| Internet-Draft | Legacy IANA IPv4 Registries | May 2026 |
| Vyncke | Expires 8 November 2026 | [Page] |
IANA maintains several registries that were created for IPv4 extensions. As the IPv4 core specification is no longer being extended, the associated IANA registries need to be updated to reflect the current practice and reflect that defining such extensions is not recommended.¶
This note is to be removed before publishing as an RFC.¶
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Several registries were created for IPv4-related protocol elements [RFC791]. These regisries were created by [RFC1700], which in turn was obsoleted by [RFC3232] which handed these registries to IANA.¶
As the IPv4 core specification (RFC 791) is no longer being extended (see also [IAB_IPV4]) and that more modern mechanisms are defined to manage names, this document closes some relevant IANA registries and changes the registration procedures of others. See more in Section 1.1.¶
The justifications for the changes to IANA registries listed in Section 4) are as follows:¶
Registrations are to be closed as Netware is not extended anymore.¶
It is commonly understood that the use of IPv4 option is broken [NOT_AN_OPTION]. As such, the registration for new IPv4 options is closed.¶
[IP_TTL]: :This registry should not have been created as the IPv4 Time to Live (TTL) (Section 3.1 of [RFC791]) header field can be freely selected by the source node.¶
There are no registration procedures for these two registries. Moreover, there were no registrations made to these registries in the last two decades. This document specifies the registration procedure as "First Come First Served" ([RFC8126], Section 4.4).¶
As some registries are closed, they cannot be extended but the existing values are still valid, i.e., they are not deprecated and can still be used. These changes do not impact existing operations that use already registered values.¶
The use of IPv4 options on the public Internet is broken. The changes in this document provides a clear signal that solutions that rely on defining such options are not reliable. More robust alternative means should be explored.¶
There is no new security considerations introduced by this document except for the registries whose registration policy is changed to "First Come First Served". Concretely, registration is still possible to such registries with the risk of having unusable non-sensible data added to it, but the IANA policy is to apply common sense filtering on the content and amount of registrations.¶
This document requests IANA to set the registration procedure to "Registration no longer accepted" with a reference to this document for the following registries:¶
The "NetWare/IP Option Type 63 Sub-Option Codes" registry under the "Dynamic Host Configuration Protocol (DHCP) and Bootstrap Protocol (BOOTP) Parameters" registry group [DHC_NETWARE].¶
The "IP Option Numbers" registry under the "Internet Protocol Version 4 (IPv4) Parameters" registry group [IP_OPTIONS].¶
This document requests IANA to set the registration procedure to "First Come First Served" ([RFC8126], Section 4.4) with a reference to this document for the following registries:¶
The "Machine Names" registry group [MACHINE_NAMES].¶
The "Terminal Type Names" registry group [TERMINAL_TYPES].¶
This document also requests IANA to completely remove the "IP Time to Live Parameter" registry under the "Internet Protocol Version 4 (IPv4) Parameters" registry group [IP_TTL]. If not possible, then IANA is requested to replace the existing note with the following note:¶
Thanks to Mohamed Boucadair for the initial idea and deep review. Thanks also to Amanda Baber for the initial list of legacy registries or registries without any specified registration procedures. Other thanks for reviewers: Tommy Jensen.¶