Guidelines for Authors and Reviewers of YANG Data Model DocumentsYumaWorksandy@yumaworks.com
This memo provides guidelines for authors and reviewers
of Standards Track specifications containing YANG
data model modules. Applicable
portions may be used as a basis for reviews of other
YANG data model documents. Recommendations and
procedures are defined, which are intended to
increase interoperability and usability
of Network Configuration Protocol (NETCONF) implementations that utilize
YANG data model modules.
The standardization of network configuration interfaces for use
with the Network Configuration Protocol
requires a modular set of data models, which can be reused
and extended over time.
This document defines a set of usage guidelines for
Standards Track documents containing
data models. YANG is used to define
the data structures, protocol operations, and notification content
used within a NETCONF server. A server that supports a particular
YANG module will support client NETCONF operation requests,
as indicated by the specific content defined in the YANG module.
This document is similar to
the Structure of Management Information version 2 (SMIv2) usage guidelines
specification in intent and structure.
However, since that document was written a decade after
SMIv2 modules had been in use, it was published as a
'Best Current Practice' (BCP). This document is
not a BCP, but rather an informational reference,
intended to promote consistency in
documents containing YANG modules.
Many YANG constructs are defined as optional to use, such as
the description statement. However, in order to
maximize interoperability of NETCONF implementations
utilizing YANG data models, it is desirable to
define a set of usage guidelines that may require
a higher level of compliance than the minimum level
defined in the YANG specification.
In addition, YANG allows constructs such as infinite length
identifiers and string values, or top-level mandatory nodes,
that a compliant server is not required to support.
Only constructs that all servers are required to support
can be used in IETF YANG modules.
This document defines usage guidelines related to
the NETCONF operations layer and NETCONF
content layer, as defined in .
These guidelines are intended to be used by authors and
reviewers to improve the readability
and interoperability of published YANG data models.
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 language is used here to express the views of the NETMOD
working group regarding content for YANG modules. YANG modules complying
with this document will treat the RFC 2119 terminology as if it were
describing best current practices.
The following terms are defined in
and are not redefined here:
capabilities
client
operation
server
The following terms are defined in
and are not redefined here:
data node
module
namespace
submodule
version
YANG
YIN
Note that the term 'module' may be used as a generic term for a YANG module or submodule.
When describing properties that are specific to submodules,
the term 'submodule' is used instead.
The following terms are used throughout this document:
published: A stable release of a module or submodule, usually contained in an RFC.
unpublished: An unstable release of a module or submodule, usually contained in
an Internet-Draft.
YANG data model modules under review are likely to be contained in
Internet-Drafts. All guidelines for Internet-Draft authors MUST be
followed. The RFC Editor provides guidelines for authors of RFCs,
which are first published as Internet-Drafts. These guidelines
should be followed and are defined in and updated in
and "RFC Document Style" .
The following sections MUST be present in an Internet-Draft
containing a module:
Narrative sections
Definitions section
Security Considerations section
IANA Considerations section
References section
The module description statement MUST contain a reference to
the latest approved IETF Trust Copyright statement,
which is available online at:
Each YANG module or submodule contained within an Internet-Draft or RFC
is considered to be a code component. The strings '<CODE BEGINS>'
and '<CODE ENDS>' MUST be used to identify each code component.
The '<CODE BEGINS>' tag SHOULD be followed by a string identifying
the file name specified in Section 5.2 of .
The following example is for the '2010‑01‑18' revision
of the 'ietf‑foo' module:
A terminology section MUST be present if any terms are defined
in the document or if any terms are imported from other documents.
If YANG tree diagrams are used, then a sub-section explaining
the YANG tree diagram syntax MUST be present, containing the following text:
YANG tree diagrams provide a concise representation of a YANG
module, and SHOULD be included to help readers understand
YANG module structure. Tree diagrams MAY be split into sections
to correspond to document structure.
The following example shows a simple YANG tree diagram:
The narrative part MUST include an overview section that describes
the scope and field of application of the module(s) defined by the
specification and that specifies the relationship (if any) of these
modules to other standards, particularly to standards containing
other YANG modules. The narrative part SHOULD include one or more
sections to briefly describe the structure of the modules defined
in the specification.
If the module(s) defined by the specification imports definitions
from other modules (except for those defined in the
or documents), or are always implemented in
conjunction with other modules, then those facts MUST be noted in
the overview section, as MUST be noted any special
interpretations of definitions in other modules.
This section contains the module(s) defined by the specification.
These modules MUST be written using the YANG syntax defined in .
A YIN syntax version of the module MAY also be present in the document.
There MAY also be other types of modules present in the document,
such as SMIv2, which are not affected by these guidelines.
See for guidelines on YANG usage.
Each specification that defines one or more modules MUST contain a
section that discusses security considerations relevant to those
modules.
This section MUST be patterned after the latest approved
template (available at
http://trac.tools.ietf.org/area/ops/trac/wiki/yang-security-guidelines).
contains the security considerations template dated
2010-06-16. Authors MUST check the webpage at the URL listed above
in case there is a more recent version available.
In particular:
Writable data nodes that could be especially
disruptive if abused MUST be explicitly listed by name and the
associated security risks MUST be explained.
Readable data nodes that contain especially sensitive
information or that raise significant privacy concerns
MUST be explicitly listed by name and the reasons for
the sensitivity/privacy concerns MUST be explained.
Operations (i.e., YANG 'rpc' statements) that are potentially
harmful to system behavior or that raise significant
privacy concerns MUST be explicitly listed by name and
the reasons for the sensitivity/privacy concerns
MUST be explained.
In order to comply with IESG policy as set forth in
http://www.ietf.org/id-info/checklist.html, every Internet-Draft that is
submitted to the IESG for publication MUST contain an IANA
Considerations section. The requirements for this section vary
depending on what actions are required of the IANA. If there are no IANA
considerations applicable to the document, then the IANA
Considerations section stating that there are no actions is removed by
the RFC Editor before publication. Refer to the guidelines in
for more details.
If an Internet-Draft defines a new namespace that is to be
administered by the IANA, then the document MUST include an IANA
Considerations section that specifies how the namespace is to be
administered.
Specifically, if any YANG module namespace statement value contained
in the document is not already registered with IANA, then a
new YANG Namespace registry entry MUST be requested from the
IANA. The specification includes the procedure
for this purpose in its IANA Considerations section.
It is possible to extend an existing namespace using
a YANG submodule that belongs to an existing module
already administered by IANA.
In this case, the document containing the main module MUST be updated
to use the latest revision of the submodule.
For every import or include statement that appears in a
module contained
in the specification, which identifies a module in a separate document,
a corresponding normative reference to that document MUST
appear in the Normative References section. The reference MUST
correspond to the specific module version actually used within
the specification.
For every normative reference statement that appears
in a module contained
in the specification, which identifies a separate document,
a corresponding normative reference to that document SHOULD
appear in the Normative References section. The reference SHOULD
correspond to the specific document version actually used within
the specification. If the reference statement identifies an
informative reference, which identifies a separate document,
a corresponding informative reference to that document MAY
appear in the Informative References section.
In general, modules in IETF Standards Track specifications MUST
comply with all syntactic and semantic requirements of YANG .
The guidelines in this section are intended
to supplement the YANG specification, which is
intended to define a minimum set of conformance
requirements.
In order to promote interoperability and establish
a set of practices based on previous experience,
the following sections establish usage guidelines
for specific YANG constructs.
Only guidelines that clarify or restrict the
minimum conformance requirements are included here.
Modules contained in Standards Track documents
SHOULD be named according to the guidelines in
the IANA Considerations section of .
A distinctive word or acronym (e.g., protocol name
or working group acronym) SHOULD be used in the
module name. If new definitions are being defined
to extend one or more existing modules, then the same
word or acronym should be reused, instead of
creating a new one.
All published module names MUST be unique.
For a YANG module published in an RFC, this
uniqueness is guaranteed by IANA. For unpublished
modules, the authors need to check that no other
work in progress is using the same module name.
Once a module name is published, it MUST NOT be reused,
even if the RFC containing the module is reclassified
to 'Historic' status.
Identifiers for all YANG identifiers
in published modules MUST be between 1 and 64 characters in length.
These include any construct specified as an 'identifier‑arg‑str'
token in the ABNF in Section 12 of .
In general, it is suggested that substatements
containing very common default values SHOULD NOT be present.
The following substatements are commonly used
with the default value, which would make the
module difficult to read if used everywhere they are allowed.
StatementDefault Valueconfigtruemandatoryfalsemax-elementsunboundedmin-elements0ordered-bysystemstatuscurrentyin-elementfalse
A module may be conceptually partitioned in several
ways, using the 'if‑feature' and/or 'when' statements.
Data model designers need to carefully consider all
modularity aspects, including the use of YANG conditional
statements.
If a data definition is optional, depending on server support for
a NETCONF protocol capability, then a YANG 'feature'
statement SHOULD be defined to indicate that the NETCONF capability
is supported within the data model.
If any notification data, or any data definition, for a
non-configuration data node is not mandatory, then
the server may or may not be required to return
an instance of this data node. If any conditional requirements
exist for returning the data node in a notification payload
or retrieval request, they MUST be documented somewhere. For example,
a 'when' or 'if‑feature' statement could apply to the data node,
or the conditional requirements could be explained in
a 'description' statement within the data node or one of
its ancestors (if any).
This section describes guidelines for using the
XML Path Language (XPath)
within YANG modules.
The 'attribute' and 'namespace' axes are not supported in YANG,
and MAY be empty in a NETCONF server implementation.
The 'position' and 'last' functions SHOULD NOT be used.
This applies to implicit use of the 'position' function as well
(e.g., '//chapter[42]').
A server is only required to maintain the relative XML document order
of all instances of a particular user-ordered list or leaf-list.
The 'position' and 'last' functions MAY be used if they are evaluated
in a context where the context node is
a user-ordered 'list' or 'leaf‑list'.
The 'preceding', and 'following' axes SHOULD NOT be used.
These constructs rely on XML document order within a NETCONF server
configuration database, which may not be supported
consistently or produce reliable results across implementations.
Predicate expressions based on static node
properties (e.g., element name or value, 'ancestor' or
'descendant' axes) SHOULD be used instead.
The 'preceding' and 'following' axes MAY be used if
document order is not relevant to the outcome of the
expression (e.g., check for global uniqueness of a
parameter value).
The 'preceding‑sibling' and 'following‑sibling' axes
SHOULD NOT used.
A server is only required to maintain the relative XML document order
of all instances of a particular user-ordered list or leaf-list.
The 'preceding‑sibling' and 'following‑sibling'
axes MAY be used if they are evaluated
in a context where the context node is
a user-ordered 'list' or 'leaf‑list'.
Data nodes that use the 'int64' and 'uint64' built-in
type SHOULD NOT be used within numeric expressions.
There are boundary conditions in which the translation
from the YANG 64-bit type to an XPath number can cause
incorrect results. Specifically, an XPath 'double' precision
floating point number cannot represent very large positive
or negative 64-bit numbers because it only provides a total precision
of 53 bits. The 'int64' and 'uint64' data types MAY be
used in numeric expressions if the value can be represented
with no more than 53 bits of precision.
Data modelers need to be careful not to
confuse the YANG value space and the XPath
value space. The data types are not the same in both,
and conversion between YANG and XPath data types
SHOULD be considered carefully.
Explicit XPath data type conversions MAY be used
(e.g., 'string', 'boolean', or 'number' functions),
instead of implicit XPath data type conversions.
XPath expressions that contain a literal value representing
a YANG identity SHOULD always include the declared prefix of
the module where the identity is defined.
XPath expressions for 'when' statements MUST NOT reference
the context node or any descendant nodes of the context node.
The status statement MUST be present if its value
is 'deprecated' or 'obsolete'.
The module or submodule name MUST NOT be changed, once
the document containing the module or submodule is published.
The module namespace URI value MUST NOT be changed,
once the document containing the module is published.
The revision-date substatement within the imports
statement SHOULD be present if any
groupings are used from the external module.
The revision-date substatement within the include
statement SHOULD be present if any
groupings are used from the external submodule.
If submodules are used, then the document containing the
main module MUST be updated so that the main module
revision date is equal or more recent than the revision date
of any submodule that is (directly or indirectly) included by the main module.
For published modules, the namespace MUST
be a globally unique
URI, as defined in .
This value is usually assigned by the IANA.
The organization statement MUST be present.
If the module is contained in a document
intended for Standards Track status, then
the organization SHOULD be the IETF working group
chartered to write the document.
The contact statement MUST be present.
If the module is contained in a document
intended for Standards Track status, then
the working group web and mailing information
MUST be present, and the main document author or
editor contact information SHOULD be present.
If additional authors or editors exist,
their contact information MAY be present.
In addition, the Area Director and other contact
information MAY be present.
The description statement MUST be present.
The appropriate IETF Trust Copyright text MUST be present,
as described in .
If the module relies on information contained
in other documents, which are not the same
documents implied by the import statements
present in the module, then these documents
MUST be identified in the reference
statement.
A revision statement MUST be present for each published
version of the module. The revision statement MUST
have a reference substatement.
It MUST identify the published document that
contains the module.
Modules are often extracted from their original
documents, and it is useful for developers
and operators to know how to find the
original source document in a consistent manner.
The revision statement MAY have a description substatement.
Each new revision MUST include a revision date that
is higher than any other revision date in the module.
The revision date does not need to be updated if the
module contents do not change in the new document revision.
It is acceptable to reuse the
same revision statement within unpublished versions
(i.e., Internet-Drafts), but the revision date
MUST be updated to a higher value each time the
Internet-Draft is re-posted.
It is RECOMMENDED that only valid YANG modules be
included in documents, whether or not they are published yet.
This allows:
the module to compile correctly instead
of generating disruptive fatal errors.
early implementors to use the modules
without picking a random value for the XML namespace.
early interoperability testing since
independent implementations will use the same
XML namespace value.
Until a URI is assigned by the IANA, a proposed namespace URI
MUST be provided for the namespace statement in a YANG module.
A value SHOULD be selected that is not likely to collide with
other YANG namespaces. Standard module names, prefixes,
and URI strings already listed in the YANG Module Registry
MUST NOT be used.
A standard namespace statement value SHOULD have the
following form:
The following URN prefix string SHOULD be used for published
and unpublished YANG modules:
The following example URNs would be valid temporary namespace
statement values for Standards Track modules:
Note that a different URN prefix string SHOULD be used for non-Standards-Track
modules. The string SHOULD be selected according to the guidelines in .
The following examples of non-Standards-Track modules are only suggestions. There are no
guidelines for this type of URN in this document:
The top-level data organization SHOULD be considered carefully,
in advance. Data model designers need to consider how
the functionality for a given protocol or protocol family
will grow over time.
The separation of configuration data and operational state SHOULD
be considered carefully. It is often useful to define separate
top-level containers for configuration and non-configuration data.
There SHOULD only be one top-level data node defined
in each YANG module for all configuration data nodes,
if any configuration data nodes are defined at all.
There MAY be one top-level data node defined
in each YANG module for all non-configuration data nodes,
if any non-configuration data nodes are defined at all.
The names and data organization SHOULD reflect persistent
information, such as the name of a protocol. The name
of the working group SHOULD NOT be used because this
may change over time.
A mandatory database data definition is defined as
a node that a client must provide for the database
to be valid. The server is not required to provide a value.
Top-level database data definitions MUST NOT be mandatory.
If a mandatory node appears at the top level, it will
immediately cause the database to be invalid.
This can occur when the server boots or when a module
is loaded dynamically at runtime.
Selection of an appropriate data type (i.e., built-in
type, existing derived type, or new derived type)
is very subjective, and therefore few requirements
can be specified on that subject.
Data model designers SHOULD use the most appropriate
built-in data type for the particular application.
If extensibility of enumerated values is required,
then the 'identityref' data type SHOULD be used
instead of an enumeration or other built-in type.
For string data types, if a machine-readable pattern
can be defined for the desired semantics, then
one or more pattern statements SHOULD be present.
For string data types, if the length of the string
is required to be bounded in all implementations,
then a length statement MUST be present.
For numeric data types, if the values allowed
by the intended semantics are different than
those allowed by the unbounded intrinsic data
type (e.g., 'int32'), then a range statement SHOULD be present.
The signed numeric data types (i.e., 'int8',
'int16', 'int32', and 'int64') SHOULD NOT be used unless
negative values are allowed for the desired semantics.
For 'enumeration' or 'bits' data types, the semantics for
each 'enum' or 'bit' SHOULD be documented. A separate
description statement (within each 'enum' or 'bit'
statement) SHOULD be present.
If an appropriate derived type exists in any
standard module, such as ,
then it SHOULD be used instead of defining a new derived type.
If an appropriate units identifier can be associated
with the desired semantics, then a units statement
SHOULD be present.
If an appropriate default value can be associated
with the desired semantics, then a default statement
SHOULD be present.
If a significant number of derived types are defined,
and it is anticipated that these data types will be reused
by multiple modules, then these derived types SHOULD be
contained in a separate module or submodule, to allow
easier reuse without unnecessary coupling.
The description statement MUST be present.
If the type definition semantics are defined
in an external document (other than another
YANG module indicated by an import
statement), then the reference
statement MUST be present.
The description statement MUST be present in the following
YANG statements:
anyxml
augment
choice
container
extension
feature
grouping
identity
leaf
leaf-list
list
notification
rpc
typedef
If the data definition semantics are defined in an external document,
(other than another
YANG module indicated by an import
statement), then a reference statement MUST be present.
The 'anyxml' construct may be useful to represent an HTML banner
containing
markup elements, such as '<b>' and '</b>',
and MAY be used in such cases. However, this construct
SHOULD NOT be used if other YANG data node types can be used instead
to represent the desired syntax and semantics.
If there are referential integrity constraints associated
with the desired semantics that
can be represented with XPath, then one or more
'must' statements SHOULD be present.
For list and leaf-list data definitions, if the number of possible instances
is required to be bounded for all implementations,
then the max-elements statements SHOULD be present.
If any 'must' or 'when' statements are used within the
data definition, then the data definition description statement
SHOULD describe the purpose of each one.
If the operation semantics are defined in an external document
(other than another YANG module indicated by an import
statement), then a reference statement MUST be present.
If the operation impacts system behavior in some way,
it SHOULD be mentioned in the description statement.
If the operation is potentially harmful to system
behavior in some way,
it MUST be mentioned in the Security Considerations
section of the document.
The description statement MUST be present.
If the notification semantics are defined in an external document
(other than another YANG module indicated by an import
statement), then a reference statement MUST be present.
This document registers one URI in the IETF XML registry .
The following registration has been made:
Per this document, the following assignment has been made in the YANG Module
Names Registry for the YANG module template in .
FieldValueNameietf-templateNamespaceurn:ietf:params:xml:ns:yang:ietf-templatePrefixtempReferenceRFC XXXX
This document defines documentation guidelines for
NETCONF content defined with the YANG data modeling
language. The guidelines for how to write a
Security Considerations section for a YANG module
are defined in the online document
http://trac.tools.ietf.org/area/ops/trac/wiki/yang-security-guidelines
This document does not introduce
any new or increased security risks into
the management system.
The following section contains the security considerations
template dated 2010-06-16. Be sure to check the webpage
at the URL listed above in case there is a more recent
version available.
Each specification that defines one or more YANG
modules MUST contain a section that discusses
security considerations relevant to those modules.
This section MUST be patterned after the latest
approved template (available at
In particular, writable data nodes that could
be especially disruptive if abused MUST be
explicitly listed by name and the associated
security risks MUST be spelled out.
Similarly, readable data nodes that contain
especially sensitive information or that raise
significant privacy concerns MUST be explicitly
listed by name and the reasons for the
sensitivity/privacy concerns MUST be explained.
Further, if new RPC operations have been defined,
then the security considerations of each new
RPC operation MUST be explained.
X. Security Considerations
The YANG module defined in this memo is designed to be accessed
via the NETCONF protocol [RFC6241]. The lowest NETCONF layer is
the secure transport layer and the mandatory-to-implement secure
transport is SSH [RFC6242].
There are a number of data nodes defined in this YANG module
which are writable/creatable/deletable (i.e., config true, which
is the default). These data nodes may be considered sensitive
or vulnerable in some network environments. Write operations
(e.g., edit-config) to these data nodes without proper protection
can have a negative effect on network operations. These are
the subtrees and data nodes and their sensitivity/vulnerability:
Some of the readable data nodes in this YANG module may be
considered sensitive or vulnerable in some network environments.
It is thus important to control read access (e.g., via get,
get-config, or notification) to these data nodes. These are the
subtrees and data nodes and their sensitivity/vulnerability:
Some of the RPC operations in this YANG module may be considered
sensitive or vulnerable in some network environments. It is thus
important to control access to these operations. These are the
operations and their sensitivity/vulnerability:
The structure and contents of this document are adapted from ,
guidelines for MIB Documents, by C. M. Heard.
The working group thanks Martin Bjorklund, Juergen
Schoenwaelder, and Ladislav Lhotka for their
extensive reviews and contributions to this document.
The following changes have been made to the guidelines published in :
Updated NETCONF reference from RFC 4741 to RFC 6241
Updated NETCONF over SSH citation from RFC 4742 to RFC 6242
Updated YANG Types reference from RFC 6021 to RFC 6991
Updated obsolete URLs for IETF resources
Changed top-level data node guideline
Clarified XPath usage for a literal value representing a YANG identity
Clarified XPath usage for a when-stmt
Added terminology guidelines
Added YANG tree diagram guideline
Key words for use in RFCs to Indicate Requirement LevelsHarvard UniversityIn many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents.Instructions to RFC AuthorsUSC/Information Sciences Institute4676 Admiralty WayMarina del ReyCA 90292+1 310-822-1511+1 310-823-6714Postel@ISI.EDUUSC/Information Sciences Institute4676 Admiralty WayMarina del ReyCA 90292+1 310-822-1511+1 310-823-6714jkrey@isi.edu
General
RFC authorsThe IETF XML RegistryThis document describes an IANA maintained registry for IETF standards which use Extensible Markup Language (XML) related items such as Namespaces, Document Type Declarations (DTDs), Schemas, and Resource Description Framework (RDF) Schemas.Uniform Resource Identifier (URI): Generic SyntaxWorld Wide Web ConsortiumMassachusetts Institute of Technology77 Massachusetts AvenueCambridgeMA02139USA+1-617-253-5702+1-617-258-5999timbl@w3.orghttp://www.w3.org/People/Berners-Lee/Day Software5251 California Ave., Suite 110IrvineCA92617USA+1-949-679-2960+1-949-679-2972fielding@gbiv.comhttp://roy.gbiv.com/Adobe Systems Incorporated345 Park AveSan JoseCA95110USA+1-408-536-3024LMM@acm.orghttp://larry.masinter.net/
Applications
uniform resource identifierURIURLURNWWWresource
A Uniform Resource Identifier (URI) is a compact sequence of characters
that identifies an abstract or physical resource. This specification
defines the generic URI syntax and a process for resolving URI references
that might be in relative form, along with guidelines and security
considerations for the use of URIs on the Internet.
The URI syntax defines a grammar that is a superset of all valid URIs,
allowing an implementation to parse the common components of a URI
reference without knowing the scheme-specific requirements of every
possible identifier. This specification does not define a generative
grammar for URIs; that task is performed by the individual
specifications of each URI scheme.
Rights Contributors Provide to the IETF TrustThe IETF policies about rights in Contributions to the IETF are designed to ensure that such Contributions can be made available to the IETF and Internet communities while permitting the authors to retain as many rights as possible. This memo details the IETF policies on rights in Contributions to the IETF. It also describes the objectives that the policies are designed to meet. This memo obsoletes RFCs 3978 and 4748 and, with BCP 79 and RFC 5377, replaces Section 10 of RFC 2026. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements.RFC Streams, Headers, and BoilerplatesIABRFC documents contain a number of fixed elements such as the title page header, standard boilerplates, and copyright/IPR statements. This document describes them and introduces some updates to reflect current usage and requirements of RFC publication. In particular, this updated structure is intended to communicate clearly the source of RFC creation and review. This document is not an Internet Standards Track specification; it is published for informational purposes.YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)YANG is a data modeling language used to model configuration and state data manipulated by the Network Configuration Protocol (NETCONF), NETCONF remote procedure calls, and NETCONF notifications. [STANDARDS TRACK]Network Configuration Protocol (NETCONF)Common YANG Data TypesThis document introduces a collection of common data types to be used with the YANG data modeling language. This document obsoletes RFC 6021.XML Path Language (XPath) Version 1.0Guidelines for Authors and Reviewers of MIB DocumentsThis memo provides guidelines for authors and reviewers of IETF standards-track specifications containing MIB modules. Applicable portions may be used as a basis for reviews of other MIB documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements.Guidelines for Writing an IANA Considerations Section in RFCsMany 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 Authority (IANA).</t><t> In order for IANA to manage a given namespace 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 namespace, 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 namespace and provides guidelines for authors on the specific text that must be included in documents that place demands on IANA.</t><t> This document obsoletes RFC 2434. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements.Guidelines for Authors and Reviewers of YANG Data Model DocumentsThis memo provides guidelines for authors and reviewers of Standards Track specifications containing YANG data model modules. Applicable portions may be used as a basis for reviews of other YANG data model documents. Recommendations and procedures are defined, which are intended to increase interoperability and usability of Network Configuration Protocol (NETCONF) implementations that utilize YANG data model modules. This document is not an Internet Standards Track specification; it is published for informational purposes.RFC Document Style
This section is adapted from RFC 4181.
The purpose of a YANG module review is to review
the YANG module both for technical correctness and
for adherence to IETF documentation requirements.
The following checklist may be helpful when reviewing
an Internet-Draft:
I-D Boilerplate -- verify that the draft contains the required
Internet-Draft boilerplate (see
http://www.ietf.org/id-info/guidelines.html), including the
appropriate statement to permit publication as an RFC, and that
I-D boilerplate does not contain references or section numbers.
Abstract -- verify that the abstract does not contain references,
that it does not have a section number, and that its content follows
the guidelines in http://www.ietf.org/id-info/guidelines.html.
Copyright Notice -- verify that the draft has the appropriate
text regarding the rights that document contributers provide to
the IETF Trust . Verify that it contains the
full IETF Trust copyright notice at the beginning of the document.
The IETF Trust Legal Provisions (TLP) can be found at:
Security Considerations section -- verify that the draft uses the
latest approved template from the OPS area website
(http://trac.tools.ietf.org/area/ops/trac/wiki/yang-security-guidelines)
and that the guidelines therein have been followed.
IANA Considerations section -- this section must always be
present. For each module within the document, ensure that the
IANA Considerations section contains entries
for the following IANA registries:
References -- verify that the references are properly divided
between normative and informative references, that RFC 2119 is
included as a normative reference if the terminology defined therein
is used in the document, that all references required by the
boilerplate are present, that all YANG modules containing imported
items are cited as normative references, and that all citations point
to the most current RFCs unless there is a valid reason to do
otherwise (for example, it is OK to include an informative reference
to a previous version of a specification to help explain a feature
included for backward compatibility). Be sure citations for all
imported modules are present somewhere in the document
text (outside the YANG module).
License -- verify that the draft contains the Simplified BSD
License in each YANG module or submodule. Some guidelines
related to this requirement are described in
.
Make sure that the correct year is used in all
copyright dates. Use
the approved text from the latest Trust Legal Provisions (TLP)
document, which can be found at:
Other Issues -- check for any issues mentioned
in http://www.ietf.org/id-info/checklist.html
that are not covered elsewhere.
Technical Content -- review the actual technical content for
compliance with the guidelines in this document. The use of a YANG
module compiler is recommended when checking for syntax errors.
A list of freely available tools and other information can be found at: