draft-ietf-netmod-yang-model-classification-02.txt   draft-ietf-netmod-yang-model-classification-03.txt 
NETMOD D. Bogdanovic NETMOD D. Bogdanovic
Internet-Draft Volta Networks, Inc. Internet-Draft Volta Networks, Inc.
Intended status: Informational B. Claise Intended status: Informational B. Claise
Expires: December 24, 2016 C. Moberg Expires: April 2, 2017 C. Moberg
Cisco Systems, Inc. Cisco Systems, Inc.
June 22, 2016 September 29, 2016
YANG Module Classification YANG Module Classification
draft-ietf-netmod-yang-model-classification-02 draft-ietf-netmod-yang-model-classification-03
Abstract Abstract
The YANG [RFC6020] data modeling language is currently being The YANG [RFC6020] data modeling language is currently being
considered for a wide variety of applications throughout the considered for a wide variety of applications throughout the
networking industry at large. Many standards-defining organizations networking industry at large. Many standards-defining organizations
(SDOs), open source software projects, vendors and users are using (SDOs), open source software projects, vendors and users are using
YANG to develop and publish YANG modules of configuration, state data YANG to develop and publish YANG modules for a wide variety of
and operations for a wide variety of applications. At the same time, applications. At the same time, there is currently no well-known
there is currently no well-known terminology to categorize various terminology to categorize various types of YANG modules.
types of YANG modules.
A consistent terminology would help with the categorization of YANG A consistent terminology would help with the categorization of YANG
modules, assist in the analysis the YANG data modeling efforts in the modules, assist in the analysis of the YANG data modeling efforts in
IETF and other organizations, and bring clarity to the YANG-related the IETF and other organizations, and bring clarity to the YANG-
discussions between the different groups. related discussions between the different groups.
This document describes a set of concepts and associated terms to This document describes a set of concepts and associated terms to
support consistent classification of YANG modules. support consistent classification of YANG modules.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on December 24, 2016. This Internet-Draft will expire on April 2, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
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publication of this document. Please review these documents publication of this document. Please review these documents
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to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
2. First Dimension: YANG Data Model Abstraction Layers . . . . . 4 2. First Dimension: YANG Module Abstraction Layers . . . . . . . 4
2.1. Network Service YANG Modules . . . . . . . . . . . . . . 6 2.1. Network Service YANG Modules . . . . . . . . . . . . . . 6
2.2. Network Element YANG Modules . . . . . . . . . . . . . . 7 2.2. Network Element YANG Modules . . . . . . . . . . . . . . 7
3. Second Dimension: Module Types . . . . . . . . . . . . . . . 7 3. Second Dimension: Module Types . . . . . . . . . . . . . . . 7
3.1. Standard YANG Modules . . . . . . . . . . . . . . . . . . 8 3.1. Standard YANG Modules . . . . . . . . . . . . . . . . . . 8
3.2. Vendor-specific YANG Modules and Extensions . . . . . . . 8 3.2. Vendor-specific YANG Modules and Extensions . . . . . . . 8
3.3. User-specific YANG Modules and Extensions . . . . . . . . 9 3.3. User-specific YANG Modules and Extensions . . . . . . . . 9
4. Adding The Classification Type to YANG Module Catalogs . . . 9 4. Adding The Classification Type to YANG Module Catalogs . . . 9
5. Security Considerations . . . . . . . . . . . . . . . . . . . 10 5. Security Considerations . . . . . . . . . . . . . . . . . . . 10
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 10 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 10
8. Change log [RFC Editor: Please remove] . . . . . . . . . . . 10 8. Change log [RFC Editor: Please remove] . . . . . . . . . . . 10
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 11 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
9.1. Normative References . . . . . . . . . . . . . . . . . . 11 9.1. Normative References . . . . . . . . . . . . . . . . . . 11
9.2. Informative References . . . . . . . . . . . . . . . . . 11 9.2. Informative References . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12
1. Introduction 1. Introduction
The Internet Engineering Steering Group (IESG) has been actively The Internet Engineering Steering Group (IESG) has been actively
encouraging IETF working groups to use the YANG [RFC6020] encouraging IETF working groups to use the YANG modeling language
[I-D.ietf-netmod-rfc6020bis] and NETCONF [RFC6241] and YANG standards [RFC6020], [RFC7950] and NETCONF protocol [RFC6241] for configuration
for configuration management purposes, especially in new working management purposes, especially in new working group charters
group charters [Writable-MIB-Module-IESG-Statement]. [Writable-MIB-Module-IESG-Statement].
YANG is also gaining wide acceptance as the de-facto standard YANG is also gaining wide acceptance as the de-facto standard
modeling language in the broader industry. This extends beyond the modeling language in the broader industry. This extends beyond the
IETF, including many standards development organizations, industry IETF, including many standards development organizations, industry
consortia, ad hoc groups, open source projects, vendors, and end- consortia, ad hoc groups, open source projects, vendors, and end-
users. users.
There are currently no clear guidelines on how to classify the There are currently no clear guidelines on how to classify the
layering of YANG modules according to abstraction, or how to classify layering of YANG modules according to abstraction, or how to classify
modules along the continuum spanning formal standards publications, modules along the continuum spanning formal standards publications,
skipping to change at page 3, line 24 skipping to change at page 3, line 24
dimensions: dimensions:
o The layering of modules based on their abstraction levels o The layering of modules based on their abstraction levels
o The type of module based on the nature and intent of the content o The type of module based on the nature and intent of the content
The intent of this document is to provide a taxonomy to simplify The intent of this document is to provide a taxonomy to simplify
human communication around YANG modules. The authors acknowledge human communication around YANG modules. The authors acknowledge
that the classification boundaries are at times blurry, but believe that the classification boundaries are at times blurry, but believe
that this document should provide a robust starting point as the YANG that this document should provide a robust starting point as the YANG
community gain further experience with designing and deploying community gains further experience with designing and deploying
modules. To be more explicit, the authors believe that the modules. To be more explicit, the authors believe that the
classification criteria will change over time. classification criteria will change over time.
An example of a type of module that have created substantial A number of module types have created substantial discussion during
discussion during the development of this document is topologies. the development of this document including those concerned with
Topology models are useful both on the Network Element level (e.g. topologies. Topology modules are useful both on the Network Element
link-state database content) as well as in the Network Service level level (e.g. link-state database content) as well as on the Network
(e.g. network-wide, configured topologies). In the end, it is the Service level (e.g. network-wide, configured topologies). In the
module developer that classifies the module according to the initial end, it is the module developer that classifies the module according
intent of the module content. to the initial intent of the module content.
This document should provide benefits to multiple audiences: This document should provide benefits to multiple audiences:
o First, a common taxonomy helps with the different standards o First, a common taxonomy helps with the different standards
development organizations and industry consortia discussions, development organizations and industry consortia discussions,
whose goals are determined in their respective areas of work. whose goals are determined in their respective areas of work.
o Second, operators might look at the YANG module classification o Second, operators might look at the YANG module classification
type to understand which Network Service YANG modules and Network type to understand which Network Service YANG modules and Network
Element YANG modules are available for their service composition. Element YANG modules are available for their service composition.
skipping to change at page 4, line 12 skipping to change at page 4, line 12
Element YANG module that contains the L2VPN data definitions Element YANG module that contains the L2VPN data definitions
required to be configured on a single device. required to be configured on a single device.
o And thirdly, this taxonomy would help equipment vendors (whether o And thirdly, this taxonomy would help equipment vendors (whether
physical or virtual), controller vendors, orchestrator vendors to physical or virtual), controller vendors, orchestrator vendors to
explain to their customers the relationship between the different explain to their customers the relationship between the different
YANG modules they propose in their products. See Figure 1. YANG modules they propose in their products. See Figure 1.
1.1. Terminology 1.1. Terminology
RFC6020bis [I-D.ietf-netmod-rfc6020bis] specifies: [RFC7950] specifies:
o data model: A data model describes how data is represented and o data model: A data model describes how data is represented and
accessed. accessed.
o module: A YANG module defines a hierarchy of nodes that can be o module: A YANG module defines a hierarchy of nodes that can be
used for NETCONF-based operations. With its definitions and the used for NETCONF-based operations. With its definitions and the
definitions it imports or includes from elsewhere, a module is definitions it imports or includes from elsewhere, a module is
self-contained and "compilable". self-contained and "compilable".
2. First Dimension: YANG Data Model Abstraction Layers 2. First Dimension: YANG Module Abstraction Layers
Model developers have taken two approaches to developing YANG Module developers have taken two approaches to developing YANG
modules: top-down and bottom-up. The top-down approach starts with modules: top-down and bottom-up. The top-down approach starts with
high level abstractions modeling business or customer requirements high level abstractions modeling business or customer requirements
and maps them to specific networking technologies. The bottom-up and maps them to specific networking technologies. The bottom-up
approach starts with fundamental networking technologies and maps approach starts with fundamental networking technologies and maps
them into more abstract constructs. them into more abstract constructs.
There are currently no specific requirements on, or well-defined best There are currently no specific requirements on, or well-defined best
practices around the development of YANG modules For the purpose of practices around the development of YANG modules. For the purpose of
this document we assume that both approaches (bottom-up and top-down) this document we assume that both approaches (bottom-up and top-down)
will be used as they both provide benefits that appeal to different will be used as they both provide benefits that appeal to different
groups. groups.
For layering purposes, this document suggests the classification of For layering purposes, this document suggests the classification of
YANG modules into two distinct abstraction layers: YANG modules into two distinct abstraction layers:
o Network Element YANG Modules describe the configuration, state o Network Element YANG Modules describe the configuration, state
data and operations of specific device-centric technologies or data, operations and notifications of specific device-centric
features technologies or features
o Network Service YANG Modules describe the configuration, state o Network Service YANG Modules describe the configuration, state
data and operations of an abstract representation of a service data, operations and notifications of abstract representations of
implemented on one or multiple network elements services implemented on one or multiple network elements
+--------------------------+
| Operations and Business |
| Support Systems |
| (OSS/BSS) |
+--------------------------+
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Network Service YANG Modules
+------------+ +-------------+ +-------------+
| | | | | |
| - L2VPN | | - L2VPN | | L3VPN |
| - VPWS | | - VPLS | | |
| | | | | |
+------------+ +-------------+ +-------------+
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Network Element YANG Modules
+------------+ +------------+ +-------------+ +------------+
| | | | | | | |
| MPLS | | BGP | | IPv4 / IPv6 | | Ethernet |
| | | | | | | |
+------------+ +------------+ +-------------+ +------------+
L2VPN: Layer 2 Virtual Private Network
L3VPN: Layer 3 Virtual Private Network
VPWS: Virtual Private Wire Service
VPLS: Virtual Private LAN Service
Figure 1: YANG Module Layers
Figure 1 illustrates the application of YANG modules at different Figure 1 illustrates the application of YANG modules at different
layers of abstraction. Layering of modules allows for reusability of layers of abstraction. Layering of modules allows for reusability of
existing lower layer modules by higher level modules while limiting existing lower layer modules by higher level modules while limiting
duplication of features across layers. duplication of features across layers.
For module developers, per-layer modeling allows for separation of For module developers, per-layer modeling allows for separation of
concern across editing teams focusing on specific areas. concern across editing teams focusing on specific areas.
As an example, experience from the IETF shows that creating useful As an example, experience from the IETF shows that creating useful
network element YANG modules for e.g. routing or switching protocols network element YANG modules for e.g. routing or switching protocols
requires teams that include developers with experience of requires teams that include developers with experience of
implementing those protocols. implementing those protocols.
On the other hand, network service YANG modules are best developed by On the other hand, network service YANG modules are best developed by
network operators experienced in defining network services for network operators experienced in defining network services for
consumption by programmers developing e.g. flow-through provisioning consumption by programmers developing e.g. flow-through provisioning
systems or self-service portals. systems or self-service portals.
+--------------------------+
| Operations and Business |
| Support Systems |
| (OSS/BSS) |
+--------------------------+
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Network Service YANG Modules
+------------+ +-------------+ +-------------+
| | | | | |
| - L2VPN | | - L2VPN | | L3VPN |
| - VPWS | | - VPLS | | |
| | | | | |
+------------+ +-------------+ +-------------+
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Network Element YANG Modules
+------------+ +------------+ +-------------+ +------------+
| | | | | | | |
| MPLS | | BGP | | IPv4 / IPv6 | | Ethernet |
| | | | | | | |
+------------+ +------------+ +-------------+ +------------+
L2VPN: Layer 2 Virtual Private Network
L3VPN: Layer 3 Virtual Private Network
VPWS: Virtual Private Wire Service
VPLS: Virtual Private LAN Service
Figure 1: YANG Module Layers
2.1. Network Service YANG Modules 2.1. Network Service YANG Modules
Network Service YANG Modules describe the characteristics of a Network Service YANG Modules describe the characteristics of a
service, as agreed upon with consumers of that service. That is, a service, as agreed upon with consumers of that service. That is, a
service model does not expose the detailed configuration parameters service module does not expose the detailed configuration parameters
of all participating network elements and features, but describes an of all participating network elements and features, but describes an
abstract model that allows instances of the service to be decomposed abstract model that allows instances of the service to be decomposed
into instance data according to the Network Element Modules of the into instance data according to the Network Element YANG Modules of
participating network elements. The service-to-element decomposition the participating network elements. The service-to-element
is a separate process with details depending on how the network decomposition is a separate process with details depending on how the
operator chooses to realize the service. For the purpose of this network operator chooses to realize the service. For the purpose of
document we will use the term "orchestrator" to describe a system this document we will use the term "orchestrator" to describe a
implementing such a process. system implementing such a process.
As an example, the Network Service YANG Module included in As an example, the Network Service YANG Module defined in
[YANG-Data-Model-for-L3VPN-service-delivery] provides an abstract [YANG-Data-Model-for-L3VPN-service-delivery] provides an abstract
model for Layer 3 IP VPN service configuration. This model includes model for Layer 3 IP VPN service configuration. This module includes
e.g. the concept of a 'site-network-access' to represent bearer and e.g. the concept of a 'site-network-access' to represent bearer and
connection parameters. An orchestrator receives operations on connection parameters. An orchestrator receives operations on
service instances according to the service model and decomposes the service instances according to the service module and decomposes the
data into specific Network Element Modules to configure the data into specific Network Element YANG Modules to configure the
participating network elements to perform the intent of the service. participating network elements to perform the intent of the service.
In the case of the L3VPN module, this would include translating the In the case of the L3VPN module, this would include translating the
'site-network-access' parameters to the appropriate parameters in the 'site-network-access' parameters to the appropriate parameters in the
Network Element YANG Module implemented on the constituent elements. Network Element YANG Module implemented on the constituent elements.
Network Service YANG Modules define services models to be consumed by Network Service YANG Modules define service models to be consumed by
external systems. These modules are commonly designed, developed and external systems. These modules are commonly designed, developed and
deployed by network infrastructure teams. deployed by network infrastructure teams.
YANG allows for different design patterns to describe network YANG allows for different design patterns to describe network
services, ranging from monolithic to component-based approaches. services, ranging from monolithic to component-based approaches.
The monolithic approach captures the entire service in a single The monolithic approach captures the entire service in a single
module and does not put focus on reusability of internal data module and does not put focus on reusability of internal data
definitions and groupings. The monolithic approach has the definitions and groupings. The monolithic approach has the
advantages of single-purpose development including speed at the advantages of single-purpose development including speed at the
skipping to change at page 7, line 15 skipping to change at page 7, line 17
As an example, an L2VPN service can be built on many different types As an example, an L2VPN service can be built on many different types
of transport network technologies, including e.g. MPLS or carrier of transport network technologies, including e.g. MPLS or carrier
ethernet. A component-based approach would allow for reuse of e.g. ethernet. A component-based approach would allow for reuse of e.g.
UNI-interface definitions independent of the underlying transport UNI-interface definitions independent of the underlying transport
network (e.g. MEF UNI interface or MPLS interface). The monolithic network (e.g. MEF UNI interface or MPLS interface). The monolithic
approach would assume a specific set of transport technologies and approach would assume a specific set of transport technologies and
interface definitions. interface definitions.
2.2. Network Element YANG Modules 2.2. Network Element YANG Modules
Network Element YANG Modules describe the configuration, state data Network Element YANG Modules describe the characteristics of a
and operations of a network device as defined by the vendor of that network device as defined by the vendor of that device. The modules
device. The modules are commonly structured around features of the are commonly structured around features of the device, e.g. interface
device, e.g. interface configuration [RFC7223], OSPF configuration configuration [RFC7223], OSPF configuration [I-D.ietf-ospf-yang], and
[I-D.ietf-ospf-yang], and firewall rules definitions firewall rules definitions [I-D.ietf-netmod-acl-model].
[I-D.ietf-netmod-acl-model].
The module provides a coherent data model representation of what is The module provides a coherent data model representation of the
commonly a very mixed software environment consisting of the software environment consisting of the operating system and
operating system and applications running on the device. The applications running on the device. The decomposition, ordering, and
decomposition, ordering, and execution of changes to the operating execution of changes to the operating system and application
system and application configuration is the task of the management configuration is the task of the agent that implements the module.
framework that implements the YANG module.
3. Second Dimension: Module Types 3. Second Dimension: Module Types
This document suggests classifying YANG module types as either This document suggests classifying YANG module types as standard YANG
standard YANG modules, vendor-specific YANG modules and extensions, modules, vendor-specific YANG modules and extensions, or user-
and user-specific YANG modules and extensions specific YANG modules and extensions
The suggested classification applies to both Network Element YANG The suggested classification applies to both Network Element YANG
Modules and Network Service YANG Modules. Modules and Network Service YANG Modules.
It is to be expected that real-world implementations of both Network It is to be expected that real-world implementations of both Network
Service and Network Element YANG Modules will include a mix of all Service YANG Modules and Network Element YANG Modules will include a
three types of modules. mix of all three types of modules.
Figure 2 illustrates the relationship between the three types of Figure 2 illustrates the relationship between the three types of
modules. modules.
+--------------+ +--------------+
| User | | User |
| Extensions | | Extensions |
+------+-------+ +------+-------+
Augments Augments
+------+-------+ +--------------+ +--------------+ +------+-------+ +--------------+ +--------------+
| Vendor | | User | | User | | Vendor | | User | | User |
| Extensions | | Extensions | | Extensions | | Extensions | | Extensions | | Extensions |
+------+-------+ +------+-------+ +------+-------+ +------+-------+ +------+-------+ +------+-------+
Augments Augments Augments Augments Augments Augments
+------+-----------------+-------+ +------+-------+ +--------------+ +------+-----------------+-------+ +------+-------+ +--------------+
| Standard | | Vendor | | User | | Standard | | Vendor | | User |
| Models | | Models | | Models | | Modules | | Modules | | Modules |
+--------------------------------+ +--------------+ +--------------+ +--------------------------------+ +--------------+ +--------------+
Figure 2: YANG Module Types Figure 2: YANG Module Types
3.1. Standard YANG Modules 3.1. Standard YANG Modules
Standard YANG Modules are published by standards-defining Standard YANG Modules are published by standards-defining
organizations (SDOs). While there is no formal definition of what organizations (SDOs). While there is no formal definition of what
construes an SDO, a common feature is that they publish construes an SDO, a common feature is that they publish
specifications along specific processes with content that reflects specifications along specific processes with content that reflects
some sort of membership consensus. The specifications are developed some sort of membership consensus. The specifications are developed
for wide use among the membership or for audiences beyond that. for wide use among the membership or for audiences beyond that.
The lifecycle of these modules is driven by the editing cycle of the The lifecycle of these modules is driven by the editing cycle of the
specification and not tied to a specific implementation. specification and not tied to a specific implementation.
Examples of SDOs in the networking industry are the IETF, the IEEE Examples of SDOs in the networking industry are the IETF, the IEEE
(Institute of Electrical and Electronics Engineers) and the MEF. and the MEF.
3.2. Vendor-specific YANG Modules and Extensions 3.2. Vendor-specific YANG Modules and Extensions
Vendor-specific YANG modules are developed by organizations with the Vendor-specific YANG Modules are developed by organizations with the
intent to support a specific set of implementations under control of intent to support a specific set of implementations under control of
that organization. For example vendors of virtual or physical that organization. For example vendors of virtual or physical
equipment, industry consortia, and opensource projects. The intent equipment, industry consortia, and opensource projects. The intent
of these modules range from providing openly published YANG modules of these modules range from providing openly published YANG modules
that may eventually be contributed back to, or adopted by an SDO, to that may eventually be contributed back to, or adopted by, an SDO, to
strictly internal YANG modules not intended for external consumption. strictly internal YANG modules not intended for external consumption.
The lifecycle of these modules are generally aligned with the release The lifecycle of these modules are generally aligned with the release
cycle of the product or open source software project deliverables. cycle of the product or open source software project deliverables.
It is worth noting that there is an increasing amount of interaction It is worth noting that there is an increasing amount of interaction
between open source projects and SDOs in the networking industry. between open source projects and SDOs in the networking industry.
This includes open source projects implementing published standards This includes open source projects implementing published standards
as well as open source projects contributing content to SDO as well as open source projects contributing content to SDO
processes. processes.
Vendors also develop Vendor-specific Extensions to standard modules Vendors also develop Vendor-specific Extensions to standard modules
using YANG constructs for extending data definitions of previously using YANG constructs for extending data definitions of previously
published modules. This is done using the 'augment' statement that published modules. This is done using the 'augment' statement that
allows locally defined data trees to be augmented into locations in allows locally defined data trees to be augmented into locations in
externally defined data trees. externally defined data trees.
Vendors use this to extend standard modules to cover the full scope Vendors use this to extend standard modules to cover the full scope
of features in implementations, which commonly is broader than what of features in implementations, which commonly is broader than that
is covered by the standard module. covered by the standard module.
3.3. User-specific YANG Modules and Extensions 3.3. User-specific YANG Modules and Extensions
User-specific YANG modules are developed by organizations that User-specific YANG Modules are developed by organizations that
operate YANG-based infrastructure including devices and operate YANG-based infrastructure including devices and
orchestrators. For example, network administrators in enterprises, orchestrators. For example, network administrators in enterprises,
or operators service providers. The intent of these modules is to or at service providers. The intent of these modules is to express
express the specific needs for a certain implementation, above and the specific needs for a certain implementation, above and beyond
beyond what is provided by vendors. what is provided by vendors.
This module type obviously requires the infrastructure to support the This module type obviously requires the infrastructure to support the
introduction of user-provided modules and extensions. This would introduction of user-provided modules and extensions. This would
include ability to describe the service-to-network decomposition in include ability to describe the service-to-network decomposition in
orchestrators and the module to configuration decomposition in orchestrators and the module to configuration decomposition in
devices. devices.
The lifecycle of these modules are generally aligned with the change The lifecycles of these modules are generally aligned with the change
cadence of the infrastructure. cadence of the infrastructure.
4. Adding The Classification Type to YANG Module Catalogs 4. Adding The Classification Type to YANG Module Catalogs
The suggested classification in this document would be an useful The suggested classification in this document would be an useful
information in a catalog of YANG modules. Such catalog allows for information in a catalog of YANG modules. Such a catalog allows for
easy lookup and reusability of YANG modules. Practically, the YANG easy lookup and reusability of YANG modules. Practically, the YANG
module classification type would be an additional leaf to YANG module module classification type would be an additional leaf to a YANG
specified in [I-D.openconfig-netmod-model-catalog]: module specified in [I-D.openconfig-netmod-model-catalog]:
leaf module-class{ leaf module-class{
type enum { type enum {
service service
device device
notApplicable notApplicable
} }
description description
"Categorization of the YANG module based on "Categorization of the YANG module based on
draft-ietf-netmod-yang-model-classification."; draft-ietf-netmod-yang-model-classification.";
} }
Note: this leaf should actually be moved to Note: this leaf should actually be moved to
[I-D.openconfig-netmod-model-catalog]. Note2: since a YANG module [I-D.openconfig-netmod-model-catalog]. Note2: since a YANG module
can belong to both service and device, the ENUM is not appropriate. can belong to both service and device, the ENUM is not appropriate.
A extensible list of module type is more appropriate. An extensible list of module type is more appropriate.
Indeed, without inspecting the YANG module itself, it's difficult to Indeed, without inspecting the YANG module itself, it's difficult to
determine whether its type is a network service or a network element. determine whether its type is a network service or a network element.
The YANG module name might provide some useful information but is not The YANG module name might provide some useful information but is not
a definite answer. a definitive answer.
5. Security Considerations 5. Security Considerations
This document doesn't have any Security Considerations". This document doesn't have any Security Considerations.
6. IANA Considerations 6. IANA Considerations
This document has no IANA actions. This document has no IANA actions.
7. Acknowledgements 7. Acknowledgements
Thanks to David Ball and David Hansford for feedback and suggestions. Thanks to David Ball and David Hansford for feedback and suggestions.
8. Change log [RFC Editor: Please remove] 8. Change log [RFC Editor: Please remove]
version 00: Renamed and small fixes based on WG feedback. version 00: Renamed and small fixes based on WG feedback.
version 01: Language fixes, collapsing of vendor data models and version 01: Language fixes, collapsing of vendor data models and
extensions, and the introduction of user data models and extensions. extensions, and the introduction of user data models and extensions.
version 02: Updated the YANG Module Catalog section, terminology version 02: Updated the YANG Module Catalog section, terminology
alignment (YANG data model versus YANG module), epxlain better the alignment (YANG data model versus YANG module), explain better the
distinction between the Network Element and Service YANG data models distinction between the Network Element and Service YANG data models
even if sometimes there are grey areas, editorial pass. Changed the even if sometimes there are grey areas, editorial pass. Changed the
use of the term 'model' to 'module' to be better aligned with use of the term 'model' to 'module' to be better aligned with
RFC6020. RFC6020.
9. References 9. References
9.1. Normative References 9.1. Normative References
[RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for [RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for
the Network Configuration Protocol (NETCONF)", RFC 6020, the Network Configuration Protocol (NETCONF)", RFC 6020,
DOI 10.17487/RFC6020, October 2010, DOI 10.17487/RFC6020, October 2010,
<http://www.rfc-editor.org/info/rfc6020>. <http://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,
<http://www.rfc-editor.org/info/rfc6241>.
[RFC7223] Bjorklund, M., "A YANG Data Model for Interface
Management", RFC 7223, DOI 10.17487/RFC7223, May 2014,
<http://www.rfc-editor.org/info/rfc7223>.
[RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
RFC 7950, DOI 10.17487/RFC7950, August 2016,
<http://www.rfc-editor.org/info/rfc7950>.
9.2. Informative References 9.2. Informative References
[I-D.ietf-netmod-acl-model] [I-D.ietf-netmod-acl-model]
Bogdanovic, D., Koushik, K., Huang, L., and D. Blair, Bogdanovic, D., Koushik, K., Huang, L., and D. Blair,
"Network Access Control List (ACL) YANG Data Model", "Network Access Control List (ACL) YANG Data Model",
draft-ietf-netmod-acl-model-07 (work in progress), March draft-ietf-netmod-acl-model-08 (work in progress), July
2016.
[I-D.ietf-netmod-rfc6020bis]
Bjorklund, M., "The YANG 1.1 Data Modeling Language",
draft-ietf-netmod-rfc6020bis-14 (work in progress), June
2016. 2016.
[I-D.ietf-ospf-yang] [I-D.ietf-ospf-yang]
Yeung, D., Qu, Y., Zhang, Z., Bogdanovic, D., and K. Yeung, D., Qu, Y., Zhang, Z., Bogdanovic, D., and K.
Koushik, "Yang Data Model for OSPF Protocol", draft-ietf- Koushik, "Yang Data Model for OSPF Protocol", draft-ietf-
ospf-yang-04 (work in progress), March 2016. ospf-yang-05 (work in progress), July 2016.
[I-D.openconfig-netmod-model-catalog] [I-D.openconfig-netmod-model-catalog]
D'Souza, K., Shaikh, A., and R. Shakir, "Catalog and D'Souza, K., Shaikh, A., and R. Shakir, "Catalog and
registry for YANG models", draft-openconfig-netmod-model- registry for YANG models", draft-openconfig-netmod-model-
catalog-00 (work in progress), October 2015. catalog-01 (work in progress), July 2016.
[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,
<http://www.rfc-editor.org/info/rfc6241>.
[RFC7223] Bjorklund, M., "A YANG Data Model for Interface
Management", RFC 7223, DOI 10.17487/RFC7223, May 2014,
<http://www.rfc-editor.org/info/rfc7223>.
[Writable-MIB-Module-IESG-Statement] [Writable-MIB-Module-IESG-Statement]
"Writable MIB Module IESG Statement", "Writable MIB Module IESG Statement",
<https://www.ietf.org/iesg/statement/writable-mib- <https://www.ietf.org/iesg/statement/writable-mib-
module.html>. module.html>.
[YANG-Data-Model-for-L3VPN-service-delivery] [YANG-Data-Model-for-L3VPN-service-delivery]
"YANG Data Model for L3VPN service delivery", "YANG Data Model for L3VPN service delivery",
<https://tools.ietf.org/id/draft-l3vpn-service-yang>. <https://tools.ietf.org/id/draft-l3vpn-service-yang>.
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