Status of This Memo

This memo documents an Internet Best Current Practice.¶

This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on BCPs is available in Section 2 of RFC 7841.¶

Information about the current status of this document, any errata, and how to provide feedback on it may be obtained athttps://www.rfc-editor.org/info/rfc9812.¶

Copyright Notice

Copyright (c) 2025 IETF Trust and the persons identified as the document authors. All rights reserved.¶

This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License.¶

Table of Contents

1.Introduction

Internet Protocol Version 6 (IPv6) and its address space aredefined by[STD86] and[RFC4291].The management of the IPv6 address space was delegated to IANAby[RFC1881], some years before the relationshipbetween the IETF and IANA was formalized[RFC2860]and registry details were clarified[RFC7020][RFC7249].¶

Occasionally, IPv6 address space allocations are performed outsidethe scope of routine allocations to Regional Internet Registries (RIRs).For example, a substantial allocation was requested by anIETF document approved by the IESG[RFC9602], which moved the range5f00::/16 from the "IPv6 Address Space" registry[IANA1]to the "IPv6 Special-Purpose Address Space" registry[IANA3].¶

At the time of writing, the allocation policy in the "IPv6 Address Space"registry[IANA1] was shown as "IESG approval", whereasa more stringent policy is appropriate for major allocations.The present document therefore strengthens the approval levelneeded for non-routine address allocations, which requires anupdate to[RFC7249].¶

This document also clarifies the status of[RFC1881].This clarification is necessary because[RFC1881], a jointpublication of the IAB and IESG following an IETF Last Call,was incorrectly listed in the RFC index at the time of writingas "Legacy", whereas it is part of the IETF Stream[RFC8729].¶

2.Approval Level of IPv6 Address Allocations

Portions of the IPv6 address space are shown in the registry as "Reserved by IETF"[IANA1]. This is the address space held in reservefor future use if ever the 125-bit unicast space (2000::/3)is found inadequate or inappropriate.¶

[RFC1881] did not specify an allocation policy for this space. At somepoint, IANA listed "IESG approval". As defined in[BCP26],this is a rather weak requirement ("Although there is norequirement that the request be documented in an RFC, the IESG hasthe discretion to request documents...") and is "a fall-backmechanism in the case where one of the other allowable approvalmechanisms cannot be employed...".¶

For something as important as the majority of the spare IPv6 addressspace, this process is clearly insufficient. The present document replacesthe "IESG approval" process by the "IETF Review" process as defined by[BCP26]. The stricter "Standards Action"policy is not considered necessary, because there may be cases where opening up a new range of address space does not in fact require a new protocol standard.¶

It may be noted that the allocation for[RFC9602], whichwas processed as a working group document, did indeed follow the morestringent "IETF Review" process proposed by this document. Indeed, theother two related registries[IANA2][IANA3] cite the "IETF Review"policy, consistent with[RFC7249].¶

This document therefore extends the first paragraph ofSection 2.3 of [RFC7249] as follows:¶

OLD:¶

The vast bulk of the IPv6 address space (approximately 7/8ths of the whole address space) is reserved by the IETF[RFC4291], with the expectation that further assignment of globally unique unicast address space will be made from this reserved space in accordance with future needs.¶

NEW:¶

The vast bulk of the IPv6 address space (approximately 7/8ths of the whole address space) is reserved by the IETF[RFC4291], with the expectation that further assignment of globally unique unicast address space will be made from this reserved space in accordance with future needs, through "IETF Review" as defined in[BCP26].¶

3.IANA Considerations

IANA has updated the registration procedure of the "IPv6 Address Space" registry[IANA1]to "IETF Review".¶

4.Security Considerations

The security considerations of[RFC7249] apply. While having no direct security impact, carefully reviewed address allocation mechanisms are necessary to ensure operational address accountability.¶

5.References

Acknowledgements

Useful comments were received fromDale Carder,Bob Hinden,Scott Kelly,Philipp Tiesel, and others.¶

Authors' Addresses