RFC 7249

Internet Numbers Registries

📅 published May 2014, from ietf

RFC 7249: Internet Numbers Registries 🎀

Okay bestie, the title block is giving: Russell Housley from Vigil Security wrote it, it's Informational (so not a Standards Track thing 🧚), it's dated May 2014, and the ISSN is 2070-1721. The header doesn't list anything it obsoletes or updates, so it doesn't do either. 💅

Abstract ✨

Okay so, RFC 7020 is the one that explains the Internet Numbers Registry System and how it gets used to hand out autonomous system (AS) numbers and globally unique unicast Internet Protocol (IP) address space. 🌸

This companion doc is the list of IANA registries that are part of that system right now. It's the cheat sheet! 📋

Status of This Memo ✨

This document is not an Internet Standards Track specification. It's published just for info, so no pressure. 🦋

This is a product of the Internet Engineering Task Force (IETF), and it represents the consensus of the IETF community. It went through public review and got approved for publication by the Internet Engineering Steering Group (IESG). Not every IESG-approved doc is a candidate for any level of Internet Standard, so check Section 2 of RFC 5741 if you want the details. 🫶

For the current status, any errata, and how to give feedback, go to http://www.rfc-editor.org/info/rfc7249. 💜

Copyright Notice ✨

This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication. Please actually read these, bestie, because they spell out your rights and restrictions for this document. 🙈

Code Components pulled out of this document must include Simplified BSD License text, as described in Section 4.e of the Trust Legal Provisions. They come without warranty, as described in the Simplified BSD License. ⚠️

1. Introduction 🌈

Following the IETF-IANA Memorandum of Understanding [RFC2860], RFC 7020 [RFC7020] explains the Internet Numbers Registry System and how it gets used to distribute autonomous system (AS) numbers and globally unique unicast Internet Protocol (IP) address space. Iconic. 👑

This companion document lists the IANA registries that are part of the Internet Numbers Registry System at this time. ✨

2. Internet Numbers Registries 🦋

Three IANA registries belong to the Internet Numbers Registry System: "Autonomous System (AS) Numbers", "IANA IPv4 Address Space Registry", and "IPv6 Global Unicast Address Assignments". BUT, and this is the lowkey twist, each one has special-purpose values, and those special-purpose values sit outside the Internet Numbers Registry System. 🙃

2.1. Autonomous System Numbers 🍓

For historical reasons, there are 16-bit AS numbers and 32-bit AS numbers. The 16-bit AS numbers are really just zero through 65535 of the 32-bit AS number space. Not me having to explain this twice 😭

The allocation and registration functions for all non-reserved AS numbers are handled by the Internet Numbers Registry System, following policies developed by the Regional Internet Registries (RIRs) under their own processes. 💅

Some special-purpose AS numbers have been reserved. Section 3 of this document sets up an IANA registry for the special-purpose AS numbers that are already reserved. Future additions to that registry can be made through "IETF Review" as defined in [RFC5226]. Once a reservation is approved, it gets recorded in the special-purpose AS numbers registry, with a reference to the IESG-approved RFC that documents the reservation. 📚

2.2. IPv4 Addresses 🌸

The allocation and registration functions for all non-reserved, globally unique unicast IPv4 addresses are handled by the Internet Numbers Registry System, following policies developed by the RIRs under their own processes. 🫶

Reservations of special-purpose IPv4 addresses live in the IANA registry [IANA-IPv4-Reg]. Future additions to this registry can be made through "IETF Review" as defined in [RFC5226]. Once a reservation is approved, it gets recorded in the special-purpose IPv4 address registry, with a reference to the IESG-approved RFC that documents the reservation. 💜

2.3. IPv6 Addresses 🧚

The vast bulk of the IPv6 address space (approximately 7/8ths of the whole thing) is reserved by the IETF [RFC4291]. The expectation is that further assignment of globally unique unicast address space will come out of that reserved space as future needs show up. Main character energy 🌟

The allocation and registration functions for all non-reserved globally unique unicast IPv6 addresses are handled by the Internet Numbers Registry System, following policies developed by the RIRs under their own processes. ✨

Reservations of special-purpose IPv6 addresses live in the IANA registry [IANA-IPv6-Reg]. Future additions to this registry can be made through "IETF Review" as defined in [RFC5226]. Once a reservation is approved, it gets recorded in the special-purpose IPv6 address registry, with a reference to the IESG-approved RFC that documents the reservation. 🎀

3. IANA Considerations 🌷

IANA has created the "Special-Purpose AS Numbers" registry. Future additions to this registry can be made through "IETF Review" as defined in [RFC5226]. At this time, the special-purpose AS numbers are:

AS Numbers             Reason for Reservation
---------------------  -------------------------------------------
0                      Reserved by [AS0-PROCESS]
23456                  AS_TRANS; reserved by [RFC6793]
64496-64511            For documentation and sample code; reserved
                         by [RFC5398]
64512-65534            For private use; reserved by [RFC6996]
65535                  Reserved by [RFC1930]
65536-65551            For documentation and sample code; reserved
                         by [RFC5398]
4200000000-4294967294  For private use; reserved by [RFC6996]
4294967295             Reserved by [LAST-AS-RES]

4. Security Considerations 🔥

This document identifies the IANA registries that are part of the Internet Numbers Registry System at the time of publication. It does not change the security posture of the Internet in any way. 🛡️

Network operators should take care that special-purpose numbers and addresses are used on the public Internet in a manner that is consistent with their reserved purpose. This is the part to not ignore, bestie 🚨

5. References 📚

5.1. Normative References 💖

[RFC2860] Carpenter, B., Baker, F., and M. Roberts, "Memorandum of Understanding Concerning the Technical Work of the Internet Assigned Numbers Authority", RFC 2860, June 2000.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 5226, May 2008.
[RFC7020] Housley, R., Curran, J., Huston, G., and D. Conrad, "The Internet Numbers Registry System", RFC 7020, August 2013.

5.2. Informative References 🧚

[AS0-PROCESS] Kumari, W., Bush, R., Schiller, H., and K. Patel, "Codification of AS 0 processing", Work in Progress, August 2012.
[IANA-IPv4-Reg] IANA, "IANA IPv4 Special-Purpose Address Registry", http://www.iana.org/assignments/iana-ipv4-special-registry.
[IANA-IPv6-Reg] IANA, "IANA IPv6 Special-Purpose Address Registry", http://www.iana.org/assignments/iana-ipv6-special-registry.
[LAST-AS-RES] Haas, J. and J. Mitchell, "Reservation of Last Autonomous System (AS) Numbers", Work in Progress, April 2014.
[RFC1930] Hawkinson, J. and T. Bates, "Guidelines for creation, selection, and registration of an Autonomous System (AS)", BCP 6, RFC 1930, March 1996.
[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing Architecture", RFC 4291, February 2006.
[RFC5398] Huston, G., "Autonomous System (AS) Number Reservation for Documentation Use", RFC 5398, December 2008.
[RFC6793] Vohra, Q. and E. Chen, "BGP Support for Four-Octet Autonomous System (AS) Number Space", RFC 6793, December 2012.
[RFC6996] Mitchell, J., "Autonomous System (AS) Reservation for Private Use", BCP 6, RFC 6996, July 2013.

Acknowledgements 💜

Huge thanks to Jari Arkko, Scott Bradner, Brian Carpenter, David Conrad, John Curran, David Farmer, Adrian Farrel, Stephen Farrell, Brian Haberman, Geoff Huston, George Michaelson, S. Moonesamy, and Thomas Narten for their insightful review and comment. They're literally the reason this is good 🫶✨

Author's Address 🎀

Russell Housley
Vigil Security, LLC
918 Spring Knoll Drive
Herndon, VA 20170
USA
EMail: housley@vigilsec.com

📦 where this page comes from

ietf: rfc7249 2014-05
💖 girlified by claude-haiku-5-5 on 2026-10-18: a language model's rewrite of the original, under its terms