Clarification of IPv6 Address Assignment Policy

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Table of Contents

1. Introduction

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

Occasionally, IPv6 address space allocations are performed outside the scope of routine allocations to regional address registries. For example, recently a substantial allocation was requested by an IETF document approved by the IESG [RFC9602].¶

The allocation policy in the IANA IPv6 Address Space registry [IANA1] is currently shown as "IESG approval", whereas for major allocations a more stringent policy is appropriate. The present document therefore strengthens the approval level needed for non-routine address allocations, which requires an update to RFC 7249.¶

This document also clarifies the status of RFC 1881. This clarification is necessary because RFC 1881, a joint publication of the IAB and IESG following an IETF Last Call, is incorrectly listed in the RFC index at the time of writing as "legacy", whereas it remains current.¶

2. Approval Level of IPv6 Address Allocations

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

RFC 1881 did not specify an allocation policy for this space. At some point, IANA listed "IESG approval". As defined in [BCP26], this is a rather weak requirement ("Although there is no requirement that the request be documented in an RFC, the IESG has the discretion to request documents...") and is "a fall-back mechanism in the case where one of the other allowable approval mechanisms cannot be employed...".¶

For something as important as the majority of the spare IPv6 address space, the currently defined process is clearly insufficient. The present document replaces the "IESG approval" process by the "IETF Review" process as defined by BCP 26. It is not considered necessary to require the stricter "Standards Action" policy, because there might be cases where opening up a new range of address space did not in fact require a new protocol standard.¶

It may be noted that the recent allocation for [RFC9602], which was processed as a working group document, did indeed follow the more stringent "IETF Review" process proposed by this document. Indeed, the other two related registries [IANA2] [IANA3] do cite the "IETF Review" policy, consistently with RFC 7249.¶

This document therefore extends the first paragraph of section 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. RFC Editor Considerations

The RFC Editor is requested to update the "Stream" information for [RFC1881] to "IETF" in place of "Legacy".¶

4. IANA Considerations

IANA is requested to update the "Registration Procedure(s)" section of the Internet Protocol Version 6 Address Space registry to show the policy as "IETF Review".¶

5. Security Considerations

Carefully reviewed address allocation mechanisms are necessary for any form of address-based security.¶

6. Acknowledgements

Useful comments were received from Dale Carder, Bob Hinden, Philipp Tiesel, and others.¶

7. References

Appendix A. IPv6 Registry Title Inconsistencies

The authors would like to draw attention to inconsistencies in the titles for two of the IPv6 Address Registries: the "Internet Protocol Version 6 Address Space" registry [IANA1] and the "IPv6 Global Unicast Address Assignments" registry [IANA2]. These two titles are inconsistent with the titles for the "IANA IPv6 Special-Purpose Address Registry" [IANA3] and the similar IPv4 registries, the "IANA IPv4 Address Space Registry" and the "IANA IPv4 Special-Purpose Address Registry."¶

While these are mostly editorial issues, likely within IANA's control, confusion caused by these different titles could have easily contributed to not updating the Registry Procedures for the "Internet Protocol Version 6 Address Space" registry at the time of RFC 7249.¶

The "IANA IPv6 Address Space Registry" and the "IANA IPv6 Global Unicast Address Space Registry" are possibly more consistent titles for these registries.¶

Appendix B. Change Log [RFC Editor: please remove]

Authors' Addresses