IETF | YANG Module Versioning and Semver: Importance and impact on Internet-Draft authors

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In October 2026, the Internet Architecture Board (IAB) held a two-day workshop in Prague with people who are deploying post-quantum authentication. These are the first impressions from the co-chairs, ahead of the full workshop report.
Email is the oldest widely used application on the Internet, but it continues to evolve. At IETF 127 four working groups will meet to improve the security and usability of mail, and two Birds-of-a-Feather sessions propose improvements in mail operations and the way users sign up for mail subscriptions.
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YANG enables comprehensive network automation by providing a standardized way to model the configuration and state data of network elements. The NETMOD Working Group (WG) is getting ready to publish the long-awaited updated versioning scheme for YANG modules published by IETF. These changes will impact current authors of Internet-Drafts (I-Ds) that contain a YANG module.
The NETwork MODeling (NETMOD) WG is responsible for the development and maintenance of the Yet Another Next Generation (YANG) language. The YANG language is a data modeling language used to define how the data is sent over network management protocols such as the NETCONF and RESTCONF. The current YANG [RFC7950] versioning mechanism follows a strict backward compatible model with a format that is represented as a date in the form of YYYY-MM-DD. Industry deployment of YANG modules has revealed that a strict adherence to the backward compatibility requirement is impeding the evolution of the language and the solutions it offers.
The NETMOD WG has submitted to the Internet Engineering Steering Group (IESG) a trio of documents for publication as RFCs—draft-ietf-netmod-yang-module-versioning, draft-ietf-netmod-yang-semver, and draft-ietf-netmod-yang-module-filename—that will update how YANG modules published by IETF will be versioned. The documents have to complete IETF Last Call and have to be reviewed by the IESG and, as such, are subject to change. However, because of the significant implications of the changes, it is important for I-D authors to be aware of them now.
Once approved for publication, the changes proposed by these documents will impact authors who want to publish YANG modules in the IETF, and WGs that progress these changes. Authors of I-Ds that contain YANG modules use tools to validate or extract the YANG module from the I-D. These will be updated to support this new capability. These changes will come into force when the three I-Ds are approved for publication by the IESG.
The first document, “Updated YANG Module Revision Handling” (draft-ietf-netmod-yang-module-versioning) refines the RFC 7950 module update rules. It specifies a new YANG module update procedure that can document, via a new YANG extension, when non-backwards-compatible changes have occurred during the evolution of a YANG module.
The second document, “YANG Semantic Versioning” (draft-ietf-netmod-yang-semver) specifies a YANG extension along with guidelines for applying an extended set of semantic versioning rules to revisions of YANG artifacts (e.g., modules and packages).
Finally, “YANG Module File Name Convention” (draft-ietf-netmod-yang-module-filename) defines a YANG module file name convention. The convention extends the current YANG module file name using revision‑date, with the YANG semantic version extension.
Typically either revision-date or ysv:version is expected to be used for a YANG module, i.e. only one file should exist. But when migrating from one schema to another, files with both versioning schemes may exist until the migration is complete.
This set of documents recognizes the need to sometimes allow YANG modules to evolve with Non-Backwards-Compatible (non-backwards-compatible) changes, which can cause breakage to clients and when importing YANG modules. Allowing for these non-backwards-compatible changes do som