Internet DRAFT - draft-narten-iana-considerations-rfc2434bis
draft-narten-iana-considerations-rfc2434bis
INTERNET-DRAFT Thomas Narten
IBM
<draft-narten-iana-considerations-rfc2434bis-09.txt> Harald Alvestrand
Obsoletes (if approved): 2434 Google
Expires: September 21, 2007 March 26, 2008
Intended Status: BCP
Guidelines for Writing an IANA Considerations Section in RFCs
<draft-narten-iana-considerations-rfc2434bis-09.txt>
Status of this Memo
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Abstract
Many protocols make use of identifiers consisting of constants and
other well-known values. Even after a protocol has been defined and
deployment has begun, new values may need to be assigned (e.g., for a
new option type in DHCP, or a new encryption or authentication
transform for IPsec). To ensure that such quantities have consistent
values and interpretations across all implementations, their
assignment must be administered by a central authority. For IETF
protocols, that role is provided by the Internet Assigned Numbers
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Authority (IANA).
In order for IANA to manage a given name space prudently, it needs
guidelines describing the conditions under which new values can be
assigned, or when modifications to existing values can be made. If
IANA is expected to play a role in the management of a name space,
the IANA must be given clear and concise instructions describing that
role. This document discusses issues that should be considered in
formulating a policy for assigning values to a name space and
provides guidelines to document authors on the specific text that
must be included in documents that place demands on IANA.
This document obsoletes RFC 2434.
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Contents
Status of this Memo.......................................... 1
1. Introduction............................................. 4
2. Why Management of a Name Space May be Necessary.......... 5
3. Designated Experts....................................... 5
3.1. The Motivation For Designated Experts............... 5
3.2. The Role of the Designated Expert................... 7
3.3. Designated Expert Reviews........................... 8
4. Creating A Registry...................................... 9
4.1. Well-Known IANA Policy Definitions.................. 10
4.2. What To Put In Documents That Create A Registry..... 13
4.3. Updating IANA Guidelines For Existing Registries.... 16
5. Registering New Values In An Existing Registry........... 16
5.1. What to Put In Documents When Registering Values.... 16
5.2. Updating Registrations.............................. 18
5.3. Overriding Registration Procedures.................. 18
6. Miscellaneous Issues..................................... 19
6.1. When There Are No IANA Actions...................... 19
6.2. Namespaces Lacking Documented Guidance.............. 20
6.3. After-The-Fact Registrations........................ 20
6.4. Reclaiming Assigned Values.......................... 20
7. Appeals.................................................. 21
8. Mailing Lists............................................ 21
9. Security Considerations.................................. 21
10. Changes Relative to RFC 2434............................ 22
11. IANA Considerations..................................... 23
12. Acknowledgments......................................... 23
13. Normative References.................................... 23
14. Informative References.................................. 23
15. Authors' Addresses...................................... 26
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1. Introduction
Many protocols make use of fields that contain constants and other
well-known values (e.g., the Protocol field in the IP header [IP] or
MIME media types [MIME-REG]). Even after a protocol has been defined
and deployment has begun, new values may need to be assigned (e.g., a
new option type in DHCP [DHCP-OPTIONS] or a new encryption or
authentication transform for IPsec [IPSEC]). To ensure that such
fields have consistent values and interpretations in different
implementations, their assignment must be administered by a central
authority. For IETF protocols, that role is provided by the Internet
Assigned Numbers Authority (IANA) [IANA-MOU].
In this document, we call the set of possible values for such a field
a "name space"; its actual value may be a text string, a number or
another kind of value. The binding or association of a specific value
with a particular purpose within a name space is called an assigned
number (or assigned value, or sometimes a "code point", "protocol
constant", or "protocol parameter"). Each assignment of a value in a
name space is called a registration.
In order for IANA to manage a given name space prudently, it needs
guidelines describing the conditions under which new values should be
assigned, or when (and how) modifications to existing values can be
made. This document provides guidelines to authors on what sort of
text should be added to their documents in order to provide IANA
clear guidelines and reviews issues that should be considered in
formulating an appropriate policy for assigning numbers to name
spaces.
Not all name spaces require centralized administration. In some
cases, it is possible to delegate a name space in such a way that
further assignments can be made independently and with no further
(central) coordination. In the Domain Name System, for example, the
IANA only deals with assignments at the higher-levels, while
subdomains are administered by the organization to which the space
has been delegated. As another example, Object Identifiers (OIDs) as
defined by the ITU are also delegated [ASSIGNED]; IANA manages the
subtree rooted at "iso.org.dod.internet" (1.3.6.1) . When a name
space is delegated, the scope of IANA is limited to the parts of the
namespace where IANA has authority.
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 [KEYWORDS].
For this document, "the specification" as used by RFC 2119 refers to
the processing of protocol documents within the IETF standards
process.
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2. Why Management of a Name Space May be Necessary
One issue to consider in managing a name space is its size. If the
space is small and limited in size, assignments must be made
carefully to prevent exhaustion of the space. If the space is
essentially unlimited, on the other hand, potential exhaustion will
probably not be a practical concern at all. 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:
- 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
that correspond to desirable names (e.g., existing company names).
- 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 (i.e., an existing assignment for an essentially
equivalent service already exists).
A second consideration is whether it makes sense to delegate the name
space in some manner. This route should be pursued when appropriate,
as it lessens the burden on IANA for dealing with assignments.
A third, and perhaps most important consideration, concerns potential
impact on interoperability of unreviewed extensions. Proposed
protocol extensions generally benefit from community review; indeed,
review is often essential to avoid future interoperability problems
[PROTOCOL-EXT].
When the name space is essentially unlimited and there are no
potential interoperability issues, assigned numbers can safely be
given out to anyone without any subjective review. In such cases,
IANA can make assignments directly, provided that IANA is given
specific instructions on what types of requests it should grant, and
what information must be provided as part of a well-formed request
for an assigned number.
3. Designated Experts
3.1. The Motivation For Designated Experts
It should be noted that IANA does not create or define assignment
policy itself; rather, it carries out policies that have been defined
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by others and published in RFCs. IANA must be given a set of
guidelines that allow it to make allocation decisions with minimal
subjectivity and without requiring any technical expertise with
respect to the protocols that make use of a registry.
In many cases, some review of prospective allocations is appropriate,
and the question becomes who should perform the review and what is
the purpose of the review. One might think that an IETF Working
Group (WG) familiar with the name space at hand should be consulted.
In practice, however, WGs eventually disband, so they cannot be
considered a permanent evaluator. It is also possible for name spaces
to be created through individual submission documents, for which no
WG is ever formed.
One way to ensure community review of prospective assignments is to
have the requester submit a document for publication as an RFC. Such
an action helps ensure that the specification is publicly and
permanently available, and allows some review of the specification
prior to publication and assignment of the requested code points.
This is the preferred way of ensuring review, and is particularly
important if any potential interoperability issues can 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
get an assignment is excessive. However, it is generally still useful
(and sometimes necessary) to discuss proposed additions on a mailing
list dedicated to the purpose (e.g., the ietf-types@iana.org for
media types) or on a more general mailing list (e.g., that of a
current or former IETF WG). Such a mailing list provides a way for
new registrations to be publicly reviewed prior to getting assigned,
or to give advice to persons wanting 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.
It should be noted that a key motivation for having designated
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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 whether or not
to make the assignment or registration.
3.2. The Role of the Designated Expert
The designated expert is responsible for initiating and coordinating
the appropriate review of an assignment request. The review may be
wide or narrow, depending to 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, or
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,RFC3575] for examples that have been done for specific name
spaces).
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, e.g., those in section 3.3.
Section 5.2 discusses disputes and appeals in more detail.
Designated experts are appointed by the IESG (normally upon
recommendation by the relevant Area Director). They are typically
named at the time a document creating or updating a name space is
approved by the IESG, but as experts originally appointed may later
become unavailable, the IESG will appoint replacements if necessary.
For some registries, it has proven useful to have multiple designated
experts. 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 (e.g., deadlock) the IESG may need to step in to
resolve the problem.
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
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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 a individual members in sequential or
approximate random order. In the event that IANA finds itself havnig
received conflicting advice from its experts, it is the
responsibility of the pool's chair to resolve the issue and provide
IANA with clear
Since the designated experts are appointed by the IESG, they may be
removed by the IESG.
3.3. Designated Expert Reviews
In the eight years since RFC 2434 was published and has been put to
use, experience has led to the following observations:
- 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.
- 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 a delay (e.g., 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 their responsibilities, or appoint a new expert.
- 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.
In the case where a designated expert is used, but there are no
specific documented criteria for performing an evaluation, 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:
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- scarcity of codepoints, where the finite remaining codepoints
should be prudently managed, or when a request for a large number
of codepoints is made, when a single codepoint is the norm.
- documentation is not of sufficient clarity to evaluate or ensure
interoperability.
- 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.
- the extension would cause problems with existing deployed systems.
- the extension would conflict with one under active development by
the IETF, and having both would harm rather than foster
interoperability.
4. Creating A Registry
Creating a registry involves describing the name spaces to be
created, an initial set of assignments (if appropriate) and
guidelines on how future assignments are to be made.
Once a registry has been created, IANA records assignments that have
been made. The following labels describe the status of an individual
(or range) of assignments:
Private Use: Private use only (not assigned), as described in
Section 4.1
Experimental: Available for experimental use as described in
[EXPERIMENTATION]. IANA does not record specific assignments for
any particular use.
Unassigned: Unused and available for assignment via documented
procedures.
Reserved: Not to be assigned. Reserved values are held for special
uses, such as to extend the name space when it become exhausted.
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Reserved values are not available for general assignment.
4.1. Well-Known IANA Policy Definitions
The following are some defined policies, some of which are in use
today. These cover a range of typical policies that have been used to
date to describe the procedure for assigning new values in a name
space. It is not required that documents use these terms; the actual
requirement is that the instructions to IANA are clear and
unambiguous. However, use of these terms is RECOMMENDED where
possible, since their meaning is widely understood.
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 [DHCP-IANA], Fibre
Channel Port Type Registry [RFC4044], Exchange Types in the
IKEv2 header [RFC4306].
Experimental Use - Similar to private or local use only, with the
purpose being to facilitate experimentation. See
[EXPERIMENTATION] for details.
Example: Experimental Values in IPv4, IPv6, ICMPv4, ICMPv6,
UDP, and TCP Headers [RFC4727].
Hierarchical allocation - Delegated managers can assign values
provided they have been given control over that part of the
name space. IANA controls the higher levels of the
namespace according to one of the other policies.
Examples: DNS names, Object Identifiers, IP addresses.
First Come First Served - 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 a point of contact (including an
email address) and a brief description of how the value
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will be used. Additional information specific to the type
of value requested may also need to be provided, as defined
by the name space. For numbers, the exact value is
generally assigned by IANA; with names, specific text
strings can usually be requested.
Examples: SASL mechanism names [RFC4422], LDAP Protocol
Mechanisms and LDAP Syntax [RFC4520].
Expert Review (or Designated Expert) - approval by a Designated
Expert 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].
Examples: EAP Method Types [RFC3748], HTTP Digest AKA
algorithm versions [RFC4169], URI schemes [RFC4395],
GEOPRIV Location Types [RFC4589].
Specification Required - Values and their meaning must be
documented in a permanent and readily available public
specification, in sufficient detail so that
interoperability between independent implementations is
possible. When used, Specification Required also implies
usage of a Designated Expert, who 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.
Examples: Diffserv-aware TE Bandwidth Constraints Model
Identifiers [RFC4124], TLS ClientCertificateType
identifiers [RFC4346], ROHC Profile Identifiers [RFC4995].
RFC Required - RFC publication (either as IETF Submission or as an
RFC Editor submission [RFC3932]) suffices. Unless otherwise
specified, any type of RFC is sufficient (e.g.,
Informational, Experimental, Standards Track, etc.)
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IETF Review - (Formerly called "IETF Consensus" in [IANA-
CONSIDERATIONS]) New values are assigned only through RFCs
that have been shepherded through the IESG as AD-Sponsored
or IETF WGs Documents [RFC3932,RFC3978]. The intention is
that the document and proposed assignment will be reviewed
by the IESG and appropriate IETF WGs (or experts, if
suitable working groups no longer exist) to ensure that the
proposed assignment will not negatively impact
interoperability or otherwise extend IETF protocols in an
inappropriate or damaging manner.
To ensure adequate community review, such documents are
shepherded through the IESG as AD-sponsored (or WG)
documents with an IETF Last Call.
Examples: IPSECKEY Algorithm Types [RFC4025], Accounting-
Auth-Method AVP values in DIAMETER [RFC4005], TLS Handshake
Hello Extensions [RFC4366].
Standards Action - Values are assigned only for Standards Track
RFCs approved by the IESG.
Examples: BGP message types [RFC4271], Mobile Node
Identifier option types [RFC4283], DCCP Packet Types
[RFC4340].
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 for making the
assignment (e.g., WG consensus).
The following guidelines are suggested for any evaluation
under IESG Approval:
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- 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 to use
that path.
- 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 [RFC3171], IPv4 IGMP
Type and Code values [RFC3228], Mobile IPv6 Mobility Header Type and
Option values [RFC3775].
It should be noted that it often makes sense to partition a name
space into multiple categories, with assignments within each category
handled differently. For example, many protocols now partition name
spaces into two (or even more) parts, where one range is reserved for
Private or Experimental Use, while other ranges are reserved for
globally unique assignments assigned following some review process.
Dividing a name space into ranges makes it possible to have different
policies in place for different ranges.
Examples: LDAP [RFC4520], Pseudowire Edge to Edge Emulation (PWE3)
[RFC4446].
4.2. What To Put In Documents That Create A Registry
The previous sections presented some issues that should be considered
in formulating a policy for assigning values in name spaces. It is
the Working Group and/or document author's job to formulate an
appropriate policy and specify it in the appropriate document. In
almost all cases, having an explicit "IANA Considerations" section is
appropriate. The following and later sections define what is needed
for the different types of IANA actions.
Documents that create a new name space (or modify the definition of
an existing space) and that expect IANA to play a role in maintaining
that space (e.g., serving as a repository for registered values) MUST
provide clear instructions on details of the name space. In
particular, instructions MUST include:
1) The name of the registry (or sub-registry) being created and/or
maintained. The 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
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chosen name not be easily confusable with the name of another
registry. When creating a sub-registry, the registry that it is
a part of should be clearly identified. When referring to an
already existing registry, providing a URL to precisely identify
the registry is helpful. All such URLs, however, will be removed
from the RFC prior to final publication. For example, documents
could contain: [TO BE REMOVED: This registration should take
place at the following location:
http://www.iana.org/assignments/foobar-registry]
2) What information must be provided as part of a request in order
to assign a new value. This information may include the need to
document relevant security considerations, if any.
3) The review process that will apply to all future requests for a
value from the namespace.
Note: When a Designated Expert is used, documents MUST NOT name
the Designated Expert in the document itself; instead, the name
should be relayed to the appropriate Area Director at the time
the document is sent to the IESG for approval.
If the request should also be reviewed on a specific public
mailing list (such as the ietf-types@iana.org for media types),
that mailing address should be specified. Note, however, that
when mailing lists are specified, the requirement for a
Designated Expert MUST also be specified (see Section 3).
If IANA is expected to make assignments without requiring an
outside review, sufficient guidance MUST be provided so that the
requests can be evaluated with minimal subjectivity.
4) The size, format and syntax of registry entries. When creating a
new name/number space, authors must describe any technical
requirements on registry (and sub-registry) values (e.g., valid
ranges for integers, length limitations on strings, etc.) as
well as the exact format that registry values should be
displayed in. For number assignments, one should specify
whether values are to be recorded in decimal, hexadecimal or
some other format. For strings, the encoding format should be
specified (e.g., ASCII, UTF8, etc.) Authors should also clearly
specify what fields to record in the registry.
5) Initial assignments and reservations. Clear instructions should
be provided to identify any initial assignments or
registrations. In addition, any ranges that are to be reserved
for "Private Use", "Reserved", "Unassigned", etc. should be
clearly indicated.
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When specifying the process for making future assignments, it is
quite acceptable to pick one (or more) of the example policies listed
in Section 4.1 and refer to it by name. Indeed, this is the
preferred mechanism in those cases where the sample policies provide
the desired level of review. It is also acceptable to cite one of the
above 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.
For example, a document could say something like:
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] [DHCP-
OPTIONS,DHCP-IANA]:
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 [IANA-CONSIDERATIONS].
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 provide detailed guidance to IANA on
the issue of assigning numbers, consult [RFC2929, RFC3575, RFC3968,
RFC4520].
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4.3. Updating IANA Guidelines For Existing Registries
Updating the registration process for an already existing (i.e.,
previously created) name space (whether created explicitly or
implicitly) follows a process similar to that used when creating a
new namespace. That is, a document is produced that makes reference
to the existing namespace and then provides detailed guidelines for
handling assignments in each individual name space. Such documents
are normally processed as BCPs [IETF-PROCESS].
Example documents that updated the guidelines for managing (then)
pre-existing registries include: [RFC2929,RFC3228,RFC3575].
5. Registering New Values In An Existing Registry
5.1. What to Put In Documents When Registering Values
Often, documents request an assignment from an already existing name
space (i.e., one created by a previously-published RFC). In such
cases:
- Documents should clearly identify the name space in which each
value is to be registered. If the registration goes into a sub-
registry, the author should clearly describe where the assignment
or registration should go. It is helpful to use the exact name
space name as listed on the IANA web page (and defining RFC), and
cite the RFC where the name space is defined.
Note 1: There is no need to mention what the assignment policy for
new assignments is, as that should be clear from the references.
Note 2: When referring to an existing registry, providing a URL to
precisely identify the registry is helpful. Such URLs, however,
should usually be removed from the RFC prior to final publication,
since IANA URLs are not guaranteed to be stable in the future. In
cases where it is important to include a URL in the document, IANA
should should concur on its inclusion.
As an example, documents could contain: [TO BE REMOVED: This
registration should take place at the following location:
http://www.iana.org/assignments/foobar-registry]
- Each value requested should be given a unique reference. When the
value is numeric, use the notation: TBD1, TBD2, etc. Throughout
the document where an actual IANA-assigned value should be filled
in, use the "TBDx" notation. This helps ensure that the final RFC
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has the correct assigned values inserted in in all of the relevant
places where the value is expected to appear in the final
document. For values that are text strings, a specific name can be
suggested. IANA will normally assign the name, unless it conflicts
with a name already in use.
- Normally, the values to be used are chosen by IANA and documents
should specify values of "TBD". However, in some cases a value may
have been used for testing or in early implementations. In such
cases, it is acceptable to include text suggesting what specific
value should be used (together with the reason for the choice).
For example, one might include the text "the value XXX is
suggested as it is used in implementations". However, it should be
noted that suggested values are just that; IANA will attempt to
assign them, but may find that impossible, if the proposed number
has already been assigned for some other use.
For some registries, IANA has a longstanding policy prohibiting
assignment of names or codes on a vanity or organization name
basis, e.g., codes are always 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 should appear on the
IANA web site. For example:
Value Description Reference
-------- ------------------- ---------
TBD1 Foobar [RFCXXXX]
Note: in cases where authors feel that including the full table is
too verbose or repetitive, authors should still include the table,
but may include a note asking 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
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defined in section 24.3 of RFC 3315.
5.2. Updating Registrations
Registrations are a request to assign a new value, including the
related information needed to evaluate and document the request. Even
after a number has been assigned, some types of registrations contain
additional information that may need to be updated over time. For
example, MIME media types, character sets, language tags, etc.
typically include more information than just the registered value
itself. Example information can include point of contact information,
security issues, pointers to updates, literature references, etc. In
such cases, the document defining the namespace must clearly state
who is responsible for maintaining and updating a registration. In
different cases, it may be appropriate to specify one or more of the
following:
- Let the author update the registration, subject to the same
constraints and review as with new registrations.
- Allow some mechanism to attach comments to the registration, for
cases where others have significant objections to claims in a
registration, but the author does not agree to change the
registration.
- Designate 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.
5.3. Overriding Registration Procedures
Since RFC 2434 was published, experience has shown that the
documented IANA considerations for individual protocols do not always
adequately cover the reality after the protocol is deployed. For
example, many older routing protocols do not have documented,
detailed IANA considerations. 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
obtain code points from IANA in advance of actual RFC publication.
In other cases, the documented procedures are unclear or neglected to
cover all the cases. In order to allow assignments in individual
cases where there is strong IETF consensus that an allocation should
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go forward, but the documented procedures do not support such an
assignment, the IESG is granted authority to approve assignments in
such cases. The intention is not to overrule properly documented
procedures, or to obviate the need for protocols to properly document
their IANA Considerations. Instead, the intention is to permit
assignments in individual cases where it is obvious that the
assignment should just be made, but updating the IANA process just to
assign a particular code point is viewed as too heavy a burden.
In general, the IETF would like to see deficient IANA registration
procedures for a namespace revised through the IETF standards
process, but not at the cost of unreasonable delay for needed
assignments. If the IESG has had to take the action in this section,
it is a strong indicator that the IANA registration procedures should
be updated, possibly in parallel with ongoing protocol work.
6. Miscellaneous Issues
6.1. When There Are No IANA Actions
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 a 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 form of words, must only be inserted
after the WG 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 name space that is not
managed by IANA, it may be useful to note this fact, e.g., with
wording such as:
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.
In some cases, the absence of IANA-assigned values may be considered
valuable information for future readers; in other cases it may be
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considered of no value once the document has been approved, and may
be removed before archival publication. This choice should be made
clear in the draft, for example by including a sentence such as
[RFC Editor: please remove this section prior to publication.]
or
[RFC Editor: please do not remove this section.]
6.2. Namespaces Lacking Documented Guidance
For all existing RFCs that either explicitly or implicitly rely on
IANA to evaluate assignments without specifying a precise evaluation
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.
All future RFCs that either explicitly or implicitly rely on IANA to
register or otherwise manage name space assignments MUST provide
guidelines for managing the name space.
6.3. After-The-Fact Registrations
Occasionally, IANA becomes aware that an unassigned value from a
managed name space is in use on the Internet, or that an assigned
value is being used for a different purpose than originally
registered. IANA will not condone such misuse, i.e., 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.
6.4. 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 name space 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:
draft-narten-iana-considerations-rfc2434bis-09.txt [Page 20]
INTERNET-DRAFT March 26, 2008
- 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.)
- 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.
- 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]
7. Appeals
Appeals on registration decisions made by IANA can be appealed using
the normal IETF appeals process as described in Section 6.5 of
[IETF-PROCESS]. Specifically, appeals should be directed to the IESG,
followed (if necessary) by an appeal to the IAB, etc.
8. 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.
9. Security Considerations
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 WG chairs, Designated
Experts and mail list participants too.
Information concerning possible security vulnerabilities of a
protocol may change over time. Likewise, security vulnerabilities
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related to how an assigned number is used (e.g., if it identifies a
protocol) 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 mislead 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.
10. Changes Relative to RFC 2434
Changes include:
- 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.
- Numerous editorial changes to improve readability.
- 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) are quick to
make incorrect assumptions about what the term means in the
context of IANA Considerations.
- Added "RFC Required" to list of defined policies.
- Much more explicit directions and examples of "what to put in
RFCs".
- "Specification Required" now implies use of Designated Expert to
evaluate specs for sufficient clarity.
- Significantly changed the wording in Section 3. 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.
- Changed wording to remove any special appeals path. The normal
RFC2026 appeals path is used.
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- Added section about reclaiming unused value.
- Added a section on after-the-fact registrations.
- Added section indicating that mailing lists used to evaluate
possible assignments (e.g., by a designated expert) are subject to
normal IETF rules.
11. IANA Considerations
This document is all about IANA Considerations, but has no IANA
actions.
12. Acknowledgments
This document has benefited from specific feedback from Jari Arkko,
Marcelo Bagnulo Braun, Brian Carpenter, Michelle Cotton, Barbara
Denny, Spencer Dawkins, Miguel Garcia, Paul Hoffman, Russ Housley,
John Klensin, Allison Mankin, Blake Ramsdell, Mark Townsley, Magnus
Westerlund and Bert Wijnen.
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 [MIME-REG].
13. Normative References
[KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
14. Informative References
[ASSIGNED] "Assigned Numbers: RFC 1700 is Replaced by an On-line
Database," J. Reynolds, Ed., RFC 3232, January
2002.
[DHCP-OPTIONS] Alexander, S. and R. Droms, "DHCP Options and BOOTP
draft-narten-iana-considerations-rfc2434bis-09.txt [Page 23]
INTERNET-DRAFT March 26, 2008
Vendor Extensions", RFC 2132, March 1997.
[DHCP-IANA] Procedures and IANA Guidelines for Definition of New DHCP
Options and Message Types. R. Droms, RFC 2939,
September 2000.
[EXPERIMENTATION] "Assigning Experimental and Testing Numbers
Considered Useful". T. Narten, RFC 3692, January
2004.
[IANA-CONSIDERATIONS] Alvestrand, H. and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP
26, RFC 2434, October 1998.
[IANA-MOU] Memorandum of Understanding Concerning the Technical Work
of the Internet Assigned Numbers Authority. B.
Carpenter, F. Baker, M. Roberts, RFC 2860, June
2000.
[IETF-PROCESS] Bradner, S., "The Internet Standards Process --
Revision 3", BCP 9, RFC 2026, October 1996.
[IP] Postel, J., "Internet Protocol", STD 5, RFC 791, September 1981.
[IPSEC] S. Kent, K. Seo., "Security Architecture for the Internet
Protocol", RFC 4301, December 2005.
[MIME-REG] "Media Type Specifications and Registration Procedures".
N. Freed, J. Klensin. December 2005, RFC 4288.
[PROTOCOL-EXT] "Design Considerations for Protocol Extensions",
draft-carpenter-extension-recs-02.txt (Work in
Progress).
[RFC2929] Domain Name System (DNS) IANA Considerations. D. Eastlake
3rd, E. Brunner-Williams, B. Manning. September
2000.
[RFC3171] "IANA Guidelines for IPv4 Multicast Address Assignments".
Z. Albanna, K. Almeroth, D. Meyer, M. Schipper.
August 2001.
[RFC3228] IANA Considerations for IPv4 Internet Group Management
Protocol (IGMP). B. Fenner. February 2002.
[RFC3552] Guidelines for Writing RFC Text on Security Considerations.
E. Rescorla, B. Korver. July 2003.
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[RFC3575] IANA Considerations for RADIUS (Remote Authentication Dial
In User Service). B. Aboba. RFC 3575, July 2003.
[RFC3748] Extensible Authentication Protocol (EAP), B. Aboba, L.
Blunk, J. Vollbrecht, J. Carlson, H. Levkowetz,
Ed., RFC 3748, June, 2004.
[RFC3978] IETF Rights in Contributions. S. Bradner, Ed.. March 2005.
[RFC3775] "Mobility Support in IPv6," D. Johnson, C. Perkins, J.
Arkko. June 2004.
[RFC3932] The IESG and RFC Editor Documents: Procedures. H.
Alvestrand. October 2004.
[RFC3942] "Reclassifying Dynamic Host Configuration Protocol version
4 (DHCPv4) Options", B. Volz. RFC 3942, November
2004
[RFC3968] "The Internet Assigned Number Authority (IANA) Header Field
Parameter Registry for the Session Initiation
Protocol (SIP)," G. Camarillo. RFC 3968, December
2004.
[RFC4005] "Diameter Network Access Server Application," P. Calhoun,
G. Zorn, D. Spence, D. Mitton. August 2005.
[RFC4025] "A Method for Storing IPsec Keying Material in DNS," M.
Richardson. March 2005.
[RFC4044] "Fibre Channel Management MIB", K. McCloghrie. May 2005.
[RFC4124] "Protocol Extensions for Support of Diffserv-aware MPLS
Traffic Engineering," F. Le Faucheur, Ed.. June
2005.
[RFC4169] "Hypertext Transfer Protocol (HTTP) Digest Authentication
Using Authentication and Key Agreement (AKA)
Version-2". V. Torvinen, J. Arkko, M. Naslund.
November 2005.
[RFC4271] "A Border Gateway Protocol 4 (BGP-4)," Y. Rekhter, Ed., T.
Li, Ed., S. Hares, Ed.. January 2006.
[RFC4283] "Mobile Node Identifier Option for Mobile IPv6 (MIPv6)," A.
Patel, K. Leung, M. Khalil, H. Akhtar, K. Chowdhury.
November 2005.
draft-narten-iana-considerations-rfc2434bis-09.txt [Page 25]
INTERNET-DRAFT March 26, 2008
[RFC4306] "Internet Key Exchange (IKEv2) Protocol", C. Kaufman, Ed.
December 2005
[RFC4340] "Datagram Congestion Control Protocol (DCCP)," E. Kohler,
M. Handley, S. Floyd. March 2006
[RFC4366] "Transport Layer Security (TLS) Extensions," S. Blake-
Wilson, M. Nystrom, D. Hopwood, J. Mikkelsen, T.
Wright. April 2006.
[RFC4346] "The Transport Layer Security (TLS) Protocol Version 1.1,"
T. Dierks, E. Rescorla. April 2006.
[RFC4395] "Guidelines and Registration Procedures for New URI
Schemes," T. Hansen, T. Hardie, L. Masinter.
February 2006.
[RFC4422] "Simple Authentication and Security Layer (SASL)". A.
Melnikov, Ed., K. Zeilenga, Ed.. June 2006.
[RFC4446] "IANA Allocations for Pseudowire Edge to Edge Emulation
(PWE3)," L. Martini. April 2006.
[RFC4520] "Internet Assigned Numbers Authority (IANA) Considerations
for the Lightweight Directory Access Protocol
(LDAP)," K. Zeilenga. June 2006.
[RFC4589] "Location Types Registry," H. Schulzrinne, H. Tschofenig.
July 2006.
[RFC4727] "Experimental Values In IPv4, IPv6, ICMPv4, ICMPv6, UDP,
and TCP Headers". B. Fenner. November 2006.
[RFC4995] "The RObust Header Compression (ROHC) Framework," L-E.
Jonsson, G. Pelletier, K. Sandlund. July 2007.
15. Authors' Addresses
Thomas Narten
IBM Corporation
3039 Cornwallis Ave.
PO Box 12195 - BRQA/502
Research Triangle Park, NC 27709-2195
Phone: 919-254-7798
EMail: narten@us.ibm.com
draft-narten-iana-considerations-rfc2434bis-09.txt [Page 26]
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Harald Tveit Alvestrand
Google
Beddingen 10
Trondheim, 7014
Norway
Email: Harald@Alvestrand.no
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This document is subject to the rights, licenses and restrictions
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