YANG Schema Item iDentifier (YANG SID)
draft-ietf-core-sid-19
| Document | Type | Active Internet-Draft (core WG) | |
|---|---|---|---|
| Authors | Michel Veillette , Alexander Pelov , Ivaylo Petrov , Carsten Bormann , Michael Richardson | ||
| Last updated | 2022-07-26 | ||
| Replaces | draft-somaraju-core-sid | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Intended RFC status | Proposed Standard | ||
| Formats | |||
| Yang Validation | 0 errors, 0 warnings | ||
| Reviews |
GENART Last Call review
(of
-15)
Not Ready
YANGDOCTORS Last Call review
(of
-15)
Ready with Nits
SECDIR Last Call Review
Incomplete, due 2021-03-17
OPSDIR Last Call Review
Incomplete, due 2021-03-17
|
||
| Additional resources |
Working Group Repo
Yang catalog entry for ietf-sid-file@2020-02-05.yang Yang impact analysis for draft-ietf-core-sid Mailing list discussion |
||
| Stream | WG state | Submitted to IESG for Publication | |
| Document shepherd | Jaime Jimenez | ||
| Shepherd write-up | Show Last changed 2021-06-22 | ||
| IESG | IESG state | IESG Evaluation::AD Followup | |
| Action Holder | |||
| Consensus boilerplate | Yes | ||
| Telechat date |
(None)
Has a DISCUSS. Needs one more YES or NO OBJECTION position to pass. |
||
| Responsible AD | Francesca Palombini | ||
| Send notices to | Carsten Bormann <cabo@tzi.org>, jaime@iki.fi | ||
| IANA | IANA review state | Version Changed - Review Needed | |
| IANA expert review state | Expert Reviews OK | ||
| IANA expert review comments | Expert comments: the CoAP Content-Format registration has been moved to draft-ietf-core-yang-cbor. No issues with either document. |
draft-ietf-core-sid-19
Internet Engineering Task Force M. V. Veillette, Ed.
Internet-Draft Trilliant Networks Inc.
Intended status: Standards Track A. P. Pelov, Ed.
Expires: 27 January 2023 Acklio
I. Petrov, Ed.
Google Switzerland GmbH
C. Bormann
Universität Bremen TZI
M. Richardson
Sandelman Software Works
26 July 2022
YANG Schema Item iDentifier (YANG SID)
draft-ietf-core-sid-19
Abstract
YANG Schema Item iDentifiers (YANG SID) are globally unique 63-bit
unsigned integers used to identify YANG items, as a more compact
method to identify YANG items that can be used for efficiency and in
constrained environments (RFC 7228). This document defines the
semantics, the registration, and assignment processes of YANG SIDs
for IETF managed YANG modules. To enable the implementation of these
processes, this document also defines a file format used to persist
and publish assigned YANG SIDs.
// The present version (-19) adds in draft text about objectives,
// parties, and roles. This attempts to record discussions at side
// meetings before, at, and after IETF 113.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 27 January 2023.
Veillette, et al. Expires 27 January 2023 [Page 1]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Terminology and Notation . . . . . . . . . . . . . . . . 4
2. Objectives . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1. Technical Objectives . . . . . . . . . . . . . . . . . . 6
2.2. Module evolution, versioning . . . . . . . . . . . . . . 7
2.3. Solution Components and Derived Objectives . . . . . . . 7
2.4. Parties and Roles . . . . . . . . . . . . . . . . . . . . 8
3. ".sid" file lifecycle . . . . . . . . . . . . . . . . . . . . 10
4. ".sid" file format . . . . . . . . . . . . . . . . . . . . . 11
5. Security Considerations . . . . . . . . . . . . . . . . . . . 18
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18
6.1. YANG Namespace Registration . . . . . . . . . . . . . . . 18
6.2. Register ".sid" File Format Module . . . . . . . . . . . 19
6.3. Create new IANA Registry: "YANG SID Mega-Range"
registry . . . . . . . . . . . . . . . . . . . . . . . . 19
6.3.1. Structure . . . . . . . . . . . . . . . . . . . . . . 19
6.3.2. Allocation policy . . . . . . . . . . . . . . . . . . 20
6.3.2.1. First allocation . . . . . . . . . . . . . . . . 20
6.3.2.2. Consecutive allocations . . . . . . . . . . . . . 21
6.3.3. Initial contents of the Registry . . . . . . . . . . 21
6.4. Create a new IANA Registry: IETF YANG SID Range Registry
(managed by IANA) . . . . . . . . . . . . . . . . . . . . 21
6.4.1. Structure . . . . . . . . . . . . . . . . . . . . . . 21
6.4.2. Allocation policy . . . . . . . . . . . . . . . . . . 21
6.4.3. Publication of the ".sid" file . . . . . . . . . . . 23
6.4.4. Initial contents of the registry . . . . . . . . . . 23
6.5. Create new IANA Registry: "IETF YANG SID Registry" . . . 25
6.5.1. Structure . . . . . . . . . . . . . . . . . . . . . . 25
6.5.2. Allocation policy . . . . . . . . . . . . . . . . . . 25
6.5.3. Recursive Allocation of YANG SID Range at Document
Adoption . . . . . . . . . . . . . . . . . . . . . . 26
6.5.4. Initial contents of the registry . . . . . . . . . . 27
Veillette, et al. Expires 27 January 2023 [Page 2]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 27
7.1. Normative References . . . . . . . . . . . . . . . . . . 27
7.2. Informative References . . . . . . . . . . . . . . . . . 28
Appendix A. ".sid" file example . . . . . . . . . . . . . . . . 30
Appendix B. SID auto generation . . . . . . . . . . . . . . . . 39
Appendix C. ".sid" file lifecycle . . . . . . . . . . . . . . . 41
C.1. ".sid" File Creation . . . . . . . . . . . . . . . . . . 41
C.2. ".sid" File Update . . . . . . . . . . . . . . . . . . . 42
Appendix D. Keeping a SID File in a YANG Instance Data file . . 43
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 44
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 44
1. Introduction
Some of the items defined in YANG [RFC7950] require the use of a
unique identifier. In both Network Configuration Protocol (NETCONF)
[RFC6241] and RESTCONF [RFC8040], these identifiers are implemented
using names. To allow the implementation of data models defined in
YANG in constrained devices [RFC7228] and constrained networks, a
more compact method to identify YANG items is required. This compact
identifier, called YANG Schema Item iDentifier or YANG SID (or simply
SID in this document and when the context is clear), is encoded using
a 63-bit unsigned integer. The limitation to 63-bit unsigned
integers allows SIDs to be manipulated more easily on platforms that
might otherwise lack 64-bit unsigned arithmetic. The loss of a
single bit of range is not significant given the size of the
remaining space.
The following items are identified using SIDs:
* identities
* data nodes (Note: including those nodes defined by the 'yang-data'
extension.)
* remote procedure calls (RPCs) and associated input(s) and
output(s)
* actions and associated input(s) and output(s)
* notifications and associated information
* YANG modules and features
It is possible that some protocols use only a subset of the assigned
SIDs, for example, for protocols equivalent to NETCONF [RFC6241] like
[I-D.ietf-core-comi] the transportation of YANG module SIDs might be
Veillette, et al. Expires 27 January 2023 [Page 3]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
unnecessary. Other protocols might need to be able to transport this
information, for example protocols related to discovery such as
Constrained YANG Module Library [I-D.ietf-core-yang-library].
SIDs are globally unique integers. A registration system is used in
order to guarantee their uniqueness. SIDs are registered in blocks
called "SID ranges". SIDs are assigned permanently. Items
introduced by a new revision of a YANG module are added to the list
of SIDs already assigned. This is discussed in more detail in
Section 2.
Assignment of SIDs to YANG items is usually automated as discussed in
Appendix B, which also discusses some cases where manual
interventions may be appropriate.
Section 3 provides more details about the registration process of
YANG modules and associated SIDs. To enable the implementation of
this registry, Section 4 defines a standard file format used to store
and publish SIDs.
IETF managed YANG modules that need to allocate SIDs use the IANA
mechanism specified in this document. YANG modules created by other
parties allocate SID ranges using the IANA allocation mechanisms via
Mega-Ranges (see Section 6.3); within the Mega-Range allocation,
those other parties are free to make up their own mechanism.
Among other uses, YANG SIDs are particularly useful to obtain a
compact encoding for YANG-CBOR [RFC9254]. At the time of writing, a
tool for automated ".sid" file generation is available as part of the
open-source project PYANG [PYANG].
1.1. Terminology and Notation
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
The following terms are defined in [RFC7950]:
* action
* feature
* module
* notification
Veillette, et al. Expires 27 January 2023 [Page 4]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
* RPC
* schema node
* schema tree
* submodule
The following term is defined in [RFC8040]:
* yang-data extension
This specification also makes use of the following terminology:
* item: A schema node, an identity, a module, or a feature defined
using the YANG modeling language.
* schema-node path: A schema-node path is a string that identifies a
schema node within the schema tree. A path consists of the list
of consecutive schema node identifier(s) separated by slashes
("/"). Schema node identifier(s) are always listed from the top-
level schema node up to the targeted schema node and could contain
namespace information. (e.g. "/ietf-system:system-state/clock/
current-datetime")
* Namespace-qualified form - a schema node identifier is prefixed
with the name of the module in which the schema node is defined,
separated from the schema node identifier by the colon character
(":").
* YANG Schema Item iDentifier (YANG SID or simply SID): Unsigned
integer used to identify different YANG items.
2. Objectives
The overriding objective of the SID assignment and registration
system is to ensure global interoperability of protocols that employ
SIDs in order to communicate about data modeled in YANG. This
objective poses certain requirements on the stability of SIDs while
at the same time not hindering active evolution of the YANG modules
the SIDs are intended to support.
Additional objectives include:
* enabling the developer of a YANG module to also be the originating
entity for the SIDs pertaining to that module.
* making it easy for YANG developers to obtain SIDs.
Veillette, et al. Expires 27 January 2023 [Page 5]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
* enabling other developers to define SIDs for a module where the
developer of the module is not interesting in assigning the SIDs.
* keeping an assignment regime that keeps short (2..4 byte) SIDs
readily available for the applications that would benefit from
them while at the same time employing the vast 63-bit SID space to
facilitate permissionless actions.
* enabling multiple entities to provide services that support the
assignment of SIDs.
* maintaining some locality in the assignment of SIDs so the
efficiencies of the SID delta mechanism can be fully employed.
* enabling various software components to deal in terms of SIDs
without having complete information about other parties in the
communication process.
While IANA ultimately maintains the registries that govern SIDs for
IETF-defined modules, various support tools such as yangcatalog.org
need to provide the support to enable SID assignment and use for
modules still in IETF development. Developers of open-source or
proprietary YANG modules also need to be able to serve as such
entities autonomously, possibly forming alliances independent of the
IETF, while still fitting in the overall SID number space managed by
IANA. Obviously, this process has a number of parallels to the
management of IP addresses, but also is very different.
2.1. Technical Objectives
As discussed in the introduction, SIDs are intended as globally
unique (unsigned) integers.
Specifically, this means that:
*Objective 1* (MUST): any 63-bit unsigned integer is either
unassigned as a SID or immutably maps to EXACTLY one YANG name.
Only the transition from unassigned to that immutable mapping is
defined.
This enables a recipient of a data structure employing SIDs to
translate them into the globally meaningful YANG names that the
existing encodings of YANG data such as YANG-XML [RFC7950] and YANG-
JSON [RFC7951] employ today.
Veillette, et al. Expires 27 January 2023 [Page 6]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
The term YANG name is not defined outside this document, and YANG has
a complex system of names and entities that can have those names.
Instead of defining the term technically, this set of objectives uses
it in such a way that the overall objectives of YANG-SID can be
achieved.
A desirable objective is that:
*Objective 2* (SHOULD): any YANG name in active use has one SID
assigned.
This means that:
1. There should not be YANG names without SIDs assigned
2. YANG names should not have multiple SIDs assigned
These objectives are unattainable in full, because YANG names are not
necessarily born with a SID assignment, and because entirely
autonomous entities might decide to assign SIDs for the same YANG
name like ships in the night. Note that as long as this autonomy is
maintained, any single observer will have the impression that
Objective 2 is attained. Only when entities that have acted
autonomously start communicating, a deviation is observed.
2.2. Module evolution, versioning
YANG modules evolve. The technical objectives listed above are
states in terms that are independent of this evolution.
However, some modules are still in a very fluid state, and the
assignment of permanent SIDs to the YANG names created in them is
less desirable. This is not only true for new modules, but also for
emerging new revisions of existing stable modules.
*Objective 3* (MUST): the SID management system is independent from
any module versioning.
2.3. Solution Components and Derived Objectives
A registration system is used in order to guarantee the uniqueness of
SIDs. To be able to provide some autonomy in allocation (and avoid
information disclosure where it is not desirable), SIDs are
registered in blocks called "SID ranges".
SIDs are assigned permanently.
Veillette, et al. Expires 27 January 2023 [Page 7]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
Items introduced by a new revision of a YANG module are added to the
list of SIDs already assigned.
2.4. Parties and Roles
In the YANG development process, we can discern a number of parties
that are concerned with a YANG module:
module controller:
The owner of the YANG module, i.e., the controller about its
evolution.
registration entity:
The controller of the module namespace, specifically also of the
prefixes that are in common use. (This is not a required party.)
module repository:
An entity that supplies modules to module users. This can be
"official" (e.g., IANA for IETF modules) or unofficial (e.g.,
yangcatalog.org). Not all repositories are in a position to act
as a registry, i.e., as a permanent record for the information
they supply; these repositories need to recur to module owners as
a stable source.
module user:
An entity that uses a module, after obtaining it from the module
controller or a module repository.
This set of parties needs to evolve to take on the additional roles
that the SID assignment process requires:
SID assigner:
An entity that assigns SIDs for a module. Objective 2 requires
that there is only one SID assigner for each module. SID
assigners preferably stay the same over a module development
process; however this specification provides SID files to ensure
an organized handover.
SID range registries:
The entities that supply a SID assigner with SID ranges that they
can use in assigning SIDs for a module. (In this specification,
there is a structure with mega-ranges and individual SID ranges;
this is not relevant here.)
SID repository:
An entity that supplies SID assignments to SID users, usually in
the form of a SID file.
Veillette, et al. Expires 27 January 2023 [Page 8]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
SID users:
The module user that uses the SIDs provided by a SID assigner for
a YANG module. SID users need to find SID assigners (or at least
their SID assignments).
During the introduction of SIDs, the distribution of the SID roles to
the existing parties for a YANG module will evolve.
The desirable end state of this evolution is:
+====================+======================================+
| Role | Party |
+====================+======================================+
| SID assigner | module developer |
+--------------------+--------------------------------------+
| SID range registry | (as discussed in this specification) |
+--------------------+--------------------------------------+
| SID repository | module repository |
+--------------------+--------------------------------------+
| SID user | module user (naturally) |
+--------------------+--------------------------------------+
Table 1
This grouping of roles and parties puts the module developer into a
position where it can achieve the objectives laid out in this section
(a "type-1", "SID-guiding" module controller). (While a third party
might theoretically assign additional SIDs and conflict with
objective 2, there is very little reason to do so if SID files are
always provided by the module developer with the module.)
The rest of this section is concerned with the transition to this end
state.
For existing modules, there is no SID file. The entity that stands
in as the SID assigner is not specified. This situation has the
highest potential of a conflict with objective 2.
Similarly, for new module development, the module owner may not have
heard about SIDs or not be interested in assigning them (e.g.,
because of lack of software or procedures within their organization).
For these two cases (which we will call type-3, "SID-oblivious"
module controller), module repositories can act as a mediator, giving
SID users access to a SID assigner that is carefully chosen to be a
likely choice by other module repositories as well, maximizing the
likelihood of achieving objective 2.
Veillette, et al. Expires 27 January 2023 [Page 9]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
If the module controller has heard about SIDs, but is not assigning
them yet, it can designate a SID assigner instead. This can lead to
a stable, unique set of SID assignments being provided indirectly by
a (type-2, "SID-aware") module developer. Entities offering
designated SID assigner services could make these available in an
easy-to-use way, e.g., via a Web interface.
The entity acting as a SID assigner minimally needs to record the SID
range it uses for the SID assignment. If the SID range registry can
record the module name and revision, and the assignment processes
(including the software used) are stable, the SID assigner can
theoretically reconstruct its assignments, but this is an invitation
for implementation bugs.
SID assigners attending to a module in development (not yet stable)
need to decide whether SIDs for a new revision are re-assigned from
scratch ("clean-slate") or use existing assignments from a previous
revision as a base, only assigning new SIDs for new names. Once a
module is declared stable, its SID assignments SHOULD be declared
stable as well (the exception being that, for existing YANG modules,
some review may be needed before this is done).
This specification does not further discuss how mediating entities
such as designated SID assigners or SID repositories could operate;
instead, it supplies objectives for their operation.
3. ".sid" file lifecycle
YANG is a language designed to model data accessed using one of the
compatible protocols (e.g. NETCONF [RFC6241], RESTCONF [RFC8040] and
CORECONF [I-D.ietf-core-comi]). A YANG module defines hierarchies of
data, including configuration, state data, RPCs, actions and
notifications.
Many YANG modules are not created in the context of constrained
applications. YANG modules can be implemented using NETCONF
[RFC6241] or RESTCONF [RFC8040] without the need to assign SIDs.
As needed, authors of YANG modules can assign SIDs to their YANG
modules. In order to do that, they should first obtain a SID range
from a registry and use that range to assign or generate SIDs to
items of their YANG module. The assignments can then be stored in a
".sid" file. For example on how this could be achieved, please refer
to Appendix C.
Registration of the ".sid" file associated to a YANG module is
optional but recommended to promote interoperability between devices
and to avoid duplicate allocation of SIDs to a single YANG module.
Veillette, et al. Expires 27 January 2023 [Page 10]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
Different registries might have different requirements for the
registration and publication of the ".sid" files. For a diagram of
one of the possibilities, please refer to the activity diagram on
Figure 4 in Appendix C.
Each time a YANG module or one of its imported module(s) or included
sub-module(s) is updated, a new ".sid" file MAY be created if the new
or updated items will need SIDs. All the SIDs present in the
previous version of the ".sid" file MUST be present in the new
version as well. The creation of this new version of the ".sid" file
SHOULD be performed using an automated tool.
If a new revision requires more SIDs than initially allocated, a new
SID range MUST be added to the 'assignment-range' as defined in
Section 4. These extra SIDs are used for subsequent assignments.
For an example of this update process, see activity diagram Figure 5
in Appendix C.
4. ".sid" file format
".sid" files are used to persist and publish SIDs assigned to the
different YANG items of a specific YANG module. It has the following
structure.
module: ietf-sid-file
structure sid-file:
+-- module-name yang:yang-identifier
+-- module-revision? revision-identifier
+-- sid-file-version? sid-file-version-identifier
+-- description? string
+-- dependency-revision* [module-name]
| +-- module-name yang:yang-identifier
| +-- module-revision revision-identifier
+-- assignment-range* [entry-point]
| +-- entry-point sid
| +-- size uint64
+-- item* [namespace identifier]
+-- namespace enumeration
+-- identifier union
+-- sid sid
Figure 1: YANG tree for ietf-sid-file
Veillette, et al. Expires 27 January 2023 [Page 11]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
The following YANG module defines the structure of this file,
encoding is performed in JSON [RFC8259] using the rules defined in
[RFC7951]. It references ietf-yang-types defined in [RFC6991] and
ietf-restconf defined in [RFC8040].
RFC Ed.: please update the date of the module and Copyright if needed
and remove this note.
<CODE BEGINS> file "ietf-sid-file@2021-11-16.yang"
module ietf-sid-file {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-sid-file";
prefix sid;
import ietf-yang-types {
prefix yang;
reference "RFC 6991: Common YANG Data Types.";
}
import ietf-yang-structure-ext {
prefix sx;
reference "RFC 8791: YANG Data Structure Extensions.";
}
organization
"IETF Core Working Group";
contact
"WG Web: <https://datatracker.ietf.org/wg/core/>
WG List: <mailto:core@ietf.org>
Editor: Michel Veillette
<mailto:michel.veillette@trilliant.com>
Editor: Andy Bierman
<mailto:andy@yumaworks.com>
Editor: Alexander Pelov
<mailto:a@ackl.io>
Editor: Ivaylo Petrov
<mailto:ivaylopetrov@google.com>";
description
"Copyright (c) 2021 IETF Trust and the persons identified as
authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with or
Veillette, et al. Expires 27 January 2023 [Page 12]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
without modification, is permitted pursuant to, and subject to
the license terms contained in, the Simplified BSD License set
forth in Section 4.c of the IETF Trust's Legal Provisions
Relating to IETF Documents
(https://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX
(https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself
for full legal notices.
The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL
NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'NOT RECOMMENDED',
'MAY', and 'OPTIONAL' in this document are to be interpreted as
described in BCP 14 (RFC 2119) (RFC 8174) when, and only when,
they appear in all capitals, as shown here.
This module defines the structure of the .sid files.
Each .sid file contains the mapping between each
string identifier defined by a YANG module and a
corresponding numeric value called YANG SID.";
revision 2021-11-16 {
description
"Initial revision.";
reference
"[RFC XXXX] YANG Schema Item iDentifier (YANG SID)";
}
typedef revision-identifier {
type string {
pattern '\d{4}-\d{2}-\d{2}';
}
description
"Represents a date in YYYY-MM-DD format.";
}
typedef sid-file-version-identifier {
type uint32;
description
"Represents the version of a .sid file.";
}
typedef sid {
type uint64 {
range "0..9223372036854775807";
}
description
Veillette, et al. Expires 27 January 2023 [Page 13]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
"YANG Schema Item iDentifier";
reference
"[RFC XXXX] YANG Schema Item iDentifier (YANG SID)";
}
typedef schema-node-path {
type string {
pattern
'/[a-zA-Z_][a-zA-Z0-9\-_.]*:[a-zA-Z_][a-zA-Z0-9\-_.]*' +
'(/[a-zA-Z_][a-zA-Z0-9\-_.]*(:[a-zA-Z_][a-zA-Z0-9\-_.]*)?)*';
}
description
"A schema-node path is an absolute YANG schema node identifier
as defined by the YANG ABNF rule absolute-schema-nodeid,
except that module names are used instead of prefixes.
This string additionally follows the following rules:
o The leftmost (top-level) data node name is always in the
namespace-qualified form.
o Any subsequent schema node name is in the
namespace-qualified form if the node is defined in a module
other than its parent node, and the simple form is used
otherwise. No predicates are allowed.";
reference
"RFC 7950, The YANG 1.1 Data Modeling Language;
Section 6.5: Schema Node Identifier;";
}
sx:structure sid-file {
uses sid-file-contents;
}
grouping sid-file {
description "A grouping that contains a YANG container
representing the file structure of a .sid files.";
container sid-file {
description
"A Wrapper container that together with the rc:yang-data
extension marks the YANG data structures inside as not being
intended to be implemented as part of a configuration
datastore or as an operational state within the server.";
uses sid-file-contents;
}
}
grouping sid-file-contents {
Veillette, et al. Expires 27 January 2023 [Page 14]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
description
"A grouping that defines the contents of a container that
represente the file structure of a .sid files.";
leaf module-name {
type yang:yang-identifier;
mandatory true;
description
"Name of the YANG module associated with this .sid file.";
}
leaf module-revision {
type revision-identifier;
description
"Revision of the YANG module associated with this .sid
file.
This leaf is not present if no revision statement is
defined in the YANG module.";
}
leaf sid-file-version {
type sid-file-version-identifier;
default 0;
description
"Optional leaf that specifies the version number of the
.sid file. .sid files and the version sequence are
specific to a given YANG module revision. This number
starts at zero when there is a new YANG module revision and
increases monotonically. This number can distinguish
updates to the .sid file which are the result of new
processing, or the result of reported errata.";
}
leaf description {
type string;
description
"Free-form meta information about the generated file. It
might include .sid file generation tool and time among
other things.";
}
list dependency-revision {
key "module-name";
description
"Information about the used revision during the .sid file
generation of each YANG module that the module in
'module-name' imported.";
Veillette, et al. Expires 27 January 2023 [Page 15]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
leaf module-name {
type yang:yang-identifier;
description
"Name of the YANG module, dependency of 'module-name',
for which revision information is provided.";
}
leaf module-revision {
type revision-identifier;
mandatory true;
description
"Revision of the YANG module, dependency of
'module-name', for which revision information is
provided.";
}
}
list assignment-range {
key "entry-point";
description
"YANG SID range(s) allocated to the YANG module identified
by 'module-name' and 'module-revision'.
- The YANG SID range first available value is entry-point
and the last available value in the range is
(entry-point + size - 1).
- The YANG SID ranges specified by all assignment-rages
MUST NOT overlap.";
leaf entry-point {
type sid;
description
"Lowest YANG SID available for assignment.";
}
leaf size {
type uint64;
mandatory true;
description
"Number of YANG SIDs available for assignment.";
}
}
list item {
key "namespace identifier";
unique "sid";
description
"Each entry within this list defined the mapping between
Veillette, et al. Expires 27 January 2023 [Page 16]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
a YANG item string identifier and a YANG SID. This list
MUST include a mapping entry for each YANG item defined by
the YANG module identified by 'module-name' and
'module-revision'.";
leaf namespace {
type enumeration {
enum module {
value 0;
description
"All module and submodule names share the same
global module identifier namespace.";
}
enum identity {
value 1;
description
"All identity names defined in a module and its
submodules share the same identity identifier
namespace.";
}
enum feature {
value 2;
description
"All feature names defined in a module and its
submodules share the same feature identifier
namespace.";
}
enum data {
value 3;
description
"The namespace for all data nodes, as defined in
YANG.";
}
}
description
"Namespace of the YANG item for this mapping entry.";
}
leaf identifier {
type union {
type yang:yang-identifier;
type schema-node-path;
}
description
"String identifier of the YANG item for this mapping
entry.
If the corresponding 'namespace' field is 'module',
Veillette, et al. Expires 27 January 2023 [Page 17]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
'feature', or 'identity', then this field MUST
contain a valid YANG identifier string.
If the corresponding 'namespace' field is 'data',
then this field MUST contain a valid schema node
path.";
}
leaf sid {
type sid;
mandatory true;
description
"YANG SID assigned to the YANG item for this mapping
entry.";
}
}
}
}
<CODE ENDS>
Figure 2: YANG module ietf-sid-file
5. Security Considerations
This document defines a new type of identifier used to encode data
that are modeled in YANG [RFC7950]. This new identifier maps
semantic concepts to integers, and if the source of this mapping is
not trusted, then new security risks might occur if an attacker can
control the mapping.
At the time of writing, it is expected that the SID files will be
processed by a software developer, within a software development
environment. Developers are advised to only import SID files from
authoritative sources. IANA is the authoritative source for IETF
managed YANG modules.
Conceptually, SID files could be processed by less-constrained target
systems such as network management systems. Such systems need to
take extra care to make sure that they are only processing SID files
from authoritative sources, as authoritative as the YANG modules that
they are using.
6. IANA Considerations
6.1. YANG Namespace Registration
This document registers the following XML namespace URN in the "IETF
XML Registry", following the format defined in [RFC3688]:
Veillette, et al. Expires 27 January 2023 [Page 18]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
URI: please assign urn:ietf:params:xml:ns:yang:ietf-sid-file
Registrant Contact: The IESG.
XML: N/A, the requested URI is an XML namespace.
Reference: RFC XXXX
// RFC Ed.: please replace XXXX with RFC number and remove this note
6.2. Register ".sid" File Format Module
This document registers one YANG module in the "YANG Module Names"
registry [RFC6020]:
* name: ietf-sid-file
* namespace: urn:ietf:params:xml:ns:yang:ietf-sid-file
* prefix: sid
* reference: RFC XXXX
// RFC Ed.: please replace XXXX with RFC number and remove this note
6.3. Create new IANA Registry: "YANG SID Mega-Range" registry
The name of this registry is "YANG SID Mega-Range". This registry is
used to record the delegation of the management of a block of SIDs to
third parties (such as SDOs or registrars).
6.3.1. Structure
Each entry in this registry must include:
* The entry point (first SID) of the registered SID block.
* The size of the registered SID block. The size SHOULD be one
million (1 000 000) SIDs, it MAY exceptionally be a multiple of
1 000 000.
* The contact information of the requesting organization including:
- The policy of SID range allocations: Public, Private or Both.
- Organization name
- URL
Veillette, et al. Expires 27 January 2023 [Page 19]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
6.3.2. Allocation policy
The IANA policy for future additions to this registry is "Expert
Review" [RFC8126].
An organization requesting to manage a YANG SID Range (and thus have
an entry in the YANG SID Mega-Range Registry), must ensure the
following capacities:
* The capacity to manage and operate a YANG SID Range Registry. A
YANG SID Range Registry MUST provide the following information for
all YANG SID Ranges allocated by the Registry:
- Entry Point of allocated YANG SID Range
- Size of allocated YANG SID Range
- Type: Public or Private
o Public Ranges MUST include at least a reference to the YANG
module and ".sid" files for that YANG SID Range (e.g.,
compare Section 6.4.3 for the IETF YANG SID registry).
o Private Ranges MUST be marked as "Private"
* A Policy of allocation, which clearly identifies if the YANG SID
Range allocations would be Private, Public or Both.
* Technical capacity to ensure the sustained operation of the
registry for a period of at least 5 years. If Private
Registrations are allowed, the period must be of at least 10
years.
If a size of the allocation beyond 1 000 000 is desired, the
organization must demonstrate the sustainability of the technical
approach for utilizing this size of allocation and how it does not
negatively impact the overall usability of the SID allocation
mechanisms; such allocations are preferably placed in the space above
4 295 000 000 (64-bit space).
6.3.2.1. First allocation
For a first allocation to be provided, the requesting organization
must demonstrate a functional registry infrastructure.
Veillette, et al. Expires 27 January 2023 [Page 20]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
6.3.2.2. Consecutive allocations
On subsequent allocation request(s), the organization must
demonstrate the exhaustion of the prior range. These conditions need
to be asserted by the assigned expert(s).
If that extra-allocation is done within 3 years from the last
allocation, the experts need to discuss this request on the CORE
working group mailing list and consensus needs to be obtained before
allocating a new Mega-Range.
6.3.3. Initial contents of the Registry
The initial entry in this registry is allocated to IANA:
+=============+=========+============+===================+==========+
| Entry Point | Size | Allocation | Organization | URL |
| | | | name | |
+=============+=========+============+===================+==========+
| 0 | 1000000 | Public | IANA | iana.org |
+-------------+---------+------------+-------------------+----------+
Table 2
6.4. Create a new IANA Registry: IETF YANG SID Range Registry (managed
by IANA)
6.4.1. Structure
Each entry in this registry must include:
* The SID range entry point.
* The SID range size.
* The YANG module name.
* Document reference.
6.4.2. Allocation policy
The first million SIDs assigned to IANA is sub-divided as follows:
* The range of 0 to 999 (size 1000) is subject to "IESG Approval" as
defined in [RFC8126]; of these, SID value 0 has been reserved for
implementations to internally signify the absence of a SID number
and does not occur in interchange.
Veillette, et al. Expires 27 January 2023 [Page 21]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
* The range of 1000 to 59,999 (size 59,000) is designated for YANG
modules defined in RFCs.
- The IANA policy for additions to this registry is either:
o "Expert Review" [RFC8126] in case the ".sid" file comes from
a YANG module from an existing RFC, or
o "RFC Required" [RFC8126] otherwise.
- The Expert MUST verify that the YANG module for which this
allocation is made has an RFC (existing RFC) OR is on track to
become RFC (early allocation with a request from the WG chairs
as defined by [BCP100]).
* The range of 60,000 to 99,999 (size 40,000) is reserved for
experimental YANG modules. This range MUST NOT be used in
operational deployments since these SIDs are not globally unique
which limit their interoperability. The IANA policy for this
range is "Experimental use" [RFC8126].
* The range of 100,000 to 999,999 (size 900,000) is "Reserved" as
defined in [RFC8126].
+=============+=========+==========================+
| Entry Point | Size | IANA policy |
+=============+=========+==========================+
| 0 | 1,000 | IESG Approval |
+-------------+---------+--------------------------+
| 1,000 | 59,000 | RFC Required |
+-------------+---------+--------------------------+
| 60,000 | 40,000 | Experimental/Private use |
+-------------+---------+--------------------------+
| 100,000 | 900,000 | Reserved |
+-------------+---------+--------------------------+
Table 3
The size of the SID range allocated for a YANG module is recommended
to be a multiple of 50 and to be at least 33% above the current
number of YANG items. This headroom allows assignment within the
same range of new YANG items introduced by subsequent revisions. The
SID range size SHOULD NOT exceed 1000; a larger size may be requested
by the authors if this recommendation is considered insufficient. It
is important to note that an additional SID range can be allocated to
an existing YANG module if the initial range is exhausted; this then
just leads to slightly less efficient representation.
Veillette, et al. Expires 27 January 2023 [Page 22]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
In case a SID range is allocated for an existing RFC through the
"Expert Review" policy, the Document reference field for the given
allocation should point to the RFC that the YANG module is defined
in.
In case a SID range is required before publishing the RFC due to
implementations needing stable SID values, early allocation as
defined in [BCP100] can be employed for the "RFC Required" range
(Section 2 of [BCP100]).
6.4.3. Publication of the ".sid" file
For a YANG module approved for publication as an RFC, a ".sid" file
SHOULD be included in the Internet-Draft as a source code block.
This ".sid" file is to be extracted by IANA/the expert reviewer and
put into the YANG SID Registry (Section 6.5) along with the YANG
module. The ".sid" file MUST NOT be published as part of the RFC:
the IANA Registry is authoritative and a link is to be inserted in
the RFC.
6.4.4. Initial contents of the registry
Initial entries in this registry are as follows:
Veillette, et al. Expires 27 January 2023 [Page 23]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
+=======+=====+==============+======================================+
| Entry | Size|Module name | Document reference |
| Point | | | |
+=======+=====+==============+======================================+
| 0 | 1|(Reserved: not| RFCXXXX |
| | |a valid SID) | |
+-------+-----+--------------+--------------------------------------+
| 1000 | 100|ietf-coreconf | [I-D.ietf-core-comi] |
+-------+-----+--------------+--------------------------------------+
| 1100 | 50|ietf-yang- | [RFC6991] |
| | |types | |
+-------+-----+--------------+--------------------------------------+
| 1150 | 50|ietf-inet- | [RFC6991] |
| | |types | |
+-------+-----+--------------+--------------------------------------+
| 1200 | 50|iana-crypt- | [RFC7317] |
| | |hash | |
+-------+-----+--------------+--------------------------------------+
| 1250 | 50|ietf-netconf- | [RFC8341] |
| | |acm | |
+-------+-----+--------------+--------------------------------------+
| 1300 | 50|ietf-sid-file | RFCXXXX |
+-------+-----+--------------+--------------------------------------+
| 1500 | 100|ietf- | [RFC8343] |
| | |interfaces | |
+-------+-----+--------------+--------------------------------------+
| 1600 | 100|ietf-ip | [RFC8344] |
+-------+-----+--------------+--------------------------------------+
| 1700 | 100|ietf-system | [RFC7317] |
+-------+-----+--------------+--------------------------------------+
| 1800 | 400|iana-if-type | [RFC7224] |
+-------+-----+--------------+--------------------------------------+
| 2400 | 50|ietf-voucher | [RFC8366] |
+-------+-----+--------------+--------------------------------------+
| 2450 | 50|ietf- | [I-D.ietf-anima-constrained-voucher] |
| | |constrained- | |
| | |voucher | |
+-------+-----+--------------+--------------------------------------+
| 2500 | 50|ietf- | [I-D.ietf-anima-constrained-voucher] |
| | |constrained- | |
| | |voucher- | |
| | |request | |
+-------+-----+--------------+--------------------------------------+
Table 4
// RFC Ed.: replace XXXX with RFC number assigned to this draft.
Veillette, et al. Expires 27 January 2023 [Page 24]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
For allocation, RFC publication of the YANG module is required as per
[RFC8126]. The YANG module must be registered in the "YANG module
Name" registry according to the rules specified in Section 14 of
[RFC6020].
6.5. Create new IANA Registry: "IETF YANG SID Registry"
The name of this registry is "IETF YANG SID Registry". This registry
is used to record the allocation of SIDs for individual YANG module
items.
6.5.1. Structure
Each entry in this registry must include:
* The YANG module name. This module name must be present in the
"Name" column of the "YANG Module Names" registry.
* A link to the associated ".yang" file. This file link must be
present in the "File" column of the "YANG Module Names" registry.
* The link to the ".sid" file which defines the allocation. The
".sid" file is stored by IANA.
* The number of actually allocated SIDs in the ".sid" file.
6.5.2. Allocation policy
The allocation policy is Expert review. The Expert MUST ensure that
the following conditions are met:
* The ".sid" file has a valid structure:
- The ".sid" file MUST be a valid JSON file following the
structure of the module defined in RFCXXXX (RFC Ed: replace XXX
with RFC number assigned to this draft).
* The ".sid" file allocates individual SIDs ONLY in the YANG SID
Ranges for this YANG module (as allocated in the IETF YANG SID
Range Registry):
- All SIDs in this ".sid" file MUST be within the ranges
allocated to this YANG module in the "IETF YANG SID Range
Registry".
* If another ".sid" file has already allocated SIDs for this YANG
module (e.g. for older or newer versions of the YANG module), the
YANG items are assigned the same SIDs as in the other ".sid" file.
Veillette, et al. Expires 27 January 2023 [Page 25]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
* If there is an older version of the ".sid" file, all allocated
SIDs from that version are still present in the current version of
the ".sid" file.
6.5.3. Recursive Allocation of YANG SID Range at Document Adoption
Due to the difficulty in changing SID values during IETF document
processing, it is expected that most documents will ask for SID
allocations using Early Allocations [BCP100]. The details of the
Early Allocation should be included in any Working Group Adoption
call. Prior to Working Group Adoption, an internet draft author can
use the experimental SID range (as per Section 6.4.2) for their SIDs
allocations or other values that do not create ambiguity with other
SID uses (for example they can use a range that comes from a non-IANA
managed "YANG SID Mega-Range" registry).
After Working Group Adoption, any modification of a ".sid" file is
expected to be discussed on the mailing list of the appropriate
Working Groups. Specific attention should be paid to implementers'
opinion after Working Group Last Call if a SID value is to change its
meaning. In all cases, a ".sid" file and the SIDs associated with it
are subject to change before the publication of an internet draft as
an RFC.
During the early use of SIDs, many existing, previously published
YANG modules will not have SID allocations. For an allocation to be
useful the included YANG modules may also need to have SID
allocations made.
The Expert Reviewer who performs the (Early) Allocation analysis will
need to go through the list of included YANG modules and perform SID
allocations for those modules as well.
* If the document is a published RFC, then the allocation of SIDs
for its referenced YANG modules is permanent. The Expert Reviewer
provides the generated ".sid" file to IANA for registration. This
process may be time-consuming during a bootstrap period (there are
over 100 YANG modules to date, none of which have SID
allocations), but should quiet down once needed entries are
allocated.
* If the document is an unprocessed Internet-Draft adopted in a WG,
then an Early Allocation is performed for this document as well.
Early Allocations require approval by an IESG Area Director. An
early allocation which requires additional allocations will list
the other allocations in its description, and will be cross-posted
to the any other working group mailing lists.
Veillette, et al. Expires 27 January 2023 [Page 26]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
* A YANG module which references a module in a document which has
not yet been adopted by any working group will be unable to
perform an Early Allocation for that other document until it is
adopted by a working group. As described in [BCP100], an AD
Sponsored document acts as if it had a working group. The
approving AD may also exempt a document from this policy by
agreeing to AD Sponsor the document.
At the end of the IETF process all the dependencies of a given module
for which SIDs are assigned, should also have SIDs assigned. Those
dependencies' assignments should be permanent (not Early Allocation).
A previously SID-allocated YANG module which changes its references
to include a YANG module for which there is no SID allocation needs
to repeat the Early Allocation process.
Early Allocations are made with a one-year period, after which they
need to be renewed or will expire.
[BCP100] also says:
Note that if a document is submitted for review to the IESG and at
the time of submission some early allocations are valid (not
expired), these allocations should not be expired while the document
is under IESG consideration or waiting in the RFC Editor's queue
after approval by the IESG.
6.5.4. Initial contents of the registry
None.
7. References
7.1. Normative References
[BCP100] Cotton, M., "Early IANA Allocation of Standards Track Code
Points", RFC 7120, BCP 100, January 2014.
<https://www.rfc-editor.org/info/bcp100>
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
DOI 10.17487/RFC3688, January 2004,
<https://www.rfc-editor.org/info/rfc3688>.
Veillette, et al. Expires 27 January 2023 [Page 27]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
[RFC6991] Schoenwaelder, J., Ed., "Common YANG Data Types",
RFC 6991, DOI 10.17487/RFC6991, July 2013,
<https://www.rfc-editor.org/info/rfc6991>.
[RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
RFC 7950, DOI 10.17487/RFC7950, August 2016,
<https://www.rfc-editor.org/info/rfc7950>.
[RFC7951] Lhotka, L., "JSON Encoding of Data Modeled with YANG",
RFC 7951, DOI 10.17487/RFC7951, August 2016,
<https://www.rfc-editor.org/info/rfc7951>.
[RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
<https://www.rfc-editor.org/info/rfc8040>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
Interchange Format", STD 90, RFC 8259,
DOI 10.17487/RFC8259, December 2017,
<https://www.rfc-editor.org/info/rfc8259>.
7.2. Informative References
[I-D.ietf-anima-constrained-voucher]
Richardson, M., Stok, P. V. D., Kampanakis, P., and E.
Dijk, "Constrained Bootstrapping Remote Secure Key
Infrastructure (BRSKI)", Work in Progress, Internet-Draft,
draft-ietf-anima-constrained-voucher-18, 11 July 2022,
<https://www.ietf.org/archive/id/draft-ietf-anima-
constrained-voucher-18.txt>.
[I-D.ietf-core-comi]
Veillette, M., Stok, P. V. D., Pelov, A., Bierman, A., and
I. Petrov, "CoAP Management Interface (CORECONF)", Work in
Progress, Internet-Draft, draft-ietf-core-comi-11, 17
January 2021, <https://www.ietf.org/archive/id/draft-ietf-
core-comi-11.txt>.
[I-D.ietf-core-yang-library]
Veillette, M. and I. Petrov, "Constrained YANG Module
Library", Work in Progress, Internet-Draft, draft-ietf-
core-yang-library-03, 11 January 2021,
<https://www.ietf.org/archive/id/draft-ietf-core-yang-
library-03.txt>.
Veillette, et al. Expires 27 January 2023 [Page 28]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
[PYANG] Bjorklund, M., "An extensible YANG validator and converter
in python", <https://github.com/mbj4668/pyang>.
[RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for
the Network Configuration Protocol (NETCONF)", RFC 6020,
DOI 10.17487/RFC6020, October 2010,
<https://www.rfc-editor.org/info/rfc6020>.
[RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
and A. Bierman, Ed., "Network Configuration Protocol
(NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
<https://www.rfc-editor.org/info/rfc6241>.
[RFC7224] Bjorklund, M., "IANA Interface Type YANG Module",
RFC 7224, DOI 10.17487/RFC7224, May 2014,
<https://www.rfc-editor.org/info/rfc7224>.
[RFC7228] Bormann, C., Ersue, M., and A. Keranen, "Terminology for
Constrained-Node Networks", RFC 7228,
DOI 10.17487/RFC7228, May 2014,
<https://www.rfc-editor.org/info/rfc7228>.
[RFC7317] Bierman, A. and M. Bjorklund, "A YANG Data Model for
System Management", RFC 7317, DOI 10.17487/RFC7317, August
2014, <https://www.rfc-editor.org/info/rfc7317>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[RFC8341] Bierman, A. and M. Bjorklund, "Network Configuration
Access Control Model", STD 91, RFC 8341,
DOI 10.17487/RFC8341, March 2018,
<https://www.rfc-editor.org/info/rfc8341>.
[RFC8343] Bjorklund, M., "A YANG Data Model for Interface
Management", RFC 8343, DOI 10.17487/RFC8343, March 2018,
<https://www.rfc-editor.org/info/rfc8343>.
[RFC8344] Bjorklund, M., "A YANG Data Model for IP Management",
RFC 8344, DOI 10.17487/RFC8344, March 2018,
<https://www.rfc-editor.org/info/rfc8344>.
[RFC8366] Watsen, K., Richardson, M., Pritikin, M., and T. Eckert,
"A Voucher Artifact for Bootstrapping Protocols",
RFC 8366, DOI 10.17487/RFC8366, May 2018,
<https://www.rfc-editor.org/info/rfc8366>.
Veillette, et al. Expires 27 January 2023 [Page 29]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
[RFC9195] Lengyel, B. and B. Claise, "A File Format for YANG
Instance Data", RFC 9195, DOI 10.17487/RFC9195, February
2022, <https://www.rfc-editor.org/info/rfc9195>.
[RFC9254] Veillette, M., Ed., Petrov, I., Ed., Pelov, A., Bormann,
C., and M. Richardson, "Encoding of Data Modeled with YANG
in the Concise Binary Object Representation (CBOR)",
RFC 9254, DOI 10.17487/RFC9254, July 2022,
<https://www.rfc-editor.org/info/rfc9254>.
Appendix A. ".sid" file example
The following ".sid" file (ietf-system@2014-08-06.sid) has been
generated using the following yang modules:
* ietf-system@2014-08-06.yang (defined in [RFC7317])
* ietf-yang-types@2013-07-15.yang (defined in [RFC6991])
* ietf-inet-types@2013-07-15.yang (defined in [RFC6991])
* ietf-netconf-acm@2018-02-14.yang (defined in [RFC8341])
* iana-crypt-hash@2014-08-06.yang (defined in [RFC7317])
For purposes of exposition, line breaks have been introduced below in
some JSON strings that represent overly long identifiers.
{
"ietf-sid-file:sid-file" : {
"module-name": "ietf-system",
"module-revision": "2014-08-06",
"dependency-revision": [
{
"module-name": "ietf-yang-types",
"module-revision": "2013-07-15"
},
{
"module-name": "ietf-inet-types",
"module-revision": "2013-07-15"
},
{
"module-name": "ietf-netconf-acm",
"module-revision": "2018-02-14"
},
{
"module-name": "iana-crypt-hash",
"module-revision": "2014-08-06"
Veillette, et al. Expires 27 January 2023 [Page 30]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
}
],
"description": "Example sid file",
"assignment-range": [
{
"entry-point": 1700,
"size": 100
}
],
"item": [
{
"namespace": "module",
"identifier": "ietf-system",
"sid": 1700
},
{
"namespace": "identity",
"identifier": "authentication-method",
"sid": 1701
},
{
"namespace": "identity",
"identifier": "local-users",
"sid": 1702
},
{
"namespace": "identity",
"identifier": "radius",
"sid": 1703
},
{
"namespace": "identity",
"identifier": "radius-authentication-type",
"sid": 1704
},
{
"namespace": "identity",
"identifier": "radius-chap",
"sid": 1705
},
{
"namespace": "identity",
"identifier": "radius-pap",
"sid": 1706
},
{
"namespace": "feature",
"identifier": "authentication",
Veillette, et al. Expires 27 January 2023 [Page 31]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
"sid": 1707
},
{
"namespace": "feature",
"identifier": "dns-udp-tcp-port",
"sid": 1708
},
{
"namespace": "feature",
"identifier": "local-users",
"sid": 1709
},
{
"namespace": "feature",
"identifier": "ntp",
"sid": 1710
},
{
"namespace": "feature",
"identifier": "ntp-udp-port",
"sid": 1711
},
{
"namespace": "feature",
"identifier": "radius",
"sid": 1712
},
{
"namespace": "feature",
"identifier": "radius-authentication",
"sid": 1713
},
{
"namespace": "feature",
"identifier": "timezone-name",
"sid": 1714
},
{
"namespace": "data",
"identifier": "/ietf-system:set-current-datetime",
"sid": 1715
},
{
"namespace": "data",
"identifier": "/ietf-system:set-current-datetime/
current-datetime",
"sid": 1716
},
Veillette, et al. Expires 27 January 2023 [Page 32]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
{
"namespace": "data",
"identifier": "/ietf-system:system",
"sid": 1717
},
{
"namespace": "data",
"identifier": "/ietf-system:system-restart",
"sid": 1718
},
{
"namespace": "data",
"identifier": "/ietf-system:system-shutdown",
"sid": 1719
},
{
"namespace": "data",
"identifier": "/ietf-system:system-state",
"sid": 1720
},
{
"namespace": "data",
"identifier": "/ietf-system:system-state/clock",
"sid": 1721
},
{
"namespace": "data",
"identifier": "/ietf-system:system-state/clock/boot-datetime",
"sid": 1722
},
{
"namespace": "data",
"identifier": "/ietf-system:system-state/clock/
current-datetime",
"sid": 1723
},
{
"namespace": "data",
"identifier": "/ietf-system:system-state/platform",
"sid": 1724
},
{
"namespace": "data",
"identifier": "/ietf-system:system-state/platform/machine",
"sid": 1725
},
{
"namespace": "data",
Veillette, et al. Expires 27 January 2023 [Page 33]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
"identifier": "/ietf-system:system-state/platform/os-name",
"sid": 1726
},
{
"namespace": "data",
"identifier": "/ietf-system:system-state/platform/os-release",
"sid": 1727
},
{
"namespace": "data",
"identifier": "/ietf-system:system-state/platform/os-version",
"sid": 1728
},
{
"namespace": "data",
"identifier": "/ietf-system:system/authentication",
"sid": 1729
},
{
"namespace": "data",
"identifier": "/ietf-system:system/authentication/user",
"sid": 1730
},
{
"namespace": "data",
"identifier": "/ietf-system:system/authentication/
user-authentication-order",
"sid": 1731
},
{
"namespace": "data",
"identifier": "/ietf-system:system/authentication/user/
authorized-key",
"sid": 1732
},
{
"namespace": "data",
"identifier": "/ietf-system:system/authentication/user/
authorized-key/algorithm",
"sid": 1733
},
{
"namespace": "data",
"identifier": "/ietf-system:system/authentication/user/
authorized-key/key-data",
"sid": 1734
},
{
Veillette, et al. Expires 27 January 2023 [Page 34]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
"namespace": "data",
"identifier": "/ietf-system:system/authentication/user/
authorized-key/name",
"sid": 1735
},
{
"namespace": "data",
"identifier": "/ietf-system:system/authentication/user/
name",
"sid": 1736
},
{
"namespace": "data",
"identifier": "/ietf-system:system/authentication/user/
password",
"sid": 1737
},
{
"namespace": "data",
"identifier": "/ietf-system:system/clock",
"sid": 1738
},
{
"namespace": "data",
"identifier": "/ietf-system:system/clock/timezone-name",
"sid": 1739
},
{
"namespace": "data",
"identifier": "/ietf-system:system/clock/timezone-utc-offset",
"sid": 1740
},
{
"namespace": "data",
"identifier": "/ietf-system:system/contact",
"sid": 1741
},
{
"namespace": "data",
"identifier": "/ietf-system:system/dns-resolver",
"sid": 1742
},
{
"namespace": "data",
"identifier": "/ietf-system:system/dns-resolver/options",
"sid": 1743
},
{
Veillette, et al. Expires 27 January 2023 [Page 35]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
"namespace": "data",
"identifier": "/ietf-system:system/dns-resolver/options/
attempts",
"sid": 1744
},
{
"namespace": "data",
"identifier": "/ietf-system:system/dns-resolver/options/
timeout",
"sid": 1745
},
{
"namespace": "data",
"identifier": "/ietf-system:system/dns-resolver/search",
"sid": 1746
},
{
"namespace": "data",
"identifier": "/ietf-system:system/dns-resolver/server",
"sid": 1747
},
{
"namespace": "data",
"identifier": "/ietf-system:system/dns-resolver/server/name",
"sid": 1748
},
{
"namespace": "data",
"identifier": "/ietf-system:system/dns-resolver/server/
udp-and-tcp",
"sid": 1749
},
{
"namespace": "data",
"identifier": "/ietf-system:system/dns-resolver/server/
udp-and-tcp/address",
"sid": 1750
},
{
"namespace": "data",
"identifier": "/ietf-system:system/dns-resolver/server/
udp-and-tcp/port",
"sid": 1751
},
{
"namespace": "data",
"identifier": "/ietf-system:system/hostname",
"sid": 1752
Veillette, et al. Expires 27 January 2023 [Page 36]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
},
{
"namespace": "data",
"identifier": "/ietf-system:system/location",
"sid": 1753
},
{
"namespace": "data",
"identifier": "/ietf-system:system/ntp",
"sid": 1754
},
{
"namespace": "data",
"identifier": "/ietf-system:system/ntp/enabled",
"sid": 1755
},
{
"namespace": "data",
"identifier": "/ietf-system:system/ntp/server",
"sid": 1756
},
{
"namespace": "data",
"identifier": "/ietf-system:system/ntp/server/
association-type",
"sid": 1757
},
{
"namespace": "data",
"identifier": "/ietf-system:system/ntp/server/iburst",
"sid": 1758
},
{
"namespace": "data",
"identifier": "/ietf-system:system/ntp/server/name",
"sid": 1759
},
{
"namespace": "data",
"identifier": "/ietf-system:system/ntp/server/prefer",
"sid": 1760
},
{
"namespace": "data",
"identifier": "/ietf-system:system/ntp/server/udp",
"sid": 1761
},
{
Veillette, et al. Expires 27 January 2023 [Page 37]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
"namespace": "data",
"identifier": "/ietf-system:system/ntp/server/udp/address",
"sid": 1762
},
{
"namespace": "data",
"identifier": "/ietf-system:system/ntp/server/udp/port",
"sid": 1763
},
{
"namespace": "data",
"identifier": "/ietf-system:system/radius",
"sid": 1764
},
{
"namespace": "data",
"identifier": "/ietf-system:system/radius/options",
"sid": 1765
},
{
"namespace": "data",
"identifier": "/ietf-system:system/radius/options/attempts",
"sid": 1766
},
{
"namespace": "data",
"identifier": "/ietf-system:system/radius/options/timeout",
"sid": 1767
},
{
"namespace": "data",
"identifier": "/ietf-system:system/radius/server",
"sid": 1768
},
{
"namespace": "data",
"identifier": "/ietf-system:system/radius/server/
authentication-type",
"sid": 1769
},
{
"namespace": "data",
"identifier": "/ietf-system:system/radius/server/name",
"sid": 1770
},
{
"namespace": "data",
"identifier": "/ietf-system:system/radius/server/udp",
Veillette, et al. Expires 27 January 2023 [Page 38]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
"sid": 1771
},
{
"namespace": "data",
"identifier": "/ietf-system:system/radius/server/udp/
address",
"sid": 1772
},
{
"namespace": "data",
"identifier": "/ietf-system:system/radius/server/udp/
authentication-port",
"sid": 1773
},
{
"namespace": "data",
"identifier": "/ietf-system:system/radius/server/udp/
shared-secret",
"sid": 1774
}
]
}
}
Figure 3: Example .sid file (ietf-system, with extra line-breaks)
For reconstructing the actual JSON file from this figure, all line
breaks that occur in what would be JSON strings need to be removed,
including any following blank space (indentation) on the line after
the line break; in each such case, a single identifier without any
embedded blank space results. This removal can be accomplished with
this simple Ruby script:
@u = %{[^"\n]*}; @q = @u + '"'
puts ARGF.read.gsub(/^(#@q(#@q#@q)*#@u) *\n +(#@q)/, "\\1\\3")
Appendix B. SID auto generation
Assignment of SIDs to YANG items SHOULD be automated. The
recommended process to assign SIDs is as follows:
1. A tool extracts the different items defined for a specific YANG
module.
2. The list of items is sorted in alphabetical order, 'namespace' in
descending order, 'identifier' in ascending order. The
'namespace' and 'identifier' formats are described in the YANG
module 'ietf-sid-file' defined in Section 4.
Veillette, et al. Expires 27 January 2023 [Page 39]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
3. SIDs are assigned sequentially from the entry point up to the
size of the registered SID range. This approach is recommended
to minimize the serialization overhead, especially when delta
between a reference SID and the current SID is used by protocols
aiming to reduce message size.
4. If the number of items exceeds the SID range(s) allocated to a
YANG module, an extra range is added for subsequent assignments.
5. The "dependency-revision" should reflect the revision numbers of
each YANG module that the YANG module imports at the moment of
the generation.
When updating a YANG module that is in active use, the existing SID
assignments are maintained. (In contrast, when evolving an early
draft that has not yet been adopted by a community of developers, SID
assignments are often better done from scratch after a revision.) If
the name of a schema node changes, but the data remain structurally
and semantically similar to what was previously available under an
old name, the SID that was used for the old name MAY continue to be
used for the new name. If the meaning of an item changes, a new SID
MAY be assigned to it; this is particularly useful to allow the new
SID to identify the new structure or semantics of the item. If the
YANG data type changes in a new revision of a published module, such
that the resulting CBOR encoding is changed, then implementations
will be aided significantly if a new SID is assigned. Note that
these decisions are generally at the discretion of the YANG module
author, who should decide if the benefits of a manual intervention
are worth the deviation from automatic assignment.
In case of an update to an existing ".sid" file, an additional step
is needed that increments the ".sid" file version number. If there
was no version number in the previous version of the ".sid" file, 0
is assumed as the version number of the old version of the ".sid"
file and the version number is 1 for the new ".sid" file. Apart from
that, changes of ".sid" files can also be automated using the same
method described above, only unassigned YANG items are processed at
step #3. Already existing items in the ".sid" file should not be
given new SIDs.
Note that ".sid" file versions are specific to a YANG module
revision. For each new YANG module or each new revision of an
existing YANG module, the version number of the initial ".sid" file
should either be 0 or should not be present.
Veillette, et al. Expires 27 January 2023 [Page 40]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
Note also that RPC or action "input" and "output" data nodes MUST
always be assigned SID even if they don't contain data nodes. The
reason for this requirement is that other modules can augment the
given module and those SIDs might be necessary.
Appendix C. ".sid" file lifecycle
Before assigning SIDs to their YANG modules, YANG module authors must
acquire a SID range from a "YANG SID Range Registry". If the YANG
module is part of an IETF draft or RFC, the SID range need to be
acquired from the "IETF YANG SID Range Registry" as defined in
Section 6.4. For the other YANG modules, the authors can acquire a
SID range from any "YANG SID Range Registry" of their choice.
Once the SID range is acquired, owners can use it to generate ".sid"
file/s for their YANG module/s. It is recommended to leave some
unallocated SIDs following the allocated range in each ".sid" file in
order to allow better evolution of the YANG module in the future.
Generation of ".sid" files should be performed using an automated
tool. Note that ".sid" files can only be generated for YANG modules
and not for submodules.
C.1. ".sid" File Creation
The following activity diagram summarizes the creation of a YANG
module and its associated ".sid" file.
+---------------+
o | Creation of a |
-+- -->| YANG module |
/ \ +------+--------+
|
v
.-------------.
/ Standardized \ yes
\ YANG module ? /------------+
'-----+-------' |
| no |
v v
.-------------. +---------------+
+--> / Constrained \ yes | SID range |
| \ application ? /---->| registration |<---------+
| '-----+-------' +------+--------+ |
| | no | |
| v v |
| +---------------+ +---------------+ |
+----+ YANG module | | SID sub-range | |
| update | | assignment |<----------+
Veillette, et al. Expires 27 January 2023 [Page 41]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
+---------------+ +-------+-------+ |
| |
v |
+---------------+ +------+------+
| ".sid" file | | Rework YANG |
| generation | | module |
+-------+-------+ +-------------+
| ^
v |
.----------. yes |
/ Work in \ -----------+
\ progress /
'----+-----'
| no
v
.-------------. .-------------.
/ RFC \ no / Open \ no
\ publication? /---> \ specification?/---+
'------+------' '------+------' |
yes | | yes |
| .------------' |
| / |
v v v
+---------------+ +---------------+
| IANA | | Third party |
| registration | | registration |
+-------+-------+ +---------+-----+
| |
+---------------------------------+
v
[DONE]
Figure 4: SID Lifecycle
C.2. ".sid" File Update
The following Activity diagram summarizes the update of a YANG module
and its associated ".sid" file.
Veillette, et al. Expires 27 January 2023 [Page 42]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
+---------------+
o | Update of the |
-+- -->| YANG module |
/ \ | or include(s) |
| or import(s) |
+------+--------+
|
v
.-------------.
/ New items \ yes
\ created ? /------+
'------+------' |
| no v
| .-------------. +----------------+
| / SID range \ yes | Extra sub-range|
| \ exhausted ? /---->| assignment |
| '------+------' +-------+--------+
| | no |
| +---------------------+
| |
| v
| +---------------+
| | ".sid" file |
| | update based |
| | on previous |
| | ".sid" file |
| +-------+-------+
| |
| v
| .-------------. +---------------+
| / Publicly \ yes | YANG module |
| \ available ? /---->| registration |
| '------+------' +-------+-------+
| | no |
+--------------+---------------------+
|
[DONE]
Figure 5: YANG and ".sid" file update
Appendix D. Keeping a SID File in a YANG Instance Data file
[RFC9195] defines a format for "YANG Instance Data". This
essentially leads to an encapsulation of the instance data within
some metadata envelope.
Veillette, et al. Expires 27 January 2023 [Page 43]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
If a SID file needs to be stored in a YANG Instance Data file, this
can be achieved by embedding the value of the SID file as the value
of the content-data member in the following template, and copying
over the second-level members as indicated with the angle brackets:
{
"ietf-yang-instance-data:instance-data-set": {
"name": "<module-name>@<module-revision>.sid",
"description": ["<description>"],
"content-schema": {
"module": "ietf-sid-file@2021-11-16"
},
"content-data": { <replace this object>
"ietf-sid-file:sid-file" : {
"module-name": ...
}
}
}
}
// RFC editor: Please replace the module date by the correct one for
// the ietf-sid-file module.
Acknowledgments
The authors would like to thank Andy Bierman, Michael Richardson,
Abhinav Somaraju, Peter van der Stok, Laurent Toutain and Randy
Turner for their help during the development of this document and
their useful comments during the review process. Special thanks go
to the IESG members who supplied very useful comments during the IESG
processing phase, in particular to Benjamin Kaduk and Rob Wilton.
Contributors
Andy Bierman
YumaWorks
685 Cochran St.
Suite #160
Simi Valley, CA 93065
United States of America
Email: andy@yumaworks.com
Authors' Addresses
Veillette, et al. Expires 27 January 2023 [Page 44]
Internet-Draft YANG Schema Item iDentifier (YANG SID) July 2022
Michel Veillette (editor)
Trilliant Networks Inc.
610 Rue du Luxembourg
Granby Quebec J2J 2V2
Canada
Phone: +14503750556
Email: michel.veillette@trilliant.com
Alexander Pelov (editor)
Acklio
1137A avenue des Champs Blancs
35510 Cesson-Sevigne
France
Email: a@ackl.io
Ivaylo Petrov (editor)
Google Switzerland GmbH
Brandschenkestrasse 110
CH-8002 Zurich
Switzerland
Email: ivaylopetrov@google.com
Carsten Bormann
Universität Bremen TZI
Postfach 330440
D-28359 Bremen
Germany
Phone: +49-421-218-63921
Email: cabo@tzi.org
Michael Richardson
Sandelman Software Works
Canada
Email: mcr+ietf@sandelman.ca
Veillette, et al. Expires 27 January 2023 [Page 45]