Here is the header for the IANA document:
INTERNET-DRAFT Thomas Narten
IBM
<draft-iesg-iana-considerations-01.txt> Harald Tveit Alvestrand
UNINETT
November 21, 1997
Guidelines for Writing an IANA Considerations Section in RFCs
<draft-iesg-iana-considerations-01.txt>
Here is the resend of the original mail, including posting of the
.doc (WORD6 so you'll need to fix up any cross references) and the .pdf
versions:
X-Sender: hastings@garfield
Date: Fri, 19 Dec 1997 14:32:19 PST
To: ipp@pwg.org
From: Tom Hastings <hastings@cp10.es.xerox.coM>
Subject: IPP> MOD - Suggested simplification of IANA Considerations
Sender: ipp-owner@pwg.org
Here is my action item on the Model Section 6 IANA Considerations.
I've consulted with Bob Herriot and Carl-Uno on these proposed
simplfications. Please send any comments immediately.
I re-read the new IANA Considerations document
(draft-iesg-iana-considerations-01.txt) and see that we should make the
following changes in order not to hold up IPP in the IESG:
1. The model needs to assign IPP Subject Matter Experts by name, not position.
2. The document suggests chairs, so I've talked to Carl-Uno and he suggests
that Carl-Uno and Steve should be the IPP Subject Matter Experts.
3. The model needs to say who can find a replacement and suggests the A-Ds,
so I've added that and included that the PWG can change them too.
4. The model needs to say who maintains each entry. Type 2 should be the
PWG, type 3 should be the proposer.
5. Don't have IANA have to assign type 3 keywords and enums, lets have
the Subject Matter Experts do it.
So all IANA has to do for type 2 and type 3 is keep the approved
registrations (the document recommends delegation). This is what we
have done for the Printer MIB "printer language" registrations
(document formats).
Here is the complete new text for section 6. (only 6.1 has changed).
I've also posted a .doc (WORD 6) and a .pdf file to show the revisions:
ftp://ftp.pwg.org/pub/pwg/ipp/new_MOD/ipp-model-iana-considerations.doc
ftp://ftp.pwg.org/pub/pwg/ipp/new_MOD/ipp-model-iana-considerations.pdf
6. IANA Considerations (registered and private extensions)
This section describes how IPP can be extended.
6.1 Typed Extensions
IPP allows for "keyword" and "enum" extensions (see sections 4.1.5 and
4.1.6). In reviewing proposals for such extensions, the IPP Subject Matter
Experts are: Carl-Uno Manros (manros@cp10.es.xerox.com) and Steve Zilles
(szilles@Adobe.com). If a replacement is needed, the IESG Applications
Area Director, in consultation with the PWG [PWG] using pwg@pwg.org, SHALL
appoint a replacement. The PWG can also specify a replacement at any time.
This document uses prefixes to the "keyword" and "enum" basic syntax type
in order to communicate extra information to the reader through its name.
This extra information need not be represented in an implementation because
it is unimportant to a client or Printer. The list below describes the
prefixes and their meaning.
"type1": The IPP standard must be revised to add a new keyword or a new
enum. No private keywords or enums are allowed.
"type2": Implementers can, at any time, add new keyword or enum values by
proposing the specification to:
- the IPP working group (IPP WG using ipp@pwg.org) while it is still
chartered, or
- the Printer Working Group [PWG] using pwg@pwg.org after the IPP working
group is disbanded
who will review the proposal and work with IANA to register the additional
keywords and enums.
For enums, the IPP WG or PWG assigns the next available unused number.
When a type 2 keyword or enum is approved by the IPP WG or PWG, the PWG
becomes the point of contact for any future maintenance that might be
required for that registration.
IANA keeps the registry of keywords and enums as it does for any registration.
"type3": Implementers can, at any time, add new keyword and enum values by
submitting the complete specification directly to the IPP Subject Matter
Experts. While no IPP working group or Printer Working Group review is
required, the IPP Subject Matter Experts may, at their discretion, forward
the proposal to the IPP WG or PWG for advice and comment.
For enums, the IPP Subject Matter Experts assigns the number for enum
values. and keeps the registry of keywords and enums.
When a type 3 keyword or enum is approved by IPP Subject Matter Experts,
the original proposer becomes the point of contact for any future
maintenance that might be required for that registration. IANA keeps the
registry of keywords and enums as it does for any registration.
"type4": Anyone (system administrators, system integrators, site managers,
etc.) can, at any time, add new installation-defined values (keywords, but
not enum values) to a local system. Care SHOULD be taken by the
implementers to see that keywords do not conflict with other keywords
defined by the standard or as defined by the implementing product. There is
no registration or approval procedure for type 4 keywords.
Note: Attributes with type 4 keywords also allow the 'name' attribute
syntax for administrator defined names. Such names are not registered.
By definition, each of the four types above assert some sort of registry or
review process in order for extensions to be considered valid. Each higher
level (1, 2, 3, 4) tends to be decreasingly less stringent than the
previous level. Therefore, any typeN value MAY be registered using a
process for some typeM where M is less than N, however such registration is
NOT REQUIRED. For example, a type4 value MAY be registered in a type 1
manner (by being included in a future version of an IPP specification)
however it is NOT REQUIRED.
This specification defines keyword and enum values for all of the above
types, including type4 keywords.
For private (unregistered) keyword extensions, implementers SHOULD use
keywords with a suitable distinguishing prefix, such as "xxx-" where xxx is
the (lowercase) fully qualified company name registered with IANA for use
in domain names [RFC1035]. For example, if the company XYZ Corp. had
obtained the domain name "XYZ.com", then a private keyword 'abc' would be:
'xyz.com-abc'.
Note: RFC 1035 [RFC1035] indicates that while upper and lower case letters
are allowed in domain names, no significance is attached to the case. That
is, two names with the same spelling but different case are to be treated
as if identical. Also, the labels in a domain name must follow the rules
for ARPANET host names: They must start with a letter, end with a letter
or digit, and have as interior characters only letters, digits, and hyphen.
Labels must be 63 characters or less. Labels are separated by the "."
character.
For private (unregistered) enum extension, implementers SHALL use values in
the reserved integer range which is 2**30 to 2**31-1.
6.2 Registration of MIME types/sub-types for document-formats
The "document-format" attribute's syntax is 'mimeMediaType'. This means
that valid values are Internet Media Types. RFC 2045 [RFC2045] defines the
syntax for valid Internet media types. IANA is the registry for all
Internet media types.
6.3 Attribute Extensibility
Attribute names are type2 keywords. Therefore, new attributes may be
registered and have the same status as attributes in this document by
following the type2 extension rules.
6.4 Attribute Syntax Extensibility
Attribute syntaxes are like type2 enums. Therefore, new attribute syntaxes
may be registered and have the same status as attribute syntaxes in this
document by following the type2 extension rules. The value codes that
identify each of the attribute syntaxes are assigned in the protocol
specification [IPP-PRO].
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INTERNET-DRAFT Thomas Narten
=
IBM
<draft-iesg-iana-considerations-01.txt> Harald Tveit Alvestrand
UNINETT
November 21, 1997
Guidelines for Writing an IANA Considerations Section in RFCs
<draft-iesg-iana-considerations-01.txt>
Status of this Memo
This document is an Internet-Draft. Internet-Drafts are working
documents of the Internet Engineering Task Force (IETF), its areas,
and its working groups. Note that other groups may also distribute
working documents as Internet-Drafts.
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."
To learn the current status of any Internet-Draft, please check the
"1id-abstracts.txt" listing contained in the Internet-Drafts Shadow
Directories on ds.internic.net (US East Coast), nic.nordu.net
(Europe), ftp.isi.edu (US West Coast), or munnari.oz.au (Pacific
Rim).
Distribution of this memo is unlimited.
This Internet Draft expires May 21, 1998.
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., a new
option type in DHCP). To insure that such quantities have unique
values, their assignment must be administered by a central authority.
In the Internet, that role is provided by the Internet Assigned
Numbers Authority (IANA).
In order for the IANA to manage a given numbering space prudently, it
needs guidelines describing the conditions under which new values can
be assigned. If the IANA is expected to play a role in the management
of a numbering space, the IANA must be given clear and=
concise
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instructions describing that role. This document discusses issues
that should be considered in formulating an identifier assignment
policy and provides guidelines to document authors on the specific
text that must be included in documents that place demands on the
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IANA.
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Contents
Status of this Memo.......................................... 1
1. Introduction............................................. 3
2. Issues To Consider....................................... 4
3. Registration maintenance................................. 6
4. What To Put In Documents................................. 6
5. Security Considerations.................................. 8
6. References............................................... 8
7. Acknowledgements......................................... 9
8. Authors' Addresses....................................... 9
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 types in mail messages [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]). To insure that
such fields have unique values, their assignment must be administered
by a central authority. In the Internet, that role is provided by the
Internet Assigned Numbers Authority (IANA).
In order for the IANA to manage a given numbering space prudently, it
needs guidelines describing the conditions under which new values
should be assigned. This document provides guidelines to authors on
what sort of text should be added to their documents, and reviews
issues that should be considered in formulating an appropriate policy
for assigning identifiers.
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]. When a name space
can be delegated, the IANA only deals with assignments at the=
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level.
2. Issues To Consider
The primary issue to consider in managing a numbering space is its
size. If the space is small and limited in size, assignments must be
made carefully to insure that the space doesn't become exhausted. If
the space is essentially unlimited, on the other hand, it may be
perfectly reasonable to hand out new values to anyone that wants one.
Even when the space is essentially unlimited, however, it is usually
desirable to have a minimal review to prevent hoarding of the space.
For example, if the space consists of text strings, it may be
desirable to prevent organizations from obtaining large sets of
strings that correspond to the "best" names (e.g., existing company
names).
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 the IANA for dealing with assignments.
In most cases, some review of prospective allocations is appropriate,
and the first question to answer is who should perform the review.
In some cases, reviewing requests is straightforward and requires no
subject subjective decision making. On those cases, it is reasonable
for the IANA to review prospective assignments, provided that the
IANA is given specific guidelines on what types of requests it should
grant, and what information must be provided before a request of an
assigned number will be considered. Note that the IANA will not
define an assignment policy; it should be given a set of guidelines
that allow it to make allocation decisions with little subjectivity.
The following are example policies, some of which are in use today:
Free For All - For 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 and assignments are not generally useful
for interoperability.
Examples: Site-specific options in DHCP [DHCP] have
significance only within a single site.
Hierarchical allocation - Delegated managers can assign
identifiers provided they have been given control over that
part of the identifier space. IANA controls the higher
levels of the namespace according to one of the other
policies.
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Examples: DNS names, Object Identifiers
First Come First Served - Anyone can obtain an identifier, so long
as they provide a point of contact and a brief description
of what the identifier would be used for. For numbers, the
exact value is generally assigned by the IANA, with names,
specific names are usually requested.
Examples: vnd. MIME types [MIME-REG], TCP and UDP port
numbers.
Specification Required - Values and their meaning must be
documented in an RFC or other permanent and readily
available reference, in sufficient detail so that
interoperability between independent implementations is
possible.
Examples: SCSP [SCSP]
IESG Action - IESG must explicitly approve new values.
Examples: SMTP extensions [SMTP-EXT]
Standards Action - Only identifiers that have been documented in
standards track RFCs approved by the IESG will be
registered.
Examples: MIME top level types [MIME-REG]
In some cases, it may be appropriate for the IANA to serve as a
point-of-contact for publishing information about numbers that have
been assigned, without actually having it evaluate and grant
requests. For example, it is 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 on which (e.g., that of a current or former IETF Working
Group). Such a mailing list may serve to give new registrations a
public review before getting registered, or give advice for persons
who want help in understanding what a proper registration should
contain.
Since the IANA cannot participate in all of these mailing lists and
cannot determine if or when such discussion reaches a consensus, the
IANA will rely on a designated subject matter expert to advise it in
these matters. That is, the IANA must be directed to forward the
requests it receives to a specific point-of-contact (one or a small
number of individuals) and act upon the returned recommendation from
the designated subject matter expert. In all cases, it is=
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designated subject matter expert that the IANA relies on for an
authoritative response. In those cases where wide review of a request
is needed, it is the responsibility of the designated subject matter
expert to initiate such a review (e.g., by engaging the relevant
mailing lists). In no cases will the IANA allow general mailing lists
(e.g., that of a former or existing IETF Working Group) to fill the
role of the designated subject matter expert.
In some cases, it makes sense to partition the number space into
several categories, with assignments out of each category handled
differently. For example, the DHCP option space [DHCP] is split into
two parts. Option numbers in the range of 1-127 are globally unique
and assigned according to the Specification Required policy described
earlier, while options number 128-254 are "site specific", i.e., Free
For All.
3. Registration maintenance
Registrations sometimes contain information that needs to be
maintained; in particular, point of contact information may need to
be changed, claims of freedom from security problems may need to be
modified, or new versions of a registration may need to be published.
A document must clearly state who is responsible for such
maintenance. It is appropriate to:
- 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 or another authority as having the right to
reassign ownership of a registration. This is mainly to get
around the problem when some registration owner cannot be
reached in order to make necessary updates.
4. What To Put In Documents
The previous section presented some issues that should be considered
in formulating a policy for assigning well-known numbers and other
protocol constants. It is the Working Group and/or document author's
job to formulate an appropriate policy and specify it in the
appropriate document. In some cases, having an "IANA=
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section may be appropriate. Such a section should state clearly:
- who reviews an application for an assigned number. If a request
should be reviewed by a designated subject matter expert,
contact information must be provided.
- who has authority to replace the designated subject matter
expert, should a replacement be needed (e.g., if multiple
attempts to reach the designated subject matter fail). The
specific procedure to appoint the person should also be
indicated; it may often be appropriate to let the relevant IESG
Area Director designate the subject matter expert when a
replacement is necessary.
- If the request should also be reviewed by a specific public
mailing list (such as the ietf-types@iana.org for media types),
that mailing address should be specified. Note, however, that a
designated subject matter expert must also be specified.
- if the IANA is expected to review requests itself, sufficient
guidance must be provided so that the requests can be evaluated
with minimal subjectivity.
It should also be noted that the following are unacceptable:
- listing a Working Group mailing list as the designated subject
matter expert
- specifying that "the current Working Group Chairs of the FooBar
Workin Group" are the designated subject matter experts, since
Working Groups eventually close down. However, it is acceptable
to list the current WG Chairs individually.
Finally, it is quite acceptable to pick one of the example policies
cited above and refer to it by name. For example, a document could
say something like:
numbers are allocated as First Come First Served as defined in
[IANA-CONSIDERATIONS]
For examples of documents that provide good and detailed guidance to
the IANA on the issue of assigning identifiers, consult [MIME-REG,
MIME-LANG].
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5. Security Considerations
Information that creates or updates a registration needs to be
authenticated.
Information concerning possible security vulnerabilities of a
protocol may change over time. Consequently, claims as to the
security properties of a registered 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 properties of a
registered protocol.
An analysis of security issues is required for for all types
registered in the IETF Tree [MIME-REG]. A similar analysis for media
types registered in the vendor or personal trees is encouraged but
not required. However, regardless of what security analysis has or
has not been done, all descriptions of security issues must be as
accurate as possible regardless of registration tree. In particular,
a statement that there are "no security issues associated with this
type" must not be confused with "the security issues associated with
this type have not been assessed".
Delegations of a name space should only be assigned to someone with
adequate security.
6. References
[ASSIGNED] Reynolds, J., Postel, J., "Assigned Numbers", October
1994k, RFC 1700.
[DHCP-OPTIONS] S. Alexander, R. Droms, DHCP Options and BOOTP
Vendor Extensions, RFC 2132, March 1997.
[IANA-CONSIDERATIONS] Alvestrand, H., Narten, T., "Guidelines for
Writing an IANA Considerations Section in RFCs", draft-
iesg-iana-considerations-01.txt.
[IP] J. Postel, Internet Protocol, RFC 791, September 1, 1981.
[MIME-LANG] Freed, N., Moore, K., "MIME Parameter Value and Encoded
Word Extensions: Character Sets, Languages, and
Continuations", RFC 2184, August, 1997.
[MIME-REG] N. Freed, J. Klensin & J. Postel, Multipurpose Internet
Mail Extension (MIME) Part Four: Registration Procedures.
RFC 2048, November,=
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[SCSP] Luciani, J., Armitage, G, Halpern, J., "Server Cache
Synchronization Protocol (SCSP)" draft-ietf-ion-scsp-
02.txt.
[SMTP-EXT] Klensin, J., Freed, N., Rose, M., Stefferud, E.,
Crocker, D.. "SMTP Service Extensions", RFC 1869, November
1995.
7. Acknowledgements
Jon Postel and Joyce Reynolds provided a detailed explanation on what
the IANA needs in order to manage assignments efficiently. Brian
Carpenter provided helpful comments on earlier versions of the
document. One paragraph in the Security Considerations section was
borrowed from [MIME-REG].
8. 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@raleigh.ibm.com
Harald Tveit Alvestrand
UNINETT
P.O.Box 6883 Elgeseter
N-7002 TRONDHEIM
NORWAY
Phone: +47 73 59 70 94
EMail:=
Harald.T.Alvestrand@uninett.no
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