Case Study in Developing Fault Tolerant and Highly Available Systems with Secure Zones of Protection

Process Control is the part of a company that controls the critical processes that company operations are dependent upon. It is part of the critical infrastructure of the company and the clients that it serves. Various parameters, status and measured values are constantly queried via Supervisory Control and Data Acquisition, (SCADA), to control the process. Legacy mainframe systems that housed the Process Control System, (PCS), became too cumbersome and expensive to maintain prompting the move to a distributed 24X7 architecture. The distribution of process control, monitoring and alerting functions to various Unix and Windows servers via network connected devices forced us to realize that we were no longer isolated from the 'world' and that securing our networks became objective number one. This paper will discuss the processes and actions taken to provide 24X7 fault tolerant and highly available systems with physical as well as cyber security in the forefront.