Decide what the diagram must explain
A CMMC network diagram should make the assessed environment understandable to people who did not build it. It should show the relevant assets, network relationships, system boundaries, and external services. For Level 2, 32 CFR 170.19 requires specified asset categories to be documented in the network diagram of the assessment scope. This is a scoping record, so attractive symbols are secondary to accurate relationships. Begin with the questions a reviewer will ask: where does protected information travel, what separates environments, and which systems provide the security functions the organization relies on?
Choose a readable level of detail
Use a high-level boundary view for the whole environment and supporting detail views where complexity requires them. Label offices, remote access, cloud tenants, identity services, managed endpoints, and external providers clearly. Use consistent asset identifiers so someone can move from a node to the inventory record. A diagram does not need every switch port to communicate a system boundary, but it needs enough detail to avoid hiding a meaningful connection. Include a legend that explains line types, trust boundaries, and asset categories. State what the view covers and when it was last verified.
Draw security dependencies as well as document paths
A monitoring service, identity provider, or management platform may affect in-scope security even when staff do not use it to store CUI. Show those dependencies and review their treatment under the rule. Mark administrative connections separately from ordinary user access when that improves clarity. Include the relevant provider relationship in the System Security Plan and responsibility records. A diagram that draws only file storage can leave the impression that security functions have no external dependencies. The team should be able to explain how access is granted, protected, monitored, and removed across the represented environment.
Validate connections with the people who operate them
Walk through ordinary work with engineering, operations, IT, and the relevant service providers. Ask where a file is received, whether it is downloaded, how it is printed, and what happens during remote support. Compare the answers with approved configurations and current inventories. For uncertain connections, record an open question instead of drawing an assumed protective boundary. Check remote access, backup paths, and shared administration particularly carefully because they can be invisible in a conventional office network picture. Technical validation turns a diagram from an illustration into a useful description of reality.
Use AI drafts as reviewable suggestions
CMMC Pulsar publicly describes an AI-assisted network diagram workflow based on intake answers, with assets, boundaries, and data flows ready for human review and export. Treat a generated picture as a starting point. The system cannot resolve a missing fact simply because its proposed architecture looks plausible. Validate provider names, node categories, connections, segmentation, and access assumptions before relying on the output. Use sanitized examples when evaluating an unfamiliar service, and confirm approved handling before entering architecture details. Document which knowledgeable person reviewed the finished diagram and what evidence informed the review.
Maintain a controlled version
Keep an editable master, an approved review version, and a record of meaningful changes. Link revisions to events such as a new cloud service, firewall redesign, provider replacement, or office move. Reconcile the diagram with the inventory and SSP so they describe the same boundary. Protect the diagram according to the sensitivity of its contents; publishing a detailed production architecture on a marketing website is unnecessary for SEO or customer education. A current, controlled diagram helps technical teams and authorized assessors understand the environment, while the organization remains responsible for implementing and demonstrating its safeguards.