Renaming the Extended Sequence Numbers Transform Type in the Internet Key Exchange Protocol Version 2
RFC 9827, “Renaming the Extended Sequence Numbers Transform Type in the Internet Key Exchange Protocol Version 2”, is a Proposed Standard document published in November 2025 by V. Smyslov. It updates RFC 7296. The canonical text is published by the RFC Editor.
Abstract
This document clarifies and extends the meaning of Transform Type 5 in Internet Key Exchange Protocol Version 2 (IKEv2). It updates RFC 7296 by renaming Transform Type 5 from "Extended Sequence Numbers (ESN)" to "Sequence Numbers (SN)". It also renames two currently defined values for this Transform Type: value 0 from "No Extended Sequence Numbers" to "32-bit Sequential Numbers" and value 1 from "Extended Sequence Numbers" to "Partially Transmitted 64-bit Sequential Numbers".
What “Proposed Standard” means
An entry-level standards-track specification: stable, peer-reviewed and a solid basis for implementation, though it may still evolve before becoming an Internet Standard.
The canonical text of RFC 9827 is hosted at rfc-editor.org. Available in HTML,TXT,PDF,XML.
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