A YANG Data Model for Tunnel Interface Types
RFC 8675



Internet Engineering Task Force (IETF)                      M. Boucadair
Request for Comments: 8675                                        Orange
Category: Standards Track                                      I. Farrer
ISSN: 2070-1721                                      Deutsche Telekom AG
                                                                R. Asati
                                                     Cisco Systems, Inc.
                                                           November 2019

              A YANG Data Model for Tunnel Interface Types

Abstract

   This document specifies the initial version of a YANG module "iana-
   tunnel-type", which contains a collection of IANA-maintained YANG
   identities used as interface types for tunnel interfaces.  The module
   reflects the "tunnelType" registry maintained by IANA.  The latest
   revision of this YANG module can be obtained from the IANA website.

   Tunnel type values are not directly added to the Tunnel Interface
   Types YANG module; they must instead be added to the "tunnelType"
   IANA registry.  Once a new tunnel type registration is made by IANA
   for a new tunneling scheme or even an existing one that is not
   already listed in the current registry (e.g., LISP, NSH), IANA will
   update the Tunnel Interface Types YANG module accordingly.

   Some of the IETF-defined tunneling techniques are not listed in the
   current IANA registry.  It is not the intent of this document to
   update the existing IANA registry with a comprehensive list of tunnel
   technologies.  Registrants must follow the IETF registration
   procedure for interface types whenever a new tunnel type is needed.

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/rfc8675.

Copyright Notice

   Copyright (c) 2019 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
   2.  IANA Tunnel Type YANG Module
   3.  Security Considerations
   4.  IANA Considerations
     4.1.  YANG Module
     4.2.  Updates to the IANA tunnelType Table
   5.  References
     5.1.  Normative References
     5.2.  Informative References
   Appendix A.  Example Usage
   Acknowledgements
   Authors' Addresses

1.  Introduction

   This document specifies the initial version of the iana-tunnel-type
   YANG module containing a collection of IANA-maintained YANG
   identities identifying tunnel interface types.  The module reflects
   IANA's tunnelType registry under the SMI Numbers registry
   [TUNNELTYPE-IANA-REGISTRY].  The latest revision of this module can
   be obtained from the IANA website.

   Tunnel-specific extensions may be added to the Interface module
   [RFC8343] as a function of the tunnel type.  An example of this is
   provided in Appendix A.  It is not the intention of this document to
   define tunnel-specific extensions for every tunnel encapsulation
   technology; those are discussed in dedicated documents such as
   [RFC8676].  Likewise, it is out of the scope of this document to
   update the existing IANA tunnelType registry
   [TUNNELTYPE-IANA-REGISTRY] with a comprehensive list of tunnel
   technologies.  Guidelines and registration procedures for interface
   types and sub-types are discussed in [IFTYPE-REG].

   This document uses the common YANG types defined in [RFC6991] and
   adopts the Network Management Datastore Architecture (NMDA
   [RFC8342]).

   The terminology for describing YANG modules is defined in [RFC7950].
   The meanings of the symbols used in the tree diagram are defined in
   [RFC8340].

2.  IANA Tunnel Type YANG Module

   The iana-tunnel-type module imports the 'iana-if-type' module defined
   in [RFC7224].

   The initial version of the module includes tunnel types defined in
   [RFC4087], [RFC7856], [RFC7870], and [RFC6346].

   <CODE BEGINS> file "iana-tunnel-type@2019-11-16.yang"
   module iana-tunnel-type {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:iana-tunnel-type";
     prefix iana-tunnel-type;

     import iana-if-type {
       prefix ift;
       reference
         "RFC 7224: IANA Interface Type YANG Module";
     }

     organization
       "IANA";
     contact
       "Internet Assigned Numbers Authority

        Postal: 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
       "This module contains a collection of YANG identities defined
        by IANA and used as interface types for tunnel interfaces.

        Copyright (c) 2019 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 8675; see
        the RFC itself for full legal notices.";

     revision 2019-11-16 {
       description
         "Initial revision.";
       reference
         "RFC 8675: A YANG Data Model for Tunnel Interface Types";
     }

     identity other {
       base ift:tunnel;
       description
         "None of the following values.";
       reference
         "RFC 4087: IP Tunnel MIB";
     }

     identity direct {
       base ift:tunnel;
       description
         "No intermediate header.";
       reference
         "RFC 2003: IP Encapsulation within IP
          RFC 4213: Basic Transition Mechanisms for IPv6 Hosts
                    and Routers";
     }

     identity gre {
       base ift:tunnel;
       description
         "GRE encapsulation.";
       reference
         "RFC 1701: Generic Routing Encapsulation (GRE)
          RFC 1702: Generic Routing Encapsulation over IPv4 networks
          RFC 7676: IPv6 Support for Generic Routing Encapsulation
                    (GRE)";
     }

     identity minimal {
       base ift:tunnel;
       description
         "Minimal encapsulation.";
       reference
         "RFC 2004: Minimal Encapsulation within IP";
     }

     identity l2tp {
       base ift:tunnel;
       description
         "L2TP encapsulation.";
       reference
         "RFC 2661: Layer Two Tunneling Protocol 'L2TP'";
     }

     identity pptp {
       base ift:tunnel;
       description
         "PPTP encapsulation.";
       reference
         "RFC 2637: Point-to-Point Tunneling Protocol (PPTP)";
     }

     identity l2f {
       base ift:tunnel;
       description
         "L2F encapsulation.";
       reference
         "RFC 2341: Cisco Layer Two Forwarding (Protocol) 'L2F'";
     }

     identity udp {
       base ift:tunnel;
       description
         "UDP encapsulation.";
       reference
         "RFC 1234: Tunneling IPX Traffic through IP Networks,
          RFC 8085: UDP Usage Guidelines, Section 3.1.11";
     }

     identity atmp {
       base ift:tunnel;
       description
         "ATMP encapsulation.";
       reference
         "RFC 2107: Ascend Tunnel Management Protocol - ATMP";
     }

     identity msdp {
       base ift:tunnel;
       description
         "MSDP encapsulation.";
       reference
         "RFC 3618: Multicast Source Discovery Protocol (MSDP)";
     }

     identity sixtofour {
       base ift:tunnel;
       description
         "6to4 encapsulation.";
       reference
         "RFC 3056: Connection of IPv6 Domains via IPv4 Clouds";
     }

     identity sixoverfour {
       base ift:tunnel;
       description
         "6over4 encapsulation.";
       reference
         "RFC 2529: Transmission of IPv6 over IPv4 Domains without
                    Explicit Tunnels";
     }

     identity isatap {
       base ift:tunnel;
       description
         "ISATAP encapsulation.";
       reference
         "RFC 5214:  Intra-Site Automatic Tunnel Addressing Protocol
                    (ISATAP)";
     }

     identity teredo {
       base ift:tunnel;
       description
         "Teredo encapsulation.";
       reference
         "RFC 4380: Teredo: Tunneling IPv6 over UDP through
                    Network Address Translations (NATs)";
     }

     identity iphttps {
       base ift:tunnel;
       description
         "IP over HTTPS (IP-HTTPS) Tunneling Protocol.";
       reference
         "Microsoft Corporation, IP over HTTPS (IP-HTTPS) Tunneling
          Protocol Specification,
          https://msdn.microsoft.com/en-us/library/dd358571.aspx";
     }

     identity softwiremesh {
       base ift:tunnel;
       description
         "softwire mesh tunnel.";
       reference
         "RFC 5565: Softwire Mesh Framework";
     }

     identity dslite {
       base ift:tunnel;
       description
         "DS-Lite tunnel.";
       reference
         "RFC 6333: Dual-Stack Lite Broadband Deployments Following
                    IPv4 Exhaustion";
     }

     identity aplusp {
       base ift:tunnel;
       description
         "A+P encapsulation.";
       reference
         "RFC 6346: The Address plus Port (A+P) Approach to the IPv4
                    Address Shortage";
     }
   }
   <CODE ENDS>

3.  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 module defined in this document defines YANG identities for the
   iana-tunnel-types registry.  These identities are intended to be
   referenced by other YANG modules, and by themselves do not expose any
   nodes which are writable, contain read-only state, or RPCs.  As such,
   there are no additional security issues to be considered relating to
   the module defined in this document.

4.  IANA Considerations

4.1.  YANG Module

   IANA has registered the following URI in the "ns" subregistry within
   the "IETF XML Registry" [RFC3688]:

   URI:  urn:ietf:params:xml:ns:yang:iana-tunnel-type
   Registrant Contact:  IANA
   XML:  N/A; the requested URI is an XML namespace.

   IANA registered the following YANG module in the "YANG Module Names"
   subregistry [RFC7950] within the "YANG Parameters" registry.

   Name:  iana-tunnel-type
   Namespace:  urn:ietf:params:xml:ns:yang:iana-tunnel-type
   Prefix:  iana-tunnel-type
   Reference:  RFC 8675

   This document defines the initial version of the IANA-maintained
   iana-tunnel-type YANG module.  IANA has added this note to the
   registry:

      Tunnel type values must not be directly added to the iana-tunnel-
      type YANG module.  They must instead be added to the "tunnelType"
      subregistry (under the "ifType definitions" registry) at [IANA
      registry smi-numbers].

   When a tunnel type is added to the "tunnelType" subregistry, a new
   "identity" statement must be added to the iana-tunnel-type YANG
   module.  The name of the "identity" is the lower-case of the
   corresponding enumeration in the IANAifType-MIB (i.e.,
   IANAtunnelType).  The "identity" statement should have the following
   sub-statements defined:

   "base":        Contains 'ift:tunnel'.

   "description":  Replicates the description from the registry.

   "reference":   Replicates the reference from the registry and adds
                  the title of the document.

   Unassigned or reserved values are not present in the module.

   When the iana-tunnel-type YANG module is updated, a new "revision"
   statement must be added in front of the existing revision statements.

   IANA has added the following note to "tunnelType" subregistry:

      When this registry is modified, the YANG module iana-tunnel-type
      must be updated as defined in RFC 8675.

4.2.  Updates to the IANA tunnelType Table

   IANA has updated the following entries in the tunnelType registry
   under the SMI Numbers registry [TUNNELTYPE-IANA-REGISTRY].

   OLD:

     +---------+--------------+------------------------+------------+
     | Decimal | Name         | Description            | References |
     +=========+==============+========================+============+
     | 2       | direct       | no intermediate header | [RFC4087]  |
     +---------+--------------+------------------------+------------+
     | 3       | gre          | GRE encapsulation      | [RFC4087]  |
     +---------+--------------+------------------------+------------+
     | 4       | minimal      | Minimal encapsulation  | [RFC4087]  |
     +---------+--------------+------------------------+------------+
     | 5       | l2tp         | L2TP encapsulation     | [RFC4087]  |
     +---------+--------------+------------------------+------------+
     | 6       | pptp         | PPTP encapsulation     | [RFC4087]  |
     +---------+--------------+------------------------+------------+
     | 7       | l2f          | L2F encapsulation      | [RFC4087]  |
     +---------+--------------+------------------------+------------+
     | 8       | udp          | UDP encapsulation      | [RFC4087]  |
     +---------+--------------+------------------------+------------+
     | 9       | atmp         | ATMP encapsulation     | [RFC4087]  |
     +---------+--------------+------------------------+------------+
     | 10      | msdp         | MSDP encapsulation     | [RFC4087]  |
     +---------+--------------+------------------------+------------+
     | 11      | sixToFour    | 6to4 encapsulation     | [RFC4087]  |
     +---------+--------------+------------------------+------------+
     | 12      | sixOverFour  | 6over4 encapsulation   | [RFC4087]  |
     +---------+--------------+------------------------+------------+
     | 13      | isatap       | ISATAP encapsulation   | [RFC4087]  |
     +---------+--------------+------------------------+------------+
     | 14      | teredo       | Teredo encapsulation   | [RFC4087]  |
     +---------+--------------+------------------------+------------+
     | 16      | softwireMesh | softwire mesh tunnel   | [RFC7856]  |
     +---------+--------------+------------------------+------------+
     | 17      | dsLite       | DS-Lite tunnel         | [RFC7870]  |
     +---------+--------------+------------------------+------------+

                                 Table 1

   NEW:

   +-------+-------------+---------------+-----------------------------+
   |Decimal| Name        | Description   | References                  |
   +=======+=============+===============+=============================+
   | 2     | direct      |no intermediate| [RFC2003][RFC4213]          |
   |       |             | header        |                             |
   +-------+-------------+---------------+-----------------------------+
   | 3     | gre         | GRE           | [RFC1701][RFC1702][RFC7676] |
   |       |             | encapsulation |                             |
   +-------+-------------+---------------+-----------------------------+
   | 4     | minimal     | Minimal       | [RFC2004]                   |
   |       |             | encapsulation |                             |
   +-------+-------------+---------------+-----------------------------+
   | 5     | l2tp        | L2TP          | [RFC2661]                   |
   |       |             | encapsulation |                             |
   +-------+-------------+---------------+-----------------------------+
   | 6     | pptp        | PPTP          | [RFC2637]                   |
   |       |             | encapsulation |                             |
   +-------+-------------+---------------+-----------------------------+
   | 7     | l2f         | L2F           | [RFC2341]                   |
   |       |             | encapsulation |                             |
   +-------+-------------+---------------+-----------------------------+
   | 8     | udp         | UDP           | [RFC8085]                   |
   |       |             | encapsulation |                             |
   +-------+-------------+---------------+-----------------------------+
   | 9     | atmp        | ATMP          | [RFC2107]                   |
   |       |             | encapsulation |                             |
   +-------+-------------+---------------+-----------------------------+
   | 10    | msdp        | MSDP          | [RFC3618]                   |
   |       |             | encapsulation |                             |
   +-------+-------------+---------------+-----------------------------+
   | 11    | sixToFour   | 6to4          | [RFC3056]                   |
   |       |             | encapsulation |                             |
   +-------+-------------+---------------+-----------------------------+
   | 12    | sixOverFour | 6over4        | [RFC2529]                   |
   |       |             | encapsulation |                             |
   +-------+-------------+---------------+-----------------------------+
   | 13    | isatap      | ISATAP        | [RFC5214]                   |
   |       |             | encapsulation |                             |
   +-------+-------------+---------------+-----------------------------+
   | 14    | teredo      | Teredo        | [RFC4380]                   |
   |       |             | encapsulation |                             |
   +-------+-------------+---------------+-----------------------------+
   | 16    |softwireMesh | softwire mesh | [RFC5565]                   |
   |       |             | tunnel        |                             |
   +-------+-------------+---------------+-----------------------------+
   | 17    | dsLite      |DS-Lite tunnel | [RFC6333]                   |
   +-------+-------------+---------------+-----------------------------+

                                  Table 2

5.  References

5.1.  Normative References

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

   [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>.

   [RFC6991]  Schoenwaelder, J., Ed., "Common YANG Data Types",
              RFC 6991, DOI 10.17487/RFC6991, July 2013,
              <https://www.rfc-editor.org/info/rfc6991>.

   [RFC7224]  Bjorklund, M., "IANA Interface Type YANG Module",
              RFC 7224, DOI 10.17487/RFC7224, May 2014,
              <https://www.rfc-editor.org/info/rfc7224>.

   [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>.

   [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>.

   [TUNNELTYPE-IANA-REGISTRY]
              IANA, "Structure of Management Information (SMI) Numbers
              (MIB Module Registrations)",
              <https://www.iana.org/assignments/smi-numbers>.

5.2.  Informative References

   [IFTYPE-REG]
              Thaler, D. and D. Romascanu, "Guidelines and Registration
              Procedures for Interface Types and Tunnel Types", Work in
              Progress, Internet-Draft, draft-thaler-iftype-reg-06, 2
              November 2019,
              <https://tools.ietf.org/html/draft-thaler-iftype-reg-06>.

   [RFC1701]  Hanks, S., Li, T., Farinacci, D., and P. Traina, "Generic
              Routing Encapsulation (GRE)", RFC 1701,
              DOI 10.17487/RFC1701, October 1994,
              <https://www.rfc-editor.org/info/rfc1701>.

   [RFC1702]  Hanks, S., Li, T., Farinacci, D., and P. Traina, "Generic
              Routing Encapsulation over IPv4 networks", RFC 1702,
              DOI 10.17487/RFC1702, October 1994,
              <https://www.rfc-editor.org/info/rfc1702>.

   [RFC2003]  Perkins, C., "IP Encapsulation within IP", RFC 2003,
              DOI 10.17487/RFC2003, October 1996,
              <https://www.rfc-editor.org/info/rfc2003>.

   [RFC2004]  Perkins, C., "Minimal Encapsulation within IP", RFC 2004,
              DOI 10.17487/RFC2004, October 1996,
              <https://www.rfc-editor.org/info/rfc2004>.

   [RFC2107]  Hamzeh, K., "Ascend Tunnel Management Protocol - ATMP",
              RFC 2107, DOI 10.17487/RFC2107, February 1997,
              <https://www.rfc-editor.org/info/rfc2107>.

   [RFC2341]  Valencia, A., Littlewood, M., and T. Kolar, "Cisco Layer
              Two Forwarding (Protocol) "L2F"", RFC 2341,
              DOI 10.17487/RFC2341, May 1998,
              <https://www.rfc-editor.org/info/rfc2341>.

   [RFC2529]  Carpenter, B. and C. Jung, "Transmission of IPv6 over IPv4
              Domains without Explicit Tunnels", RFC 2529,
              DOI 10.17487/RFC2529, March 1999,
              <https://www.rfc-editor.org/info/rfc2529>.

   [RFC2637]  Hamzeh, K., Pall, G., Verthein, W., Taarud, J., Little,
              W., and G. Zorn, "Point-to-Point Tunneling Protocol
              (PPTP)", RFC 2637, DOI 10.17487/RFC2637, July 1999,
              <https://www.rfc-editor.org/info/rfc2637>.

   [RFC2661]  Townsley, W., Valencia, A., Rubens, A., Pall, G., Zorn,
              G., and B. Palter, "Layer Two Tunneling Protocol "L2TP"",
              RFC 2661, DOI 10.17487/RFC2661, August 1999,
              <https://www.rfc-editor.org/info/rfc2661>.

   [RFC3056]  Carpenter, B. and K. Moore, "Connection of IPv6 Domains
              via IPv4 Clouds", RFC 3056, DOI 10.17487/RFC3056, February
              2001, <https://www.rfc-editor.org/info/rfc3056>.

   [RFC3618]  Fenner, B., Ed. and D. Meyer, Ed., "Multicast Source
              Discovery Protocol (MSDP)", RFC 3618,
              DOI 10.17487/RFC3618, October 2003,
              <https://www.rfc-editor.org/info/rfc3618>.

   [RFC4087]  Thaler, D., "IP Tunnel MIB", RFC 4087,
              DOI 10.17487/RFC4087, June 2005,
              <https://www.rfc-editor.org/info/rfc4087>.

   [RFC4213]  Nordmark, E. and R. Gilligan, "Basic Transition Mechanisms
              for IPv6 Hosts and Routers", RFC 4213,
              DOI 10.17487/RFC4213, October 2005,
              <https://www.rfc-editor.org/info/rfc4213>.

   [RFC4380]  Huitema, C., "Teredo: Tunneling IPv6 over UDP through
              Network Address Translations (NATs)", RFC 4380,
              DOI 10.17487/RFC4380, February 2006,
              <https://www.rfc-editor.org/info/rfc4380>.

   [RFC5214]  Templin, F., Gleeson, T., and D. Thaler, "Intra-Site
              Automatic Tunnel Addressing Protocol (ISATAP)", RFC 5214,
              DOI 10.17487/RFC5214, March 2008,
              <https://www.rfc-editor.org/info/rfc5214>.

   [RFC5565]  Wu, J., Cui, Y., Metz, C., and E. Rosen, "Softwire Mesh
              Framework", RFC 5565, DOI 10.17487/RFC5565, June 2009,
              <https://www.rfc-editor.org/info/rfc5565>.

   [RFC6333]  Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual-
              Stack Lite Broadband Deployments Following IPv4
              Exhaustion", RFC 6333, DOI 10.17487/RFC6333, August 2011,
              <https://www.rfc-editor.org/info/rfc6333>.

   [RFC6346]  Bush, R., Ed., "The Address plus Port (A+P) Approach to
              the IPv4 Address Shortage", RFC 6346,
              DOI 10.17487/RFC6346, August 2011,
              <https://www.rfc-editor.org/info/rfc6346>.

   [RFC7676]  Pignataro, C., Bonica, R., and S. Krishnan, "IPv6 Support
              for Generic Routing Encapsulation (GRE)", RFC 7676,
              DOI 10.17487/RFC7676, October 2015,
              <https://www.rfc-editor.org/info/rfc7676>.

   [RFC7856]  Cui, Y., Dong, J., Wu, P., Xu, M., and A. Yla-Jaaski,
              "Softwire Mesh Management Information Base (MIB)",
              RFC 7856, DOI 10.17487/RFC7856, May 2016,
              <https://www.rfc-editor.org/info/rfc7856>.

   [RFC7870]  Fu, Y., Jiang, S., Dong, J., and Y. Chen, "Dual-Stack Lite
              (DS-Lite) Management Information Base (MIB) for Address
              Family Transition Routers (AFTRs)", RFC 7870,
              DOI 10.17487/RFC7870, June 2016,
              <https://www.rfc-editor.org/info/rfc7870>.

   [RFC8085]  Eggert, L., Fairhurst, G., and G. Shepherd, "UDP Usage
              Guidelines", BCP 145, RFC 8085, DOI 10.17487/RFC8085,
              March 2017, <https://www.rfc-editor.org/info/rfc8085>.

   [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>.

   [RFC8343]  Bjorklund, M., "A YANG Data Model for Interface
              Management", RFC 8343, DOI 10.17487/RFC8343, March 2018,
              <https://www.rfc-editor.org/info/rfc8343>.

   [RFC8676]  Farrer, I., Ed. and M. Boucadair, Ed., "YANG Modules for
              IPv4-in-IPv6 Address plus Port (A+P) Softwires", RFC 8676,
              DOI 10.17487/RFC8676, November 2019,
              <https://www.rfc-editor.org/info/rfc8676>.

Appendix A.  Example Usage

   The following example illustrates how the Interface YANG module can
   be augmented with tunnel-specific parameters.  In this example, the
   module is augmented with a 'remote-endpoint' for the tunnel.  A tree
   structure is provided below:

   module: example-iftunnel-extension
     augment /if:interfaces/if:interface:
       +--rw remote-endpoint?   inet:ipv6-address

   The 'example-iftunnel-extension' module imports the modules defined
   in [RFC6991] and [RFC8343] in addition to the "iana-tunnel-type"
   module defined in this document.

   module example-iftunnel-extension {
     yang-version 1.1;

     namespace "urn:ietf:params:xml:ns:yang:example-iftunnel-extension";
     prefix example;

     import ietf-inet-types {
       prefix inet;
       reference
         "RFC 6991: Common YANG Data Types, Section 4";
     }

     import ietf-interfaces {
       prefix if;
       reference
         "RFC 8343: A YANG Data Model for Interface Management";
     }

     import iana-tunnel-type  {
       prefix iana-tunnel-type;
       reference
         "RFC 8675:  A Tunnel Extension to the Interface Management
                     YANG Module";
     }

     organization "IETF Softwire Working Group";

     contact

       "WG Web:   <https://datatracker.ietf.org/wg/softwire/>
        WG List:  <mailto:softwire@ietf.org>

        Author:  Mohamed Boucadair
                 <mailto:mohamed.boucadair@orange.com>";

      description
         "This is an example YANG module to extend the Interface YANG
          module with tunnel-specific parameters.

         Copyright (c) 2019 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
         (http://trustee.ietf.org/license-info).

         This version of this YANG module is part of RFC 8675; see
         the RFC itself for full legal notices.";

     revision 2019-10-21 {
       description
         "Initial revision.";
       reference
         "RFC 8675:  Tunnel Interface Types YANG Module";
     }

     augment "/if:interfaces/if:interface" {
       when "derived-from(if:type, 'iana-tunnel-type:gre')";
       description
         "Augments Interface module with specific tunnel parameters.";

       leaf remote-endpoint {
         type inet:ipv6-address;
         description
           "IPv6 address of the remote GRE endpoint.";
       }
     }
   }

Acknowledgements

   Special thanks to Tom Petch and Martin Bjorklund for the detailed
   review and suggestions.

   Thanks to Andy Bierman for the Yangdoctors review.

   Thanks to Dale Worley, David Black, and Yaron Sheffer for the review.

Authors' Addresses

   Mohamed Boucadair
   Orange
   35000 Rennes
   France

   Email: mohamed.boucadair@orange.com

   Ian Farrer
   Deutsche Telekom AG
   CTO-ATI, Landgrabenweg 151
   53227 Bonn
   Germany

   Email: ian.farrer@telekom.de

   Rajiv Asati
   Cisco Systems, Inc.
   7025 Kit Creek Rd.
   RTP, NC 27709
   United States of America

   Email: Rajiva@cisco.com