[NGO] A proposed WG Charter for NETMOD: NETCONF Data Modeling

David Partain <david.partain@ericsson.com> Mon, 31 March 2008 19:31 UTC

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From: David Partain <david.partain@ericsson.com>
Organization: Ericsson AB
To: "'NETCONF Goes On'" <ngo@ietf.org>
Date: Mon, 31 Mar 2008 21:30:34 +0200
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Subject: [NGO] A proposed WG Charter for NETMOD: NETCONF Data Modeling
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Since the last IETF, a group of people has been working on
creating a charter proposal for work in new working group as a
result of the many discussions, BoFs, semi-BoFs, bar BoFs...  on
a modeling language for NETCONF.  We did this at the request of
our O&M ADs.

The group included Alex Clemm, Balázs Lengyel, Bernd Linowski,
Bert Wijnen, David Harrington, David Partain, Jung Tjong,
Ladislav Lhotka, Martin Björklund, Martin Storch, Mehmet Ersue,
Phil Shafer, Randy Presuhn, Rohan Mahy, and Sharon Chisholm.

We've worked very hard on this (LOTS of email), and, while we don't all agree 
on every word, I believe we're all in agreement on the general direction 

Our proposal is below and we look forward to your comments here on NGO.

With kind regards,

David Partain


Chairs: TBD

The NETCONF Working Group has completed a base protocol to be
used for configuration management.  However, the NETCONF protocol
does not include a standard content layer.  The specifications do
not include a modeling language or accompanying rules that can be
used to model the management information that is to be configured
using NETCONF. This has resulted in inconsistent syntax and
interoperability problems. The purpose of NETMOD is to support
the ongoing development of IETF and vendor-defined data models

NETMOD's requirements are drawn from the RCDML requirements draft
(draft-presuhn-rcdml) and documents referenced therein.

The WG will define a "human-friendly" modeling language defining
the semantics of operational data, configuration data,
notifications, and operations.  This language will focus on
readability and ease of use.  This language must be able to serve
as the normative description of NETCONF data models.  The WG will
use YANG (draft-bjorklund-yang) as its starting point for this

Language abstractions that facilitate model extensibility and
reuse have been identified as a work area and will be considered
as a work item or may be integrated into the YANG document based
on WG consensus.

The WG will define a canonical mapping of this language to
NETCONF XML instance documents, the on-the-wire format of
YANG-defined XML content.  Only data models defined in YANG will
have to adhere to this on-the-wire format.

In order to leverage existing XML tools for validating NETCONF
data in various contexts and also facilitate exchange of data
models and schemas with other IETF working groups, the WG will
define standard mappings from YANG to the DSDL data modeling
framework (ISO/IEC 19757) with additional annotations to preserve

The initial YANG mapping specifications are expressly defined for
NETCONF modeling.  However, there may be future areas of
applicability beyond NETCONF, and the WG must provide suitable
language extensibility mechanisms to allow for such future work.
The NETMOD WG will only address modeling NETCONF devices and the
language extensibility mechanisms.  Any application of YANG to
other protocols is future work.

The WG will consult with the NETCONF WG to ensure that NETMOD's
decision do not conflict with planned work in NETCONF (e.g.,
locking, notifications).

While it is desirable to provide a migration path from existing
MIBs to YANG data models, it is not a requirement to provide full
compatibility between SMIv2 and YANG. YANG is permitted to
introduce constructs that cannot be expressed in SMIv2.  However,
everything that can be expressed in SMIv2 must be expressible in

Initial deliverables are below.  The working group may choose to
combine multiple deliverables into a single document where deemed

1. An architecture document explaining the relationship
between YANG and its inputs and outputs. (informational)

2. The YANG data modeling language and semantics (proposed

3. Mapping of YANG to XML instance data in NETCONF (proposed

4. A semantically equivalent two-way mapping to an XML-based
syntax for YANG (currently called YIN) (proposed standard)

5. Mapping of YANG to DSDL data modeling framework (ISO/IEC
19757) (proposed standard)

6. Definition of annotations for DSDL to preserve top-level
semantics during translation (proposed standard)

7. A standard type library for use by YANG (proposed standard)

Goals and Milestones:

Jun 2008 - All _individual_ drafts available that will be used as
input into the WG documents (draft-bjorklund-yang, architecture
draft, YIN draft, YANG standard library draft, DSDL mapping

Aug 2008 - Initial set of WG drafts: architecture, YANG, YIN,
YANG standard library, DSDL mapping (if there is one/more
individual draft), based on WG decisions in Dublin

Sep 2008 - Initial DSDL mapping document

Oct 2008 - 01 of YANG, DSDL, architecture, YIN, and standard
library draft.  If split out, -00 of on-the-wire XML draft.

Feb 2009 - WGLC for architecture doc

Mar 2009 - Submit the architecture doc to the IESG for
publication as an Informational RFC

Aug 2009 - WGLC for YANG, YIN, XML on-the-wire (if split out),
YANG standard library, DSDL mapping

Sep 2009 - Submit YANG, YIN, XML on-the-wire (if split out), YANG
standard library, DSDL mapping to the IESG for publication as a
Proposed Standard
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