Network Working Group M. Cotton
Internet-Draft ICANN
BCP: 26 B. Leiba
Obsoletes: 5226 (if approved) Huawei Technologies
Intended status: Best Current Practice T. Narten
Expires: February 28, 2015 IBM Corporation
August 29, 2014
Guidelines for Writing an IANA Considerations Section in RFCs
draft-leiba-cotton-iana-5226bis-07
Abstract
Many protocols make use of points of extensibility that use constants
to identify various protocol parameters. To ensure that the values
used in these fields do not have conflicting uses, and to promote
interoperability, their allocation is often coordinated by a central
authority. For IETF protocols, that role is filled by the Internet
Assigned Numbers Authority (IANA).
To make assignments in a given namespace prudently, IANA needs
guidance describing the conditions under which new values should be
assigned, as well as when and how modifications to existing values
can be made. This document defines a framework for the documentation
of these guidelines by specification authors, in order to assure that
the guidance given to IANA is clear and addresses the various issues
that are likely in the operation of a registry.
This is the third edition, and obsoletes RFC 5226.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on February 28, 2015.
Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved.
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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 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 Simplified BSD License text
as described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Keep IANA Considerations for IANA . . . . . . . . . . . . 3
1.2. For More Information . . . . . . . . . . . . . . . . . . . 4
1.3. Terminology Used In This Document . . . . . . . . . . . . 4
2. Creating and Revising Registries . . . . . . . . . . . . . . . 4
2.1. Hierarchical Registry Structure . . . . . . . . . . . . . 5
2.2. Documentation Requirements for Registries . . . . . . . . 6
2.3. Defining an Appropriate Registry Policy . . . . . . . . . 8
2.3.1. Using the Well-Known Registration Policies . . . . . . 10
2.3.2. Using Multiple Policies in Combination . . . . . . . . 11
2.3.3. Specifying Change Control for a Registry . . . . . . . 12
2.4. Revising Existing Registries . . . . . . . . . . . . . . . 12
3. Registering New Values in an Existing Registry . . . . . . . . 13
3.1. Documentation Requirements for Registrations . . . . . . . 13
3.2. Updating Existing Registrations . . . . . . . . . . . . . 14
3.3. Overriding Registration Procedures . . . . . . . . . . . . 15
3.4. Early Allocations . . . . . . . . . . . . . . . . . . . . 15
4. Well-Known Registration Policies . . . . . . . . . . . . . . . 16
4.1. Private Use . . . . . . . . . . . . . . . . . . . . . . . 17
4.2. Experimental Use . . . . . . . . . . . . . . . . . . . . . 17
4.3. Hierarchical Allocation . . . . . . . . . . . . . . . . . 17
4.4. First Come First Served . . . . . . . . . . . . . . . . . 17
4.5. Expert Review . . . . . . . . . . . . . . . . . . . . . . 18
4.6. Specification Required . . . . . . . . . . . . . . . . . . 19
4.7. RFC Required . . . . . . . . . . . . . . . . . . . . . . . 19
4.8. IETF Review . . . . . . . . . . . . . . . . . . . . . . . 19
4.9. Standards Action . . . . . . . . . . . . . . . . . . . . . 20
4.10. IESG Approval . . . . . . . . . . . . . . . . . . . . . . 20
5. Designated Experts . . . . . . . . . . . . . . . . . . . . . . 21
5.1. The Motivation for Designated Experts . . . . . . . . . . 21
5.2. The Role of the Designated Expert . . . . . . . . . . . . 22
5.2.1. Managing Designated Experts in the IETF . . . . . . . 23
5.3. Designated Expert Reviews . . . . . . . . . . . . . . . . 23
5.4. Expert Reviews and the Document Lifecycle . . . . . . . . 25
6. Well-Known Registration Status Terminology . . . . . . . . . . 25
7. Documentation References in IANA Registries . . . . . . . . . 26
8. What to Do in "bis" Documents . . . . . . . . . . . . . . . . 26
9. Miscellaneous Issues . . . . . . . . . . . . . . . . . . . . . 27
9.1. When There Are No IANA Actions . . . . . . . . . . . . . . 27
9.2. Namespaces Lacking Documented Guidance . . . . . . . . . . 28
9.3. After-the-Fact Registrations . . . . . . . . . . . . . . . 28
9.4. Reclaiming Assigned Values . . . . . . . . . . . . . . . . 29
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9.5. Contact Person vs Assignee or Owner . . . . . . . . . . . 29
9.6. Closing or Obsoleting a Registry . . . . . . . . . . . . . 30
10. Appeals . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
11. Mailing Lists . . . . . . . . . . . . . . . . . . . . . . . . 30
12. Security Considerations . . . . . . . . . . . . . . . . . . . 30
13. Changes Relative to Earlier Editions of BCP 26 . . . . . . . . 31
13.1. 2014: Changes in This Document Relative to RFC 5226 . . . 31
13.2. 2008: Changes in RFC 5226 Relative to RFC 2434 . . . . . 32
14. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 33
14.1. Acknowledgments for This Document (2014) . . . . . . . . 33
14.2. Acknowledgments from the second edition (2008) . . . . . 33
14.3. Acknowledgments from the first edition (1998) . . . . . . 33
15. References . . . . . . . . . . . . . . . . . . . . . . . . . . 33
15.1. Normative References . . . . . . . . . . . . . . . . . . 34
15.2. Informative References . . . . . . . . . . . . . . . . . 34
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 36
1. Introduction
Many protocols make use of points of extensibility that use constants
to identify various protocol parameters. To ensure that the values
used in these fields do not have conflicting uses, and to promote
interoperability, their allocation is often coordinated by a central
authority. For IETF protocols, that role is filled by the Internet
Assigned Numbers Authority (IANA) [RFC2860]. IANA services are
currently provided by the International Corporation for Assigned
Names and Numbers (ICANN).
The Protocol field in the IP header [RFC0791] and MIME media types
[RFC4288] are two examples of such coordinations.
In this document, we call the range of possible values for such a
field a "namespace". The binding or association of a specific value
with a particular purpose within a namespace is called an assignment
(or, variously: an assigned number, assigned value, code point,
protocol constant, or protocol parameter). The act of assignment is
called a registration, and it takes place in the context of a
registry. The terms "assignment" and "registration" are used
interchangably throughout this document.
To make assignments in a given namespace prudently, IANA needs
guidance describing the conditions under which new values should be
assigned, as well as when and how modifications to existing values
can be made. This document defines a framework for the documentation
of these guidelines by specification authors, in order to assure that
the guidance given to IANA is clear and addresses the various issues
that are likely in the operation of a registry.
Typically, this information is recorded in a dedicated section of the
specification with the title "IANA Considerations".
1.1. Keep IANA Considerations for IANA
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The purpose of having a dedicated IANA Considerations section is to
provide a single place to collect clear and concise information and
instructions for IANA. Technical documentation should reside in
other parts of the document, and should be included by reference
only. Using the IANA Considerations section as primary technical
documentation both hides it from the target audience of the document
and interferes with IANA's review of the actions they need to take.
If, for example, the registration of an item in a registry includes a
short description of the item being registered, that should be placed
in the IANA Considerations directly. But if it's necessary to
include a longer technical explanation of the purpose and use of the
item, the IANA Considerations should refer to a technical section of
the document where that information resides. Similarly, if the
document is pointing out the use of an existing assignment in a
registry, but makes no modification to the registration, that should
be in a technical section of the document, reserving the IANA
Considerations section for instructions to IANA.
An ideal IANA Considerations section clearly enumerates and specifies
each requested IANA action; includes all information IANA needs, such
as the full names of all applicable registries; and includes clear
references to elsewhere in the document for other information.
1.2. For More Information
IANA maintains a web page that includes current important information
from IANA. Document authors should check that page for additional
information, beyond what is provided here.
<http://www.iana.org/important-information>.
[[***** The URI above is not yet ready. IANA is setting it up.
*****]]
1.3. Terminology Used In This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
For this document, "the specification" as used by RFC 2119 refers to
the processing of protocol documents within the IETF standards
process.
2. Creating and Revising Registries
Defining a registry involves describing the namespace(s) to be
created, listing an initial set of assignments (if appropriate), and
documenting guidelines on how future assignments are to be made.
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Before defining a registry, however, consider delegating the
namespace in some manner. This route should be pursued when
appropriate, as it lessens the burden on IANA for dealing with
assignments.
In particular, not all namespaces require a registry; in some cases,
assignments can be made independently and with no further (central)
coordination. In the Domain Name System, for example, IANA only
deals with assignments at the higher levels, while subdomains are
administered by the organization to which the space has been
delegated. When a namespace is delegated in this manner, the scope
of IANA is limited to the parts of the namespace where IANA has
authority.
2.1. Hierarchical Registry Structure
It's important to start with a word on the IANA registry structure.
All registries are anchored from the IANA "Protocol Registries" page:
<http://www.iana.org/protocols>.
That page lists registries in protocol category groups, like this:
---------------------------------------------------------------
Author Domain Signing Practices (ADSP) Parameters
ADSP Outbound Signing Practices RFC 5617
IETF Review
ADSP Specification Tags RFC 5617
IETF Review
Automatic Responses to Electronic Mail Parameters
Auto-Submitted Header Field RFC 5436
Keywords Specification Required
Auto-Submitted header field RFC 3834
optional parameters IETF Consensus
Autonomous System (AS) Numbers
16-bit Autonomous System Numbers RFC 1930, RFC 5398, RFC 6996
RIR request to the IANA
or IETF Review
32-bit Autonomous System Numbers RFC 1930, RFC 5398, RFC 6793,
RFC 6996
RIR request to the IANA
or IETF Review
---------------------------------------------------------------
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The grouping allows related registries to be placed together, making
it easier for users of the registries to find the necessary
information. In the example section above, there are two registries
related to the ADSP protocol, and they are both placed in the "ADSP
Parameters" group.
Within the "ADSP Parameters" group are two registries: "ADSP Outbound
Signing Practices" and "ADSP Specification Tags". Clicking on the
title of one of these registries on the IANA Protocol Registries page
will take the reader to the details page for that registry. Often,
multiple registries are shown on the same details page.
Unfortunately, we have been inconsistent in how we refer to these
entities. The group names, as they are referred to here, have been
variously called "protocol category groups", "groups", "top-level
registries", or just "registries". The registries under them have
been called "registries" or "sub-registries". And when new
registries are created, the documents that define them often don't
specify the grouping at all, but only name the new registry. This
results in questions from IANA and delays in processing, or, worse,
in related registries that should have been grouped together, but
that are instead scattered about and hard to find and correlate.
Regardless of the terminology used, document authors should pay
attention to the registry groupings, should request that related
registries be grouped together, and, when creating a new registry,
should check whether that registry might best be included in an
existing group. That grouping information should be clearly
communicated to IANA in the registry creation request.
2.2. Documentation Requirements for Registries
Documents that create a new namespace (or modify the definition of an
existing space) and that expect IANA to play a role in maintaining
that space (serving as a repository for registered values) MUST
provide clear instructions on details of the namespace, either in the
IANA Considerations section, or referenced from it.
In particular, such instructions MUST include:
The name of the registry (or sub-registry)
This name will appear on the IANA web page and will be referred to
in future documents that need to allocate a value from the new
space. The full name (and abbreviation, if appropriate) should be
provided. It is highly desirable that the chosen name not be
easily confused with the name of another registry.
When creating a sub-registry, the registry that it is a part of
must be identified using its full name, exactly as it appears in
the IANA registry list.
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Providing a URL to precisely identify the registry helps IANA
understand the request. Such URLs can be removed from the RFC
prior to final publication. If they are to be left in, it is
important that they be permanent links -- IANA intends to include
the permalink for each registry in the registry header. [[*****
This is not yet done, but is planned. *****]]
For example, a document could contain something like this:
This registration should be made in the Foobar Operational
Parameters registry, located at <http://www.iana.org/
assignments/foobar-registry>.
It might be tempting to use the URL that appears in your web
browser's address bar, which might look something like this for
the example above:
http://www.iana.org/assignments/foobar-registry/foobar-
registry.xml
...but that is not the permanent link to the registry.
Required information for registrations
This information may include the need to document relevant
Security Considerations, if any.
Applicable review process
The review process that will apply to all future requests for
registration. See Section 2.3.
Size, format and syntax of registry entries
What fields to record in the registry, any technical requirements
on registry entries (valid ranges for integers, length limitations
on strings, and such), and the exact format in which registry
values should be displayed. For numeric assignments, one should
specify whether values are to be recorded in decimal, in
hexadecimal, or in some other format. For strings, the encoding
format should be specified (ASCII, UTF8, etc.).
Initial assignments and reservations
Any initial assignments or registrations to be included. In
addition, any ranges that are to be reserved for "Private Use",
"Reserved", "Unassigned", etc. should be indicated.
For example, a document might specify a new registry by including:
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---------------------------------------------------------------
X. IANA Considerations
This document defines a new DHCP option, entitled "FooBar" (see
Section y), assigned a value of TBD1 from the DHCP Option space
[to be removed upon publication:
http://www.iana.org/assignments/bootp-dhcp-parameters]
[RFC2132] [RFC2939]:
Data
Tag Name Length Meaning
---- ---- ------ -------
TBD1 FooBar N FooBar server
The FooBar option also defines an 8-bit FooType field, for which
IANA is to create and maintain a new sub-registry entitled
"FooType values" under the FooBar option. Initial values for the
DHCP FooBar FooType registry are given below; future assignments
are to be made through Expert Review [BCP26].
Assignments consist of a DHCP FooBar FooType name and its
associated value.
Value DHCP FooBar FooType Name Definition
---- ------------------------ ----------
0 Reserved
1 Frobnitz See Section y.1
2 NitzFrob See Section y.2
3-254 Unassigned
255 Reserved
---------------------------------------------------------------
For examples of documents that establish registries, consult
[RFC3575], [RFC3968], and [RFC4520].
2.3. Defining an Appropriate Registry Policy
There are several issues to consider when defining the policy for the
new assignments in a registry.
If the registry's namespace is limited, assignments will need to be
made carefully to prevent exhaustion.
Even when the space is essentially unlimited, however, it is usually
desirable to have at least a minimal review prior to assignment in
order to:
o prevent the hoarding of or unnecessary wasting of values. For
example, if the space consists of text strings, it may be
desirable to prevent entities from obtaining large sets of strings
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that correspond to desirable names (existing company names, for
example).
o provide a sanity check that the request actually makes sense and
is necessary. Experience has shown that some level of minimal
review from a subject matter expert is useful to prevent
assignments in cases where the request is malformed or not
actually needed (for example, an existing assignment for an
essentially equivalent service already exists).
Perhaps most importantly, unreviewed extensions can impact
interoperability and security. See [RFC6709].
When the namespace is essentially unlimited and there are no
potential interoperability or security issues, assigned numbers can
usually be given out to anyone without any subjective review. In
such cases, IANA can make assignments directly, provided that IANA is
given detailed instructions on what types of requests it should
grant, and it is able to do so without exercising subjective
judgement.
When this is not the case, some level of review is required.
However, it's important to balance adequate review and ease of
registration. In many cases, those making registrations will not be
IETF participants; requests often come from other standards
organizations, from organizations not directly involved in standards,
from ad-hoc community work (from an open-source project, for
example), and so on. Registration must not be unnecessarily
difficult, unnecessarily costly (in terms of time and other
resources), nor unnecessarily subject to denial.
While it is sometimes necessary to restrict what gets registered
(e.g., for limited resources such as bits in a byte, or for items for
which unsupported values can be damaging to protocol operation), in
many cases having what's in use represented in the registry is more
important. Overly strict review criteria and excessive cost (in time
and effort) discourage people from even attempting to make a
registration. If a registry fails to reflect the protocol elements
actually in use, it can adversely affect deployment of protocols on
the Internet, and the registry itself is devalued.
In particular, when a registry policy that requires involvement of
Working Groups, directorates, or other bodies to be actively involved
and to support the effort, requests frequently run into concerns that
"it's not worth doing a Standards-Track RFC for something this
trivial," when, in fact, that requirement was created by the Working
Group in the first place, by placing the bar that high.
Indeed, publishing any RFC is costly, and a Standards Track RFC is
especially so, requiring a great deal of community time for review
and discussion, IETF-wide last call, involvement of the entire IESG
as well as concentrated time and review from the sponsoring AD,
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review and action by IANA, and RFC-Editor processing.
Therefore, Working Groups and other document developers should use
care in selecting appropriate registration policies when their
documents create registries. They should select the least strict
policy that suits a registry's needs, and look for specific
justification for policies that require significant community
involvement (Specification Required, in terms of the well-known
policies).
2.3.1. Using the Well-Known Registration Policies
This document defines a number of registration policies in Section 4.
Because they benefit from both community experience and wide
understanding, their use is encouraged when appropriate.
It is also acceptable to cite one of the well-known policies and
include additional guidelines for what kind of considerations should
be taken into account by the review process.
For example, RADIUS [RFC3575] specifies the use of a Designated
Expert, but includes specific additional criteria the Designated
Expert should follow.
The well-known policies from "First Come First Served" to "Standards
Action" specify a range of policies in increasing order of strictness
(using the numbering from the full list in Section 4):
4. First Come First Served
No review, minimal documentation.
5. Expert Review
Expert review, sufficient documentation for review.
6. Specification Required
Expert review, significant, stable public documentation.
7. RFC Required
Any RFC publication, IETF or a non-IETF Stream.
8. IETF Review
RFC publication, IETF Stream only, but need not be Standards
Track.
9. Standards Action
RFC publication, IETF Stream, Standards Track only.
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Examples of situations that might merit RFC Required, IETF Review, or
Standards Action include the following:
o When a resource is limited, such as bits in a byte (or in two
bytes, or four), or numbers in a limited range. In these cases,
allowing registrations that haven't been carefully reviewed and
agreed by community consensus could too quickly deplete the
allowable values.
o When thorough community review is necessary to avoid extending or
modifying the protocol in ways that could be damaging. One
example is in defining new command codes, as opposed to options
that use existing command codes: the former might require a strict
policy, where a more relaxed policy could be adequate for the
latter. Another example is in defining protocol elements that
change the semantics of existing operations.
The description in Section 4.10 of "IESG Approval" suggests that the
IESG "can (and should) reject a request if another path for
registration is available that is more appropriate and there is no
compelling reason not to use that path." The IESG should give
similar consideration to any registration policy more stringent than
Specification Required, asking for justification and ensuring that
more relaxed policies have been considered, and the strict policy is
the right one.
Accordingly, document developers need to anticipate this and document
their considerations for selecting the specified policy (ideally, in
the document itself; failing that, in the shepherd writeup).
Likewise, the document shepherd should ensure that the selected
policies have been justified before sending the document to the IESG.
When specifications are revised, registration policies should be
reviewed in light of experience since the policies were set.
Note that the well-known policies are not exclusive; there are
situations where a different policy might be more appropriate.
2.3.2. Using Multiple Policies in Combination
In some situations, it is necessary to define multiple registration
policies. For example, registrations through the normal IETF process
might use one policy, while registrations from outside the process
would have a different policy applied.
Thus, a particular registry might want to use a policy such as "RFC
Required" or "IETF Review" sometimes, with a designated expert
checking a "Specification Required" policy at other times.
The alternative to using a combination requires either that all
requests come through RFCs or that requests in RFCs go through review
by the designated expert, even though they already have IETF review
and consensus.
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This can be documented in the IANA Considerations section when the
registry is created:
IANA is asked to create the registry "Fruit Access Flags" as a
sub-registry of "Fruit Parameters". New registrations will be
permitted through either the IETF Review policy or the
Specification Required policy [BCP26].
Such combinations will commonly use one of {Standards Action, IETF
Review, RFC Required} in combination with one of {Specification
Required, Expert Review}.
2.3.3. Specifying Change Control for a Registry
Registry definitions and registrations within registries often need
to be changed after they are created. The process of making such
changes is complicated when it is unclear who is authorized to make
the changes. For registries created by RFCs in the IETF stream,
change control for the registry lies by default with the IETF, via
the IESG. The same is true for value registrations made in IETF-
stream RFCs.
Because registries can be created and registrations can be made
outside the IETF stream, it can sometimes be desired to have change
control outside the IETF and IESG, and clear specification of change
control policies is always helpful.
It is advised, therefore, that all registries that are created
clearly specify a change control policy and a change controller. It
is also advised that registries that allow registrations from outside
the IETF stream include, for each value, the designation of a change
controller for that value. If the definition or reference for a
registered value ever needs to change, or if a registered value needs
to be deprecated, it is critical that IANA know who is authorized to
make the change. See also Section 9.5.
2.4. Revising Existing Registries
Updating the registration process or making changes to the format of
an already existing (previously created) registry (whether created
explicitly or implicitly) follows a process similar to that used when
creating a new registry. That is, a document is produced that makes
reference to the existing namespace and then provides detailed
guidance for handling assignments in the registry, or detailed
instructions about the changes required.
If a change requires a new column in the registry, the instructions
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need to be clear about how to populate that column for the existing
entries. Other changes may require similar clarity. Remember to
check this, and give clear instructions to IANA.
Such documents are normally processed with the same document status
as the document that created the registry, or as Best Current
Practices (BCPs) [RFC2026].
Example documents that updated the guidelines for assignments in pre-
existing registries include: [RFC6195], [RFC3228], and [RFC3575].
3. Registering New Values in an Existing Registry
3.1. Documentation Requirements for Registrations
Often, documents request an assignment in an existing namespace (one
created by a previously published document).
Such documents should clearly identify the namespace into which each
value is to be registered. If the registration goes into a sub-
registry, the author should clearly explain that. Use the exact
namespace name as listed on the IANA web page, and cite the RFC where
the namespace is defined.
There is no need to mention what the assignment policy is when making
new assignments in existing registries, as that should be clear from
the references.
When referring to an existing registry, providing a URL to precisely
identify the registry is helpful. See Section 2.2 for details on
specifying the correct URL.
For example, a document could contain something like this:
This registration should be made in the Foobar Operational
Parameters registry, located at <http://www.iana.org/assignments/
foobar-registry>.
Normally, numeric values to be used are chosen by IANA when the
document is approved, and drafts should not specify final values.
Instead, placeholders such as "TBD1" and "TBD2" should be used
consistently throughout the document, giving each item to be
registered a different placeholder. The IANA Considerations should
ask the RFC Editor to replace the placeholder names with the IANA-
assigned values. When drafts need to specify numeric values for
testing or early implementations, they will either request early
allocation (see Section 3.4) or use values that have already been set
aside for testing or experimentation. It is important that drafts
not choose their own values, lest IANA assign one of those values to
another document in the meantime. A draft can request a specific
value in the IANA Considerations section, and IANA will accommodate
such requests when that's possible, but the proposed number might
have been assigned to some other use by the time the draft is
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approved.
Normally, text-string values to be used are specified in the
document, as collisions are less likely with text strings. IANA will
consult with the authors if there is, in fact, a collision, and a
different value has to be used. When drafts need to specify string
values for testing or early implementations, they sometimes use the
expected final value. But it is often useful to use a draft value
instead, possibly including the draft version number. This allows
the early implementations to be distinguished from those implementing
the final version. A document that intends to use "foobar" in the
final version might use "foobar-testing-draft-05" for the -05 version
of the draft, for example.
For some registries, IANA has a long-standing policy prohibiting
assignment of names or codes on a vanity or organization-name basis.
For example, codes might always be assigned sequentially unless there
is a strong reason for making an exception. Nothing in this document
is intended to change those policies or prevent their future
application.
The IANA Considerations section should summarize all of the IANA
actions, with pointers to the relevant sections elsewhere in the
document as appropriate. When multiple values are requested, it is
generally helpful to include a summary table. It is also helpful for
this table to be in the same format as it appears or will appear on
the IANA web site. For example:
Value Description Reference
-------- ------------------- ---------
TBD1 Foobar [[this RFC]]
Note: In cases where authors feel that including the full table is
too verbose or repetitive, authors should still include the table in
the draft, but may include a note asking that the table be removed
prior to publication of the final RFC.
As an example, the following text could be used to request assignment
of a DHCPv6 option number:
IANA has assigned an option code value of TBD1 to the DNS
Recursive Name Server option and an option code value of TBD2 to
the Domain Search List option from the DHCP option code space
defined in Section 24.3 of RFC 3315.
3.2. Updating Existing Registrations
Even after a number has been assigned, some types of registrations
contain additional information that may need to be updated over time.
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For example, MIME media types, character sets, and language tags
typically include more information than just the registered value
itself, and may need updates to items such as point-of-contact
information, security issues, pointers to updates, and literature
references.
In such cases, the document defining the namespace must clearly state
who is responsible for maintaining and updating a registration.
Depending on the registry, it may be appropriate to specify one or
more of:
o Letting registrants and/or nominated change controllers update
their own registrations, subject to the same constraints and
review as with new registrations.
o Allowing attachment of comments to the registration. This can be
useful in cases where others have significant objections to a
registration, but the author does not agree to change the
registration.
o Designating the IESG, a designated expert, or another entity as
having the right to change the registrant associated with a
registration and any requirements or conditions on doing so. This
is mainly to get around the problem when a registrant cannot be
reached in order to make necessary updates.
3.3. Overriding Registration Procedures
Experience has shown that the documented IANA considerations for
individual protocols do not always adequately cover the reality of
registry operation, or are not sufficiently clear. In addition,
documented IANA considerations are sometimes found to be too
stringent to allow even working group documents (for which there is
strong consensus) to perform a registration in advance of actual RFC
publication.
In order to allow assignments in such cases, the IESG is granted
authority to override registration procedures and approve assignments
on a case-by-case basis.
The intention here is not to overrule properly documented procedures,
or to obviate the need for protocols to properly document their IANA
considerations. Rather, it is to permit assignments in specific
cases where it is obvious that the assignment should just be made,
but updating the IANA process beforehand is too onerous.
When the IESG is required to take action as described in this
section, it is a strong indicator that the applicable registration
procedures should be updated, possibly in parallel with the work that
instigated it.
3.4. Early Allocations
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IANA normally takes its actions when a document is approved for
publication. There are times, though, when early allocation of a
value is important for the development of a technology: for example,
when early implementations are created while the document is still
under development.
IANA has a mechanism for handling such early allocations in some
cases. See [RFC7120] for details.
4. Well-Known Registration Policies
The following are some defined policies, most of which are in use
today. These cover a range of typical policies that have been used
to describe the procedure for assigning new values in a namespace.
It is not strictly required that documents use these terms; the
actual requirement is that the instructions to IANA be clear and
unambiguous. However, use of these terms is strongly RECOMMENDED,
because their meanings are widely understood. The terms are fully
explained in the following subsections.
1. Private Use
2. Experimental Use
3. Hierarchical Allocation
4. First Come First Served
5. Expert Review
6. Specification Required
7. RFC Required
8. IETF Review
9. Standards Action
10. IESG Approval
It should be noted that it often makes sense to partition a namespace
into multiple categories, with assignments within each category
handled differently. Many protocols now partition namespaces into
two or more parts, with one range reserved for Private or
Experimental Use while other ranges are reserved for globally unique
assignments assigned following some review process. Dividing a
namespace into ranges makes it possible to have different policies in
place for different ranges and different use cases.
Similarly, it will often be useful to specify multiple policies in
parallel, with each policy being used under different circumstances.
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For more discussion of that topic, see Section 2.3.2.
Examples of RFCs that specify multiple policies in parallel:
LDAP [RFC4520]
TLS ClientCertificateType Identifiers [RFC5246] (as detailed in
the subsections below)
Pseudowire Edge to Edge Emulation (PWE3) [RFC4446]
4.1. Private Use
For private or local use only, with the type and purpose defined by
the local site. No attempt is made to prevent multiple sites from
using the same value in different (and incompatible) ways. There is
no need for IANA to review such assignments (since IANA does not
record them) and assignments are not generally useful for broad
interoperability. It is the responsibility of the sites making use
of the Private Use range to ensure that no conflicts occur (within
the intended scope of use).
Examples:
Site-specific options in DHCP [RFC2939]
Fibre Channel Port Type Registry [RFC4044]
TLS ClientCertificateType Identifiers 224-255 [RFC5246]
4.2. Experimental Use
Experimental Use is similar to Private Use only, but with the purpose
being to facilitate experimentation. See [RFC3692] for details.
Example:
Experimental Values in IPv4, IPv6, ICMPv4, ICMPv6, UDP, and TCP
Headers [RFC4727]
4.3. Hierarchical Allocation
With Hierarchical Allocation, delegated administrators are given
control over part of the namespace, and can assign values in that
part of the namespace. IANA makes allocations in the higher levels
of the namespace according to one of the other policies.
Examples:
DNS names
Object Identifiers
IP addresses
4.4. First Come First Served
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For the First Come First Served policy, assignments are made to
anyone on a first come, first served basis. There is no substantive
review of the request, other than to ensure that it is well-formed
and doesn't duplicate an existing assignment. However, requests must
include a minimal amount of clerical information, such as a point of
contact (including an email address, and sometimes a postal address)
and a brief description of how the value will be used. Additional
information specific to the type of value requested may also need to
be provided, as defined by the namespace. For numbers, the exact
value is generally assigned by IANA; with names, specific text
strings can usually be requested.
When creating a new registry with First Come First Served as the
registration policy, in addition to the contact person field or
reference, the registry should contain a field for change controller.
Having a change controller for each entry for these types of
registrations makes authorization of future modifications more clear.
See Section 2.3.3
Examples:
SASL mechanism names [RFC4422]
LDAP Protocol Mechanisms and LDAP Syntax [RFC4520]
4.5. Expert Review
(Also called "Designated Expert" in earlier editions of this
document.) For the Expert Review policy, review and approval by a
designated expert (see Section 5) is required. The required
documentation and review criteria for use by the designated expert
should be provided when defining the registry. For example, see
Sections 6 and 7.2 in [RFC3748].
It is particularly important, when using a designated expert, to give
clear guidance to the expert, laying out criteria for performing an
evaluation and reasons for rejecting a request. When specifying a
policy that involves a designated expert, the IANA Considerations
SHOULD contain such guidance. It is also a good idea to include,
when possible, a sense of whether many registrations are expected
over time, or if the registry is expected to be updated infrequently
or in exceptional circumstances only.
When creating a new registry with Expert Review as the registration
policy, in addition to the contact person field or reference, the
registry should contain a field for change controller. Having a
change controller for each entry for these types of registrations
makes authorization of future modifications more clear. See Section
2.3.3
Examples:
EAP Method Types [RFC3748]
HTTP Digest AKA algorithm versions [RFC4169]
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URI schemes [RFC4395]
GEOPRIV Location Types [RFC4589]
4.6. Specification Required
For the Specification Required policy, review and approval by a
designated expert (see Section 5) is required, and the values and
their meanings must be documented in a permanent and readily
available public specification, in sufficient detail so that
interoperability between independent implementations is possible.
The designated expert will review the public specification and
evaluate whether it is sufficiently clear to allow interoperable
implementations. The intention behind "permanent and readily
available" is that a document can reasonably be expected to be
findable and retrievable long after IANA assignment of the requested
value. Publication of an RFC is an ideal means of achieving this
requirement, but Specification Required is intended to also cover the
case of a document published outside of the RFC path. For RFC
publication, the normal RFC review process is expected to provide the
necessary review for interoperability, though the designated expert
may be a particularly well-qualified person to perform such a review.
When specifying this policy, just use the term "Specification
Required". Some specifications have chosen to refer to it as "Expert
Review with Specification Required", and that only causes confusion.
Examples:
Diffserv-aware TE Bandwidth Constraints Model Identifiers
[RFC4124]
TLS ClientCertificateType Identifiers 64-223 [RFC5246]
ROHC Profile Identifiers [RFC5795]
4.7. RFC Required
With the RFC Required policy, the registration request, along with
associated documentation, must be published in an RFC. The RFC need
not be in the IETF stream, but may be in any RFC stream (currently an
RFC may be in the IETF, IRTF, or IAB stream, or an RFC Editor
Independent Submission [RFC5742]). Unless otherwise specified, any
type of RFC is sufficient (currently Standards Track, BCP,
Informational, Experimental, or Historic).
4.8. IETF Review
(Formerly called "IETF Consensus" in the first edition of this
document.) With the IETF Review policy, new values are assigned only
through RFCs in the IETF Stream -- those that have been shepherded
through the IESG as AD-Sponsored or IETF working group Documents
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[RFC2026] [RFC5378].
The intent is that the document and proposed assignment will be
reviewed by the IETF community (including appropriate IETF working
groups, directorates, and other experts) and by the IESG, to ensure
that the proposed assignment will not negatively affect
interoperability or otherwise extend IETF protocols in an
inappropriate or damaging manner. To ensure adequate community
review, such documents will always undergo an IETF Last Call.
Examples:
IPSECKEY Algorithm Types [RFC4025]
Accounting-Auth-Method AVP values in DIAMETER [RFC4005]
TLS Extension Types [RFC5246]
4.9. Standards Action
For the Standards Action policy, values are assigned only through
Standards Track RFCs approved by the IESG.
Examples:
BGP message types [RFC4271]
Mobile Node Identifier option types [RFC4283]
TLS ClientCertificateType Identifiers 0-63 [RFC5246]
DCCP Packet Types [RFC4340]
4.10. IESG Approval
New assignments may be approved by the IESG. Although there is no
requirement that the request be documented in an RFC, the IESG has
discretion to request documents or other supporting materials on a
case-by-case basis.
IESG Approval is not intended to be used often or as a "common case";
indeed, it has seldom been used in practice during the period RFC
2434 was in effect. Rather, it is intended to be available in
conjunction with other policies as a fall-back mechanism in the case
where one of the other allowable approval mechanisms cannot be
employed in a timely fashion or for some other compelling reason.
IESG Approval is not intended to circumvent the public review
processes implied by other policies that could have been employed for
a particular assignment. IESG Approval would be appropriate,
however, in cases where expediency is desired and there is strong
consensus (such as from a working group) for making the assignment.
The following guidelines are suggested for any evaluation under IESG
Approval:
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o The IESG can (and should) reject a request if another path for
registration is available that is more appropriate and there is no
compelling reason not to use that path.
o Before approving a request, the community should be consulted, via
a "call for comments" that provides as much information as is
reasonably possible about the request.
Examples:
IPv4 Multicast address assignments [RFC5771]
IPv4 IGMP Type and Code values [RFC3228]
Mobile IPv6 Mobility Header Type and Option values [RFC6275]
5. Designated Experts
5.1. The Motivation for Designated Experts
IANA does not define registry policy itself; rather, it carries out
policies that have been defined by others and published in RFCs. As
part of that process, review of proposed registrations is often
appropriate.
A common way to ensure such review is for a proposed registration to
be published as an RFC, as this ensures that the specification is
publicly and permanently available. It is particularly important if
any potential interoperability issues might arise. For example, some
assignments are not just assignments, but also involve an element of
protocol specification. A new option may define fields that need to
be parsed and acted on, which (if specified poorly) may not fit
cleanly with the architecture of other options or the base protocols
on which they are built.
In some cases, however, the burden of publishing an RFC in order to
register a protocol element is excessive.
However, it is generally still useful (and sometimes necessary) to
discuss proposed registrations within the community, on a mailing
list. Such a mailing list provides opportunity for public review
prior to assignment, and allows for a consultative process when
registrants want help in understanding what a proper registration
should contain.
While discussion on a mailing list can provide valuable technical
feedback, opinions may vary and discussions may continue for some
time without clear resolution. In addition, IANA cannot participate
in all of these mailing lists and cannot determine if or when such
discussions reach consensus. Therefore, IANA relies on a "designated
expert" for advice regarding the specific question of whether an
assignment should be made. The designated expert is an individual
who is responsible for carrying out an appropriate evaluation and
returning a recommendation to IANA.
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It should be noted that a key motivation for having designated
experts is for the IETF to provide IANA with a subject matter expert
to whom the evaluation process can be delegated. IANA forwards
requests for an assignment to the expert for evaluation, and the
expert (after performing the evaluation) informs IANA as to whether
or not to make the assignment or registration.
It will often be useful to use a designated expert only some of the
time, as a supplement to other processes. For more discussion of
that topic, see Section 2.3.2.
5.2. The Role of the Designated Expert
The designated expert is responsible for coordinating the appropriate
review of an assignment request. The review may be wide or narrow,
depending on the situation and the judgment of the designated expert.
This may involve consultation with a set of technology experts,
discussion on a public mailing list, consultation with a working
group (or its mailing list if the working group has disbanded), etc.
Ideally, the designated expert follows specific review criteria as
documented with the protocol that creates or uses the namespace. See
the IANA Considerations sections of [RFC3748] and [RFC3575] for
specific examples.
Designated experts are expected to be able to defend their decisions
to the IETF community, and the evaluation process is not intended to
be secretive or bestow unquestioned power on the expert. Experts are
expected to apply applicable documented review or vetting procedures,
or in the absence of documented criteria, follow generally accepted
norms such as those in Section 5.3.
In registries where a pool of experts evaluates requests, the pool
should have a single chair responsible for defining how requests are
to be assigned to and reviewed by experts. In some cases, the expert
pool may consist of a primary and backups, with the backups involved
only when the primary expert is unavailable. In other cases, IANA
might assign requests to individual members in sequential or
approximate random order. In the event that IANA finds itself having
received conflicting advice from its experts, it is the
responsibility of the pool's chair to resolve the issue and provide
IANA with clear instructions.
If a designated expert is conflicted for a particular review (is, for
example, an author or significant proponent of a specification
related to the registration under review), that expert should recuse
himself. In the event that all the designated experts are
conflicted, they should ask that a temporary expert be designated for
the conflicted review.
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It has proven useful to have multiple designated experts for some
registries. Sometimes those experts work together in evaluating a
request, while in other cases additional experts serve as backups.
In cases of disagreement among those experts, it is the
responsibility of those experts to make a single clear recommendation
to IANA. It is not appropriate for IANA to resolve disputes among
experts. In extreme situations, such as deadlock, the designating
body may need to step in to resolve the problem.
This document defines the designated expert mechanism with respect to
documents in the IETF stream only. Documents in other streams may
only use a registration policy that requires a designated expert if
those streams (or those documents) specify how designated experts are
appointed and managed. What is described below, with management by
the IESG, is only appropriate for the IETF stream.
5.2.1. Managing Designated Experts in the IETF
Designated experts for registries created by the IETF are appointed
by the IESG, normally upon recommendation by the relevant Area
Director. They may be appointed at the time a document creating or
updating a namespace is approved by the IESG, or subsequently, when
the first registration request is received. Because experts
originally appointed may later become unavailable, the IESG will
appoint replacements as necessary. The IESG may remove any
designated expert that it appointed, at its discretion.
The normal appeals process, as described in [RFC2026], Section 6.5.1,
applies to issues that arise with the designated expert team. For
this purpose, the designated expert team takes the place of the
working group in that description.
5.3. Designated Expert Reviews
In the years since RFC 2434 was published and has been put to use,
experience has led to the following observations:
o A designated expert must respond in a timely fashion, normally
within a week for simple requests to a few weeks for more complex
ones. Unreasonable delays can cause significant problems for
those needing assignments, such as when products need code points
to ship. This is not to say that all reviews can be completed
under a firm deadline, but they must be started, and the requester
and IANA should have some transparency into the process if an
answer cannot be given quickly.
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o If a designated expert does not respond to IANA's requests within
a reasonable period of time, either with a response or with a
reasonable explanation for the delay (some requests may be
particularly complex), and if this is a recurring event, IANA must
raise the issue with the IESG. Because of the problems caused by
delayed evaluations and assignments, the IESG should take
appropriate actions to ensure that the expert understands and
accepts his or her responsibilities, or appoint a new expert.
o The designated expert is not required to personally bear the
burden of evaluating and deciding all requests, but acts as a
shepherd for the request, enlisting the help of others as
appropriate. In the case that a request is denied, and rejecting
the request is likely to be controversial, the expert should have
the support of other subject matter experts. That is, the expert
must be able to defend a decision to the community as a whole.
When a designated expert is used, the documentation should give clear
guidance to the designated expert, laying out criteria for performing
an evaluation and reasons for rejecting a request. In the case where
there are no specific documented criteria, the presumption should be
that a code point should be granted unless there is a compelling
reason to the contrary. Possible reasons to deny a request include
these:
o Scarcity of code points, where the finite remaining code points
should be prudently managed, or where a request for a large number
of code points is made and a single code point is the norm.
o Documentation is not of sufficient clarity to evaluate or ensure
interoperability.
o The code point is needed for a protocol extension, but the
extension is not consistent with the documented (or generally
understood) architecture of the base protocol being extended, and
would be harmful to the protocol if widely deployed. It is not
the intent that "inconsistencies" refer to minor differences "of a
personal preference nature". Instead, they refer to significant
differences such as inconsistencies with the underlying security
model, implying a change to the semantics of an existing message
type or operation, requiring unwarranted changes in deployed
systems (compared with alternate ways of achieving a similar
result), etc.
o The extension would cause problems with existing deployed systems.
o The extension would conflict with one under active development by
the IETF, and having both would harm rather than foster
interoperability.
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When a designated expert is used, documents MUST NOT name the
designated expert in the document itself; instead, any suggested
names should be relayed to the appropriate Area Director at the time
the document is sent to the IESG for approval. This is usually done
in the document shepherd writeup.
If the request should also be reviewed on a specific public mailing
list, its address should be specified.
5.4. Expert Reviews and the Document Lifecycle
Review by the designated expert is necessarily done at a particular
point in time, and represents review of a particular version of the
document. Deciding when the review should take place is a question
of good judgment. And while re-reviews might be done when it's
acknowledged that the documentation of the registered item has
changed substantially, making sure that re-review happens requires
attention and care.
It is possible, through carelessness, accident, inattentiveness, or
even willful disregard, that changes might be made after the
designated expert's review and approval that would, if the document
were re-reviewed, cause the expert not to approve the registration.
It is up to the IESG, with the token held by the responsible Area
Director, to be alert to such situations and to recognize that such
changes need to be checked.
6. Well-Known Registration Status Terminology
The following labels describe the status of an assignment or range of
assignments:
Private Use: Private use only (not assigned), as described in
Section 4.1.
Experimental: Available for general experimental use as described
in [RFC3692]. IANA does not record specific assignments for
any particular use.
Unassigned: Not currently assigned, and available for assignment
via documented procedures. While it's generally clear that
any values that are not registered are unassigned and
available for assignment, it is sometimes useful to
explicitly specify that situation. Note that this is
distinctly different from "Reserved".
Reserved: Not assigned and not available for assignment. Reserved
values are held for special uses, such as to extend the
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namespace when it becomes exhausted. Note that this is
distinctly different from "Unassigned".
Reserved values can be released for assignment by the change
controller for the registry (this is often the IESG, for
registries created by RFCs in the IETF stream).
7. Documentation References in IANA Registries
Usually, registries and registry entries include references to
documentation (RFCs or other documents). The purpose of these
references is to provide pointers for implementors to find details
necessary for implementation, NOT to simply note what document
created the registry or entry. Therefore:
o If a document registers an item that is defined and explained
elsewhere, the registered reference should be to that document,
and not to the document that is merely performing the
registration.
o If the registered item is defined and explained in the current
document, it is important to include sufficient information to
enable implementors to understand the item and to create a proper
implementation.
o If the registered item is explained primarily in a specific
section of the reference document, it is useful to include a
section reference. For example, "[RFC9876], Section 3.2", rather
than just "[RFC9876]".
o For documentation of a new registry, the reference should provide
information about the registry itself, not just a pointer to the
creation of it. Useful information includes the purpose of the
registry, a rationale for its creation, documentation of the
process and policy for new registrations, guidelines for new
registrants or designated experts, and other such related
information. But note that, while it's important to include this
information in the document, it needn't (and shouldn't) all be in
the IANA Considerations section. See Section 1.1.
8. What to Do in "bis" Documents
On occasion, an RFC is issued that obsoletes a previous edition of
the same document. We sometimes call these "bis" documents, such as
when RFC 9876 is updated by draft-ietf-foo-rfc9876bis. When the
original document created registries and/or registered entries, there
is a question of how to handle the IANA Considerations section in the
"bis" document.
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If the registrations specify the original document as a reference,
those registrations should be updated to point to the current (not
obsolete) documentation for those items. Usually, that will mean
changing the reference to be the "bis" document. There will, though,
be times when a document updates another, and changes the definitive
reference for some items, but not for others. Be sure that the
references are always set to point to the correct, current
documentation for each item.
For example, suppose RFC 9876 registered the "BANANA" flag in the
"Fruit Access Flags" registry, and the documentation for that flag is
in Section 3.2.
The current registry might look, in part, like this:
Name Description Reference
-------- ------------------- ---------
BANANA Flag for bananas [RFC9876], Section 3.2
If draft-ietf-foo-rfc9876bis obsoletes RFC 9876 and, because of some
rearrangement, now documents the flag in Section 4.1.2, the IANA
Considerations of the bis document might contain text such as this:
IANA is asked to change the registration information for the
BANANA flag in the "Fruit Access Flags" registry to the following:
Name Description Reference
-------- ------------------- ---------
BANANA Flag for bananas [[this RFC]], Section 4.2.1
In many cases, if there are a number of registered references to the
original RFC and the document organization has not changed the
registered section numbering much, it may simply be reasonable to do
this:
Because this document obsoletes RFC 9876, IANA is asked to change
all registration information that references [RFC9876] to instead
reference [[this RFC]].
If information for registered items has been or is being moved to
other documents, then, of course, the registration information should
be changed to point to those other documents. In no case is it
reasonable to leave documentation pointers to the obsoleted document
for any registries or registered items that are still in current use.
It is extremely important to be clear in your instructions regarding
updating references, especially in cases where some references need
to be updated and others do not.
9. Miscellaneous Issues
9.1. When There Are No IANA Actions
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Before an Internet-Draft can be published as an RFC, IANA needs to
know what actions (if any) it needs to perform. Experience has shown
that it is not always immediately obvious whether a document has no
IANA actions, without reviewing the document in some detail. In
order to make it clear to IANA that it has no actions to perform (and
that the author has consciously made such a determination), such
documents should include an IANA Considerations section that states:
This document has no IANA actions.
This statement, or an equivalent, must only be inserted after the
working group or individual submitter has carefully verified it to be
true. Using such wording as a matter of "boilerplate" or without
careful consideration can lead to incomplete or incorrect IANA
actions being performed.
If a specification makes use of values from a namespace in which
assignments are not made by IANA, it may be useful to note this fact,
with wording such as this:
The values of the Foobar parameter are assigned by the Barfoo
registry on behalf of the Rabfoo Forum. Therefore, this document
has no IANA actions.
IANA prefers that these "empty" IANA Considerations sections be left
in the document for the record. This is a change from the prior
practice of requesting that such sections be removed by the RFC
Editor, and authors are asked to accommodate this change.
9.2. Namespaces Lacking Documented Guidance
For all existing RFCs that either explicitly or implicitly rely on
IANA to make assignments without specifying a precise assignment
policy, IANA (in consultation with the IESG) will continue to decide
what policy is appropriate. Changes to existing policies can always
be initiated through the normal IETF consensus process, or through
the IESG when appropriate.
All future RFCs that either explicitly or implicitly rely on IANA to
register or otherwise administer namespace assignments MUST provide
guidelines for administration of the namespace.
9.3. After-the-Fact Registrations
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Occasionally, the IETF becomes aware that an unassigned value from a
namespace is in use on the Internet or that an assigned value is
being used for a different purpose than it was registered for. The
IETF does not condone such misuse; procedures of the type described
in this document MUST be applied to such cases. In the absence of
specifications to the contrary, values may only be reassigned for a
different purpose with the consent of the original assignee (when
possible) and with due consideration of the impact of such a
reassignment. In cases of likely controversy, consultation with the
IESG is advised.
9.4. Reclaiming Assigned Values
Reclaiming previously assigned values for reuse is tricky, because
doing so can lead to interoperability problems with deployed systems
still using the assigned values. Moreover, it can be extremely
difficult to determine the extent of deployment of systems making use
of a particular value. However, in cases where the namespace is
running out of unassigned values and additional ones are needed, it
may be desirable to attempt to reclaim unused values. When
reclaiming unused values, the following (at a minimum) should be
considered:
o Attempts should be made to contact the original party to which a
value is assigned, to determine if the value was ever used, and if
so, the extent of deployment. (In some cases, products were never
shipped or have long ceased being used. In other cases, it may be
known that a value was never actually used at all.)
o Reassignments should not normally be made without the concurrence
of the original requester. Reclamation under such conditions
should only take place where there is strong evidence that a value
is not widely used, and the need to reclaim the value outweighs
the cost of a hostile reclamation. In any case, IESG Approval is
needed in this case.
o It may be appropriate to write up the proposed action and solicit
comments from relevant user communities. In some cases, it may be
appropriate to write an RFC that goes through a formal IETF
process (including IETF Last Call) as was done when DHCP reclaimed
some of its "Private Use" options [RFC3942].
9.5. Contact Person vs Assignee or Owner
Many registries include designation of a technical or administrative
contact associated with each entry. Often, this is recorded as
contact information for an individual. It is unclear, though, what
role the individual has with respect to the registration: is this
item registered on behalf of the individual, the company the
individual worked for, or perhaps another organization the individual
was acting for?
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This matters because some time later, when the individual has changed
jobs or roles, and perhaps can no longer be contacted, someone might
want to update the registration. IANA has no way to know what
company, organization, or individual should be allowed to take the
registration over. For registrations rooted in RFCs, the stream
owner (such as the IESG or the IAB) can make an overriding decision.
But in other cases, there is no recourse.
Registries can include, in addition to a "Contact" field, an
"Assignee" or "Owner" field that can be used to address this
situation, giving IANA clear guidance as to the actual owner of the
registration. This is strongly advised especially for registries
that do not require RFCs to manage their information (registries with
policies such as First Come First Served Section 4.4, Expert Review
Section 4.5, and Specification Required Section 4.6). Alternatively,
organizations can put an organizational role into the "Contact" field
in order to make their ownership clear.
9.6. Closing or Obsoleting a Registry
Sometimes there is a request to "close" a registry to further
registrations. When a registry is closed, no further registrations
will be accepted. The information in the registry will still be
valid and registrations already in the registry can still be updated.
A closed registry can also be marked as "obsolete", as an indication
that the information in the registry is no longer in current use.
Specific entries in a registry can be marked as "obsolete" (no longer
in use) or "deprecated" (use is not recommended).
Such changes to registries and registered values are subject to
normal change controls (see Section 2.3.3). Any closure,
obsolescence, or deprecation serves to annotate the registry
involved; the information in the registry remains there for
informational and historic purposes.
10. Appeals
Appeals of protocol parameter registration decisions can be made
using the normal IETF appeals process as described in [RFC2026],
Section 6.5. That is, an initial appeal should be directed to the
IESG, followed (if necessary) by an appeal to the IAB.
11. Mailing Lists
All IETF mailing lists associated with evaluating or discussing
assignment requests as described in this document are subject to
whatever rules of conduct and methods of list management are
currently defined by Best Current Practices or by IESG decision.
12. Security Considerations
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Information that creates or updates a registration needs to be
authenticated and authorized. IANA updates registries according to
instructions in published RFCs and from the IESG. It also may accept
clarifications from document authors, relevant working group chairs,
Designated Experts, and mail list participants, too.
Information concerning possible security vulnerabilities of a
protocol may change over time. Likewise, security vulnerabilities
related to how an assigned number is used may change as well. As new
vulnerabilities are discovered, information about such
vulnerabilities may need to be attached to existing registrations, so
that users are not misled as to the true security issues surrounding
the use of a registered number.
An analysis of security issues is generally required for all
protocols that make use of parameters (data types, operation codes,
keywords, etc.) used in IETF protocols or registered by IANA. Such
security considerations are usually included in the protocol document
[RFC3552]. It is the responsibility of the IANA considerations
associated with a particular registry to specify what (if any)
security considerations must be provided when assigning new values,
and the process for reviewing such claims.
13. Changes Relative to Earlier Editions of BCP 26
13.1. 2014: Changes in This Document Relative to RFC 5226
Significant additions:
o Added Section 1.1, Keep IANA Considerations for IANA
o Added Section 1.2, For More Information
o Added Section 2.1, Hierarchical Registry Structure
o Added Section 2.3, Best Practice for Selecting an Appropriate
Policy.
o Added Section 2.3.2, Using Multiple Policies in Combination.
o Added Section 2.3.3, Specifying Change Control for a Registry
o Added Section 3.4, Early Allocations
o Moved well-known policies into a separate section for each,
subsections of Section 4.
o Added Section 5.4, Expert Reviews and the Document Lifecycle
o Added Section 7, Documentation References in IANA Registries
o Added Section 8, What to Do in "bis" Documents
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o Added Section 9.5, Contact Person vs Assignee or Owner
o Added Section 9.6, Closing or Obsoleting a Registry
Clarifications and such:
o Some reorganization -- moved text around for clarity and easier
reading.
o Made clarifications about identification of IANA registries and
use of URLs for them.
o Clarified the distinction between "Unassigned" and "Reserved".
o Made some clarifications in "Expert Review" about instructions to
the designated expert.
o Made some clarifications in "Specification Required" about how to
declare this policy.
o Assorted minor clarifications and editorial changes throughout.
13.2. 2008: Changes in RFC 5226 Relative to RFC 2434
Changes include:
o Major reordering of text to expand descriptions and to better
group topics such as "updating registries" vs. "creating new
registries", in order to make it easier for authors to find the
text most applicable to their needs.
o Numerous editorial changes to improve readability.
o Changed the term "IETF Consensus" to "IETF Review" and added more
clarifications. History has shown that people see the words "IETF
Consensus" (without consulting the actual definition) and are
quick to make incorrect assumptions about what the term means in
the context of IANA Considerations.
o Added "RFC Required" to list of defined policies.
o Much more explicit directions and examples of "what to put in
RFCs".
o "Specification Required" now implies use of a Designated Expert to
evaluate specs for sufficient clarity.
o Significantly changed the wording in the Designated Experts
section. Main purpose is to make clear that Expert Reviewers are
accountable to the community, and to provide some guidance for
review criteria in the default case.
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o Changed wording to remove any special appeals path. The normal
RFC 2026 appeals path is used.
o Added a section about reclaiming unused values.
o Added a section on after-the-fact registrations.
o Added a section indicating that mailing lists used to evaluate
possible assignments (such as by a Designated Expert) are subject
to normal IETF rules.
14. Acknowledgments
14.1. Acknowledgments for This Document (2014)
Thomas Narten and Harald Tveit Alvestrand edited the two earlier
editions of this document (RFCs 2434 and 5226), and Thomas continues
his role in this third edition. Much of the text from RFC 5226
remains in this edition.
Thank you to Amanda Baber and Pearl Liang for their multiple reviews
and suggestions for making this document as thorough as possible.
This document has benefited from thorough review and comments by Tony
Hansen, John Klensin, and Mark Nottingham.
Special thanks to Mark Nottingham for reorganizing some of the text
for better organization and readability, and to Tony Hansen for
acting as document shepherd.
14.2. Acknowledgments from the second edition (2008)
The original acknowledgments section in RFC 5226 was:
This document has benefited from specific feedback from Jari Arkko,
Marcelo Bagnulo Braun, Brian Carpenter, Michelle Cotton, Spencer
Dawkins, Barbara Denny, Miguel Garcia, Paul Hoffman, Russ Housley,
John Klensin, Allison Mankin, Blake Ramsdell, Mark Townsley, Magnus
Westerlund, and Bert Wijnen.
14.3. Acknowledgments from the first edition (1998)
The original acknowledgments section in RFC 2434 was:
Jon Postel and Joyce Reynolds provided a detailed explanation on what
IANA needs in order to manage assignments efficiently, and patiently
provided comments on multiple versions of this document. Brian
Carpenter provided helpful comments on earlier versions of the
document. One paragraph in the Security Considerations section was
borrowed from [RFC4288].
15. References
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15.1. Normative References
[RFC2026] Bradner, S., "The Internet Standards Process -- Revision
3", BCP 9, RFC 2026, October 1996.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
15.2. Informative References
[RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791, September
1981.
[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.
[RFC2939] Droms, R., "Procedures and IANA Guidelines for Definition
of New DHCP Options and Message Types", BCP 43, RFC 2939,
September 2000.
[RFC3228] Fenner, B., "IANA Considerations for IPv4 Internet Group
Management Protocol (IGMP)", BCP 57, RFC 3228, February
2002.
[RFC3552] Rescorla, E. and B. Korver, "Guidelines for Writing RFC
Text on Security Considerations", BCP 72, RFC 3552, July
2003.
[RFC3575] Aboba, B., "IANA Considerations for RADIUS (Remote
Authentication Dial In User Service)", RFC 3575, July
2003.
[RFC3692] Narten, T., "Assigning Experimental and Testing Numbers
Considered Useful", BCP 82, RFC 3692, January 2004.
[RFC3748] Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J. and H.
Levkowetz, "Extensible Authentication Protocol (EAP)", RFC
3748, June 2004.
[RFC3942] Volz, B., "Reclassifying Dynamic Host Configuration
Protocol version 4 (DHCPv4) Options", RFC 3942, November
2004.
[RFC3968] Camarillo, G., "The Internet Assigned Number Authority
(IANA) Header Field Parameter Registry for the Session
Initiation Protocol (SIP)", BCP 98, RFC 3968, December
2004.
[RFC4005] Calhoun, P., Zorn, G., Spence, D. and D. Mitton, "Diameter
Network Access Server Application", RFC 4005, August 2005.
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[RFC4025] Richardson, M., "A Method for Storing IPsec Keying
Material in DNS", RFC 4025, March 2005.
[RFC4044] McCloghrie, K., "Fibre Channel Management MIB", RFC 4044,
May 2005.
[RFC4124] Le Faucheur, F., "Protocol Extensions for Support of
Diffserv-aware MPLS Traffic Engineering", RFC 4124, June
2005.
[RFC4169] Torvinen, V., Arkko, J. and M. Naslund, "Hypertext
Transfer Protocol (HTTP) Digest Authentication Using
Authentication and Key Agreement (AKA) Version-2", RFC
4169, November 2005.
[RFC4271] Rekhter, Y., Li, T. and S. Hares, "A Border Gateway
Protocol 4 (BGP-4)", RFC 4271, January 2006.
[RFC4283] Patel, A., Leung, K., Khalil, M., Akhtar, H. and K.
Chowdhury, "Mobile Node Identifier Option for Mobile IPv6
(MIPv6)", RFC 4283, November 2005.
[RFC4288] Freed, N. and J. Klensin, "Media Type Specifications and
Registration Procedures", BCP 13, RFC 4288, December 2005.
[RFC4340] Kohler, E., Handley, M. and S. Floyd, "Datagram Congestion
Control Protocol (DCCP)", RFC 4340, March 2006.
[RFC4395] Hansen, T., Hardie, T. and L. Masinter, "Guidelines and
Registration Procedures for New URI Schemes", BCP 35, RFC
4395, February 2006.
[RFC4422] Melnikov, A. and K. Zeilenga, "Simple Authentication and
Security Layer (SASL)", RFC 4422, June 2006.
[RFC4446] Martini, L., "IANA Allocations for Pseudowire Edge to Edge
Emulation (PWE3)", BCP 116, RFC 4446, April 2006.
[RFC4520] Zeilenga, K., "Internet Assigned Numbers Authority (IANA)
Considerations for the Lightweight Directory Access
Protocol (LDAP)", BCP 64, RFC 4520, June 2006.
[RFC4589] Schulzrinne, H. and H. Tschofenig, "Location Types
Registry", RFC 4589, July 2006.
[RFC4727] Fenner, B., "Experimental Values In IPv4, IPv6, ICMPv4,
ICMPv6, UDP, and TCP Headers", RFC 4727, November 2006.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246, August 2008.
[RFC5378] Bradner, S. and J. Contreras, "Rights Contributors Provide
to the IETF Trust", BCP 78, RFC 5378, November 2008.
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[RFC5742] Alvestrand, H. and R. Housley, "IESG Procedures for
Handling of Independent and IRTF Stream Submissions", BCP
92, RFC 5742, December 2009.
[RFC5771] Cotton, M., Vegoda, L. and D. Meyer, "IANA Guidelines for
IPv4 Multicast Address Assignments", BCP 51, RFC 5771,
March 2010.
[RFC5795] Sandlund, K., Pelletier, G. and L-E. Jonsson, "The RObust
Header Compression (ROHC) Framework", RFC 5795, March
2010.
[RFC6195] Eastlake, D., "Domain Name System (DNS) IANA
Considerations", BCP 42, RFC 6195, March 2011.
[RFC6275] Perkins, C., Johnson, D. and J. Arkko, "Mobility Support
in IPv6", RFC 6275, July 2011.
[RFC6709] Carpenter, B., Aboba, B. and S. Cheshire, "Design
Considerations for Protocol Extensions", RFC 6709,
September 2012.
[RFC7120] Cotton, M., "Early IANA Allocation of Standards Track Code
Points", BCP 100, RFC 7120, January 2014.
Authors' Addresses
Michelle Cotton
Internet Corporation for Assigned Names and Numbers
12025 Waterfront Drive, Suite 300
Los Angeles, CA 90094-2536
US
Phone: +1 310 823 9358
Email: michelle.cotton@icann.org
URI: http://www.icann.org/
Barry Leiba
Huawei Technologies
Phone: +1 646 827 0648
Email: barryleiba@computer.org
URI: http://internetmessagingtechnology.org/
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Thomas Narten
IBM Corporation
3039 Cornwallis Ave., PO Box 12195 - BRQA/502
Research Triangle Park, NC 27709-2195
US
Phone: +1 919 254 7798
Email: narten@us.ibm.com
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