Decide, for every system and system component in the inventory, whether it will be brought within the scope of the enhanced security requirements or instead placed on a network dedicated to its purpose. The convergence of information technology with operational technology and connected devices widens the attack surface considerably, and much of that equipment was never designed with security as a foundational property: its connections are commonly unencrypted, unauthenticated, unmonitored and unlogged. Some of it nonetheless stores, transmits or processes CUI, and some is needed for essential missions, so it cannot simply be removed. Where intermediary components cannot supply the missing encryption, authentication, scanning and logging, the remaining answer is to isolate the equipment from the internet and from general purpose networks.
NIST SP 800-172 3.14.3e is one control. If you already hold one of the frameworks below, a reviewed crosswalk already says how much of NIST SP 800-172 your existing evidence covers. Hold NIST SP 800-53 Rev 5 and 24 of 35 NIST SP 800-172 controls already carry evidence.
Each report names every control your existing framework evidences, every one it does not, the reasoning behind each claim, and the claims that were argued against and rejected. 5 were rejected on the NIST SP 800-53 Rev 5 pair alone.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.