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+Internet Engineering Task Force (IETF)                 郑好棉 (H. Zheng)
+Request for Comments: 9093        华为技术有限公司 (Huawei Technologies)
+Category: Standards Track                                         Y. Lee
+ISSN: 2070-1721                                                  Samsung
+                                                                  A. Guo
+                                                               Futurewei
+                                                                V. Lopez
+                                                                   Nokia
+                                                                 D. King
+                                                 University of Lancaster
+                                                             August 2021
+
+
+                  A YANG Data Model for Layer 0 Types
+
+Abstract
+
+   This document defines a collection of common data types and groupings
+   in the YANG data modeling language.  These derived common types and
+   groupings are intended to be imported by modules that model Layer 0
+   optical Traffic Engineering (TE) configuration and state capabilities
+   such as Wavelength Switched Optical Networks (WSONs) and flexi-grid
+   Dense Wavelength Division Multiplexing (DWDM) networks.
+
+Status of This Memo
+
+   This is an Internet Standards Track document.
+
+   This document is a product of the Internet Engineering Task Force
+   (IETF).  It represents the consensus of the IETF community.  It has
+   received public review and has been approved for publication by the
+   Internet Engineering Steering Group (IESG).  Further information on
+   Internet Standards is available in Section 2 of RFC 7841.
+
+   Information about the current status of this document, any errata,
+   and how to provide feedback on it may be obtained at
+   https://www.rfc-editor.org/info/rfc9093.
+
+Copyright Notice
+
+   Copyright (c) 2021 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 Simplified BSD License text as described in Section 4.e of
+   the Trust Legal Provisions and are provided without warranty as
+   described in the Simplified BSD License.
+
+Table of Contents
+
+   1.  Introduction
+     1.1.  Terminology and Notations
+     1.2.  Prefix in Data Node Names
+   2.  Layer 0 Types Module Contents
+   3.  YANG Module for Layer 0 Types
+   4.  Security Considerations
+   5.  IANA Considerations
+   6.  References
+     6.1.  Normative References
+     6.2.  Informative References
+   Acknowledgements
+   Contributors
+   Authors' Addresses
+
+1.  Introduction
+
+   YANG [RFC7950] is a data modeling language used to model
+   configuration data, state data, Remote Procedure Calls, and
+   notifications for network management protocols such as the Network
+   Configuration Protocol (NETCONF) [RFC6241].  The YANG language
+   supports a small set of built-in data types and provides mechanisms
+   to derive other types from the built-in types.
+
+   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
+   model(s) defined outside of this document.  The applicability of
+   Layer 0 types specified in this document includes Wavelength Switched
+   Optical Networks (WSONs) [RFC6163] [ITU-Tg6982] and flexi-grid Dense
+   Wavelength Division Multiplexing (DWDM) networks [RFC7698]
+   [ITU-Tg6941].
+
+1.1.  Terminology and Notations
+
+   Refer to [RFC7446] and [RFC7581] for the key terms used in this
+   document, and the terminology for describing YANG data models can be
+   found in [RFC7950].
+
+   The YANG data model in this document conforms to the Network
+   Management Datastore Architecture defined in [RFC8342].
+
+1.2.  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 modules.
+
+               +==========+===================+===========+
+               | Prefix   | YANG module       | Reference |
+               +==========+===================+===========+
+               | l0-types | ietf-layer0-types | RFC 9093  |
+               +----------+-------------------+-----------+
+
+                         Table 1: Data Node Names
+
+   The YANG module "ietf-layer0-types" (defined in Section 3) references
+   [RFC4203], [RFC6163], [RFC6205], [RFC7698], [RFC7699], [RFC8363],
+   [ITU-Tg6941], and [ITU-Tg6942].
+
+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.  The "ietf-layer0-types" module contains the following YANG
+   reusable types and groupings:
+
+   l0-grid-type:
+      A base YANG identity for the grid type as defined in [RFC6163] and
+      [RFC7698].
+
+   dwdm-ch-spc-type:
+      A base YANG identity for the DWDM channel-spacing type as defined
+      in [RFC6205].
+
+   cwdm-ch-spc-type:
+      A base YANG identity for the Coarse Wavelength Division
+      Multiplexing (CWDM) channel-spacing type as defined in [RFC6205].
+
+   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.
+
+   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.
+
+   l0-label-range-info:
+      A YANG grouping that defines the Layer 0 label range information
+      applicable for WSON as defined in [RFC6205].  This grouping is
+      used in the flexi-grid DWDM by adding more flexi-grid-specific
+      parameters.
+
+   wson-label-step:
+      A YANG grouping that defines label steps for WSON as defined in
+      [RFC8776].
+
+   flexi-grid-label-start-end:
+      The flexi-grid label range was defined in [RFC7698], 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.
+
+   flexi-grid-label-hop:
+      The flexi-grid label range was defined in [RFC7698], and the
+      generic topology model defines the label-hop in [RFC8795].  This
+      grouping shows the WSON-specific label-hop information.
+
+   flexi-grid-label-range-info:
+      A YANG grouping that defines flexi-grid label range information as
+      defined in [RFC7698] and [RFC8363].
+
+   flexi-grid-label-step:
+      A YANG grouping that defines flexi-grid label steps as defined in
+      [RFC8776].
+
+3.  YANG Module for Layer 0 Types
+
+   <CODE BEGINS> file "ietf-layer0-types@2021-08-13.yang"
+   module ietf-layer0-types {
+     yang-version 1.1;
+     namespace "urn:ietf:params:xml:ns:yang:ietf-layer0-types";
+     prefix l0-types;
+
+     organization
+       "IETF CCAMP Working Group";
+     contact
+       "WG Web: <https://datatracker.ietf.org/wg/ccamp/>
+        WG List: <mailto:ccamp@ietf.org>
+
+        Editor: Haomian Zheng
+          <mailto:zhenghaomian@huawei.com>
+
+        Editor: Young Lee
+          <mailto:younglee.tx@gmail.com>
+
+        Editor: Aihua Guo
+          <mailto:aihuaguo.ietf@gmail.com>
+
+        Editor: Victor Lopez
+          <mailto:victor.lopez@nokia.com>
+
+        Editor: Daniel King
+          <mailto:d.king@lancaster.ac.uk>";
+
+     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
+        Division Multiplexing) and DWDM (Dense Wavelength Division
+        Multiplexing)) and flexi-grid optical networks.
+
+        Copyright (c) 2021 IETF Trust and the persons identified
+        as authors of the code.  All rights reserved.
+
+        Redistribution and use in source and binary forms, with
+        or without modification, is permitted pursuant to, and
+        subject to the license terms contained in, the Simplified
+        BSD License set forth in Section 4.c of the IETF Trust's
+        Legal Provisions Relating to IETF Documents
+        (https://trustee.ietf.org/license-info).
+
+        This version of this YANG module is part of RFC 9093; see
+        the RFC itself for full legal notices.";
+
+     revision 2021-08-13 {
+       description
+         "Initial version";
+       reference
+         "RFC 9093: A YANG Data Model for Layer 0 Types";
+     }
+
+     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
+         "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 flexi-ch-spc-type.
+
+          Note that the term 'channel spacing' can be substituted by the
+          term 'nominal central frequency granularity' defined in
+          clause 8 of ITU-T G.694.1.";
+       reference
+         "RFC 7698: Framework and Requirements for GMPLS-Based Control
+          of Flexi-Grid Dense Wavelength Division Multiplexing (DWDM)
+          Networks,
+          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 7698: Framework and Requirements for GMPLS-Based Control
+          of Flexi-Grid Dense Wavelength Division Multiplexing (DWDM)
+          Networks.
+          ITU-T G.694.1 (10/2020): Spectral grids for WDM applications:
+          DWDM frequency grid";
+     }
+
+     identity l0-grid-type {
+       description
+         "Layer 0 grid type";
+       reference
+         "RFC 6163: Framework for GMPLS and Path Computation Element
+          (PCE) Control of Wavelength Switched Optical Networks (WSONs),
+          ITU-T G.694.1 (10/2020): Spectral grids for WDM applications:
+          DWDM frequency grid,
+          ITU-T G.694.2 (12/2003): Spectral grids for WDM applications:
+          CWDM wavelength grid";
+     }
+
+     identity flexi-grid-dwdm {
+       base l0-grid-type;
+       description
+         "Flexi-grid";
+       reference
+         "RFC 7698: Framework and Requirements for GMPLS-Based Control
+          of Flexi-Grid Dense Wavelength Division Multiplexing (DWDM)
+          Networks,
+          ITU-T G.694.1 (10/2020): Spectral grids for WDM applications:
+          DWDM frequency grid";
+     }
+
+     identity wson-grid-dwdm {
+       base l0-grid-type;
+       description
+         "DWDM grid";
+       reference
+         "RFC 6163:Framework for GMPLS and Path Computation Element
+          (PCE) Control of Wavelength Switched Optical Networks (WSONs),
+          ITU-T G.694.1 (10/2020): Spectral grids for WDM applications:
+          DWDM frequency grid";
+     }
+
+     identity wson-grid-cwdm {
+       base l0-grid-type;
+       description
+         "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 dwdm-ch-spc-type {
+       description
+         "DWDM channel-spacing type";
+       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";
+     }
+
+     identity dwdm-100ghz {
+       base dwdm-ch-spc-type;
+       description
+         "100 GHz channel spacing";
+     }
+
+     identity dwdm-50ghz {
+       base dwdm-ch-spc-type;
+       description
+         "50 GHz channel spacing";
+     }
+
+     identity dwdm-25ghz {
+       base dwdm-ch-spc-type;
+       description
+         "25 GHz channel spacing";
+     }
+
+     identity dwdm-12p5ghz {
+       base dwdm-ch-spc-type;
+       description
+         "12.5 GHz channel spacing";
+     }
+
+     identity flexi-ch-spc-type {
+       description
+         "Flexi-grid channel-spacing type";
+       reference
+         "RFC 7698: Framework and Requirements for GMPLS-Based Control
+          of Flexi-Grid Dense Wavelength Division Multiplexing (DWDM)
+          Networks,
+          ITU-T G.694.1 (10/2020): Spectral grids for WDM applications:
+          DWDM frequency grid";
+     }
+
+     identity flexi-ch-spc-6p25ghz {
+       base flexi-ch-spc-type;
+       description
+         "6.25 GHz channel spacing";
+     }
+
+     identity flexi-slot-width-granularity {
+       description
+         "Flexi-grid slot width granularity";
+     }
+
+     identity flexi-swg-12p5ghz {
+       base flexi-slot-width-granularity;
+       description
+         "12.5 GHz slot width granularity";
+     }
+
+     identity cwdm-ch-spc-type {
+       description
+         "CWDM channel-spacing 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";
+     }
+
+     identity cwdm-20nm {
+       base cwdm-ch-spc-type;
+       description
+         "20nm channel spacing";
+     }
+
+     /* Groupings. */
+
+     grouping wson-label-start-end {
+       description
+         "The WSON label-start or label-end used to specify WSON label
+          range.";
+       choice grid-type {
+         description
+           "Label for DWDM or CWDM grid";
+         case dwdm {
+           leaf dwdm-n {
+             when "derived-from-or-self(../../../grid-type,
+                   \"wson-grid-dwdm\")" {
+               description
+                 "Valid only when grid type is DWDM.";
+             }
+             type l0-types: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,
+                   \"wson-grid-cwdm\")" {
+               description
+                 "Valid only when grid type is CWDM.";
+             }
+             type l0-types:cwdm-n;
+             description
+               "Channel wavelength computing input.";
+             reference
+               "RFC 6205: Generalized Labels for Lambda-Switch-Capable
+                (LSC) Label Switching Routers";
+           }
+         }
+       }
+       reference
+         "RFC 6205: Generalized Labels for Lambda-Switch-Capable (LSC)
+          Label Switching Routers";
+     }
+
+     grouping wson-label-hop {
+       description
+         "Generic label-hop information for WSON";
+       choice grid-type {
+         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 l0-types:dwdm-n;
+                 description
+                   "The given value 'N' is used to determine the
+                    nominal central frequency.";
+               }
+             }
+             case super {
+               leaf-list subcarrier-dwdm-n {
+                 type l0-types:dwdm-n;
+                 description
+                   "The given values 'N' are used to determine the
+                    nominal central frequency for each subcarrier
+                    channel.";
+                 reference
+                   "ITU-T Recommendation G.694.1: Spectral grids for
+                    WDM applications: DWDM frequency grid";
+               }
+             }
+           }
+         }
+         case cwdm {
+           leaf cwdm-n {
+             type l0-types: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";
+           }
+         }
+       }
+       reference
+         "RFC 6205: Generalized Labels for Lambda-Switch-Capable (LSC)
+          Label Switching Routers";
+     }
+
+     grouping l0-label-range-info {
+       description
+         "Information about Layer 0 label range.";
+       leaf grid-type {
+         type identityref {
+           base l0-grid-type;
+         }
+         description
+           "Grid type";
+       }
+       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)";
+       }
+       reference
+         "RFC 6205: Generalized Labels for Lambda-Switch-Capable (LSC)
+          Label Switching Routers";
+     }
+
+     grouping wson-label-step {
+       description
+         "Label step information for WSON";
+       choice l0-grid-type {
+         description
+           "Grid type: DWDM, CWDM, etc.";
+         case dwdm {
+           leaf wson-dwdm-channel-spacing {
+             when "derived-from-or-self(../../grid-type,
+                   \"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,
+                   \"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";
+           }
+         }
+       }
+       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";
+     }
+
+     grouping flexi-grid-label-start-end {
+       description
+         "The flexi-grid label-start or label-end used to specify
+          flexi-grid label range.";
+       leaf flexi-n {
+         type l0-types:flexi-n;
+         description
+           "The given value 'N' is used to determine the nominal
+            central frequency.";
+       }
+       reference
+         "RFC 7698: Framework and Requirements for GMPLS-Based Control
+          of Flexi-Grid Dense Wavelength Division Multiplexing (DWDM)
+          Networks";
+     }
+
+     grouping flexi-grid-frequency-slot {
+       description
+         "Flexi-grid frequency slot grouping.";
+       uses flexi-grid-label-start-end;
+       leaf flexi-m {
+         type l0-types:flexi-m;
+         description
+           "The given value 'M' is used to determine the slot width.";
+       }
+       reference
+         "RFC 7698: Framework and Requirements for GMPLS-Based Control
+          of Flexi-Grid Dense Wavelength Division Multiplexing (DWDM)
+          Networks";
+     }
+
+     grouping flexi-grid-label-hop {
+       description
+         "Generic label-hop information for flexi-grid";
+       choice single-or-super-channel {
+         description
+           "single or super channel";
+         case single {
+           uses flexi-grid-frequency-slot;
+         }
+         case super {
+           list subcarrier-flexi-n {
+             key "flexi-n";
+             uses flexi-grid-frequency-slot;
+             description
+               "List of subcarrier channels for flexi-grid super
+                channel.";
+           }
+         }
+       }
+       reference
+         "RFC 7698: Framework and Requirements for GMPLS-Based Control
+          of Flexi-Grid Dense Wavelength Division Multiplexing (DWDM)
+          Networks";
+     }
+
+     grouping flexi-grid-label-range-info {
+       description
+         "Flexi-grid-specific label range related information";
+       uses l0-label-range-info;
+       container flexi-grid {
+         description
+           "flexi-grid definition";
+         leaf slot-width-granularity {
+           type identityref {
+             base flexi-slot-width-granularity;
+           }
+           default "flexi-swg-12p5ghz";
+           description
+             "Minimum space between slot widths. Default is 12.500
+              GHz.";
+           reference
+             "RFC 7698: Framework and Requirements for GMPLS-Based
+              Control of Flexi-Grid Dense Wavelength Division
+              Multiplexing (DWDM) Networks";
+         }
+         leaf min-slot-width-factor {
+           type uint16 {
+             range "1..max";
+           }
+           default "1";
+           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 flexi-grid-label-step {
+       description
+         "Label step information for flexi-grid";
+       leaf flexi-grid-channel-spacing {
+         type identityref {
+           base flexi-ch-spc-type;
+         }
+         default "flexi-ch-spc-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 in RFC 8363.";
+         reference
+           "RFC 8363: GMPLS OSPF-TE Extensions in Support of Flexi-Grid
+            Dense Wavelength Division Multiplexing (DWDM) Networks";
+       }
+     }
+   }
+   <CODE ENDS>
+
+4.  Security Considerations
+
+   The YANG module specified in this document defines a schema for data
+   that is designed to be accessed via network management protocols such
+   as NETCONF [RFC6241] or RESTCONF [RFC8040].  The lowest NETCONF layer
+   is the secure transport layer, and the mandatory-to-implement secure
+   transport is Secure Shell (SSH) [RFC6242].  The lowest RESTCONF layer
+   is HTTPS, and the mandatory-to-implement secure transport is TLS
+   [RFC8446].
+
+   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 NETCONF protocol over
+   Secure Shell (SSH) specification [RFC6242] describes a method for
+   invoking and running NETCONF within a Secure Shell (SSH) session as
+   an SSH subsystem.
+
+   The objects in this YANG module are common data types and groupings.
+   No object in this module can be read or written to.  These
+   definitions can be imported and used by other Layer 0 specific
+   modules.  It is critical to consider how imported definitions will be
+   utilized and accessible via RPC operations, as the resultant schema
+   will have data nodes that can be writable, or readable, and will have
+   a significant effect on the network operations if used incorrectly or
+   maliciously.  All of these considerations belong in the document that
+   defines the modules that import from this YANG module.  Therefore, it
+   is important to manage access to resultant data nodes that are
+   considered sensitive or vulnerable in some network environments.
+
+   The security considerations spelled out in the YANG 1.1 specification
+   [RFC7950] apply for this document as well.
+
+5.  IANA Considerations
+
+   IANA has assigned new URIs from the "IETF XML Registry" [RFC3688] as
+   follows:
+
+   URI:  urn:ietf:params:xml:ns:yang:ietf-layer0-types
+   Registrant Contact:  The IESG
+   XML:  N/A; the requested URI is an XML namespace.
+
+   This document registers the following YANG module in the "YANG Module
+   Names" registry [RFC7950].
+
+   Name:  ietf-layer0-types
+   Namespace:  urn:ietf:params:xml:ns:yang:ietf-layer0-types
+   Prefix:  l0-types
+   Reference:  RFC 9093
+
+6.  References
+
+6.1.  Normative References
+
+   [ITU-Tg6982]
+              ITU-T, "Amplified multichannel dense wavelength division
+              multiplexing applications with single channel optical
+              interfaces", ITU-T Recommendation G.698.2, November 2018.
+
+   [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/info/rfc4203>.
+
+   [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/info/rfc6163>.
+
+   [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/info/rfc6205>.
+
+   [RFC6241]  Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
+              and A. Bierman, Ed., "Network Configuration Protocol
+              (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
+              <https://www.rfc-editor.org/info/rfc6241>.
+
+   [RFC6242]  Wasserman, M., "Using the NETCONF Protocol over Secure
+              Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011,
+              <https://www.rfc-editor.org/info/rfc6242>.
+
+   [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/info/rfc7698>.
+
+   [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/info/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/info/rfc7950>.
+
+   [RFC8040]  Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
+              Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
+              <https://www.rfc-editor.org/info/rfc8040>.
+
+   [RFC8341]  Bierman, A. and M. Bjorklund, "Network Configuration
+              Access Control Model", STD 91, RFC 8341,
+              DOI 10.17487/RFC8341, March 2018,
+              <https://www.rfc-editor.org/info/rfc8341>.
+
+   [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/info/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/info/rfc8363>.
+
+   [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/info/rfc8446>.
+
+   [RFC8776]  Saad, T., Gandhi, R., Liu, X., Beeram, V., and I. Bryskin,
+              "Common YANG Data Types for Traffic Engineering",
+              RFC 8776, DOI 10.17487/RFC8776, June 2020,
+              <https://www.rfc-editor.org/info/rfc8776>.
+
+   [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/info/rfc8795>.
+
+6.2.  Informative References
+
+   [ITU-Tg6941]
+              ITU-T, "Spectral grids for WDM applications: DWDM
+              frequency grid", ITU-T Recommendation G.694.1, October
+              2020.
+
+   [ITU-Tg6942]
+              ITU-T, "Spectral grids for WDM applications: CWDM
+              wavelength grid", ITU-T Recommendation G.694.2, December
+              2003.
+
+   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
+              DOI 10.17487/RFC3688, January 2004,
+              <https://www.rfc-editor.org/info/rfc3688>.
+
+   [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/info/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/info/rfc7581>.
+
+Acknowledgements
+
+   The authors and the working group give their sincere thanks to Robert
+   Wilton for the YANG doctor review and Tom Petch for his comments
+   during the model and document development.
+
+Contributors
+
+   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
+
+
+   Italo Busi
+   Huawei
+
+   Email: Italo.Busi@huawei.com
+
+
+Authors' Addresses
+
+   Haomian Zheng
+   Huawei Technologies
+   H1, Huawei Xiliu Beipo Village, Songshan Lake
+   Dongguan
+   Guangdong, 523808
+   China
+
+   Email: zhenghaomian@huawei.com
+
+   Additional contact information:
+
+      郑好棉
+      中国
+      523808
+      广东 东莞
+      松山湖华为溪流背坡村H1
+      华为技术有限公司
+
+
+   Young Lee
+   Samsung
+   South Korea
+
+   Email: younglee.tx@gmail.com
+
+
+   Aihua Guo
+   Futurewei
+
+   Email: aihuaguo.ietf@gmail.com
+
+
+   Victor Lopez
+   Nokia
+
+   Email: victor.lopez@nokia.com
+
+
+   Daniel King
+   University of Lancaster
+
+   Email: d.king@lancaster.ac.uk