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Common YANG Data Types for Layer 0 Optical Networks
draft-ietf-ccamp-rfc9093-bis-19

Document Type Active Internet-Draft (ccamp WG)
Authors Sergio Belotti , Italo Busi , Dieter Beller , Esther Le Rouzic , Aihua Guo
Last updated 2025-11-03
Replaces draft-ietf-ccamp-layer0-types-ext
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Details
draft-ietf-ccamp-rfc9093-bis-19
CCAMP Working Group                                      S. Belotti, Ed.
Internet-Draft                                                     Nokia
Obsoletes: 9093 (if approved)                               I. Busi, Ed.
Intended status: Standards Track                                  Huawei
Expires: 7 May 2026                                       D. Beller, Ed.
                                                                   Nokia
                                                            E. Le Rouzic
                                                                  Orange
                                                                  A. Guo
                                                  Futurewei Technologies
                                                         3 November 2025

          Common YANG Data Types for Layer 0 Optical Networks
                    draft-ietf-ccamp-rfc9093-bis-19

Abstract

   This document defines a collection of common data types, identities,
   and groupings in the YANG data modeling language.  These common types
   and groupings, derived from the built-in YANG data types, identities,
   and groupings are intended to be imported by modules that model
   Optical Layer 0 configuration and state capabilities, such as
   Wavelength Switched Optical Networks (WSONs) and flexi-grid Dense
   Wavelength Division Multiplexing (DWDM) networks.

   This document obsoletes RFC 9093 by replacing the YANG module it
   contained with a new revision that includes additional YANG data
   types, identities and groupings.

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 7 May 2026.

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Copyright Notice

   Copyright (c) 2025 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  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Editorial Note (To be removed by RFC Editor)  . . . . . .   3
     1.2.  Terminology and Notations . . . . . . . . . . . . . . . .   4
     1.3.  Prefix in Data Node Names . . . . . . . . . . . . . . . .   4
   2.  Layer 0 Types Module Contents . . . . . . . . . . . . . . . .   4
     2.1.  Identities  . . . . . . . . . . . . . . . . . . . . . . .   5
     2.2.  Data Types  . . . . . . . . . . . . . . . . . . . . . . .   6
       2.2.1.  Reporting unknown values  . . . . . . . . . . . . . .   6
     2.3.  Groupings . . . . . . . . . . . . . . . . . . . . . . . .   7
     2.4.  WDM Label and Label Range . . . . . . . . . . . . . . . .   9
   3.  YANG Module for Layer 0 Types . . . . . . . . . . . . . . . .  12
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .  62
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  63
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  63
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .  63
     6.2.  Informative References  . . . . . . . . . . . . . . . . .  67
   Appendix A.  The Complete Schema Trees  . . . . . . . . . . . . .  69
   Appendix B.  Changes from RFC 9093  . . . . . . . . . . . . . . .  74
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .  78
   Contributors  . . . . . . . . . . . . . . . . . . . . . . . . . .  78
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  80

1.  Introduction

   This document introduces a collection of common data types derived
   from the built-in YANG data types.  The derived types and groupings
   are designed to be the common types applicable for modeling Traffic
   Engineering (TE) features as well as non-TE features (e.g., physical
   network configuration aspects) for Layer 0 optical networks in models
   defined outside of this document.  The applicability of Layer 0 types
   specified in this document includes Wavelength Switched Optical
   Networks (WSONs) [RFC6163] [ITU-T_G.694.1] and [ITU-T_G.694.2], and

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   flexi-grid Dense Wavelength Division Multiplexing (DWDM) networks
   [RFC7698] [ITU-T_G.694.1].

   This document adds new type definitions to the YANG modules and
   obsoletes [RFC9093].  For further details, see the revision
   statements of the YANG module in Section 3 or the summary in
   Appendix B.

   This document obsoletes [RFC9093] by replacing it in its entirety.
   It provides a new revision of the YANG module contained in that RFC,
   and retains the data types previously defined, but also adds new type
   definitions to the YANG module.  For further details, see Appendix B.

   The YANG data model in this document conforms to the Network
   Management Datastore Architecture defined in [RFC8342].

1.1.  Editorial Note (To be removed by RFC Editor)

      Note to the RFC Editor: This section is to be removed prior to
      publication.

   This document contains placeholder values that need to be replaced
   with finalized values at the time of publication.  This note
   summarizes all of the substitutions that are needed.

   Please apply the following replacements:

   *  XXXX --> the assigned RFC number for this I-D

   *  YYYY --> the assigned RFC number for
      [I-D.ietf-teas-rfc8776-update]

   *  ZZZZ --> the assigned RFC number for
      [I-D.ietf-ccamp-optical-impairment-topology-yang]

   Please replace the revision date of the latest revision of the 'ietf-
   layer0-types' module with the publication date of this I-D, using the
   the format (year-month-day).

   Please manually fix the YANG trees in Appendix A which have been
   generated by pyang and have some bugs.

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1.2.  Terminology and Notations

   In the context of this document, the term "layer 0" refers to the
   photonic layer or WDM layer network in the architecture of the
   optical transport network (OTN) as defined in [ITU-T_G.709],
   [ITU-T_G.872], and [ITU-T_G.807] as opposed to the electrical
   switching layers of the OTN, which are typically referred to as layer
   1 (L1).

   The term "layer 0" may also be used for other transport network
   technologies (e.g., copper-based, radio-based, or free space optics-
   based, etc.), which are outside the scope of this document.

   Refer to [RFC7446] and [RFC7581] for other key terms used in this
   document, and the terminology for describing YANG data models can be
   found in [RFC7950].

   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.

1.3.  Prefix in Data Node Names

   In this document, names of data nodes and other data model objects
   are prefixed using the standard prefix associated with the
   corresponding YANG imported module.

               +==========+===================+===========+
               | Prefix   | YANG module       | Reference |
               +==========+===================+===========+
               | te-types | ietf-te-types     | [RFCYYYY] |
               +----------+-------------------+-----------+
               | l0-types | ietf-layer0-types | RFC XXXX  |
               +----------+-------------------+-----------+

                 Table 1: Prefixes and corresponding YANG
                                  module

2.  Layer 0 Types Module Contents

   This document defines a YANG module for common Layer 0 types, ietf-
   layer0-types.  This module is used for WSON and flexi-grid DWDM
   networks.

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2.1.  Identities

   The "ietf-layer0-types" module contains the following YANG reusable
   YANG identities:

   l0-grid-type:  A base YANG identity for the grid type as defined in
      [RFC6205] and [RFC7699].

   cwdm-ch-spc-type:  A base YANG identity for the Coarse Wavelength
      Division Multiplexing (CWDM) channel-spacing type as defined in
      [RFC6205].

   dwdm-ch-spc-type:  A base YANG identity for the DWDM channel-spacing
      type as defined in [RFC6205].

   flexi-ncfg-type:  A base YANG identity for the DWDM flexi-grid
      Nominal Central Frequency Granularity (NCFG) type as defined in
      [RFC7699].

      Note that the only value for NCFG standardized in [ITU-T_G.694.1]
      is 6.25GHz.

   flexi-slot-width-granularity:  A base YANG identity for the DWDM
      flexi-grid Slot Width Granularity (SWG) type, as defined in
      [RFC7699].

      Note that the only value for SWG standardized in [ITU-T_G.694.1]
      is 12.5GHz.

   fec-type:  A base YANG identity from which specific FEC (Forward
      Error Correction) type identities are derived.

   line-coding:  A base YANG identity from which specific identities
      defining the bit rate/line coding of optical tributary signals are
      derived.

   wavelength-assignment:  A base YANG identity from which specific
      identities defining the Wavelength selection methods, as defined
      in [RFC7689], are derived.

   modulation:  A base YANG identity to define the different modulation
      types, as defined in [ITU-T_G.Sup39]

   switching-wson-lsc:  A YANG identity for the Wavelength Switched
      Optical Network Lambda-Switch Capable (WSON-LSC) interface
      switching capability as defined in [RFC7688].

   switching-flexi-grid-lsc:  A YANG identity for the Flexi-Grid Lambda-

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      Switch Capable (Flexi-Grid-LSC) interface switching capability as
      defined in [RFC8363].

   It is worth noting that there is an inheritance relationship between
   the Lambda-Switch Capable (LSC) switching capability, defined in
   [RFC3471], and the WSON-LSC and Flexi-Grid-LSC, defined respectively
   in [RFC7688] and [RFC8363].  As a consequence, the 'switching-wson-
   lsc' and 'switching-flexi-grid-lsc' YANG identities are defined as
   derived identities from the 'switching-lsc', defined in
   [I-D.ietf-teas-rfc8776-update].

2.2.  Data Types

   The "ietf-layer0-types" module contains the following YANG reusable
   YANG data types:

   operational-mode:  A YANG data type used to identify an organization
      (e.g., vendor) specific mode for transceiver capability
      description, as defined in Section 2.6.2 of
      [I-D.ietf-ccamp-optical-impairment-topology-yang]

   snr:  A YANG data type used to represent an (Optical) Signal-to-noise
      ratio measured over 0.1 nm resolution bandwidth, as defined in
      [ITU-T_G.977.1]

   psd:  A YANG data type used to represent a Power Spectral Density
      (PSD), as defined in [ITU-T_G.9700]

2.2.1.  Reporting unknown values

   Some data types, whose identifiers are suffixed as "-or-unknown", are
   defined as a union with the data type 'unknown-value' (e.g., snr-or-
   unknown), which is defined as an enumeration having only one assigned
   name (i.e., 'unknown').

   The unknown-value data type is used to report when the value is
   unknown in order to differentiate the case where an attribute is
   unknown from the case where an attribute is not applicable:

   *  if the value of a mandatory attribute is unknown, it MUST be
      reported using the unknown-value type;

   *  if an optional attribute is applicable but its value is unknown,
      it MUST be reported using the unknown-value type;

   *  if an optional attribute is not applicable to an entity, it MUST
      be omitted (not be present in the datastore).

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2.3.  Groupings

   The "ietf-layer0-types" module contains the following YANG reusable
   YANG groupings:

   wson-label-start-end:  The WSON label range was defined in [RFC6205],
      and the generic topology model defines the label-start/label-end
      in [RFC8795].  This grouping shows the WSON-specific label-start
      and label-end information.  See Section 2.4 for more details.

   wson-label-hop:  The WSON label range was defined in [RFC6205], and
      the generic topology model defines the label-hop in [RFC8795].
      This grouping shows the WSON-specific label-hop information.  See
      Section 2.4 for more details.

   l0-label-range-info:  A YANG grouping that defines the Layer 0 label
      range information applicable for WSON as defined in [RFC6205].
      The label range info is defined per priority [RFC4203].

      This grouping is used in the flexi-grid DWDM by adding more flexi-
      grid-specific parameters.  See Section 2.4 for more details.

   wson-label-step:  A YANG grouping that defines label steps for WSON
      as defined in [I-D.ietf-teas-rfc8776-update].  See Section 2.4 for
      more details.

   flexi-grid-label-start-end:  The flexi-grid label range was defined
      in [RFC7699], and the generic topology model defines the label-
      start/label-end in [RFC8795].

      This grouping shows the flexi-grid-specific label-start and label-
      end information which is used to describe the range of available
      nominal central frequencies.  See Section 2.4 for more details.

      As described in Section 3.1 of [RFC8363], the range of available
      nominal central frequencies is advertised for m=1, which means
      that for an available central frequency n, the frequency slot from
      central frequency n-1 to central frequency n+1 is available.

   flexi-grid-label-hop:  The flexi-grid label range was defined in
      [RFC8363], and the generic topology model defines the label-hop in
      [RFC8795].

      This grouping shows the WSON-specific label-hop information.  See
      Section 2.4 for more details.

   flexi-grid-label-range-info:  A YANG grouping that defines flexi-grid

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      label range information as defined in [RFC8363].  See Section 2.4
      for more details.  See Section 2.4 for more details.

   flexi-grid-label-step:  A YANG grouping that defines flexi-grid label
      steps as defined in [I-D.ietf-teas-rfc8776-update].  See
      Section 2.4 for more details.

   wdm-label-start-end:  A YANG grouping that combines the definition of
      label-start/label-end information that was defined separately in
      wson-label-start-end and flexi-grid-label-start-end, to support
      optical network scenarios that contain both fixed- and flexi-grid
      links.  See Section 2.4 for more details.

   wdm-label-hop:  A YANG grouping that combines the definition of label
      hop information that was defined separately in wson-label-hop and
      flexi-grid-label-hop, to support optical network scenarios that
      contain both fixed- and flexi-grid links.  See Section 2.4 for
      more details.

   wdm-label-range-info:  A YANG grouping that combines the definition
      of label range information that was defined separately in wson-
      label-range-info and flexi-grid-label-range-info, to support
      optical network scenarios that contain both fixed- and flexi-grid
      links.  See Section 2.4 for more details.

   wdm-label-step:  A YANG grouping that combines the definition of
      label step information defined separately in wson-label-step and
      flexi-grid-label-step, to support optical network scenarios that
      contain both fixed- and flexi-grid links.  See Section 2.4 for
      more details.

   transceiver-capabilities:  A YANG grouping to define the transceiver
      capabilities (also called "modes") needed to determine optical
      signal compatibility.

      When this grouping is used, the explicit-mode container shall be
      augmented with a leafref to an explicit mode template with the
      proper XPath, which depends from where this grouping is actually
      used.

      Examples of how the transceiver-capabilities grouping can be used
      and augmented with a leafref to an explicit mode template are
      provided in the YANG models defined in
      [I-D.ietf-ccamp-optical-impairment-topology-yang] and
      [I-D.ietf-ccamp-dwdm-if-param-yang].

   standard-mode:  A YANG grouping for the standard modes defined in
      [ITU-T_G.698.2].

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   organizational-mode:  A YANG grouping to define transponder
      operational mode supported by organizations or vendors, as defined
      in [I-D.ietf-ccamp-optical-impairment-topology-yang].

   explicit-mode:  A YANG grouping to define the list of attributes
      related to the limits of the optical impairments, in case of
      transceiver explicit mode, as defined in
      [I-D.ietf-ccamp-optical-impairment-topology-yang].

      Note that the actual portion of the spectrum occupied by an OTSi
      is not explicitly reported within the explicit-mode parameters
      because it can be calculated using the available-baud-rate, the
      roll-off and the min-carrier-spacing attributes.

   transceiver-tuning-range:  A YANG grouping that defines the
      transceiver tuning range, which includes the minimum and maximum
      tuning frequency, as well as the frequency tuning granularity.

   common-all-modes:  A YANG grouping used to define the common
      attributes used by all transceiver's modes.

   penalty-value:  A YANG grouping to define the penalty value for
      multiple penalty types, such as Chromatic Dispersion (CD),
      Polarization Mode Dispersion (PMD), as defined in [ITU-T_G.666] or
      Polarization Dependent Loss(PDL)

2.4.  WDM Label and Label Range

   As described in [RFC6205] and [RFC7699], the WDM label represents the
   frequency slots assigned to a WDM Label Switched Path (LSP) on a
   given WDM Link, which models an Optical Multiplex Section (OMS) Media
   Channel Group (MCG) as described in
   [I-D.ietf-ccamp-optical-impairment-topology-yang].

   The same WDM label (which represents the frequency slots associated
   with the WDM LSP) will be assigned on all the WDM Links along a
   regen-free LSP path or path segment (i.e., an LSP path or path
   segment which does not include any 3R regenerator).  Depending on the
   3R capabilities, the WDM label may or may not change at a 3R
   regenerator: see Section 2.7 of
   [I-D.ietf-ccamp-optical-impairment-topology-yang] for more details on
   3R regenerators.

   A frequency slot is defined in [ITU-T_G.694.1] as a contiguous
   frequency range characterized by its nominal central frequency and
   slot width.  The frequency range allocated to a frequency slot is
   unavailable to other frequency slots.

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   The definition of the frequency slot depends on the WDM grid type:

   *  In case of CWDM fixed-grid, defined in [ITU-T_G.694.2], the
      frequency slot is defined by a fixed CWDM channel spacing (cwdm-
      ch-spc-type) and by the nominal central wavelength which is
      computed as described in [RFC6205].  The formula in [RFC6205] is
      copied here for reader convenience:

         lambda = 1471 nm + n * channel spacing (measured in nm)

      where 'n' is defined in [RFC6205] as integer (positive, negative,
      or 0)

   *  In case of DWDM fixed-grid, defined in [ITU-T_G.694.1], the
      frequency slot is defined by a fixed DWDM channel spacing (dwdm-
      ch-spc-type) and by the nominal central frequency, which is
      computed as described in [RFC6205].  The formula in [RFC6205] is
      copied here for reader convenience:

         f = 193100.000 GHz + n * channel spacing (measured in GHz)

      where 'n' is defined in [RFC6205] as integer (positive, negative,
      or 0)

   *  In case of DWDM flexible-grid, defined in [ITU-T_G.694.1], the
      frequency slot is defined by the slot width and by the nominal
      central frequency, which are computed, based on the slot width
      granularity (SWG, fixed at 12.5GHz in [ITU-T_G.694.1]), and of the
      nominal central frequency granularity (NCFG, fixed at 6.25GHz in
      [ITU-T_G.694.1]) respectively, as described in [RFC7698] and
      [RFC7699].  The formulas in [RFC7699] can be generalized as
      follows:

         SW = m * SWG (measured in GHz)
         f = 193100.000 GHz + N * NCFG (measured in GHz)

      where 'n' is defined in [RFC7699] as integer (positive, negative,
      or 0) and 'm' is defined in [RFC7698] as an integer greater than
      or equal to 1.

   The definition of the channel spacing, NCFG and SWG in the YANG model
   have been generalized to support modelling of vendor-specific values
   (e.g., finer vendor-specific granularity for NCFG and SWG).

   The WDM Label Range represents the frequency slots that are available
   for WDM LSPs to be set up over a given WDM Link.

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   The WDM Label Range is defined by augmenting the label-restriction
   list, defined in [I-D.ietf-teas-rfc8776-update], with WDM technology-
   specific attributes, using the l0-label-range-info grouping (for WSON
   only models) or the flexi-grid-label-range-info grouping (for DWDM
   flexible-grid only models) or the wdm-label-range-info grouping (for
   models that support both WSON and DWDM flexible-grid).

   Each entry in the label-restriction list represents either the range
   of the available central wavelength values (in case of CWDM fixed-
   grid) or the range of the available nominal central frequencies
   values (in case of DWDM fixed or flexible grids): the grid-type
   attribute defines the type of grid for each entry of the list.

   In case of DWDM flexible grid, each entry in the label-restriction
   list also represents the range of the supported slot width values
   based on the following attributes, defined based on concepts used in
   [RFC7699]:

   *  slot-width-granularity, which represents the minimum space between
      slot widths;

   *  min-slot-width-factor: a multiplier of the slot width granularity,
      indicating the minimum slot width supported by each entry in the
      label-restriction list;

   *  max-slot-width-factor: a multiplier of the slot width granularity,
      indicating the maximum slot width supported by each entry in the
      label-restriction list.

   Each entry of the label-restriction list, as defined in
   [I-D.ietf-teas-rfc8776-update], defines a label-start, a label-end, a
   label-step and a range-bitmap.

   The label-start and label-end definitions, when used for representing
   WDM label range, are augmented with WDM technology-specific
   attributes, using the wson-label-start-end grouping (for WSON only
   models) or the flexi-grid-label-start-end grouping (for DWDM
   flexible-grid only models) or the wdm-label-start-end grouping (for
   models that support both WSON and DWDM flexible-grid).

   The label-step definition, when used for representing WDM label
   range, is augmented with WDM technology-specific attributes, using
   the wson-label-step grouping (for WSON only models) or the flexi-
   grid-label-step grouping (for DWDM flexible-grid only models) or the
   wdm-label-step grouping (for models that support both WSON and DWDM
   flexible-grid).  The label-step definition for WDM depends on the WDM
   grid type:

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   *  For CWDM and DWDM fixed grids, it describes the channel spacing,
      as defined in [RFC6205];

   *  For DWDM flexible grids, it describes the nominal central
      frequency granularity (e.g., 6,25 GHz) as well as the multiplier
      for the supported values of n, as defined in [RFC7699].

3.  YANG Module for Layer 0 Types

   This YANG module references [RFC6205], [RFC7689], [RFC7699],
   [RFC8363], [RFC9093], [ITU-T_G.666], [ITU-T_G.694.1],
   [ITU-T_G.694.2], [ITU-T_G.698.2], [ITU-T_G.709], [ITU-T_G.709.2],
   [ITU-T_G.709.3], [ITU-T_G.959.1] [ITU-T_G.975], [ITU-T_G.975.1],
   [ITU-T_G.977.1], [ITU-T_G.9700] and [OIF_400ZR].

   <CODE BEGINS> file "ietf-layer0-types@2025-11-03.yang"
   module ietf-layer0-types {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-layer0-types";
     prefix l0-types;

     import ietf-te-types {
       prefix te-types;
       reference
         "RFC YYYY: Common YANG Data Types for Traffic Engineering";
     }

     organization
       "IETF CCAMP Working Group";
     contact
       "WG Web:  <https://datatracker.ietf.org/wg/ccamp/>
        WG List: <mailto:ccamp@ietf.org>

        Editor:  Dieter Beller
                 <mailto:Dieter.Beller@nokia.com>

        Editor:  Sergio Belotti
                 <mailto:Sergio.Belotti@nokia.com>

        Editor:  Italo Busi
                 <mailto:Italo.Busi@huawei.com>

        Editor:  Haomian Zheng
                 <mailto:zhenghaomian@huawei.com>";
     description
       "This module defines Optical Layer 0 types.  This module
        provides groupings that can be applicable to Layer 0
        Fixed Optical Networks (e.g., CWDM (Coarse Wavelength

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        Division Multiplexing) and DWDM (Dense Wavelength Division
        Multiplexing)) and flexi-grid optical networks.

        Copyright (c) 2025 IETF Trust and the persons identified
        as authors of the code.  All rights reserved.

        Redistribution and use in source and binary forms, with
        or without modification, is permitted pursuant to, and
        subject to the license terms contained in, the Revised
        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).

        All revisions of IETF and IANA published modules can be found
        at the YANG Parameters registry group
        (https://www.iana.org/assignments/yang-parameters).

        This version of this YANG module is part of RFC XXXX; 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.";

     revision 2025-11-03 {
       description
         "This revision adds the following new identities:
          - cwdm-ch-spc-type;
          - flexi-ncfg-type;
          - flexi-ncfg-6p25gh;
          - modulation;
          - dpsk;
          - qpsk;
          - dp-qpsk;
          - qam8;
          - dp-qam8;
          - qam16;
          - dp-qam16;
          - qam32;
          - dp-qam32;
          - qam64;
          - dp-qam64;
          - fec-type;
          - g-fec;
          - super-fec;
          - no-fec;

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          - sc-fec;
          - o-fec;
          - c-fec;
          - line-coding;
          - nrz-2p5g;
          - nrz-otu1;
          - nrz-10g;
          - nrz-otu2;
          - otl4.4-sc;
          - foic1.4-sc;
          - wavelength-assignment;
          - first-fit-wavelength-assignment;
          - random-wavelength-assignment;
          - least-loaded-wavelength-assignment;
          - lower-first-wavelength-assignment;
          - upper-first-wavelength-assignment;
          - type-power-mode;
          - power-spectral-density;
          - carrier-power;
          - switching-wson-lsc;
          - switching-flexi-grid-lsc.

          This revision adds the following new data types:
          - standard-mode
          - organization-identifier
          - operational-mode
          - frequency-thz
          - frequency-ghz
          - unknown-value
          - snr
          - snr-or-unknown
          - decimal-2
          - decimal-2-or-unknown
          - power-gain
          - power-gain-or-unknown
          - power-loss
          - power-loss-or-unknown
          - power-ratio
          - power-ratio-or-unknown
          - power-dbm
          - power-dbm-or-unknown
          - decimal-5
          - decimal-5-or-unknown
          - psd
          - psd-or-unknown.

          This revision adds the following new groupings:
          - wdm-label-start-end;

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          - wdm-label-step;
          - wdm-label-hop;
          - wdm-label-range-info;
          - transceiver-capabilities;
          - standard-mode;
          - organizational-mode;
          - penalty-value;
          - explicit-mode;
          - common-standard-organizational-mode;
          - transceiver-tuning-range;
          - common-all-mode;
          - common-transceiver-param;
          - common-transceiver-configured-param;
          - common-transceiver-readonly-param;
          - tunnel-attributes;
          - frequency-range;
          - frequency-range-with-identifier;
          - path-constraints;
          - path-properties.

          The default value of the min-slot-width-factor data node
          within flexi-grid-label-range-info grouping has been removed
          (bug fixing).
         ";
       reference
         "RFC XXXX: Common YANG Data Types for Layer 0 Optical
          Networks";
     }
     revision 2021-08-13 {
       description
         "Initial version";
       reference
         "RFC 9093: A YANG Data Model for Layer 0 Types";
     }

     /*
      * Identities
      */

     identity l0-grid-type {
       description
         "Base identity for the WDM grid types.";
       reference
         "RFC 6205: Generalized Labels for Lambda-Switch-Capable
                    (LSC), Label Switching Routers
          ITU-T G.694.2 (12/2003): Spectral grids for WDM applications:
                   CWDM wavelength grid";
     }

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     identity wson-grid-cwdm {
       base l0-grid-type;
       description
         "Coarse Wavelength Division Multiplexing (CWDM) grid.";
       reference
         "RFC 6205: Generalized Labels for Lambda-Switch-Capable (LSC)
                    Label Switching Routers
          ITU-T G.694.2 (12/2003): Spectral grids for WDM applications:
                    CWDM wavelength grid";
     }

     identity wson-grid-dwdm {
       base l0-grid-type;
       description
         "Fixed Dense Wavelength Division Multiplexing (DWDM) grid.";
       reference
         "RFC 6205: Generalized Labels for Lambda-Switch-Capable
                    (LSC), Label Switching Routers
          ITU-T G.694.1 (10/2020): Spectral grids for WDM applications:
                    DWDM frequency grid, Clause 7.";
     }

     identity flexi-grid-dwdm {
       base l0-grid-type;
       description
         "Flexible Dense Wavelength Division Multiplexing (DWDM) grid
          (flexi-grid).";
       reference
         "RFC 7699: Generalized Labels for the Flexi-Grid in Lambda
                    Switch Capable (LSC) Label Switching Routers
          ITU-T G.694.1 (10/2020): Spectral grids for WDM applications:
                   DWDM frequency grid, Clause 8";
     }

     identity cwdm-ch-spc-type {
       description
         "Base identity for CWDM channel-spacing types.";
       reference
         "RFC 6205: Generalized Labels for Lambda-Switch-Capable (LSC)
                    Label Switching Routers, Section 3.3
          ITU-T G.694.2 (12/2003): Spectral grids for WDM applications:
                    CWDM wavelength grid";
     }

     identity cwdm-20nm {
       base cwdm-ch-spc-type;
       description
         "20nm channel spacing";

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       reference
         "RFC 6205: Generalized Labels for Lambda-Switch-Capable (LSC)
                    Label Switching Routers, Section 3.3
          ITU-T G.694.2 (12/2003): Spectral grids for WDM applications:
                   CWDM wavelength grid";
     }

     identity dwdm-ch-spc-type {
       description
         "Base identity for DWDM channel-spacing types.";
       reference
         "RFC 6205: Generalized Labels for Lambda-Switch-Capable (LSC)
                    Label Switching Routers, Section 3.2
          ITU-T G.694.1 (10/2020): Spectral grids for WDM applications:
                    DWDM frequency grid";
     }

     identity dwdm-100ghz {
       base dwdm-ch-spc-type;
       description
         "100 GHz channel spacing.";
       reference
         "RFC 6205: Generalized Labels for Lambda-Switch-Capable (LSC)
                    Label Switching Routers, Section 3.2
          ITU-T G.694.1 (10/2020): Spectral grids for WDM applications:
                   DWDM frequency grid";
     }

     identity dwdm-50ghz {
       base dwdm-ch-spc-type;
       description
         "50 GHz channel spacing.";
       reference
         "RFC 6205: Generalized Labels for Lambda-Switch-Capable (LSC)
                    Label Switching Routers, Section 3.2
          ITU-T G.694.1 (10/2020): Spectral grids for WDM applications:
                    DWDM frequency grid";
     }

     identity dwdm-25ghz {
       base dwdm-ch-spc-type;
       description
         "25 GHz channel spacing.";
       reference
         "RFC 6205: Generalized Labels for Lambda-Switch-Capable (LSC)
                    Label Switching Routers, Section 3.2
          ITU-T G.694.1 (10/2020): Spectral grids for WDM applications:
                    DWDM frequency grid";

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     }

     identity dwdm-12p5ghz {
       base dwdm-ch-spc-type;
       description
         "12.5 GHz channel spacing.";
       reference
         "RFC 6205: Generalized Labels for Lambda-Switch-Capable (LSC)
                    Label Switching Routers, Section 3.2
          ITU-T G.694.1 (10/2020): Spectral grids for WDM applications:
                    DWDM frequency grid";
     }

     identity flexi-ch-spc-type {
       status obsolete;
       description
         "Flexi-grid channel-spacing type";
     }

     identity flexi-ch-spc-6p25ghz {
       base flexi-ch-spc-type;
       status obsolete;
       description
         "6.25 GHz channel spacing";
     }

     identity flexi-ncfg-type {
       description
         "Flexi-grid Nominal Central Frequency Granularity (NCFG)
          type.";
       reference
         "RFC 7699: Generalized Labels for the Flexi-Grid in Lambda
                    Switch Capable (LSC) Label Switching Routers
          ITU-T G.694.1 (10/2020): Spectral grids for WDM applications:
                    DWDM frequency grid";
     }

     identity flexi-ncfg-6p25ghz {
       base flexi-ncfg-type;
       description
         "6.25 GHz Nominal Central Frequency Granularity (NCFG).";
       reference
         "RFC 7699: Generalized Labels for the Flexi-Grid in Lambda
                    Switch Capable (LSC) Label Switching Routers
          ITU-T G.694.1 (10/2020): Spectral grids for WDM applications:
                    DWDM frequency grid";
     }

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     identity flexi-slot-width-granularity {
       description
         "Flexi-grid slot width granularity.";
       reference
         "RFC 7699: Generalized Labels for the Flexi-Grid in Lambda
                    Switch Capable (LSC) Label Switching Routers
          ITU-T G.694.1 (10/2020): Spectral grids for WDM applications:
                    DWDM frequency grid";
     }

     identity flexi-swg-12p5ghz {
       base flexi-slot-width-granularity;
       description
         "12.5 GHz slot width granularity.";
       reference
         "RFC 7699: Generalized Labels for the Flexi-Grid in Lambda
                    Switch Capable (LSC) Label Switching Routers
          ITU-T G.694.1 (10/2020): Spectral grids for WDM applications:
                    DWDM frequency grid";
     }

     identity modulation {
       description
         "base identity for modulation type.";
     }

     identity dpsk {
       base modulation;
       description
         "Differential Phase Shift Keying (DPSK) modulation.";
     }

     identity qpsk {
       base modulation;
       description
         "Quadrature Phase Shift Keying (QPSK) modulation.";
     }

     identity dp-qpsk {
       base modulation;
       description
         "Dual Polarization Quadrature Phase Shift Keying
          (DP-QPSK) modulation.";
     }

     identity qam8 {
       base modulation;
       description

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         "8 symbols Quadrature Amplitude Modulation (8QAM).";
     }

     identity dp-qam8 {
       base modulation;
       description
         "8 symbols Dual Polarization Quadrature Amplitude
          Modulation (DP-QAM8).";
     }

     identity qam16 {
       base modulation;
       description
         "16 symbols Quadrature Amplitude Modulation (QAM16).";
     }

     identity dp-qam16 {
       base modulation;
       description
         "16 symbols Dual Polarization Quadrature Amplitude
          Modulation (DP-QAM16).";
     }

     identity qam32 {
       base modulation;
       description
         "32 symbols Quadrature Amplitude Modulation (QAM32)";
     }

     identity dp-qam32 {
       base modulation;
       description
         "32 symbols Dual Polarization Quadrature Amplitude
          Modulation (DP-QAM32).";
     }

     identity qam64 {
       base modulation;
       description
         "64 symbols Quadrature Amplitude Modulation (QAM64).";
     }

     identity dp-qam64 {
       base modulation;
       description
         "64 symbols Dual Polarization Quadrature Amplitude
          Modulation (DP-QAM64).";
     }

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     identity fec-type {
       description
         "Base identity from which specific Forward Error Correction
          (FEC) type identities are derived.";
     }

     identity g-fec {
       base fec-type;
       description
         "Generic Forward Error Correction (G-FEC).";
       reference
         "ITU-T G.975 v2.0 (10/2000): Forward error correction for
                      submarine systems.";
     }

     identity super-fec {
       base fec-type;
       description
         "Super Forward Error Correction (S-FEC).";
       reference
         "ITU-T G.975.1 v1.2 (07/2013): Forward error correction for
                        high bit-rate DWDM submarine systems.";
     }

     identity no-fec {
       base fec-type;
       description
         "No FEC.";
     }

     identity sc-fec {
       base fec-type;
       description
         "Staircase Forward Error Correction (SC-FEC).";
       reference
         "Annex A of ITU-T G.709.2 v1.1 (09/2020):OTU4 long-reach
                         interface.";
     }

     identity o-fec {
       base fec-type;
       description
         "Open Forward Error Correction (O-FEC) which reuses the
          Bose, Chaudhuri and Hocquenghem (BCH) FEC.";
       reference
         "ITU-T G.709.3 v2.1 (11/2022): Flexible OTN
                  long-reach interfaces, Clause 16.4.4
          ITU-T G.709.3 v2.1 (11/2022): Flexible OTN

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                  long-reach interfaces, Annex E";
     }

     identity c-fec {
       base fec-type;
       description
         "Concatenated FEC (C-FEC) that combines an outer Staircase
          Forward Error Correction (SC-FEC) code and an inner
          double-extended SD-FEC (128,119) Hamming code.

          More details are provided in clause 15/G.709.3 where it is
          called DSH instead of concatenated FEC.";
       reference
         "ITU-T G.709.2 v1.1 (09/2020):OTU4 long-reach
                      interface, Annex A
          ITU-T G.709.3 v2.1 (11/2022): Flexible OTN long-reach
                      interfaces, Annex D
          ITU-T G.709.3 v2.1 (11/2022): Flexible OTN long-reach
                      interfaces, Clause 15";
     }

     identity line-coding {
       description
         "Base identity to define the bit rate/line coding of optical
          tributary signals.";
       reference
         "ITU-T G.698.2 v3.0 (11/2018): Amplified multichannel dense
                       wavelength division multiplexing applications
                       with single channel optical interfaces Optical
                       transport network, Clause 7.1.2";
     }

     identity nrz-2p5g {
       base line-coding;
       description
         "The non return to zero (NRZ) bit rate/line coding used by
          the optical tributary signal class NRZ 2.5G.";
       reference
         "ITU-T G.959.1 v8.0 (07/2018): Optical transport network
                         physical layer interfaces, Clause 3.2.6";
     }

     identity nrz-otu1 {
       base line-coding;
       description
         "The Non-Return to Zero (NRZ) bit rate/line coding used by
          the Optical channel Transport Unit order 1 (OTU1) optical
          tributary signals.";

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       reference
         "ITU-T G.959.1 v8.0 (07/2018): Optical transport network
                      physical layer interfaces, Clause 7.2.1.2";
     }

     identity nrz-10g {
       description
         "The non return to zero (NRZ) bit rate/line coding used by
          the optical tributary signal class NRZ 10G.";
       reference
         "ITU-T G.959.1 v8.0 (07/2018): Optical transport network
                      physical layer interfaces, Clause 3.2.7";
     }

     identity nrz-otu2 {
       base line-coding;
       description
         "The non return to zero (NRZ) bit rate/line coding used by
          the Optical channel Transport Unit order 2 (OTU2) optical
          tributary signals.";
       reference
         "ITU-T G.959.1 v8.0 (07/2018): Optical transport network
                      physical layer interfaces, Clause 7.2.1.2";
     }

     identity otl4.4-sc {
       base line-coding;
       description
         "The bit rate/line coding used by optical tributary
          signals carrying a 100G Optical Transport Unit order 4
          (OTU4) with Staircase Forward Error Correction (SC FEC)
          from a group of four Optical Transport Lanes (OTL).";
       reference
         "ITU-T G.698.2 v3.0 (11/2018): Amplified multichannel dense
                      wavelength division multiplexing applications
                      with single channel optical interfaces Optical
                      transport network, Clause 3.2.1";
     }

     identity foic1.4-sc {
       base line-coding;
       description
         "The bit rate/line coding used by optical tributary signals
          carrying a FlexO Interface of order C1 with 4 lanes
          (FOIC1.1) with Staircase Forward Error Correction
          (SC FEC).";
       reference
         "ITU-T G.698.2 v3.0 (11/2018): Amplified multichannel dense

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                      wavelength division multiplexing applications
                      with single channel optical interfaces Optical
                      transport network, Clause 3.2.1";
     }

     identity wavelength-assignment {
       description
         "Base identity for Wavelength Assignment (WA) method.";
       reference
         "RFC 7689: Signaling Extensions for Wavelength Switched
                    Optical Networks";
     }

     identity first-fit-wavelength-assignment {
       base wavelength-assignment;
       description
         "All the available wavelengths are numbered, and this WA
          method chooses the available wavelength with the lowest
          index.";
       reference
         "RFC 7689: Signaling Extensions for Wavelength Switched
                    Optical Networks";
     }

     identity random-wavelength-assignment {
       base wavelength-assignment;
       description
         "This WA method chooses an available wavelength randomly.";
       reference
         "RFC 7689: Signaling Extensions for Wavelength Switched
                    Optical Networks";
     }

     identity least-loaded-wavelength-assignment {
       base wavelength-assignment;
       description
         "This WA method selects the wavelength that
          has the largest residual capacity on the most loaded
          link along the route (in multi-fiber networks).";
       reference
         "RFC 7689: Signaling Extensions for Wavelength Switched
                    Optical Networks";
     }

     identity lower-first-wavelength-assignment {
       base wavelength-assignment;
       description
         "Allocate wavelengths in ascending order, beginning from the

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          lowest frequency and progressing toward the highest
          frequency within the permissible frequency range.";
     }

     identity upper-first-wavelength-assignment {
       base wavelength-assignment;
       description
         "Allocate wavelengths in descending order, beginning from the
          highest frequency and progressing toward the lowest
          frequency within the permissible frequency range.";
     }

     identity type-power-mode {
       description
         "power equalization mode used within the
          Optical Multiplex Section (OMS) and its elements.";
     }

     identity power-spectral-density {
       base type-power-mode;
       description
         "All elements must use power spectral density (W/Hz).";
     }

     identity carrier-power {
       base type-power-mode;
       description
         "All elements must use power (dBm).";
     }

     identity switching-wson-lsc {
       base te-types:switching-lsc;
       description
         "Wavelength Switched Optical Network Lambda-Switch Capable
          (WSON-LSC).";
       reference
         "RFC 7688: GMPLS OSPF Enhancement for Signal and Network
                    Element Compatibility for Wavelength Switched
                    Optical Networks, Section 3";
     }

     identity switching-flexi-grid-lsc {
       base te-types:switching-lsc;
       description
         "Flexi-grid Lambda-Switch Capable (Flexi-Grid-LSC).";
       reference
         "RFC 8363: GMPLS OSPF-TE Extensions in Support of Flexi-Grid
                    Dense Wavelength Division Multiplexing (DWDM)

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                    Networks, Section 4.1";
     }

     /*
      * Typedefs
      */

     typedef dwdm-n {
       type int16;
       description
         "The given value 'N' is used to determine the nominal central
          frequency.

          The nominal central frequency, 'f', is defined by:
            f = 193100.000 GHz + N x channel spacing (measured in GHz),

          where 193100.000 GHz (193.100000 THz) is the ITU-T 'anchor
          frequency' for transmission over the DWDM grid, and where
          'channel spacing' is defined by the dwdm-ch-spc-type.";
       reference
         "RFC6205: Generalized Labels for Lambda-Switch-Capable (LSC)
                   Label Switching Routers
          ITU-T G.694.1 (10/2020): Spectral grids for WDM applications:
                   DWDM frequency grid";
     }

     typedef cwdm-n {
       type int16;
       description
         "The given value 'N' is used to determine the nominal central
          wavelength.

          The nominal central wavelength is defined by:
            Wavelength = 1471 nm + N x channel spacing (measured in nm)

          where 1471 nm is the conventional 'anchor wavelength' for
          transmission over the CWDM grid, and where 'channel spacing'
          is defined by the cwdm-ch-spc-type.";
       reference
         "RFC 6205: Generalized Labels for Lambda-Switch-Capable (LSC)
                    Label Switching Routers
          ITU-T G.694.2 (12/2003): Spectral grids for WDM applications:
                    CWDM wavelength grid";
     }

     typedef flexi-n {
       type int16;
       description

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         "The given value 'N' is used to determine the nominal central
          frequency.

          The nominal central frequency, 'f', is defined by:
            f = 193100.000 GHz + N x NCFG (measured in GHz),

          where 193100.000 GHz (193.100000 THz) is the ITU-T 'anchor
          frequency' for transmission over the DWDM grid, and where
          NCFG is defined by the flexi-ncfg-type.";
       reference
         "RFC 7699: Generalized Labels for the Flexi-Grid in Lambda
                    Switch Capable (LSC) Label Switching Routers
          ITU-T G.694.1 (10/2020): Spectral grids for WDM applications:
                    DWDM frequency grid";
     }

     typedef flexi-m {
       type uint16;
       description
         "The given value 'M' is used to determine the slot width.

          A slot width is defined by:
            slot width = M x SWG (measured in GHz),

          where SWG is defined by the flexi-slot-width-granularity.";
       reference
         "RFC 7699: Generalized Labels for the Flexi-Grid in Lambda
                    Switch Capable (LSC) Label Switching Routers
          ITU-T G.694.1 (10/2020): Spectral grids for WDM applications:
                    DWDM frequency grid";
     }

     typedef standard-mode {
       type string;
       description
         "Identifies an ITU-T G.698.2 standard application code.

          It MUST be a string with a format that follows the
          nomenclature defined in clause 5.3 of ITU-T G.698.2.";
       reference
         "ITU-T G.698.2 v3.0 (11/2018): Amplified multichannel dense
                      wavelength division multiplexing applications
                      with single channel optical interfaces Optical
                      transport network, Clause 5.3";
     }

     typedef organization-identifier {
       type string;

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       description
         "vendor/organization identifier that uses a private mode
          out of already defined in G.698.2 ITU-T application-code";
       reference
         "RFC ZZZZ: A YANG Data Model for Optical Impairment-aware
                    Topology, Section 2.5.2";
     }

     typedef operational-mode {
       type string;
       description
         "Identifies an organization (e.g., vendor) specific mode.

          The format of the string has to be defined by the
          organization which is responsible for defining the
          corresponding optical interface specification.";
       reference
         "RFC ZZZZ: A YANG Data Model for Optical Impairment-aware
                    Topology, Section 2.5.2";
     }

     typedef frequency-thz {
       type decimal64 {
         fraction-digits 9;
       }
       units "THz";
       description
         "The DWDM frequency in THz, e.g., 193.112500000";
     }

     typedef frequency-ghz {
       type decimal64 {
         fraction-digits 6;
       }
       units "GHz";
       description
         "The DWDM frequency in GHz, e.g., 193112.500000.";
     }

     typedef unknown-value {
       type enumeration {
         enum unknown {
           description
             "The value is unknown.";
         }
       }
       description
         "This data type is used to report when a value of an attribute

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          is 'unknown', to differentiate from the case where the
          attribute is not applicable.";
       reference
         "RFC XXXX: Common YANG Data Types for Layer 0 Optical
                    Networks, section 2.2.1";
     }

     typedef snr {
       type decimal-2;
       units "dB@0.1nm";
       description
         "(Optical) Signal to Noise Ratio measured over 0.1 nm
          resolution bandwidth.";
       reference
         "ITU-T G.977.1 (02/2021): Transverse compatible dense
                    wavelength division multiplexing applications for
                    repeatered optical fibre submarine cable systems";
     }

     typedef snr-or-unknown {
       type union {
         type snr;
         type unknown-value;
       }
       description
         "(Optical) Signal to Noise Ratio measured over 0.1 nm
          resolution bandwidth, when known, or an empty value when
          unknown.";
     }

     typedef decimal-2 {
       type decimal64 {
         fraction-digits 2;
       }
       description
         "A decimal64 value with two fractional digits.";
     }

     typedef decimal-2-or-unknown {
       type union {
         type decimal-2;
         type unknown-value;
       }
       description
         "A decimal64 value with two digits, when the value is known or
          an empty value when the value is not known.";
     }

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     typedef power-gain {
       type decimal-2 {
         range "0..max";
       }
       units "dB";
       description
         "The gain in dB.";
     }

     typedef power-gain-or-unknown {
       type union {
         type power-gain;
         type unknown-value;
       }
       description
         "The gain in dB, when it is known or an empty
          value when the power gain/loss is not known.";
     }

     typedef power-loss {
       type decimal-2 {
         range "0..max";
       }
       units "dB";
       description
         "The power attenuation in dB.";
     }

     typedef power-loss-or-unknown {
       type union {
         type power-loss;
         type unknown-value;
       }
       description
         "The power attenuation in dB, when it is known or an empty
          value when the loss is not known.";
     }

     typedef power-ratio {
       type decimal-2;
       units "dB";
       description
         "The power difference in dB.";
     }

     typedef power-ratio-or-unknown {
       type union {
         type power-ratio;

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         type unknown-value;
       }
       description
         "The power difference in dB, when it is known or an empty
          value when the difference is not known.";
     }

     typedef power-dbm {
       type decimal-2;
       units "dBm";
       description
         "The power in dBm.";
     }

     typedef power-dbm-or-unknown {
       type union {
         type power-dbm;
         type unknown-value;
       }
       description
         "The power in dBm, when it is known or an empty value when the
          power is not known.";
     }

     typedef decimal-5 {
       type decimal64 {
         fraction-digits 5;
       }
       description
         "A decimal64 value with five fractional digits.";
     }

     typedef decimal-5-or-unknown {
       type union {
         type decimal-5;
         type unknown-value;
       }
       description
         "A decimal64 value with five digits, when the value is known
          or an empty value when the value is not known.";
     }

     typedef psd {
       type decimal64 {
         fraction-digits 16;
       }
       units "W/Hz";
       description

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         "The power spectral density (PSD).

          Typical value : 3.9 E-14, resolution 0.1nW/MHz.";
       reference
         "ITU-T G.9700 (07/2019): Fast access to subscriber terminals
                       (G.fast) - Power spectral density specification";
     }

     typedef psd-or-unknown {
       type union {
         type psd;
         type unknown-value;
       }
       description
         "The PSD, when it is known or an empty value when the PSD is
          not known.";
     }

     typedef decimal-18 {
       type decimal64 {
         fraction-digits 18;
       }
       description
         "A decimal64 value with fractional eighteen digits.";
     }

     typedef decimal-18-or-unknown {
       type union {
         type decimal-18;
         type unknown-value;
       }
       description
         "A decimal64 value with eighteen digits, when the value is
          known or an empty value when the value is not known.";
     }

     /*
      * Groupings
      */

     grouping l0-label-range-info {
       description
         "Common grouping used to define WSON, flexi-grid and WDM label
          ranges.

          When used to define a WSON label range, this grouping SHOULD
          be used together with the wson-label-start-end and
          wson-label-step groupings to provide WSON technology-specific

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          label information to the models which use the
          label-restriction-info grouping defined in the module
          ietf-te-types.";
       leaf grid-type {
         type identityref {
           base l0-grid-type;
         }
         description
           "The type of WDM grid.";
         reference
           "RFC 6205: Generalized Labels for Lambda-Switch-Capable
                      (LSC), Label Switching Routers
            ITU-T G.694.2 (12/2003): Spectral grids for WDM
                      applications: CWDM wavelength grid";
       }
       leaf priority {
         type uint8;
         description
           "Priority in Interface Switching Capability Descriptor
            (ISCD).";
         reference
           "RFC 4203: OSPF Extensions in Support of Generalized
                      Multi-Protocol Label Switching (GMPLS)";
       }
     }

     grouping wson-label-start-end {
       description
         "The WSON label-start or label-end used to specify WSON label
          range.

          This grouping is dependent on the range-type defined in the
          l0-label-range-info grouping.

          This grouping SHOULD be used together with the
          l0-label-range-info and wson-label-step groupings to provide
          WSON technology-specific label information to the models which
          use the label-restriction-info grouping defined in the module
          ietf-te-types.";
       reference
         "RFC 6205: Generalized Labels for Lambda-Switch-Capable (LSC)
                    Label Switching Routers";
       choice grid-type {
         description
           "Label for DWDM or CWDM grid";
         case dwdm {
           leaf dwdm-n {
             when 'derived-from-or-self(../../../grid-type, '

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                + '"l0-types:wson-grid-dwdm")' {
               description
                 "Valid only when grid type is DWDM.";
             }
             type dwdm-n;
             description
               "The central frequency of DWDM.";
             reference
               "RFC 6205: Generalized Labels for Lambda-Switch-Capable
                          (LSC) Label Switching Routers";
           }
         }
         case cwdm {
           leaf cwdm-n {
             when 'derived-from-or-self(../../../grid-type, '
                + '"l0-types:wson-grid-cwdm")' {
               description
                 "Valid only when grid type is CWDM.";
             }
             type cwdm-n;
             description
               "Channel wavelength computing input.";
             reference
               "RFC 6205: Generalized Labels for Lambda-Switch-Capable
                         (LSC) Label Switching Routers";
           }
         }
       }
     }

     grouping wson-label-step {
       description
         "Label step information for WSON.

          This grouping is dependent on the range-type defined in the
          l0-label-range-info grouping.

          This grouping SHOULD be used together with the
          l0-label-range-info and wson-label-start-end groupings to
          provide WSON technology-specific label information to the
          models which use the label-restriction-info grouping defined
          in the module ietf-te-types.";
       reference
         "RFC 6205: Generalized Labels for Lambda-Switch-Capable (LSC)
                    Label Switching Routers
          ITU-T G.694.2 (12/2003): Spectral grids for WDM applications:
                   CWDM wavelength grid";
       choice l0-grid-type {

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         description
           "Grid type: DWDM, CWDM, etc.";
         case dwdm {
           leaf wson-dwdm-channel-spacing {
             when 'derived-from-or-self(../../grid-type, '
                + '"l0-types:wson-grid-dwdm")' {
               description
                 "Valid only when grid type is DWDM.";
             }
             type identityref {
               base dwdm-ch-spc-type;
             }
             description
               "Label-step is the channel spacing (GHz), e.g., 100.000,
                50.000, 25.000, or 12.500 GHz for DWDM.";
             reference
               "RFC 6205: Generalized Labels for Lambda-Switch-Capable
                          (LSC) Label Switching Routers";
           }
         }
         case cwdm {
           leaf wson-cwdm-channel-spacing {
             when 'derived-from-or-self(../../grid-type, '
                + '"l0-types:wson-grid-cwdm")' {
               description
                 "Valid only when grid type is CWDM.";
             }
             type identityref {
               base cwdm-ch-spc-type;
             }
             description
               "Label-step is the channel spacing (nm), i.e., 20 nm
                for CWDM, which is the only value defined for CWDM.";
             reference
               "RFC 6205: Generalized Labels for Lambda-Switch-Capable
                         (LSC) Label Switching Routers";
           }
         }
       }
     }

     grouping wson-label-hop {
       description
         "Generic label-hop information for WSON.";
       reference
         "RFC 6205: Generalized Labels for Lambda-Switch-Capable (LSC)
                    Label Switching Routers";
       choice grid-type {

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         description
           "Label for DWDM or CWDM grid.";
         case dwdm {
           choice single-or-super-channel {
             description
               "Single or super channel.";
             case single {
               leaf dwdm-n {
                 type dwdm-n;
                 description
                   "The given value 'N' is used to determine the
                    nominal central frequency.";
                 reference
                   "ITU-T G.694.1 (10/2020): Spectral grids for WDM
                                  applications: DWDM frequency grid";
               }
             }
             case super {
               leaf-list subcarrier-dwdm-n {
                 type dwdm-n;
                 description
                   "The given values 'N' are used to determine the
                    nominal central frequency for each subcarrier
                    channel.";
                 reference
                   "ITU-T G.694.1 (10/2020): Spectral grids for WDM
                                  applications: DWDM frequency grid";
               }
             }
           }
         }
         case cwdm {
           leaf cwdm-n {
             type cwdm-n;
             description
               "The given value 'N' is used to determine the nominal
                central wavelength.";
             reference
               "RFC 6205: Generalized Labels for Lambda-Switch-Capable
                          (LSC) Label Switching Routers";
           }
         }
       }
     }

     grouping flexi-grid-label-range-info {
       description
         "Flexi-grid-specific label range related information.

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          This grouping SHOULD be used together with the
          flexi-grid-label-start-end and flexi-grid-label-step groupings
          to provide flexi-grid technology-specific label information to
          the models which use the label-restriction-info grouping
          defined in the module ietf-te-types.";
       uses l0-label-range-info;
       container flexi-grid {
         description
           "flexi-grid definition";
         leaf slot-width-granularity {
           type identityref {
             base flexi-slot-width-granularity;
           }
           default "l0-types:flexi-swg-12p5ghz";
           description
             "Minimum space between slot widths.";
           reference
             "RFC 8363: GMPLS OSPF-TE Extensions in Support of
                        Grid Dense Wavelength Division Multiplexing
                        (DWDM) Networks";
         }
         leaf min-slot-width-factor {
           type uint16 {
             range "1..max";
           }
           description
             "A multiplier of the slot width granularity, indicating
              the minimum slot width supported by an optical port.

              Minimum slot width is calculated by:
                Minimum slot width (GHz) =
                  min-slot-width-factor * slot-width-granularity.";
           reference
             "RFC 8363: GMPLS OSPF-TE Extensions in Support of Flexi-
                        Grid Dense Wavelength Division Multiplexing
                        (DWDM) Networks";
         }
         leaf max-slot-width-factor {
           type uint16 {
             range "1..max";
           }
           must '. >= ../min-slot-width-factor' {
             error-message
               "Maximum slot width must be greater than or equal to
                minimum slot width.";
           }
           description
             "A multiplier of the slot width granularity, indicating

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              the maximum slot width supported by an optical port.

              Maximum slot width is calculated by:
                Maximum slot width (GHz) =
                  max-slot-width-factor * slot-width-granularity

              If specified, maximum slot width must be greater than or
              equal to minimum slot width.  If not specified, maximum
              slot width is equal to minimum slot width.";
           reference
             "RFC 8363: GMPLS OSPF-TE Extensions in Support of Flexi-
                        Grid Dense Wavelength Division Multiplexing
                        (DWDM) Networks";
         }
       }
     }

     grouping flexi-grid-label-start-end {
       description
         "Common grouping used to define the value 'N' which is used to
          determine the nominal central frequency (e.g., as the
          flexi-grid label-start or label-end used to specify flexi-grid
          label range).

          When used to define a flexi-grid label range, this grouping
          SHOULD be used together with the flexi-grid-label-range-info
          and flexi-grid-label-step groupings to provide flexi-grid
          technology-specific label information to the models which use
          the label-restriction-info grouping defined in the module
          ietf-te-types.";
       reference
         "RFC 7699: Generalized Labels for the Flexi-Grid in Lambda
                    Switch Capable (LSC) Label Switching Routers";
       leaf flexi-n {
         type flexi-n;
         description
           "The given value 'N' is used to determine the nominal
            central frequency.

            As described in Section 3.1 of RFC 8363, the range of
            available nominal central frequencies are advertised for
            m=1, which means that for an available central frequency n,
            the frequency slot from central frequency n-1 to central
            frequency n+1 is available.";
       }
     }

     grouping flexi-grid-label-step {

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       description
         "Label step information for flexi-grid label ranges.

          This grouping SHOULD be used together with the
          flexi-grid-label-range-info and flexi-grid-label-start-end
          groupings to provide flexi-grid technology-specific label
          information to the models which use the label-restriction-info
          grouping defined in the module ietf-te-types.";
       leaf flexi-grid-channel-spacing {
         type identityref {
           base flexi-ch-spc-type;
         }
         default "l0-types:flexi-ch-spc-6p25ghz";
         status obsolete;
         description
           "Label-step is the nominal central frequency granularity
            (GHz), e.g., 6.25 GHz.";
         reference
           "RFC 7699: Generalized Labels for the Flexi-Grid in Lambda
                      Switch Capable (LSC) Label Switching Routers";
       }
       leaf flexi-ncfg {
         type identityref {
           base flexi-ncfg-type;
         }
         default "l0-types:flexi-ncfg-6p25ghz";
         description
           "Label-step is the nominal central frequency granularity
            (GHz), e.g., 6.25 GHz.";
         reference
           "RFC 7699: Generalized Labels for the Flexi-Grid in Lambda
                      Switch Capable (LSC) Label Switching Routers";
       }
       leaf flexi-n-step {
         type uint8;
         description
           "This attribute defines the multiplier for the supported
            values of 'N'.

            For example, given a grid with a nominal central frequency
            granularity of 6.25 GHz, the granularity of the supported
            values of the nominal central frequency could be 12.5 GHz.
            In this case, the values of flexi-n should be even and this
            constraint is reported by setting the flexi-n-step to 2.

            This attribute is also known as central frequency
            granularity.";
         reference

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           "RFC 8363: GMPLS OSPF-TE Extensions in Support of Flexi-Grid
                      Dense Wavelength Division Multiplexing (DWDM)
                      Networks";
       }
     }

     grouping flexi-grid-frequency-slot {
       description
         "Flexi-grid frequency slot grouping.";
       reference
         "RFC 7699: Generalized Labels for the Flexi-Grid in Lambda
                    Switch Capable (LSC) Label Switching Routers";
       uses flexi-grid-label-start-end;
       leaf flexi-m {
         type flexi-m;
         description
           "The given value 'M' is used to determine the slot width.";
       }
     }

     grouping flexi-grid-label-hop {
       description
         "Generic label-hop information for flexi-grid.";
       reference
         "RFC 7699: Generalized Labels for the Flexi-Grid in Lambda
                    Switch Capable (LSC) Label Switching Routers";
       choice single-or-super-channel {
         description
           "single or super channel";
         case single {
           uses flexi-grid-frequency-slot;
         }
         case super {
           status obsolete;
           list subcarrier-flexi-n {
             key "flexi-n";
             status obsolete;
             description
               "List of subcarrier channels for flexi-grid super
                channel.";
             uses flexi-grid-frequency-slot {
               status obsolete;
             }
           }
         }
         case multi {
           container frequency-slots {
             description

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               "The top level container for the list of frequency
                slots used for flexi-grid super channel.";
             list frequency-slot {
               key "flexi-n";
               min-elements 2;
               description
                 "List of frequency slots used for flexi-grid super
                  channel.";
               uses flexi-grid-frequency-slot;
             }
           }
         }
       }
     }

     grouping wdm-label-range-info {
       description
         "Label range information for WDM.

          This grouping SHOULD be used together with the
          wdm-label-start-end and wdm-label-step groupings to provide
          WDM technology-specific label information to the models which
          use the label-restriction-info grouping defined in the module
          ietf-te-types.";
       container wdm-label-range {
         description
           "Label range information for WDM.";
         uses l0-label-range-info;
         container flexi-grid {
           when 'derived-from-or-self(../grid-type, '
              + '"l0-types:flexi-grid-dwdm")' {
             description
               "Applicable only when the grid type is flexi-grid-dwdm.";
           }
           description
             "flexi-grid definition.";
           leaf slot-width-granularity {
             type identityref {
               base flexi-slot-width-granularity;
             }
             default "l0-types:flexi-swg-12p5ghz";
             description
               "Minimum space between slot widths.";
             reference
               "RFC 8363: GMPLS OSPF-TE Extensions in Support of Flexi-
                         Grid Dense Wavelength Division Multiplexing
                         (DWDM) Networks";
           }

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           leaf min-slot-width-factor {
             type uint16 {
               range "1..max";
             }
             description
               "A multiplier of the slot width granularity, indicating
                the minimum slot width supported by an optical port.

                Minimum slot width is calculated by:
                   Minimum slot width (GHz) =
                     min-slot-width-factor * slot-width-granularity.";
             reference
               "RFC 8363: GMPLS OSPF-TE Extensions in Support of Flexi-
                         Grid Dense Wavelength Division Multiplexing
                         (DWDM) Networks";
           }
           leaf max-slot-width-factor {
             type uint16 {
               range "1..max";
             }
             must '. >= ../min-slot-width-factor' {
               error-message
                 "Maximum slot width must be greater than or equal to
                  minimum slot width.";
             }
             description
               "A multiplier of the slot width granularity, indicating
                the maximum slot width supported by an optical port.

                Maximum slot width is calculated by:
                   Maximum slot width (GHz) =
                     max-slot-width-factor * slot-width-granularity

                If specified, maximum slot width must be greater than or
                equal to minimum slot width.  If not specified, maximum
                slot width is equal to minimum slot width.";
             reference
               "RFC 8363: GMPLS OSPF-TE Extensions in Support of Flexi-
                         Grid Dense Wavelength Division Multiplexing
                         (DWDM) Networks";
           }
         }
       }
     }

     grouping wdm-label-start-end {
       description
         "The WDM label-start or label-end used to specify DWDM and

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          CWDM label ranges.

          This grouping is dependent on the range-type defined in the
          wdm-label-range-info grouping.

          This grouping SHOULD be used together with the
          wdm-label-range-info and wdm-label-step groupings to provide
          WDM technology-specific label information to the models which
          use the label-restriction-info grouping defined in the module
          ietf-te-types.";
       reference
         "RFC 6205: Generalized Labels for Lambda-Switch-Capable (LSC)
                    Label Switching Routers
          RFC 7699: Generalized Labels for the Flexi-Grid in Lambda
                    Switch Capable (LSC) Label Switching Routers";
       container wdm-label {
         description
           "Label start or label end for WDM.

            The format of the label depends on the type of WDM grid
            specified in the 'grid-type' leaf defined in the
            wdm-label-range-info grouping.";
         leaf dwdm-n {
           when 'derived-from-or-self(../../../../wdm-label-range'
              + '/grid-type, "l0-types:wson-grid-dwdm")' {
             description
               "Valid only when grid type is a fixed DWDM grid.";
           }
           type dwdm-n;
           description
             "The given value 'N' is used to determine the
              nominal central frequency on a DWDM fixed grid.";
           reference
             "RFC 6205: Generalized Labels for Lambda-Switch-Capable
                       (LSC) Label Switching Routers";
         }
         leaf cwdm-n {
           when 'derived-from-or-self(../../../../wdm-label-range'
              + '/grid-type, "l0-types:wson-grid-cwdm")' {
             description
               "Valid only when grid type is a CWDM grid.";
           }
           type cwdm-n;
           description
             "The given value 'N' is used to determine the nominal
              central wavelength on a CWDM fixed grid.";
           reference
             "RFC 6205: Generalized Labels for Lambda-Switch-Capable

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                       (LSC) Label Switching Routers";
         }
         uses flexi-grid-label-start-end {
           when 'derived-from-or-self(../../../wdm-label-range'
              + '/grid-type, "l0-types:flexi-grid-dwdm")' {
             description
               "Valid only when grid type is a flexible DWDM grid.";
           }
         }
       }
     }

     grouping wdm-label-step {
       description
         "The WDM label-step used to specify DWDM and CWDM label
          ranges.

          This grouping is dependent on the range-type defined in the
          wdm-label-range-info grouping.

          This grouping SHOULD be used together with the
          wdm-label-range-info and wdm-label-start-end groupings to
          provide WDM technology-specific label information to the
          models which use the label-restriction-info grouping defined
          in the module ietf-te-types.";
       reference
         "RFC 6205: Generalized Labels for Lambda-Switch-Capable (LSC)
                    Label Switching Routers
          RFC 7699: Generalized Labels for the Flexi-Grid in Lambda
                    Switch Capable (LSC) Label Switching Routers
          RFC 8363: GMPLS OSPF-TE Extensions in Support of Flexi-Grid
                    Dense Wavelength Division Multiplexing (DWDM)
                    Networks";
       container wdm-label-step {
         description
           "Label step for WDM.

            The format of the label depends on the type of WDM grid
            specified in the 'grid-type' leaf defined in the
            wdm-label-range-info grouping.";
         leaf wson-dwdm-channel-spacing {
           when 'derived-from-or-self(../../../wdm-label-range'
              + '/grid-type, "l0-types:wson-grid-dwdm")' {
             description
               "Valid only when grid type is a fixed DWDM grid.";
           }
           type identityref {
             base dwdm-ch-spc-type;

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           }
           description
             "The channel spacing (GHz) of a fixed DWDM grid, e.g.,
              100 GHz, 50 GHz, 25 GHz, or 12.5 GHz.";
           reference
             "RFC 6205: Generalized Labels for Lambda-Switch-Capable
                       (LSC) Label Switching Routers";
         }
         leaf wson-cwdm-channel-spacing {
           when 'derived-from-or-self(../../../wdm-label-range'
              + '/grid-type, "l0-types:wson-grid-cwdm")' {
             description
               "Valid only when grid type is a CWDM grid.";
           }
           type identityref {
             base cwdm-ch-spc-type;
           }
           description
             "The channel spacing (nm) of a fixed CWDM grid, e.g., 20nm
              (which is the only standardized value).";
           reference
             "RFC 6205: Generalized Labels for Lambda-Switch-Capable
                       (LSC) Label Switching Routers";
         }
         container flexi-grid-cfg {
           when 'derived-from-or-self(../../../wdm-label-range'
              + '/grid-type, "l0-types:flexi-grid-dwdm")' {
             description
               "Valid only when grid type is a flexible DWDM grid.";
           }
           description
             "The Central Frequency Granularity (CFG) of a flexible DWDM
              grid (flexi-grid), defined as a multiplier of the Nominal
              central frequency granularity (NCFG).";
           uses flexi-grid-label-step;
         }
       }
     }

     grouping wdm-label-hop {
       description
         "Generic label-hop information for DWDM and CWDM labels.";
       container wdm-label {
         description
           "Label hop for WDM.";
         choice grid-type {
           description
             "Label for DWDM or CWDM grid.";

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           reference
             "RFC 6205: Generalized Labels for Lambda-Switch-Capable
                        (LSC) Label Switching Routers";
           case fixed-dwdm {
             choice fixed-single-or-multi-channel {
               description
                 "Single channel or multichannel.";
               case single {
                 leaf dwdm-n {
                   type dwdm-n;
                   description
                     "The given value 'N' is used to determine the
                      nominal central frequency.";
                 }
               }
               case multi {
                 leaf-list subcarrier-dwdm-n {
                   type dwdm-n;
                   min-elements 2;
                   description
                     "The given values 'N' are used to determine the
                      nominal central frequency for each subcarrier
                      channel.";
                   reference
                     "ITU-T G.694.1 (10/2020): Spectral grids for WDM
                                 applications: DWDM frequency grid";
                 }
               }
             }
           }
           case cwdm {
             leaf cwdm-n {
               type cwdm-n;
               description
                 "The given value 'N' is used to determine the nominal
                  central wavelength.";
               reference
                 "RFC 6205: Generalized Labels for Lambda-Switch-Capable
                           (LSC) Label Switching Routers";
             }
           }
           case flexi-grid {
             uses flexi-grid-label-hop;
           }
         }
       }
     }

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     grouping transceiver-capabilities {
       description
         "This grouping is intended to be used for reporting the
          capabilities of a transceiver.

          When this grouping is used, the explicit-mode container shall
          be augmented with a leafref to an explicit mode template with
          the proper XPath which depends on where this grouping is
          actually used.";
       reference
         "RFC ZZZZ: A YANG Data Model for Optical Impairment-aware
                    Topology.";
       container supported-modes {
         presence
           "When present, it indicates that the modes supported by a
            transceiver are reported.";
         config false;
         description
           "The top level container for the list supported
            transceiver's modes.";
         list supported-mode {
           key "mode-id";
           min-elements 1;
           description
             "The list of supported transceiver's modes.";
           leaf mode-id {
             type string {
               length "1..255";
             }
             description
               "An identifier for the supported transceiver's mode.";
           }
           choice mode {
             mandatory true;
             description
               "Indicates whether the transceiver's mode is a standard
                mode, an organizational mode or an explicit mode.";
             case g.698.2 {
               container g.698.2 {
                 description
                   "The set of attributes for a standard mode defined
                    in ITU-T G.698.2.";
                 reference
                   "ITU-T G.698.2 v3.0 (11/2018): Amplified multichannel
                           dense wavelength division multiplexing
                           applications with single channel optical
                           interfaces Optical transport network";
                 uses standard-mode {

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                   refine "standard-mode" {
                     mandatory true;
                   }
                 }
                 uses common-standard-organizational-mode;
                 uses common-all-modes;
               }
             }
             case organizational-mode {
               container organizational-mode {
                 description
                   "The set of attributes for an organizational mode.";
                 uses organizational-mode {
                   refine "operational-mode" {
                     mandatory true;
                   }
                   refine "organization-identifier" {
                     mandatory true;
                   }
                 }
                 uses common-standard-organizational-mode;
                 uses common-all-modes;
               }
             }
             case explicit-mode {
               container explicit-mode {
                 description
                   "The set of attributes for an explicit mode.";
                 uses common-all-modes;
                 container compatible-modes {
                   description
                     "Container for all the standard and organizational
                      modes supported by the transceiver's explicit
                      mode.";
                   leaf-list supported-application-code {
                     type leafref {
                       path "../../../../supported-mode/mode-id";
                     }
                     must '../../../../'
                        + 'supported-mode[mode-id=current()]/'
                        + 'g.698.2' {
                       description
                         "The pointer is only for application codes
                          supported by transceiver.";
                     }
                     description
                       "List of pointers to the application codes
                        supported by the transceiver's explicit mode.";

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                   }
                   leaf-list supported-organizational-mode {
                     type leafref {
                       path "../../../../supported-mode/mode-id";
                     }
                     must '../../../../'
                        + 'supported-mode[mode-id=current()]/'
                        + 'organizational-mode' {
                       description
                         "The pointer is only for organizational modes
                          supported by transceiver.";
                     }
                     description
                       "List of pointers to the organizational modes
                         supported by the transceiver's explicit mode.";
                   }
                 }
               }
             }
           }
         }
       }
     }

     grouping standard-mode {
       description
         "Identifies an ITU-T G.698.2 standard application code.";
       reference
         "ITU-T G.698.2 v3.0 (11/2018): Amplified multichannel dense
                    wavelength division multiplexing applications
                    with single channel optical interfaces Optical
                    transport network, Clause 5.3";
       leaf standard-mode {
         type standard-mode;
         description
           "Identifies an ITU-T G.698.2 standard application code.

            It MUST be a string with a format that follows the
            nomenclature defined in clause 5.3 of ITU-T G.698.2.";
       }
     }

     grouping organizational-mode {
       description
         "Transponder operational mode supported by organizations or
          vendor";
       reference
         "RFC ZZZZ: A YANG Data Model for Optical Impairment-aware

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                     Topology, Section 2.6.2";
       leaf operational-mode {
         type operational-mode;
         description
           "configured organization- or vendor-specific
            application identifiers (AI) supported by the transponder";
       }
       leaf organization-identifier {
         type organization-identifier;
         description
           "The identifier of the organization that defines the
            organizational-mode.";
       }
     }

     grouping penalty-value {
       description
         "A common definition of the Optical Signal-to-Noise Ratio
          (OSNR) penalty value used for describing multiple penalty
          types (e.g., CD, PMD, or PDL).";
       leaf penalty-value {
         type union {
           type decimal-2 {
             range "0..max";
           }
           type unknown-value;
         }
         units "dB";
         mandatory true;
         description
           "The OSNR penalty associated with the related optical
            impairment at the receiver, when the value is known or an
            empty value when the value is not known.";
       }
     }

     grouping explicit-mode {
       description
         "The attributes describing capabilities of an explicit
          transceiver's mode.

          This grouping also contains the list of attributes related to
          optical impairment limits for explicit mode (min OSNR,
          max PMD, max CD, max PDL, Q-factor limit, etc.).

          In case of standard and operational mode the attributes are
          implicit.";
       leaf line-coding-bitrate {

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         type identityref {
           base line-coding;
         }
         config false;
         description
           "Bit rate/line coding of the optical tributary signal.";
         reference
           "ITU-T G.698.2 v3.0 (11/2018): Amplified multichannel dense
                        wavelength division multiplexing applications
                        with single channel optical interfaces Optical
                        transport network, Clause 7.1.2";
       }
       leaf bitrate {
         type uint16;
         units "Gbit/sec";
         config false;
         description
           "The gross bitrate (e.g., 100 or 200) of the optical
            tributary signal.";
       }
       leaf max-diff-group-delay {
         type decimal-2;
         units "ps";
         config false;
         description
           "The maximum Differential Group Delay (DGD)  the receiver can
            tolerate.";
       }
       leaf max-chromatic-dispersion {
         type decimal-2 {
           range "0..max";
         }
         units "ps/nm";
         config false;
         description
           "Maximum acceptable accumulated chromatic dispersion (CD) on
            the receiver at Rx-power reference point
            (rx-ref-channel-power) and in absence of other
            impairments.";
         reference
           "RFC ZZZZ: A YANG Data Model for Optical
                      Impairment-aware Topology, Section 2.6.4";
       }
       list cd-penalty {
         key "cd-value";
         config false;
         description
           "Optional penalty associated with a given accumulated

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            chromatic dispersion (CD) value measured in
            absence of other impairments.

            This list of pair CD and OSNR penalty can be used to
            sample the function OSNR penalty = f(CD).";
         reference
           "RFC ZZZZ: A YANG Data Model for Optical
                      Impairment-aware Topology, Section 2.6.4";
         leaf cd-value {
           type decimal-2;
           units "ps/nm";
           description
             "The Chromatic Dispersion (CD).";
         }
         uses penalty-value;
       }
       leaf max-polarization-mode-dispersion {
         type decimal-2 {
           range "0..max";
         }
         units "ps";
         config false;
         description
           "Maximum acceptable accumulated polarization mode
            dispersion (PMD) on the receiver at Rx-power reference point
            (rx-ref-channel-power) and in absence of other impairments";
         reference
           "ITU-T G.666 (02/2011): Characteristics of polarization
                      mode dispersion compensators and of receivers that
                      compensate for polarization mode dispersion
            RFC ZZZZ: A YANG Data Model for Optical Impairment-aware
                      Topology, Section 2.4.6";
       }
       list pmd-penalty {
         key "pmd-value";
         config false;
         description
           "Optional penalty associated with a given accumulated
            polarization mode dispersion (PMD) value measured in
            absence of other impairments.

            This list of pair PMD and OSNR penalty can be used to
            sample the function OSNR penalty = f(PMD).";
         reference
           "RFC ZZZZ: A YANG Data Model for Optical Impairment-aware
                      Topology, Section 2.4.6";
         leaf pmd-value {
           type decimal-2 {

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             range "0..max";
           }
           units "ps";
           description
             "The Polarization Mode Dispersion (PMD).";
         }
         uses penalty-value;
       }
       leaf max-polarization-dependent-loss {
         type power-loss-or-unknown;
         config false;
         mandatory true;
         description
           "Maximum acceptable accumulated polarization dependent
            loss (PDL) on the receiver at Rx-power reference point
            (rx-ref-channel-power) and in absence of other
            impairments.";
         reference
           "RFC ZZZZ: A YANG Data Model for Optical Impairment-aware
                      Topology, Section 2.4.6";
       }
       list pdl-penalty {
         key "pdl-value";
         config false;
         description
           "Optional penalty associated with a given accumulated
            polarization dependent loss (PDL) value, measured in
            absence of other impairments.

            This list of pair PDL and OSNR penalty can be used to
            sample the function OSNR penalty = f(PDL).";
         reference
           "RFC ZZZZ: A YANG Data Model for Optical Impairment-aware
                      Topology, Section 2.4.6";
         leaf pdl-value {
           type power-loss;
           description
             "Maximum acceptable accumulated polarization dependent
              loss (PDL).";
         }
         uses penalty-value;
       }
       leaf available-modulation-type {
         type identityref {
           base modulation;
         }
         config false;
         description

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           "Modulation type the specific transceiver in the list
            can support.";
       }
       leaf min-osnr {
         type snr;
         units "dBm";
         config false;
         description
           "Minimum OSNR measured over 0.1 nm resolution bandwidth:
            if received OSNR at Rx-power reference point
            (rx-ref-channel-power) is lower than min-osnr, an increased
            level of bit-errors post-FEC needs to be expected.";
       }
       leaf rx-ref-channel-power {
         type power-dbm;
         config false;
         description
           "The channel power used as reference for defining penalties
            and min-osnr.";
       }
       list rx-channel-power-penalty {
         key "rx-channel-power-value";
         config false;
         description
           "Optional penalty associated with a received power
            lower than rx-ref-channel-power.

            This list of pair power and OSNR penalty can be used to
            sample the function OSNR penalty = f(rx-channel-power).";
         leaf rx-channel-power-value {
           type power-dbm;
           units "dBm";
           description
             "The Received Power.";
         }
         uses penalty-value;
       }
       leaf min-q-factor {
         type decimal-2;
         units "dB";
         config false;
         description
           "The value of the Q factor at the FEC threshold
            (fec-threshold).";
         reference
           "ITU-T O.201 (07/2003): Q-factor test equipment to estimate
                      the transmission performance of optical channels";
       }

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       leaf available-baud-rate {
         type decimal64 {
           fraction-digits 1;
         }
         units "Bd";
         config false;
         description
           "Baud-rate the specific transceiver in
            the list can support.
            Baud-rate is the unit for symbol rate or modulation rate
            in symbols per second or pulses per second.
            It is the number of distinct symbol changes (signal events)
            made to the transmission medium per second in a digitally
            modulated signal or a line code";
       }
       leaf roll-off {
         type decimal64 {
           fraction-digits 4;
           range "0..1";
         }
         config false;
         description
           "the roll-off factor (beta with values from 0 to 1)
            identifies how the real signal shape exceed
            the baud rate. If=0 it is exactly matching
            the baud rate.If=1 the signal exceeds the
            50% of the baud rate at each side.";
       }
       leaf min-carrier-spacing {
         type frequency-ghz;
         config false;
         description
           "This attribute specifies the minimum nominal difference
            between the carrier frequencies of two homogeneous OTSis
            (which have the same optical characteristics but the central
            frequencies) such that if they are placed next to each other
            the interference due to spectrum overlap between them can be
            considered negligible.

            In case of heterogeneous OTSi it is up to path computation
            engine to determine the minimum distance between the carrier
            frequency of the two adjacent OTSi.";
       }
       leaf available-fec-type {
         type identityref {
           base fec-type;
         }
         config false;

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         description
           "Available FEC.";
       }
       leaf fec-code-rate {
         type decimal64 {
           fraction-digits 8;
           range "0..max";
         }
         config false;
         description
           "FEC-code-rate";
       }
       leaf fec-threshold {
         type decimal64 {
           fraction-digits 8;
           range "0..max";
         }
         config false;
         description
           "Threshold on the BER, for which FEC
            is able to correct errors";
       }
       leaf in-band-osnr {
         type snr;
         config false;
         description
           "The OSNR defined within the bandwidth of the transmit
            spectral excursion (i.e.,  between the nominal central
            frequency of the channel and the -3.0dB points of the
            transmitter spectrum furthest from the nominal central
            frequency) measured at reference point Ss.

            The in-band OSNR is referenced to an optical bandwidth of
            0.1nm @ 193.7 THz or 12.5 GHz.";
         reference
           "OIF-400ZR-01.0: Implementation Agreement 400ZR";
       }
       leaf out-of-band-osnr {
         type snr;
         config false;
         description
           "The ratio of the peak transmitter power to the integrated
            power outside the transmitter spectral excursion.

            The spectral resolution of the measurement shall be better
            than the maximum spectral width of the peak.

            The out-of-band OSNR is referenced to an optical bandwidth

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            of 0.1nm @ 193.7 THz or 12.5 GHz";
         reference
           "OIF-400ZR-01.0: Implementation Agreement 400ZR";
       }
       leaf tx-polarization-power-difference {
         type power-ratio;
         config false;
         description
           "The transmitter polarization dependent power difference
            defined as the power difference between X and Y
            polarizations.";
         reference
           "OIF-400ZR-01.0: Implementation Agreement 400ZR";
       }
       leaf polarization-skew {
         type decimal-2;
         units "ps";
         config false;
         description
           "The X-Y skew, included as a fixed value in the receiver
            polarization mode dispersion (PMD) tolerance limits.";
         reference
           "OIF-400ZR-01.0: Implementation Agreement 400ZR";
       }
     }

     grouping common-standard-organizational-mode {
       description
         "The attributes describing the capabilities for a standard or
          an organizational transceiver's mode.";
       leaf-list line-coding-bitrate {
         type identityref {
           base line-coding;
         }
         config false;
         description
           "The list of the bit rate/line coding of the optical
            tributary signal supported by the transceiver.

            Reporting this list is optional when the standard or
            organization mode supports only one bit rate/line coding.";
         reference
           "ITU-T G.698.2 v3.0 (11/2018): Amplified multichannel dense
                        wavelength division multiplexing applications
                        with single channel optical interfaces Optical
                        transport network, Clause 7.1.2";
       }
     }

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     grouping transceiver-tuning-range {
       description
         "Transceiver tuning range (f-min, f-max, f-granularity)";
       leaf min-central-frequency {
         type frequency-thz;
         description
           "This parameter indicates the minimum frequency for the
            transceiver tuning range.";
       }
       leaf max-central-frequency {
         type frequency-thz;
         description
           "This parameter indicates the maximum frequency for the
            transceiver tuning range.";
       }
       leaf transceiver-tunability-granularity {
         type frequency-ghz;
         description
           "This parameter indicates the transceiver frequency
            fine-tuning granularity e.g 3.125GHz or 0.001GHz.";
       }
     }

     grouping common-all-modes {
       description
         "The attributes describing the capabilities for any type of
          transceiver's mode.";
       container transceiver-tuning-range {
         config false;
         description
           "Transceiver tuning range (f-min, f-max, f-granularity)";
         uses transceiver-tuning-range;
       }
       leaf tx-channel-power-min {
         type power-dbm;
         config false;
         description
           "The minimum output power of this interface";
       }
       leaf tx-channel-power-max {
         type power-dbm;
         config false;
         description
           "The maximum output power of this interface";
       }
       leaf rx-channel-power-min {
         type power-dbm;
         config false;

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         description
           "The minimum input power of this interface";
       }
       leaf rx-channel-power-max {
         type power-dbm;
         config false;
         description
           "The maximum input power of this interface";
       }
       leaf rx-total-power-max {
         type power-dbm;
         config false;
         description
           "Maximum rx optical power for all the channels.

            It is applicable only to multichannel modes.";
       }
     }

     grouping common-transceiver-param {
       description
         "The common parameters of an optical transceiver,
          that supplement the configured mode.";
       uses common-transceiver-configured-param;
       uses common-transceiver-readonly-param;
     }

     grouping common-transceiver-configured-param {
       description
         "The configured parameters of an optical transceiver,
          that supplement the configured mode.";
       leaf line-coding-bitrate {
         type identityref {
           base line-coding;
         }
         description
           "Bit rate/line coding of the optical tributary signal.

            Support of this attribute is optional when the configured
            mode supports only one bit rate/line coding.";
         reference
           "ITU-T G.698.2 v3.0 (11/2018): Amplified multichannel dense
                        wavelength division multiplexing applications
                        with single channel optical interfaces Optical
                        transport network, Clause 7.1.2";
       }
       leaf tx-channel-power {
         type power-dbm-or-unknown;

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         description
           "The current channel transmit power.

            The 'unknown' value MUST NOT be used when this attribute is
            configured.";
       }
     }

     grouping common-transceiver-readonly-param {
       description
         "The common read-only parameters of an optical transceiver,
          that supplement the configured mode.";
       leaf rx-channel-power {
         type power-dbm-or-unknown;
         config false;
         description
           "The current channel received power.";
       }
       leaf rx-total-power {
         type power-dbm-or-unknown;
         config false;
         description
           "The current total received power.";
       }
     }

     grouping tunnel-attributes {
       description
         "Parameters for Layer0 (WSON or Flexi-Grid) Tunnels.";
       leaf wavelength-assignment {
         type identityref {
           base wavelength-assignment;
         }
         description
           "Wavelength Allocation Method.";
       }
     }

     grouping frequency-range {
       description
         "This grouping defines the lower and upper bounds of a
          frequency range (e.g., a band).

          This grouping SHOULD NOT be used to define a frequency slot,
          which SHOULD be defined using the n and m values instead.";
       leaf lower-frequency {
         type frequency-thz;
         mandatory true;

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         description
           "The lower frequency boundary of the
            frequency range.";
       }
       leaf upper-frequency {
         type frequency-thz;
         must '. > ../lower-frequency' {
           error-message
             "The upper frequency must be greater than the lower
              frequency.";
         }
         mandatory true;
         description
           "The upper frequency boundary of the
            frequency range.";
       }
     }

     grouping frequency-range-with-identifier {
       description
         "This grouping extends the frequency-range with an identifier,
          which used as a key when it is needed to define different
          properties (e.g., optical impairments) for different
          frequency ranges.";
       leaf frequency-range-id {
         type uint16;
         description
           "The identifier of the frequency range.";
       }
       container frequency-range {
         description
           "The frequency range for which these optical
            impairments apply.";
         uses frequency-range;
       }
     }

     grouping path-constraints {
       description
         "Common attribute for Layer 0 path constraints to be used by
          Layer 0 computation.";
       leaf gsnr-extra-margin {
         type snr {
           range "0..max";
         }
         default "0";
         description
           "An additional margin to be added to the OSNR-min of the

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            transceiver when checking the estimated received Generalized
            SNR (GSNR).";
       }
     }

     grouping path-properties {
       description
         "Common attribute for reporting the Layer 0 computed path
          properties.";
       leaf estimated-gsnr {
         type snr;
         config false;
         description
           "The estimate received GSNR for the computed path.";
       }
       leaf estimated-eol-gsnr {
         type snr;
         config false;
         description
           "The estimate received GSNR for the computed path
            degraded at the end of life.";
       }
       leaf estimated-lowest-gsnr {
         type snr;
         config false;
         description
           "The estimate lowest received GSNR for the computed path
            among all possible wavelength channels along the same
            path.";
       }
     }
   }
   <CODE ENDS>

                    Figure 1: Layer 0 Types YANG module

4.  Security Considerations

   This section is modeled after the template described in Section 3.7
   of [I-D.ietf-netmod-rfc8407bis].

   The "ietf-layer0-types" YANG module defines a data model that is
   designed to be accessed via YANG-based management protocols, such as
   NETCONF [RFC6241] and RESTCONF [RFC8040].  These YANG-based
   management protocols (1) have to use a secure transport layer (e.g.,
   SSH [RFC4252], TLS [RFC8446], and QUIC [RFC9000]) and (2) have to use
   mutual authentication.

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   The Network Configuration Access Control Model (NACM) [RFC8341]
   provides the means to restrict access for particular NETCONF or
   RESTCONF users to a preconfigured subset of all available NETCONF or
   RESTCONF protocol operations and content.

   The YANG module defines a set of identities, types, and groupings.
   These nodes are intended to be reused by other YANG modules.  The
   module by itself does not expose any data nodes that are writable,
   data nodes that contain read-only state, or RPCs.  As such, there are
   no additional security issues related to the YANG module that need to
   be considered.

   Modules that use the groupings that are defined in this document
   should identify the corresponding security considerations.

5.  IANA Considerations

   IANA is requested to update the following registration in the "ns"
   registry within the "IETF XML Registry" group [RFC3688] to reference
   this document:

         URI: urn:ietf:params:xml:ns:yang:ietf-layer0-types
         Registrant Contact:  The IESG.
         XML: N/A; the requested URI is an XML namespace.

   IANA is requested to register the following YANG module in the "YANG
   Module Names" registry [RFC6020] within the "YANG Parameters"
   registry group.

         Name: ietf-layer0-types
         Maintained by IANA? N
         Namespace: urn:ietf:params:xml:ns:yang:ietf-layer0-types
         Prefix: l0-types
         Reference: RFC XXXX

6.  References

6.1.  Normative References

   [I-D.ietf-ccamp-optical-impairment-topology-yang]
              Beller, D., Le Rouzic, E., Belotti, S., Galimberti, G.,
              and I. Busi, "A YANG Data Model for Optical Impairment-
              aware Topology", Work in Progress, Internet-Draft, draft-
              ietf-ccamp-optical-impairment-topology-yang-20, 10 October
              2025, <https://datatracker.ietf.org/doc/html/draft-ietf-
              ccamp-optical-impairment-topology-yang-20>.

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   [I-D.ietf-teas-rfc8776-update]
              Busi, I., Guo, A., Liu, X., Saad, T., and I. Bryskin,
              "Common YANG Data Types for Traffic Engineering", Work in
              Progress, Internet-Draft, draft-ietf-teas-rfc8776-update-
              19, 20 October 2025,
              <https://datatracker.ietf.org/doc/html/draft-ietf-teas-
              rfc8776-update-19>.

   [ITU-T_G.666]
              International Telecommunication Union, "Characteristics of
              polarization mode dispersion compensators and of receivers
              that compensate for polarization mode dispersion"", ITU-T
              Recommendation G.666 , February 2011,
              <https://www.itu.int/rec/T-REC-G.666>.

   [ITU-T_G.694.1]
              International Telecommunication Union, "Spectral grids for
              WDM applications: DWDM frequency grid", ITU-T
              Recommendation G.694.1 , October 2020,
              <https://www.itu.int/rec/T-REC-G.694.1>.

   [ITU-T_G.694.2]
              International Telecommunication Union, "Spectral grids for
              WDM applications: CWDM wavelength grid", ITU-T
              Recommendation G.694.2 , December 2003,
              <https://www.itu.int/rec/T-REC-G.694.2>.

   [ITU-T_G.698.2]
              International Telecommunication Union, "Amplified
              multichannel dense wavelength division multiplexing
              applications with single channel optical interfaces",
              ITU-T Recommendation G.698.2 , November 2018,
              <https://www.itu.int/rec/T-REC-G.698.2>.

   [ITU-T_G.709]
              International Telecommunication Union, "Interfaces for the
              optical transport network", ITU-T Recommendation G.709 ,
              June 2020, <https://www.itu.int/rec/T-REC-G.709>.

   [ITU-T_G.709.2]
              International Telecommunication Union, "OTU4 long-reach
              interface", ITU-T Recommendation G.709.2, Corrigendum 1 ,
              September 2020, <https://www.itu.int/rec/T-REC-G.709.2>.

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   [ITU-T_G.709.3]
              International Telecommunication Union, "Flexible OTN B100G
              long-reach interfaces", ITU-T Recommendation G.709.3,
              Amendment 1 , November 2022,
              <https://www.itu.int/rec/T-REC-G.709.3>.

   [ITU-T_G.959.1]
              International Telecommunication Union, "Optical transport
              network physical layer interfaces", ITU-T Recommendation
              G.959.1 , July 2018,
              <https://www.itu.int/rec/T-REC-G.959.1>.

   [ITU-T_G.9700]
              International Telecommunication Union, "Fast access to
              subscriber terminals (G.fast) - Power spectral density
              specification", ITU-T Recommendation G.9700 , July 2019,
              <https://www.itu.int/rec/T-REC-G.9700>.

   [ITU-T_G.975]
              International Telecommunication Union, "Forward error
              correction for submarine systems", ITU-T Recommendation
              G.975 , October 2000,
              <https://www.itu.int/rec/T-REC-G.975>.

   [ITU-T_G.975.1]
              International Telecommunication Union, "Forward error
              correction for high bit-rate DWDM submarine systems",
              ITU-T Recommendation G.975.1, Corrigendum 2 , July 2013,
              <https://www.itu.int/rec/T-REC-G.975.1>.

   [ITU-T_G.977.1]
              International Telecommunication Union, "Transverse
              compatible dense wavelength division multiplexing
              applications for repeatered optical fibre submarine cable
              systems", ITU-T Recommendation G.977.1 , February 2021,
              <https://www.itu.int/rec/T-REC-G.977.1>.

   [OIF_400ZR]
              Optical Internetworking Forum, "Implementation Agreement
              400ZR", OIF-400ZR-01.0 Implementation Agreement , March
              2020, <https://www.oiforum.com/wp-content/uploads/OIF-
              400ZR-01.0_reduced2.pdf>.

   [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/rfc/rfc2119>.

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   [RFC3471]  Berger, L., Ed., "Generalized Multi-Protocol Label
              Switching (GMPLS) Signaling Functional Description",
              RFC 3471, DOI 10.17487/RFC3471, January 2003,
              <https://www.rfc-editor.org/rfc/rfc3471>.

   [RFC4203]  Kompella, K., Ed. and Y. Rekhter, Ed., "OSPF Extensions in
              Support of Generalized Multi-Protocol Label Switching
              (GMPLS)", RFC 4203, DOI 10.17487/RFC4203, October 2005,
              <https://www.rfc-editor.org/rfc/rfc4203>.

   [RFC6205]  Otani, T., Ed. and D. Li, Ed., "Generalized Labels for
              Lambda-Switch-Capable (LSC) Label Switching Routers",
              RFC 6205, DOI 10.17487/RFC6205, March 2011,
              <https://www.rfc-editor.org/rfc/rfc6205>.

   [RFC7688]  Lee, Y., Ed. and G. Bernstein, Ed., "GMPLS OSPF
              Enhancement for Signal and Network Element Compatibility
              for Wavelength Switched Optical Networks", RFC 7688,
              DOI 10.17487/RFC7688, November 2015,
              <https://www.rfc-editor.org/rfc/rfc7688>.

   [RFC7689]  Bernstein, G., Ed., Xu, S., Lee, Y., Ed., Martinelli, G.,
              and H. Harai, "Signaling Extensions for Wavelength
              Switched Optical Networks", RFC 7689,
              DOI 10.17487/RFC7689, November 2015,
              <https://www.rfc-editor.org/rfc/rfc7689>.

   [RFC7699]  Farrel, A., King, D., Li, Y., and F. Zhang, "Generalized
              Labels for the Flexi-Grid in Lambda Switch Capable (LSC)
              Label Switching Routers", RFC 7699, DOI 10.17487/RFC7699,
              November 2015, <https://www.rfc-editor.org/rfc/rfc7699>.

   [RFC7950]  Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
              RFC 7950, DOI 10.17487/RFC7950, August 2016,
              <https://www.rfc-editor.org/rfc/rfc7950>.

   [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/rfc/rfc8174>.

   [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/rfc/rfc8341>.

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   [RFC8342]  Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K.,
              and R. Wilton, "Network Management Datastore Architecture
              (NMDA)", RFC 8342, DOI 10.17487/RFC8342, March 2018,
              <https://www.rfc-editor.org/rfc/rfc8342>.

   [RFC8363]  Zhang, X., Zheng, H., Casellas, R., Gonzalez de Dios, O.,
              and D. Ceccarelli, "GMPLS OSPF-TE Extensions in Support of
              Flexi-Grid Dense Wavelength Division Multiplexing (DWDM)
              Networks", RFC 8363, DOI 10.17487/RFC8363, May 2018,
              <https://www.rfc-editor.org/rfc/rfc8363>.

   [RFC8795]  Liu, X., Bryskin, I., Beeram, V., Saad, T., Shah, H., and
              O. Gonzalez de Dios, "YANG Data Model for Traffic
              Engineering (TE) Topologies", RFC 8795,
              DOI 10.17487/RFC8795, August 2020,
              <https://www.rfc-editor.org/rfc/rfc8795>.

6.2.  Informative References

   [I-D.ietf-ccamp-dwdm-if-param-yang]
              Galimberti, G., Hiremagalur, D., Grammel, G., Manzotti,
              R., and D. Breuer, "A YANG data model to manage
              configurable DWDM optical interfaces", Work in Progress,
              Internet-Draft, draft-ietf-ccamp-dwdm-if-param-yang-14, 20
              October 2025, <https://datatracker.ietf.org/doc/html/
              draft-ietf-ccamp-dwdm-if-param-yang-14>.

   [I-D.ietf-netmod-rfc8407bis]
              Bierman, A., Boucadair, M., and Q. Wu, "Guidelines for
              Authors and Reviewers of Documents Containing YANG Data
              Models", Work in Progress, Internet-Draft, draft-ietf-
              netmod-rfc8407bis-28, 5 June 2025,
              <https://datatracker.ietf.org/doc/html/draft-ietf-netmod-
              rfc8407bis-28>.

   [ITU-T_G.807]
              International Telecommunication Union, "Generic functional
              architecture of the optical media network", ITU-T
              Supplement G.807, Amendment 1 , January 2021.

   [ITU-T_G.872]
              International Telecommunication Union, "Architecture of
              optical transport networks", ITU-T Supplement G.872,
              Amendment 1 , January 2021.

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   [ITU-T_G.Sup39]
              International Telecommunication Union, "Optical system
              design and engineering considerations", ITU-T Supplement
              G.Sup39 , February 2016.

   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              DOI 10.17487/RFC3688, January 2004,
              <https://www.rfc-editor.org/rfc/rfc3688>.

   [RFC4252]  Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH)
              Authentication Protocol", RFC 4252, DOI 10.17487/RFC4252,
              January 2006, <https://www.rfc-editor.org/rfc/rfc4252>.

   [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/rfc/rfc6020>.

   [RFC6163]  Lee, Y., Ed., Bernstein, G., Ed., and W. Imajuku,
              "Framework for GMPLS and Path Computation Element (PCE)
              Control of Wavelength Switched Optical Networks (WSONs)",
              RFC 6163, DOI 10.17487/RFC6163, April 2011,
              <https://www.rfc-editor.org/rfc/rfc6163>.

   [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/rfc/rfc6241>.

   [RFC7446]  Lee, Y., Ed., Bernstein, G., Ed., Li, D., and W. Imajuku,
              "Routing and Wavelength Assignment Information Model for
              Wavelength Switched Optical Networks", RFC 7446,
              DOI 10.17487/RFC7446, February 2015,
              <https://www.rfc-editor.org/rfc/rfc7446>.

   [RFC7581]  Bernstein, G., Ed., Lee, Y., Ed., Li, D., Imajuku, W., and
              J. Han, "Routing and Wavelength Assignment Information
              Encoding for Wavelength Switched Optical Networks",
              RFC 7581, DOI 10.17487/RFC7581, June 2015,
              <https://www.rfc-editor.org/rfc/rfc7581>.

   [RFC7698]  Gonzalez de Dios, O., Ed., Casellas, R., Ed., Zhang, F.,
              Fu, X., Ceccarelli, D., and I. Hussain, "Framework and
              Requirements for GMPLS-Based Control of Flexi-Grid Dense
              Wavelength Division Multiplexing (DWDM) Networks",
              RFC 7698, DOI 10.17487/RFC7698, November 2015,
              <https://www.rfc-editor.org/rfc/rfc7698>.

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   [RFC8040]  Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
              Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
              <https://www.rfc-editor.org/rfc/rfc8040>.

   [RFC8340]  Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
              BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
              <https://www.rfc-editor.org/rfc/rfc8340>.

   [RFC8446]  Rescorla, E., "The Transport Layer Security (TLS) Protocol
              Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
              <https://www.rfc-editor.org/rfc/rfc8446>.

   [RFC9000]  Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based
              Multiplexed and Secure Transport", RFC 9000,
              DOI 10.17487/RFC9000, May 2021,
              <https://www.rfc-editor.org/rfc/rfc9000>.

   [RFC9093]  Zheng, H., Lee, Y., Guo, A., Lopez, V., and D. King, "A
              YANG Data Model for Layer 0 Types", RFC 9093,
              DOI 10.17487/RFC9093, August 2021,
              <https://www.rfc-editor.org/rfc/rfc9093>.

Appendix A.  The Complete Schema Trees

   This appendix presents the complete tree of the Layer 0 Types data
   model.  See [RFC8340] for an explanation of the symbols used.  The
   data type of every leaf node is shown near the right end of the
   corresponding line.

   module: ietf-layer0-types

     grouping l0-label-range-info:
       +-- grid-type?   identityref
       +-- priority?    uint8
     grouping wson-label-start-end:
       +-- (grid-type)?
          +--:(dwdm)
          |  +-- dwdm-n?   dwdm-n
          +--:(cwdm)
             +-- cwdm-n?   cwdm-n
     grouping wson-label-step:
       +-- (l0-grid-type)?
          +--:(dwdm)
          |  +-- wson-dwdm-channel-spacing?   identityref
          +--:(cwdm)
             +-- wson-cwdm-channel-spacing?   identityref
     grouping wson-label-hop:
       +-- (grid-type)?

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          +--:(dwdm)
          |  +-- (single-or-super-channel)?
          |     +--:(single)
          |     |  +-- dwdm-n?              dwdm-n
          |     +--:(super)
          |        +-- subcarrier-dwdm-n*   dwdm-n
          +--:(cwdm)
             +-- cwdm-n?                    cwdm-n
     grouping flexi-grid-label-range-info:
       +-- grid-type?    identityref
       +-- priority?     uint8
       +-- flexi-grid
          +-- slot-width-granularity?   identityref
          +-- min-slot-width-factor?    uint16
          +-- max-slot-width-factor?    uint16
     grouping flexi-grid-label-start-end:
       +-- flexi-n?   flexi-n
     grouping flexi-grid-label-step:
       o-- flexi-grid-channel-spacing?   identityref
       +-- flexi-ncfg?                   identityref
       +-- flexi-n-step?                 uint8
     grouping flexi-grid-frequency-slot:
       +-- flexi-n?   flexi-n
       +-- flexi-m?   flexi-m
     grouping flexi-grid-label-hop:
       +-- (single-or-super-channel)?
          +--:(single)
          |  +-- flexi-n?              flexi-n
          |  +-- flexi-m?              flexi-m
          o--:(super)
          |  o-- subcarrier-flexi-n* [flexi-n]
          |     +-- flexi-n?   flexi-n
          |     +-- flexi-m?   flexi-m
          +--:(multi)
             +-- frequency-slots
                +-- frequency-slot* [flexi-n]
                   +-- flexi-n?   flexi-n
                   +-- flexi-m?   flexi-m
     grouping wdm-label-range-info:
       +-- wdm-label-range
          +-- grid-type?    identityref
          +-- priority?     uint8
          +-- flexi-grid
             +-- slot-width-granularity?   identityref
             +-- min-slot-width-factor?    uint16
             +-- max-slot-width-factor?    uint16
     grouping wdm-label-start-end:
       +-- wdm-label

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          +-- dwdm-n?    dwdm-n
          +-- cwdm-n?    cwdm-n
          +-- flexi-n?   flexi-n
     grouping wdm-label-step:
       +-- wdm-label-step
          +-- wson-dwdm-channel-spacing?   identityref
          +-- wson-cwdm-channel-spacing?   identityref
          +-- flexi-grid-cfg
             o-- flexi-grid-channel-spacing?   identityref
             +-- flexi-ncfg?                   identityref
             +-- flexi-n-step?                 uint8
     grouping wdm-label-hop:
       +-- wdm-label
          +-- (grid-type)?
             +--:(fixed-dwdm)
             |  +-- (fixed-single-or-multi-channel)?
             |     +--:(single)
             |     |  +-- dwdm-n?               dwdm-n
             |     +--:(multi)
             |        +-- subcarrier-dwdm-n*    dwdm-n
             +--:(cwdm)
             |  +-- cwdm-n?                     cwdm-n
             +--:(flexi-grid)
                +-- (single-or-super-channel)?
                   +--:(single)
                   |  +-- flexi-n?              flexi-n
                   |  +-- flexi-m?              flexi-m
                   o--:(super)
                   |  o-- subcarrier-flexi-n* [flexi-n]
                   |     +-- flexi-n?   flexi-n
                   |     +-- flexi-m?   flexi-m
                   +--:(multi)
                      +-- frequency-slots
                         +-- frequency-slot* [flexi-n]
                            +-- flexi-n?   flexi-n
                            +-- flexi-m?   flexi-m
     grouping transceiver-capabilities:
       +--ro supported-modes!
          +--ro supported-mode* [mode-id]
             +--ro mode-id?                     string
             +--ro (mode)
                +--:(g.698.2)
                |  +--ro g.698.2
                |     +--ro standard-mode               standard-mode
                |     +--ro line-coding-bitrate*        identityref
                |     +--ro transceiver-tuning-range
                |     |  +--ro min-central-frequency?
                |     |  |       frequency-thz

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                |     |  +--ro max-central-frequency?
                |     |  |       frequency-thz
                |     |  +--ro transceiver-tunability-granularity?
                |     |          frequency-ghz
                |     +--ro tx-channel-power-min?       power-dbm
                |     +--ro tx-channel-power-max?       power-dbm
                |     +--ro rx-channel-power-min?       power-dbm
                |     +--ro rx-channel-power-max?       power-dbm
                |     +--ro rx-total-power-max?         power-dbm
                +--:(organizational-mode)
                |  +--ro organizational-mode
                |     +--ro operational-mode            operational-mode
                |     +--ro organization-identifier
                |     |       organization-identifier
                |     +--ro line-coding-bitrate*        identityref
                |     +--ro transceiver-tuning-range
                |     |  +--ro min-central-frequency?
                |     |  |       frequency-thz
                |     |  +--ro max-central-frequency?
                |     |  |       frequency-thz
                |     |  +--ro transceiver-tunability-granularity?
                |     |          frequency-ghz
                |     +--ro tx-channel-power-min?       power-dbm
                |     +--ro tx-channel-power-max?       power-dbm
                |     +--ro rx-channel-power-min?       power-dbm
                |     +--ro rx-channel-power-max?       power-dbm
                |     +--ro rx-total-power-max?         power-dbm
                +--:(explicit-mode)
                   +--ro explicit-mode
                      +--ro transceiver-tuning-range
                      |  +--ro min-central-frequency?
                      |  |       frequency-thz
                      |  +--ro max-central-frequency?
                      |  |       frequency-thz
                      |  +--ro transceiver-tunability-granularity?
                      |          frequency-ghz
                      +--ro tx-channel-power-min?       power-dbm
                      +--ro tx-channel-power-max?       power-dbm
                      +--ro rx-channel-power-min?       power-dbm
                      +--ro rx-channel-power-max?       power-dbm
                      +--ro rx-total-power-max?         power-dbm
                      +--ro compatible-modes
                         +--ro supported-application-code*
                         |       -> ../../../../supported-mode/mode-id
                         +--ro supported-organizational-mode*
                                 -> ../../../../supported-mode/mode-id
     grouping standard-mode:
       +-- standard-mode?   standard-mode

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     grouping organizational-mode:
       +-- operational-mode?          operational-mode
       +-- organization-identifier?   organization-identifier
     grouping penalty-value:
       +-- penalty-value    union
     grouping explicit-mode:
       +--ro line-coding-bitrate?                identityref
       +--ro bitrate?                            uint16
       +--ro max-diff-group-delay?               decimal-2
       +--ro max-chromatic-dispersion?           decimal-2
       +--ro cd-penalty* [cd-value]
       |  +--ro cd-value?        decimal-2
       |  +--ro penalty-value    union
       +--ro max-polarization-mode-dispersion?   decimal-2
       +--ro pmd-penalty* [pmd-value]
       |  +--ro pmd-value?       decimal-2
       |  +--ro penalty-value    union
       +--ro max-polarization-dependent-loss     power-loss-or-unknown
       +--ro pdl-penalty* [pdl-value]
       |  +--ro pdl-value?       power-loss
       |  +--ro penalty-value    union
       +--ro available-modulation-type?          identityref
       +--ro min-osnr?                           snr
       +--ro rx-ref-channel-power?               power-dbm
       +--ro rx-channel-power-penalty* [rx-channel-power-value]
       |  +--ro rx-channel-power-value?   power-dbm
       |  +--ro penalty-value             union
       +--ro min-q-factor?                       decimal-2
       +--ro available-baud-rate?                decimal64
       +--ro roll-off?                           decimal64
       +--ro min-carrier-spacing?                frequency-ghz
       +--ro available-fec-type?                 identityref
       +--ro fec-code-rate?                      decimal64
       +--ro fec-threshold?                      decimal64
       +--ro in-band-osnr?                       snr
       +--ro out-of-band-osnr?                   snr
       +--ro tx-polarization-power-difference?   power-ratio
       +--ro polarization-skew?                  decimal-2
     grouping common-standard-organizational-mode:
       +--ro line-coding-bitrate*   identityref
     grouping transceiver-tuning-range:
       +-- min-central-frequency?                frequency-thz
       +-- max-central-frequency?                frequency-thz
       +-- transceiver-tunability-granularity?   frequency-ghz
     grouping common-all-modes:
       +--ro transceiver-tuning-range
       |  +--ro min-central-frequency?                frequency-thz
       |  +--ro max-central-frequency?                frequency-thz

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       |  +--ro transceiver-tunability-granularity?   frequency-ghz
       +--ro tx-channel-power-min?       power-dbm
       +--ro tx-channel-power-max?       power-dbm
       +--ro rx-channel-power-min?       power-dbm
       +--ro rx-channel-power-max?       power-dbm
       +--ro rx-total-power-max?         power-dbm
     grouping common-transceiver-param:
       +-- line-coding-bitrate?   identityref
       +-- tx-channel-power?      power-dbm-or-unknown
       +--ro rx-channel-power?      power-dbm-or-unknown
       +--ro rx-total-power?        power-dbm-or-unknown
     grouping common-transceiver-configured-param:
       +-- line-coding-bitrate?   identityref
       +-- tx-channel-power?      power-dbm-or-unknown
     grouping common-transceiver-readonly-param:
       +--ro rx-channel-power?   power-dbm-or-unknown
       +--ro rx-total-power?     power-dbm-or-unknown
     grouping tunnel-attributes:
       +-- wavelength-assignment?   identityref
     grouping frequency-range:
       +-- lower-frequency    frequency-thz
       +-- upper-frequency    frequency-thz
     grouping frequency-range-with-identifier:
       +-- frequency-range-id?   uint16
       +-- frequency-range
          +-- lower-frequency    frequency-thz
          +-- upper-frequency    frequency-thz
     grouping path-constraints:
       +-- gsnr-extra-margin?   snr
     grouping path-properties:
       +--ro estimated-gsnr?          snr
       +--ro estimated-eol-gsnr?      snr
       +--ro estimated-lowest-gsnr?   snr

                                  Figure 2

Appendix B.  Changes from RFC 9093

   This version adds new identities, data types, and groupings to the
   'ietf-layer0-types' YANG module.  It also fixes few bugs in
   [RFC9093].

   The following new YANG identities have been added to the 'ietf-
   layer0-types' module:

   *  cwdm-ch-spc-type;

   *  flexi-ncfg-type;

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   *  flexi-ncfg-6p25gh;

   *  modulation;

   *  dpsk;

   *  qpsk;

   *  dp-qpsk;

   *  qam8;

   *  dp-qam8;

   *  qam16;

   *  dp-qam16;

   *  qam32;

   *  dp-qam32;

   *  qam64;

   *  dp-qam64;

   *  fec-type;

   *  g-fec;

   *  super-fec;

   *  no-fec;

   *  sc-fec;

   *  o-fec;

   *  c-fec;

   *  line-coding;

   *  nrz-2p5g;

   *  nrz-otu1;

   *  nrz-10g;

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   *  nrz-otu2;

   *  otl4.4-sc;

   *  foic1.4-sc;

   *  wavelength-assignment;

   *  first-fit-wavelength-assignment;

   *  random-wavelength-assignment;

   *  least-loaded-wavelength-assignment;

   *  lower-first-wavelength-assignment;

   *  upper-first-wavelength-assignment;

   *  type-power-mode;

   *  power-spectral-density;

   *  carrier-power;

   *  switching-wson-lsc;

   *  switching-flexi-grid-lsc.

   The following new YANG data types have been added to the 'ietf-
   layer0-types' module:

   *  standard-mode

   *  organization-identifier

   *  operational-mode

   *  frequency-thz

   *  frequency-ghz

   *  unknown-value

   *  snr

   *  snr-or-unknown

   *  decimal-2

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   *  decimal-2-or-unknown

   *  power-gain

   *  power-gain-or-unknown

   *  power-loss

   *  power-loss-or-unknown

   *  power-ratio

   *  power-ratio-or-unknown

   *  power-dbm

   *  power-dbm-or-unknown

   *  decimal-5

   *  decimal-5-or-unknown

   *  psd

   *  psd-or-unknown

   The following new YANG groupings have been added to the 'ietf-
   layer0-types' module:

   *  wdm-label-start-end

   *  wdm-label-step

   *  wdm-label-hop

   *  wdm-label-range-info

   *  transceiver-capabilities

   *  standard-mode

   *  organizational-mode

   *  penalty-value

   *  explicit-mode

   *  common-standard-organizational-mode

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   *  transceiver-tuning-range

   *  common-all-mode

   *  common-transceiver-param

   *  common-transceiver-configured-param

   *  common-transceiver-readonly-param

   *  tunnel-attributes

   *  frequency-range

   *  frequency-range-with-identifier

   *  path-constraints

   *  path-properties

   The following YANG identities have been obsolted (bug fixing) in the
   'ietf-layer0-types' module:

   *  flexi-ch-spc-type;

   *  flexi-ch-spc-6p25ghz.

   The case super within the flexi-grid-label-hop has been obsolted (bug
   fixing).

   The flexi-grid-channel-spacing data node in flexi-grid-label-step
   grouping has been obsoleted (bug fixing).

   The default value of the min-slot-width-factor data node within
   flexi-grid-label-range-info grouping has been removed (bug fixing).

Acknowledgments

   The authors and the working group give their sincere thanks to Robert
   Wilton for the YANG doctor review and to Adrian Farrel and Tom Petch
   for their comments during the model and document development.

   This document was prepared using kramdown.

Contributors

   Haomian Zheng
   Huawei

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   Email: zhenghaomian@huawei.com

   Daniel King
   University of Lancaster
   Email: d.king@lancaster.ac.uk

   Gabriele Galimberti
   Nokia
   Email: gabriele.galimberti@nokia.com

   Enrico Griseri
   Nokia
   Email: Enrico.Griseri@nokia.com

   Dhruv Dhody
   Huawei
   Email: dhruv.ietf@gmail.com

   Bin Yeong Yoon
   ETRI
   Email: byyun@etri.re.kr

   Ricard Vilalta
   CTTC
   Email: ricard.vilalta@cttc.es

   Young Lee
   Samsung
   Email: younglee.tx@gmail.com

   Victor Lopez
   Nokia
   Email: victor.lopez@nokia.com

   Roberto Manzotti
   Cisco
   Email: rmanzott@cisco.com

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   Gert Grammel
   Juniper
   Email: ggrammel@juniper.net

Authors' Addresses

   Sergio Belotti (editor)
   Nokia
   Email: sergio.belotti@nokia.com

   Italo Busi (editor)
   Huawei
   Email: italo.busi@huawei.com

   Dieter Beller (editor)
   Nokia
   Email: dieter.beller@nokia.com

   Esther Le Rouzic
   Orange
   Email: esther.lerouzic@orange.com

   Aihua Guo
   Futurewei Technologies
   Email: aihuaguo.ietf@gmail.com

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