Practical Industrial Cybersecurity

Chapter 2ICS Architecture

OBJECTIVES

Upon completion of this chapter, you should be able to:

1. Explain knowledge of communication medium and external network communications:
   • Copper
   • Light
   • Wireless
2. Describe basic field device architecture including:
   • Relays
   • PLC
   • Switch
   • Process unit
3. Understand the functions of common Industrial Control System protocols:
   • Modbus
   • Modbus TCP
   • DNP3
   • Ethernet/IP
   • OPC
4. Discuss the functions of common network protocols:
   • DNS
   • DHCP
   • TCP/IP

Introduction

In the previous chapter you were introduced to the basic components of a typical industrial/utility control system. This chapter will build on those introductory topics to describe standard ICS architectures. In particular, it will bring together four major areas of knowledge associated with operational OT architectures:

• Communication media
• Field device architecture
• Industrial network protocols
• IT network protocols

The ICS Architecture objectives listed for the GICSP certification exam also list the subsections Network Segmentation and Security Zones, as well as Wireless Security. These topics will be addressed in Chapter 3, “Secure ICS Architecture.”

In the introduction to the previous chapter, it was mentioned that OT networks tend to be very different than the IT networks found in enterprise and small business environments. For example, as you already know, many of the connectivity ...