Subject: [IPv6]Protocol Action: 'Prioritizing known-local IPv6 ULAs through address selection policy' to Proposed Standard (draft-ietf-6man-rfc6724-update-25.txt)
From: The IESG <[email-masked]>
To: "IETF-Announce" <[email-masked]>
Cc: [email-masked], The IESG <[email-masked]>, [email-masked], [email-masked], [email-masked]
Date: Wed, 03 Sep 2025 09:16:18 -0700
List-Id: "IPv6 Maintenance Working Group (6man)" <ipv6.ietf.org>

The IESG has approved the following document:
- 'Prioritizing known-local IPv6 ULAs through address selection policy'
  (draft-ietf-6man-rfc6724-update-25.txt) as Proposed Standard

This document is the product of the IPv6 Maintenance Working Group.

The IESG contact persons are Erik Kline and Éric Vyncke.

A URL of this Internet-Draft is:
https://datatracker.ietf.org/doc/draft-ietf-6man-rfc6724-update/

Technical Summary

   This document draws on several years of operational experience to
   update RFC 6724, defining the concept of "known-local" ULA prefixes
   that enable ULA-to-ULA communications within fd00::/8 to become
   preferred over both IPv4-IPv4 and GUA-to-GUA for local use.  The
   document defines the means by which nodes can both identify and
   insert such prefixes into their address selection policy table.  It
   also clarifies the mandatory, unconditional requirement for support
   for Rule 5.5 and demotes the preference for 6to4 addresses.  These
   changes to default behavior improve supportability of common use
   cases, including automatic / unmanaged scenarios, and makes
   preference for IPv6 over IPv4 consistent in local site networks for
   both ULA and GUA prefixes.  It is recognized that some less common
   deployment scenarios may require explicit configuration or custom
   changes to achieve desired operational parameters.

Working Group Summary

   The document has been actively discussed in the WG mailing list and
   during 6MAN sessions, with many participants expressing their opinions,
   comments and suggestions.

Document Quality

   There are two implementations of the proposed changes to RFC6724:

   - Android implements the proposed changes to insert "known-local" ULAs
     into the policy table: https://r.android.com/3046000

   - The authors created a proof-of-concept implementation, available at
      https://github.com/jeremy-duncan/raio_ula

Those details are also reported in The "Implementation Status" section of the
document.

Personnel

   The Document Shepherd for this document is Jen Linkova. The Responsible
   Area Director is Erik Kline.