Fieldbus protocols

ICS networks involves deterministic, tight control loops. Fieldbus refers to the family of ICS networks used for real-time distributed control. These protocols are usually defined to satisfy the requirements of specific industry verticals, are proprietary, and as such have limited interoperability. Examples include the Common Industrial Protocol (CIP), Modbus (Modbus-serial, Modbus-TCP), DNP3, Profibus, Profinet, Powerlink Ethernet, OPC, EtherCAT, HTTP/FTP, GOOSE, GSSE for automated power substations (defined in the IEC 61850 standard), and so on.

Many of these protocols support both serial and Ethernet-based TCP/IP stacks, and have been in deployment since as far back as the 1960s. Many vulnerabilities exist in these protocols, and these will be examined in Chapter 5, Securing Connectivity and Communications.

To sum up this section, OT technologies have evolved over a very different runway than information technologies, with a life cycle that runs into decades. In industrial operations, maximizing equipment uptime is critical. So, many industrial deployments today adhere to age-old technologies, which were never designed with security and interoperability in mind. Understanding these technologies is important for planning and designing secured IIoT architectures.

Even though security technologies for OT deployments exist today, the Industrial Internet pushes the boundaries much further with state-of the-art software, firmware, and connectivity paradigms, thus calling for a major shift in mindsets. How does IIoT provide an evolutionary path for existing ICS systems? Let's discuss that now.