ICS architecture. For a color version of this figure, see www.iste.co.uk/flaus/cybersecurity.zip

2.1.1. Purdue model and CIM model

The typical architecture (Figure 2.1) of an industrial control system includes several types of networks. We can distinguish between

• – the field network that connects sensors and actuators to programmable logic controllers (PLCs);
• – the control network that connects the PLCs and associated equipment, such as the human–machine interface (HMI) and the supervision system;
• – the production network that links the various control networks of the site and the manufacturing execution systems (MES) or historical servers;
• – the corporate network (or IT network).

A number of models have been proposed to structure this architecture and organize it hierarchically. These models simplify reality a little and introduce a level of decomposition that is not always so clear, but they are useful and serve as a basis for the breakdown into zones.

Figure 2.2. (a) Purdue and (b) ISA85 models. For a color version of this figure, see www.iste.co.uk/flaus/cybersecurity.zip

The first of these models is Purdue’s model (Williams 1994). It introduces five levels: ...