MPLS Working Group

Internet Engineering Task Force (IETF)                             Y. Qu
Internet-Draft
Request for Comments: 9702                        Futurewei Technologies
Intended status:
Category: Standards Track                                      A. Lindem
Expires: 6 January 2025
ISSN: 2070-1721                                  LabN Consulting, L.L.C.
                                                            S. Litkowski
                                                           Cisco Systems
                                                             J. Tantsura
                                                                  Nvidia
                                                             5 July
                                                           December 2024

 YANG Data Model for Maximum SID Segment Identifier (SID) Depth (MSD) Types
                              and MPLS Maximum SID Depth
                      draft-ietf-mpls-msd-yang-12 MSD

Abstract

   This document defines two YANG data modules.  The first module is the
   initial version of the IANA-maintained YANG module for Maximum
   Segment Identifier (SID) Depths (MSDs) Depth (MSD) Types, which includes identities
   for both the MPLS data plane and SRv6 Segment Routing over IPv6 (SRv6)
   data planes. plane.  The second module augments the IETF MPLS YANG data model
   to provide support for MPLS MSDs as defined in RFC RFCs 8476 and RFC 8491.

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 an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list  It represents the consensus of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid the IETF community.  It has
   received public review and has been approved for a maximum 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 six months this document, any errata,
   and how to provide feedback on it may be updated, replaced, or obsoleted by other documents obtained 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 6 January 2025.
   https://www.rfc-editor.org/info/rfc9702.

Copyright Notice

   Copyright (c) 2024 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)
   (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.  Overview  . . . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Design of the Model . . . . . . . . . . . . . . . . . . . . .   2
     2.1.  IANA MSD Types Module . . . . . . . . . . . . . . . . . .   3
     2.2.  IETF MPLS MSD Module  . . . . . . . . . . . . . . . . . .   3
   3.  Tree for IETF MPLS MSD Types YANG Module  . . . . . . . . . .   3
   4.  YANG Modules  . . . . . . . . . . . . . . . . . . . . . . . .   4
     4.1.  IANA-Maintained Module for MSD-Types  . . . . . . . . . .   4
     4.2.  MPLS MSD YANG . . . . . . . . . . . . . . . . . . . . . .   7
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
     6.1.  Registering YANG Modules  . . . . . . . . . . . . . . . .  10
     6.2.  IANA MSD-Types Module . . . . . . . . . . . . . . . . . .  11
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  12
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  13
     8.1.
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .  13
     8.2.
     7.2.  Informative References  . . . . . . . . . . . . . . . . .  14
   Acknowledgements
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  15

1.  Overview

   There are two YANG modules [RFC7950] defined in this document.
   Module iana-
   msd-types iana-msd-types defines the identities for Maximum Segment Identifier (SID) SID Depth
   (MSD) Types as per the "IGP MSD-Types" IANA IGP MSD-Types registry
   [IANA-IGP-MSD-Types], which include includes MSD types for both the MPLS data
   plane and the
   SRv6 data plane. planes.  This document also defines module ietf-mpls-msd
   augmenting the IETF MPLS YANG data model [RFC8960], which
   itself augments
   the routing RIB data model [RFC8349], [RFC8349] to provide operational state for
   various MSDs[RFC8662] MSDs [RFC8662] for the MPLS data plane.  The module augments
   the base MPLS model with a list of various types of node MSDs, Node MSDs as well
   as various types of MSDs on links. Link MSDs.

   The YANG modules in this document conform to the Network Management
   Datastore Architecture (NMDA) [RFC8342].

2.  Design of the Model

2.1.  IANA MSD Types Module

   IANA has created an IANA-managed a registry titled "IGP MSD-Types" under the
   "Interior Gateway Protocol (IGP) Parameters" registry group to
   identify MSD-Types.  Module iana-msd-types is an IANA-maintained
   module, which defines the identities for the MSD-Types as in the IANA
   IGP MSD-Types
   "IGP MSD-Types" registry.  This module references [RFC8476],
   [RFC8491], [RFC8662], [RFC8664], [RFC8814], [RFC9088], and [RFC9352].

   On top of the base identity "msd-base", identity "msd-base-mpls" is
   defined to serve as the base for MSD types for the MPLS data plane,
   and identity "msd-base-srh" is defined to serve as the base for MSD
   types for the Segment Routing Header (SRH) in the IPv6 data plane.

   This module will be is maintained by IANA and will be updated if and when
   there is any change to the registry.

2.2.  IETF MPLS MSD Module

   Module ietf-mpls-msd augments the base MPLS model [RFC8960], and it
   provides support of different types of MSDs in the MPLS data plane.

   As defined in [RFC8491], a Link MSD is the number of SIDs supported
   by a node's link, while a Node MSD is the smallest MSD supported by
   the node across all its interfaces. links.  The module defines lists of MSDs
   with different and
   their MSD Types for a node and its links.  Please note that these are
   read-only data as per the nodes exposing a node's hardware capability.

3.  Tree for IETF MPLS MSD Types YANG Module

   This document uses the graphical representation of data models per
   [RFC8340].

   module: ietf-mpls-msd

     augment /rt:routing/mpls:mpls:
       +--ro node-msds
          +--ro node-msd* [msd-type]
             +--ro msd-type     identityref
             +--ro msd-value?   uint8
     augment /rt:routing/mpls:mpls/mpls:interfaces/mpls:interface:
       +--ro link-msds
          +--ro link-msd* [msd-type]
             +--ro msd-type     identityref
             +--ro msd-value?   uint8

4.  YANG Modules

   There are two YANG modules defined in this document.

4.1.  IANA-Maintained Module for MSD-Types

   This document defines the initial version of the IANA-maintained YANG
   module for MSD Types, which Types that mirrors the IANA IGP MSD-Types "IGP MSD-Types" registry
   [IANA-IGP-MSD-Types].

   <CODE BEGINS> file "iana-msd-types@2024-07-04.yang"
   module iana-msd-types {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:iana-msd-types";
     prefix iana-msd-types;

     organization
       "Internet Assigned Numbers Authority (IANA)";

     contact
       "Internet Assigned Numbers Authority

        ICANN
        12025 Waterfront Drive, Suite 300
        Los Angeles, CA 90094-2536
        United States of America

        Tel:    +1 310 301 5800
        <mailto:iana@iana.org>";

     description
       "The YANG module defines the identities for Maximum Segment
        Identifier (SID) Depth (MSD) Types.

        This YANG module is maintained by IANA and reflects the 'IGP
        MSD-Types' registry.

        Copyright (c) 2024 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).

        This initial version of this YANG module is part of RFC XXXX
        (https://www.rfc-editor.org/info/rfcXXXX); 9702
        (https://www.rfc-editor.org/info/rfc9702); see the RFC itself
        for full legal notices.

        //RFC Ed.: replace XXXX with actual RFC number and remove
          this note

        //RFC Ed.: replace IANA_FOO_URL and remove this note.

        The latest version of this YANG module is available at
        <IANA_FOO_URL>.";
        https://www.iana.org/assignments/yang-parameters.";

     revision 2024-07-04 {
       description
         "Initial Version";
       reference
         "RFC XXXX: 9702: YANG Data Model for Maximum SID Segment Identifier (SID)
                    Depth Types and MPLS Maximum SID Depth";
     }

     identity msd-base {
       description
         "Base identity for Maximum SID Depth (MSD) Type. The MSD type
          definition is defined in the IANA IGP MSD-Types 'IGP MSD-Types' registry.";
     }

     identity msd-base-mpls {
       base msd-base;
       description
         "Base identity of MSD types for the MPLS data plane.";
     }

     identity base-mpls-imposition-msd {
       base msd-base-mpls;
       description
         "Base MPLS Imposition MSD.";
       reference
         "RFC 8491: Signaling Maximum SID Depth (MSD) using Using IS-IS
          RFC 8476: Signaling Maximum SID Depth (MSD) using Using OSPF
          RFC 8664: Path Computation Element Communication Protocol
                    (PCEP) Extensions for Segment Routing
          RFC 8814: Signaling Maximum SID Depth (MSD) Using the Border
                    Gateway Protocol - Link State";
     }

     identity erld-msd {
       base msd-base-mpls;
       description
         "msd-erld is defined to advertise the Entropy Readable
          Label Depth (ERLD).";
       reference
         "RFC 8662: Entropy Label for Source Packet Routing in
                    Networking (SPRING) Tunnels
          RFC 9088: Signaling Entropy Label Capability and Entropy
                    Readable Label Depth Using IS-IS";
     }

     identity msd-base-srh {
       base msd-base;
       description
         "Base identity of MSD types for Segment Routing Header (SRH).";
     }

     identity srh-max-sl {
       base msd-base-srh;
       description
         "The Maximum Segment Segments Left MSD type.";
       reference
         "RFC 9352: IS-IS Extensions to Support Segment Routing
                    over the IPv6 Data Plane";
     }

     identity srh-max-end-pop {
       base msd-base-srh;
       description
         "The Maximum End Pop MSD Type.";
       reference
         "RFC 9352: IS-IS Extensions to Support Segment Routing
                    over the IPv6 Data Plane";
     }

     identity srh-max-h-encaps {
       base msd-base-srh;
       description
         "The Maximum H.Encaps MSD Type.";
       reference
         "RFC 9352: IS-IS Extensions to Support Segment Routing
                    over the IPv6 Data Plane";
     }

     identity srh-max-end-d {
       base msd-base-srh;
       description
         "The Maximum End D MSD Type.";
       reference
         "RFC 9352: IS-IS Extensions to Support Segment Routing
                    over the IPv6 Data Plane";
     }
   }
   <CODE ENDS>

4.2.  MPLS MSD YANG

   This document also defines a YANG module for MSD extensions
   [RFC8476][RFC8491] [RFC8476]
   [RFC8491] to the MPLS base model as defined in [RFC8960].

   <CODE BEGINS> file "ietf-mpls-msd@2024-07-05.yang"
   module ietf-mpls-msd {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-mpls-msd";
     prefix mpls-msd;

     import ietf-routing {
       prefix rt;
       reference
         "RFC 8349: A YANG Data Model for Routing
                    Management (NMDA Version)";
     }
     import ietf-mpls {
       prefix mpls;
       reference
         "RFC 8960: A YANG Data Model for MPLS Base";
     }
     import iana-msd-types {
       prefix iana-msd-types;
     }

     organization
       "IETF Multiprotocol Label Switching (MPLS) Working Group";
     contact
       "WG Web:   <https://datatracker.ietf.org/wg/mpls/>
        WG List:  <mailto:mpls@ietf.org>

        Author:    Yingzhen Qu
                  <mailto:yingzhen.ietf@gmail.com>
        Author:    Acee Lindem
                  <mailto:acee.ietf@gmail.com>
        Author:    Stephane Litkowski
                  <mailto:slitkows.ietf@gmail.com>
        Author:    Jeff Tantsura
                  <mailto:jefftant.ietf@gmail.com>

       ";
     description
       "The
       "This YANG module augments the base MPLS model, and it is to
        provide support for different types of Maximum SID Depth (MSD).

        This YANG model module conforms to the Network Management
        Datastore Architecture (NMDA) as described in RFC 8342.

        Copyright (c) 2024 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).

        This version of this YANG module is part of RFC XXXX; 9702;
        see the RFC itself for full legal notices.";

     revision 2024-07-05 {
       description
         "Initial Version";
       reference
         "RFC XXXX: 9702: YANG Data Model for Maximum SID Segment Identifier (SID)
                    Depth Types and MPLS Maximum SID Depth";
     }

     grouping msd-type-value {
       description
         "Grouping for MSD type and value.";
       leaf msd-type {
         type identityref {
           base iana-msd-types:msd-base-mpls;
         }
         description
           "MSD types. The MSD type is defined in IANA IGP
            MSD-Types 'IGP
            MSD-Types' registry.";
       }
       leaf msd-value {
         type uint8;
         description
           "MSD value, in the range of 0-255. 0 represents the lack
            of ability to support a SID stack of any depth.";
       }
     }
     augment "/rt:routing/mpls:mpls" {
       description
         "This module augments MPLS data model (RFC 8960)
          with node Node MSD.";
       container node-msds {
         config false;
         description
           "Maximum SID Depth (MSD) of a node.";
         list node-msd {
           key "msd-type";
           uses msd-type-value;
           description
             "List of different types of node Node MSDs. For the same
              type, the value of node Node MSD is the smallest among link Link MSD
              values.";
         }
       }
     }

     augment "/rt:routing/mpls:mpls/mpls:interfaces/mpls:interface" {
       description
         "This module augments MPLS data model (RFC 8960)
          with link Link MSD.";
       container link-msds {
         config false;
         description
           "Maximum SID Depth (MSD) of an interface.";
         list link-msd {
           key "msd-type";
           uses msd-type-value;
           description
             "List of different types of MSDs on the link.";
         }
       }
     }
   }
   <CODE ENDS>

5.  Security Considerations

   The YANG modules specified in this document define a schema for data
   that is designed to be accessed via network management protocols such
   as NETCONF [RFC6241] or RESTCONF [RFC8040].  These network management
   protocols are required to use a  The lowest NETCONF layer
   is the secure transport layer layer, and mutual
   authentication, e.g., SSH [RFC6242] without the "none" authentication
   option, Transport Layer Security (TLS) [RFC8446] with mutual X.509
   authentication, mandatory-to-implement secure
   transport is Secure Shell (SSH) [RFC6242].  The lowest RESTCONF layer
   is HTTPS, and HTTPS with HTTP authentication (Section 11 of
   [RFC9110]). the mandatory-to-implement secure transport is TLS
   [RFC8446].

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

   Some of the readable data nodes in the ietf-mpls-msd YANG module may
   be considered sensitive or vulnerable in some network environments.
   It is thus important to control read access (e.g., via get, get-
   config, or notification) to these data nodes.  These are the subtrees
   and data nodes and their sensitivity/vulnerability:

      /rt:routing/mpls:mpls/msd/node-msds

      /rt:routing/mpls:mpls/msd/link-msds

      Exposure of the node's maximum SID depth may be useful in mounting
      a Denial-of-Service (DoS) attack by sending packets to the node
      that the router can't process.

   The iana-msd-types YANG module defines a set of identities, which
   mirrors identities that
   mirror the IANA IGP MSD-Types "IGP MSD-Types" registry.  These identities are
   intended to be reused by other YANG modules.  The module by itself
   does not expose any data nodes that are writable or readable.  As
   such, there are no additional security issues related to this YANG
   module that need to be considered.

6.  IANA Considerations

6.1.  Registering YANG Modules

   This document registers URIs in the IETF XML registry [RFC3688].
   Following the format as defined in [RFC3688], the
   [RFC3688].  The following registrations are
   requested to be have been made:

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

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

   This document registers the YANG modules in the YANG "YANG Module Names Names"
   registry as defined in [RFC6020].

      name:

   Name:  iana-msd-types
   Maintained by IANA?  Y
      namespace:
   Namespace:  urn:ietf:params:xml:ns:yang:iana-msd-types
      prefix:
   Prefix:  iana-msd-types
      reference:
   Reference:  RFC XXXX

      name: 9702

   Name:  ietf-mpls-msd
   Maintained by IANA?  N
      namespace:
   Namespace:  urn:ietf:params:xml:ns:yang:ietf-mpls-msd
      prefix:
   Prefix:  mpls-msd
      reference:
   Reference:  RFC XXXX 9702

6.2.  IANA MSD-Types Module

   This document defines the initial version of the IANA-maintained
   "iana-msd-types" YANG module Section 4.1. (Section 4.1).  The latest version of
   the YANG module is available from the "YANG Parameters" registry
   [IANA-YANG-Parameters].

   IANA is requested to add has added this note to the "YANG Module Names" registry:

      MSD Types

   |  New values must not be added directly added to the iana-msd-types "iana-msd-types" YANG
   |  module.  They must first instead be added to [IANA-IGP-MSD-Types], which
      it mirrors. the "IGP MSD-Types"
   |  registry in the "Interior Gateway Protocol (IGP) Parameters"
   |  registry group [IANA-IGP-MSD-Types].

   The identities defined in the iana-msd-types YANG module are
   organized hierarchically based on the data plane.  In this initial
   version, only MPLS and SRv6 data planes are supported, hence "msd-
   base-mpls" and "msd-base-srh" are defined.  When a new data plane is
   added to the "IGP MSD-Types" registry, a new "identity" statement
   should be added to the "iana-msd-types" YANG module.  The name of the
   "identity" is the prefix "msd-base-" plus a lower-case lowercase version of the
   data plane name . name.  The identity statement should have the following
   sub-statements defined:

   "base":  Contains 'msd-base'.

   "description":  Replicates the description from "msd-base-mpls" and
                  change
      changes the corresponding data plane name.

   "reference":  Replicates the reference from the registry with the
      title of the document added.

   When an MSD type is added to the "IGP MSD-Types" registry, a new
   "identity" statement must be added to the "iana-msd-types" YANG
   module.  Then  The name of the "identity" is a lower-case lowercase version of the
   type name provided in the name with the space replaced with "-".  The
   "identity" statement should have the following sub-statements
   defined:

   "base":  Contains the base name of the corresponding data plane.

   "description":  Replicates the name from the registry.

   "reference":  Replicates the reference from the registry with the
      title of the document added.

   Unassigned or reserved values are not present in the module.

   When the "iana-msd-types" YANG module is updated, a new "revision"
   statement with a unique revision date must be added in front of the
   existing revision statements.

   IANA is requested to the add has added a "data-plane" "Data Plane" column to the "IGP MSD-
   Types" MSD-Types" registry.
   This will unequivocally identify the base identity for MSD-Types.
   The values for the Data-Plane "Data Plane" column for existing MSD-Types are:

      +=========+==========================+============+===========+
      | Value   | Name                      Data-Plane                     | Data Plane | Reference |
      +=========+==========================+============+===========+
      | 0       | Reserved                  N/A                 |            | [RFC8491] |
      +---------+--------------------------+------------+-----------+
      | 1       | Base MPLS Imposition MSD | MPLS       | [RFC8491] |
      +---------+--------------------------+------------+-----------+
      | 2       | ERLD-MSD                 | MPLS       | [RFC9088] |
      +---------+--------------------------+------------+-----------+
      | 3-40    | Unassigned                N/A               |            |           |
      +---------+--------------------------+------------+-----------+
      | 41      | SRH Max SL               | SRv6       | [RFC9352] |
      +---------+--------------------------+------------+-----------+
      | 42      | SRH Max End Pop          | SRv6       | [RFC9352] |
      +---------+--------------------------+------------+-----------+
      | 43      | Unassigned                N/A               |            |           |
      +---------+--------------------------+------------+-----------+
      | 44      | SRH Max H.encaps         | SRv6       | [RFC9352] |
      +---------+--------------------------+------------+-----------+
      | 45      | SRH Max End              | SRv6       | [RFC9352] |
      +---------+--------------------------+------------+-----------+
      | 46-250  | Unassigned                N/A               |            |           |
      +---------+--------------------------+------------+-----------+
      | 251-254 | Experimental Use          N/A         |            | [RFC8491] |
      +---------+--------------------------+------------+-----------+
      | 255     | Reserved                  N/A                 |            | [RFC8491] |
      +---------+--------------------------+------------+-----------+

                                  Table 1

   IANA is requested to add has added this note to [IANA-IGP-MSD-Types]:

   |  When this registry is modified, the YANG module "iana-msd-types"
   |  must be updated as defined in RFC XXXX. 9702.

7.  Acknowledgements

   This document was produced using Marshall Rose's xml2rfc tool.

   The YANG model was developed using the suite of YANG tools written
   and maintained by numerous authors.

   We would like to thank Jan Lindblad, Tom Petch, Dhruv Dhody, Mohamed
   Boucadair and Susan Hares for their reviews and comments.

8.  References

8.1.

7.1.  Normative References

   [IANA-IGP-MSD-Types]
              IANA, "IGP MSD-Types", <https://www.iana.org/assignments/
              igp-parameters/igp-parameters.xhtml#igp-msd-types>.
              <https://www.iana.org/assignments/igp-parameters>.

   [IANA-YANG-Parameters]
              IANA, "YANG Module Names",
              <https://www.iana.org/assignments/yang-parameters>.

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

   [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/info/rfc6020>.

   [RFC6241]  Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
              and A. Bierman, Ed., "Network Configuration Protocol
              (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
              <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>.

   [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>.

   [RFC8349]  Lhotka, L., Lindem, A., and Y. Qu, "A YANG Data Model for
              Routing Management (NMDA Version)", RFC 8349,
              DOI 10.17487/RFC8349, March 2018,
              <https://www.rfc-editor.org/info/rfc8349>.

   [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>.

   [RFC8476]  Tantsura, J., Chunduri, U., Aldrin, S., and P. Psenak,
              "Signaling Maximum SID Depth (MSD) Using OSPF", RFC 8476,
              DOI 10.17487/RFC8476, December 2018,
              <https://www.rfc-editor.org/info/rfc8476>.

   [RFC8491]  Tantsura, J., Chunduri, U., Aldrin, S., and L. Ginsberg,
              "Signaling Maximum SID Depth (MSD) Using IS-IS", RFC 8491,
              DOI 10.17487/RFC8491, November 2018,
              <https://www.rfc-editor.org/info/rfc8491>.

   [RFC8960]  Saad, T., Raza, K., Gandhi, R., Liu, X., and V. Beeram, "A
              YANG Data Model for MPLS Base", RFC 8960,
              DOI 10.17487/RFC8960, December 2020,
              <https://www.rfc-editor.org/info/rfc8960>.

   [RFC9088]  Xu, X., Kini, S., Psenak, P., Filsfils, C., Litkowski, S.,
              and M. Bocci, "Signaling Entropy Label Capability and
              Entropy Readable Label Depth Using IS-IS", RFC 9088,
              DOI 10.17487/RFC9088, August 2021,
              <https://www.rfc-editor.org/info/rfc9088>.

   [RFC9110]  Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
              Ed., "HTTP Semantics", STD 97, RFC 9110,
              DOI 10.17487/RFC9110, June 2022,
              <https://www.rfc-editor.org/info/rfc9110>.

   [RFC9352]  Psenak, P., Ed., Filsfils, C., Bashandy, A., Decraene, B.,
              and Z. Hu, "IS-IS Extensions to Support Segment Routing
              over the IPv6 Data Plane", RFC 9352, DOI 10.17487/RFC9352,
              February 2023, <https://www.rfc-editor.org/info/rfc9352>.

8.2.

7.2.  Informative References

   [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/info/rfc8340>.

   [RFC8662]  Kini, S., Kompella, K., Sivabalan, S., Litkowski, S.,
              Shakir, R., and J. Tantsura, "Entropy Label for Source
              Packet Routing in Networking (SPRING) Tunnels", RFC 8662,
              DOI 10.17487/RFC8662, December 2019,
              <https://www.rfc-editor.org/info/rfc8662>.

   [RFC8664]  Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W.,
              and J. Hardwick, "Path Computation Element Communication
              Protocol (PCEP) Extensions for Segment Routing", RFC 8664,
              DOI 10.17487/RFC8664, December 2019,
              <https://www.rfc-editor.org/info/rfc8664>.

   [RFC8814]  Tantsura, J., Chunduri, U., Talaulikar, K., Mirsky, G.,
              and N. Triantafillis, "Signaling Maximum SID Depth (MSD)
              Using the Border Gateway Protocol - Link State", RFC 8814,
              DOI 10.17487/RFC8814, August 2020,
              <https://www.rfc-editor.org/info/rfc8814>.

Acknowledgements

   The YANG data model was developed using the suite of YANG tools
   written and maintained by numerous authors.

   We would like to thank Jan Lindblad, Tom Petch, Dhruv Dhody, Mohamed
   Boucadair, and Susan Hares for their reviews and comments.

Authors' Addresses

   Yingzhen Qu
   Futurewei Technologies
   Email: yingzhen.ietf@gmail.com

   Acee Lindem
   LabN Consulting, L.L.C.
   Email: acee.ietf@gmail.com

   Stephane Litkowski
   Cisco Systems
   Email: slitkows.ietf@gmail.com

   Jeff Tantsura
   Nvidia
   Email: jefftant.ietf@gmail.com