RFC 5131 PROPOSED STANDARD MANAGEMENT · MIB · LANGUAGES
MIB Language Tag: A MIB Textual Convention for Language Tags
One shared MIB definition for writing down a BCP 47 language tag, so every MIB module does not reinvent it.
RFC EDITOR
McWalter, D., Ed., "A MIB Textual Convention for Language Tags", RFC 5131, DOI 10.17487/RFC5131, December 2007, <https://www.rfc-editor.org/info/rfc5131>.
BIBTEX
@misc{rfc5131,
series = {Request for Comments},
number = 5131,
howpublished = {RFC 5131},
publisher = {RFC Editor},
doi = {10.17487/RFC5131},
url = {https://www.rfc-editor.org/info/rfc5131},
author = {D. McWalter},
title = {{A MIB Textual Convention for Language Tags}},
pagetotal = 6,
year = 2007,
month = dec,
} RFC text
Contents
Network Working Group D. McWalter, Ed.
Request for Comments: 5131 Data Connection Ltd
Category: Standards Track December 2007
A MIB Textual Convention for Language Tags
Status of This Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Abstract
This MIB module defines a textual convention to represent BCP 47
language tags. The intent is that this textual convention will be
imported and used in MIB modules that would otherwise define their
own representation.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. The Internet-Standard Management Framework . . . . . . . . . . 2
4. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . 3
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 4
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 4
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 4
8.1. Normative References . . . . . . . . . . . . . . . . . . . 4
8.2. Informative References . . . . . . . . . . . . . . . . . . 5
1. Introduction
This memo defines a portion of the Management Information Base (MIB)
for use with network management protocols in the Internet community.
It defines a textual convention to represent BCP 47 [RFC4646]
language tags.
The LangTag TEXTUAL-CONVENTION defined by this RFC replaces the
similar LanguageTag TEXTUAL-CONVENTION defined by RFC 2932 [RFC2932].
The old LanguageTag TEXTUAL-CONVENTION is used by some existing MIB
modules. New MIB modules should use the LangTag TEXTUAL-CONVENTION,
which has been created (and is to be preferred) for the following
reasons:
o Its syntax description is current, and is more comprehensive.
o It is short enough to use as an index object without subtyping,
yet is of adequate length to represent any language tag in
practice.
o It is provided in a dedicated MIB module to simplify module
dependencies.
It is not possible to apply changes in syntax and length to an
existing textual convention. This is why the creation of a new
textual convention with a new name was necessary.
2. Terminology
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].
3. The Internet-Standard Management Framework
For a detailed overview of the documents that describe the current
Internet-Standard Management Framework, please refer to section 7 of
RFC 3410 [RFC3410].
Managed objects are accessed via a virtual information store, termed
the Management Information Base or MIB. MIB objects are generally
accessed through the Simple Network Management Protocol (SNMP).
Objects in the MIB are defined using the mechanisms defined in the
Structure of Management Information (SMI). This memo specifies a MIB
module that is compliant to the SMIv2, which is described in STD 58,
RFC 2578 [RFC2578], STD 58, RFC 2579 [RFC2579] and STD 58, RFC 2580
[RFC2580].
4. Definitions
LANGTAG-TC-MIB DEFINITIONS ::= BEGIN
IMPORTS
MODULE-IDENTITY, mib-2 FROM SNMPv2-SMI -- [RFC2578]
TEXTUAL-CONVENTION FROM SNMPv2-TC; -- [RFC2579]
langTagTcMIB MODULE-IDENTITY
LAST-UPDATED "200711090000Z" -- 9 November 2007
ORGANIZATION "IETF Operations and Management (OPS) Area"
CONTACT-INFO "EMail: ops-area@ietf.org
Home page: http://www.ops.ietf.org/"
DESCRIPTION
"This MIB module defines a textual convention for
representing BCP 47 language tags."
REVISION "200711090000Z" -- 9 November 2007
DESCRIPTION
"Initial revision, published as RFC 5131.
Copyright (C) The IETF Trust (2007). This version of this
MIB module is part of RFC 5131; see the RFC itself for full
legal notices."
::= { mib-2 165 }
LangTag ::= TEXTUAL-CONVENTION
DISPLAY-HINT "1a"
STATUS current
DESCRIPTION
"A language tag, constructed in accordance with BCP 47.
Only lowercase characters are allowed. The purpose of this
restriction is to provide unique language tags for use as
indexes. BCP 47 recommends case conventions for user
interfaces, but objects using this TEXTUAL-CONVENTION MUST
use only lowercase.
Values MUST be well-formed language tags, in conformance
with the definition of well-formed tags in BCP 47. An
implementation MAY further limit the values it accepts to
those permitted by a 'validating' processor, as defined in
BCP 47.
In theory, BCP 47 language tags are of unlimited length.
The language tag described in this TEXTUAL-CONVENTION is of
limited length. The analysis of language tag lengths in BCP
47 confirms that this limit will not pose a problem in
practice. In particular, this length is greater than the
minimum requirements set out in Section 4.3.1.
A zero-length language tag is not a valid language tag.
This can be used to express 'language tag absent' where
required, for example, when used as an index field."
REFERENCE "RFC 4646 BCP 47"
SYNTAX OCTET STRING (SIZE (0 | 2..63))
END
5. Security Considerations
This MIB module does not define any management objects. Instead, it
defines a textual convention that may be imported by other MIB
modules and used for object definitions.
Meaningful security considerations can only be written in the MIB
modules that define management objects. This document therefore has
no impact on the security of the Internet.
6. IANA Considerations
LANGTAG-TC-MIB is rooted under the mib-2 subtree. IANA has assigned
{ mib-2 165 } to the LANGTAG-TC-MIB module specified in this
document.
7. Acknowledgements
This MIB module is a reworking of existing material from RFC 2932.
This module was generated by editing together contributions from
Randy Presuhn, Dan Romascanu, Bill Fenner, Juergen Schoenwaelder,
Bert Wijnen, Doug Ewell, and Ira McDonald.
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2578] McCloghrie, K., Ed., Perkins, D., Ed., and J.
Schoenwaelder, Ed., "Structure of Management Information
Version 2 (SMIv2)", STD 58, RFC 2578, April 1999.
[RFC2579] McCloghrie, K., Ed., Perkins, D., Ed., and J.
Schoenwaelder, Ed., "Textual Conventions for SMIv2",
STD 58, RFC 2579, April 1999.
[RFC2580] McCloghrie, K., Perkins, D., and J. Schoenwaelder,
"Conformance Statements for SMIv2", STD 58, RFC 2580,
April 1999.
[RFC4646] Phillips, A. and M. Davis, "Tags for Identifying
Languages", BCP 47, RFC 4646, September 2006.
8.2. Informative References
[RFC2932] McCloghrie, K., Farinacci, D., and D. Thaler, "IPv4
Multicast Routing MIB", RFC 2932, October 2000.
[RFC3410] Case, J., Mundy, R., Partain, D., and B. Stewart,
"Introduction and Applicability Statements for Internet-
Standard Management Framework", RFC 3410, December 2002.
Author's Address
David McWalter (editor)
Data Connection Ltd
100 Church Street
Enfield EN2 6BQ
United Kingdom
EMail: dmcw@dataconnection.com
Full Copyright Statement
Copyright (C) The IETF Trust (2007).
This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors
retain all their rights.
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
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Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in
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The IETF invites any interested party to bring to its attention any
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AI ELI5
On this page
PROBLEMMIB modules that need to store a language tag each defined their own representation, and the older shared one (LanguageTag from RFC 2932) had an outdated, less complete syntax description.
MECHANISMRFC 5131 defines the LangTag textual convention in its own small MIB module: a lowercase-only BCP 47 language tag stored as an octet string of 2 to 63 octets, or empty to mean no tag.
WHY IT MATTERSNew MIB modules should import LangTag instead of LanguageTag. The module defines no managed objects, so it has no security impact of its own.
§1Why a New Language Tag Type
RFC 5131 defines a textual convention named LangTag that represents a BCP 47 language tag. The intent is that other MIB modules import it, instead of defining their own representation.
It replaces the similar LanguageTag textual convention from RFC 2932, which some existing MIB modules still use. New MIB modules should use LangTag because its syntax description is current and more comprehensive, it is short enough to use as an index object without subtyping, and it lives in a dedicated MIB module that keeps module dependencies simple.
A new name was needed because changes in syntax and length cannot be applied to an existing textual convention.
The old label for language names was out of date and could not be fixed in place. So the authors made a new label with a new name, and asked everyone building new things to use it.
§2The Management Framework Context
Managed objects live in a virtual information store called the Management Information Base (MIB), and are usually accessed through the Simple Network Management Protocol (SNMP). Objects are defined with the Structure of Management Information (SMI).
This memo specifies a module that is compliant with SMIv2, described in RFC 2578, RFC 2579 and RFC 2580. For the wider picture of the Internet-Standard Management Framework, it points to section 7 of RFC 3410.
Think of a big shared filing cabinet that network tools use to read and set facts about devices. This document adds one new type of label to the cabinet's rulebook.
§3The LangTag Definition
The module is named LANGTAG-TC-MIB. Its LangTag type has the display hint 1a, status current, and the syntax OCTET STRING (SIZE (0 | 2..63)).
- Only lowercase characters are allowed, so that tags are unique when used as indexes. BCP 47 recommends case conventions for user interfaces, but objects using this type MUST use only lowercase.
- Values MUST be well-formed language tags as defined in BCP 47. An implementation MAY limit itself further to what a validating processor accepts.
- BCP 47 tags are in theory of unlimited length. This type is limited, and the text says the analysis of tag lengths in BCP 47 confirms the limit will not pose a problem in practice.
- A zero-length value is not a valid language tag. It can be used to express that a language tag is absent, for example in an index field.
The label must be written in small letters only, so that two spellings of the same language do not look like two different languages. An empty label means no language is given.
§4Security Considerations
The module defines no management objects. It defines only a textual convention that other MIB modules may import and use in their own object definitions.
The RFC states that meaningful security considerations can only be written in the MIB modules that define management objects. It therefore concludes that this document has no impact on the security of the Internet.
This document is only a label, not a thing you can poke at, so there is nothing here to attack. Any safety rules belong to the tools that use the label.
§5IANA Assignment
LANGTAG-TC-MIB is rooted under the mib-2 subtree. IANA assigned { mib-2 165 } to the module. The module identity is named langTagTcMIB, and its first and only revision is dated 9 November 2007.
IANA is like the registry office. It gave this new module its own spot, number 165, in the big numbered list of management modules.
§6References
[RFC2119]RFC 2119Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.March 1997[RFC2578]RFC 2578McCloghrie, K., Ed., Perkins, D., Ed., and J. Schoenwaelder, Ed., "Structure of Management Information Version 2 (SMIv2)", STD 58, RFC 2578, April 1999.April 1999[RFC2579]RFC 2579McCloghrie, K., Ed., Perkins, D., Ed., and J. Schoenwaelder, Ed., "Textual Conventions for SMIv2", STD 58, RFC 2579, April 1999.April 1999[RFC2580]RFC 2580McCloghrie, K., Perkins, D., and J. Schoenwaelder, "Conformance Statements for SMIv2", STD 58, RFC 2580, April 1999.April 1999[RFC4646]RFC 4646Phillips, A. and M. Davis, "Tags for Identifying Languages", BCP 47, RFC 4646, September 2006.September 2006[RFC2932]RFC 2932McCloghrie, K., Farinacci, D., and D. Thaler, "IPv4 Multicast Routing MIB", RFC 2932, October 2000.October 2000[RFC3410]RFC 3410Case, J., Mundy, R., Partain, D., and B. Stewart, "Introduction and Applicability Statements for Internet-Standard Management Framework", RFC 3410, December 2002.December 2002