2.4.9 NETCONF Data Modeling Language (netmod)

NOTE: This charter is a snapshot of the 72nd IETF Meeting in Dublin, Ireland. It may now be out-of-date.

Last Modified: 2005-05-11


Sharon Chisholm <schishol@nortel.com>

Operations and Management Area Director(s):

Dan Romascanu <dromasca@avaya.com>
Ronald Bonica <rbonica@juniper.net>

Operations and Management Area Advisor:

TBD <noreply@ietf.org>

Mailing Lists:

General Discussion:
To Subscribe:

Description of Working Group:

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 mapping rules from YANG to the DSDL data modeling
framework (ISO/IEC 19757) with additional annotations to preserve

The initial YANG mapping rules 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
MIB modules to YANG data models (modules), it is not a
requirement to provide full compatibility between SMIv2 and YANG.
The Working Group will determine which constructs (e.g., conformance
statements) are not relevant for translation from SMIv2 to YANG. YANG
also permitted to introduce constructs that cannot be expressed in
SMIv2.  However, all basic types that can be represented in SMIv2 must
be expressible in YANG.

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 rules of YANG to XML instance data in NETCONF
(proposed standard)

4. YIN, a semantically equivalent fully reversible mapping to an
XML-based syntax for YANG.  YIN is simply the data model in an XML
syntax that can be manipulated using existing XML tools (e.g., XSLT)
(proposed standard)

5. Mapping rules of YANG to DSDL data modeling framework (ISO/IEC
19757), including annotations for DSDL to preserve top-level
semantics during translation (proposed standard).

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

Goals and Milestones:

No Current Internet-Drafts

No Request For Comments

Meeting Minutes


NETMOD Architecture
YANG High­Level Presentation, YIN, XML on the wire
Common YANG Data Types
Representing Netconf Data Models using Document Schema Definition Languages (DSDL)
Mapping of YANG to DSDL
YANG Open Issues
RPCs and Notifications inside Lists in YANG
Augmenting YANG Groupings