Level 3, site operations, represents the highest level of the manufacturing zone of an ICS. The systems and applications that exist at this level support and manage plant wide ICS functions. The following systems and functions are typically found at level 3:
- ICS network functions, such as inter-VLAN routing and traffic inspection
- Process reporting (for example, cycle times, quality index, and predictive maintenance)
- Plant data historian
- Detailed production scheduling
- Virtual infrastructure for (remote) workstation access and remote desktop sessions
- OS/application/AV patching servers
- File servers
- Network and domain services, such as Active Directory (AD), Dynamic Host Configuration Protocol ...
