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DHC Working Group                                                 Y. Cui
Internet-Draft                                                    L. Sun
Intended status: Standards Track                     Tsinghua University
Expires: 7 June 2021                                         I.F. Farrer
                                                            S.Z. Zechlin
                                                     Deutsche Telekom AG
                                                                   Z. He
                                                     Tsinghua University
                                                         M.N. Nowikowski
                                             Internet Systems Consortium
                                                         4 December 2020


                YANG Data Model for DHCPv6 Configuration
                     draft-ietf-dhc-dhcpv6-yang-12

Abstract

   This document describes YANG data modules for the configuration and
   management of DHCPv6 servers, relays, and clients.

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

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

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 7 June 2021.






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Copyright Notice

   Copyright (c) 2020 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  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Scope . . . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.2.  Extensibility of the DHCPv6 Server YANG Module  . . . . .   3
       1.2.1.  DHCPv6 Option Definitions . . . . . . . . . . . . . .   4
     1.3.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   4
   2.  DHCPv6 Tree Diagrams  . . . . . . . . . . . . . . . . . . . .   5
     2.1.  DHCPv6 Server Tree Diagram  . . . . . . . . . . . . . . .   5
     2.2.  DHCPv6 Relay Tree Diagram . . . . . . . . . . . . . . . .  12
     2.3.  DHCPv6 Client Tree Diagram  . . . . . . . . . . . . . . .  14
   3.  DHCPv6 YANG Modules . . . . . . . . . . . . . . . . . . . . .  17
     3.1.  DHCPv6 Server YANG Module . . . . . . . . . . . . . . . .  17
     3.2.  DHCPv6 Relay YANG Module  . . . . . . . . . . . . . . . .  31
     3.3.  DHCPv6 Client YANG Module . . . . . . . . . . . . . . . .  40
     3.4.  RFC8415 Server Options YANG Module  . . . . . . . . . . .  49
     3.5.  RFC8415 Relay Options YANG Module . . . . . . . . . . . .  56
     3.6.  RFC8415 Client Options YANG Module  . . . . . . . . . . .  62
     3.7.  DHCPv6 Common YANG Module . . . . . . . . . . . . . . . .  67
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .  71
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  72
   6.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  73
   7.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .  74
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  74
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  74
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  76
   Appendix A.  Example of Augmenting Additional DHCPv6 Option
           Definitions . . . . . . . . . . . . . . . . . . . . . . .  76
   Appendix B.  Example Vendor Specific Server Configuration
           Module  . . . . . . . . . . . . . . . . . . . . . . . . .  79
   Appendix C.  Example definition of class selector
           configuration . . . . . . . . . . . . . . . . . . . . . .  85
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  91




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1.  Introduction

   DHCPv6 [RFC8415] is widely used for supplying configuration and other
   relevant parameters to clients in IPv6 networks.  This document
   defines YANG modules for the configuration and management of DHCPv6
   servers, relays and clients.  Separate 'element' modules are defined
   for each of these.  There is an additional module per-element
   defining DHCP options which are relevant for that element (taken from
   the options defined in [RFC8415].

   Additionally, a 'common' module contains typedefs and groupings used
   by all of the element modules.

   It is worth noting that as DHCPv6 is itself a client configuration
   protocol, it is not the intention of this document to provide a
   replacement for the allocation of DHCPv6 assigned addressing and
   parameters by using NETCONF/YANG.  The DHCPv6 client module is
   intended for the configuration and monitoring of the DHCPv6 client
   function and does not play a part in the normal DHCPv6 message flow.

1.1.  Scope

   [RFC8415] describes the current version of the DHCPv6 base protocol
   specification.  A large number of additional specifications have also
   been published, extending DHCPv6 element functionality and adding new
   options.  The YANG modules contained in this document do not attempt
   to capture all of these extensions and additions, rather to model the
   DHCPv6 functions and options covered in [RFC8415].  A focus has also
   been given on the extensibility of the modules so that it is easy to
   augment in additional functionality as required by a particular
   implementation or deployment scenario.

1.2.  Extensibility of the DHCPv6 Server YANG Module

   The modules in this document only attempt to model DHCPv6 specific
   behavior and do not cover the configuration and management of
   functionality relevant for specific server implementations.  The
   level of variance between implementations is too great to attempt to
   standardize in a way that is useful without being restrictive.

   However, it is recognized that implementation specific configuration
   and management is also an essential part of DHCP deployment and
   operations.  To resolve this, Appendix B contains an example YANG
   module for the configuration of implementation specific functions,
   illustrating how this functionality can be augmented into the main
   'ietf-dhcpv6-server.yang' module.





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   In DHCPv6 the concept of 'class selection' for messages received by
   the server is common.  This is the identification and classification
   of messages based on a number of parameters so that the correct
   provisioning information can be supplied.  For example, allocating a
   prefix from the correct pool, or supplying a set of options relevant
   for a specific vendor's client implementation.  During the
   development of this document, research has been carried out into a
   number of vendor's class selection implementations and the findings
   were that while this function is common to all, the method for
   configuring and implementing this function differs greatly.
   Therefore, configuration of the class selection function has been
   omitted from the DHCPv6 server module to allow implementors to define
   their own suitable YANG module.  Appendix C provides an example of
   this, to demonstrate how this is can be integrated with the main
   'ietf-dhcpv6-server.yang' module.

1.2.1.  DHCPv6 Option Definitions

   A large number of DHCPv6 options have been created in addition to
   those defined in [RFC8415].  As implementations differ widely in
   which DHCPv6 options that they support, the following approach has
   been taken to defining options: Only the DHCPv6 options defined in
   [RFC8415] are included in this document.

   Of these, only the options that require operator configuration are
   modelled.  E.g.  OPTION_IA_NA (3) is created by the DHCP server when
   requested by the client.  The contents of the fields in the option
   are based on a number of input configuration parameters which the
   server will apply when it receives the request (e.g., the T1/T2
   timers that are relevant for the pool of addresses).  As a result,
   there are no fields that are directly configurable in the option, so
   it is not modelled.

   Further options definitions can be added by additional YANG modules
   via augmentation into the relevant element modules from this
   document.  Appendix A contains an example module showing how the
   DHCPv6 option definitions can be extended in this manner.  Some
   guidance on how to write YANG modules for additional DHCPv6 options
   is also provided.

1.3.  Terminology

   The reader should be familiar with the YANG data modelling language
   defined in [RFC7950].

   The YANG modules in this document adopt the Network Management
   Datastore Architecture (NMDA) [RFC8342].  The meanings of the symbols
   used in tree diagrams are defined in [RFC8340].



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   The reader should be familiar with DHCPv6 relevant terminology as
   defined in [RFC8415] and other relevant documents.

2.  DHCPv6 Tree Diagrams

2.1.  DHCPv6 Server Tree Diagram

   The tree diagram in Figure 1 provides an overview of the DHCPv6
   server module.  The tree also includes the augmentations of the
   relevant option definitions from Section 3.4 and the common functions
   module Section 3.7.

    module: ietf-dhcpv6-server
      +--rw dhcpv6-node-type?   identityref
      +--rw dhcpv6-server
         +--rw server-duid
         |  +--rw type-code?                           uint16
         |  +--rw (duid-type)?
         |  |  +--:(duid-llt)
         |  |  |  +--rw duid-llt-hardware-type?        uint16
         |  |  |  +--rw duid-llt-time?                 yang:timeticks
         |  |  |  +--rw duid-llt-link-layer-address?
         |  |  |          yang:mac-address
         |  |  +--:(duid-en)
         |  |  |  +--rw duid-en-enterprise-number?     uint32
         |  |  |  +--rw duid-en-identifier?            string
         |  |  +--:(duid-ll)
         |  |  |  +--rw duid-ll-hardware-type?         uint16
         |  |  |  +--rw duid-ll-link-layer-address?
         |  |  |          yang:mac-address
         |  |  +--:(duid-uuid)
         |  |  |  +--rw uuid?                          yang:uuid
         |  |  +--:(duid-unstructured)
         |  |     +--rw data?                          binary
         |  +--ro active-duid?                         binary
         +--rw vendor-config
         +--rw option-sets
         |  +--rw option-set* [option-set-id]
         |     +--rw option-set-id
         |     |       uint32
         |     +--rw description?
         |     |       string
         |     +--rw rfc8415-srv:preference-option
         |     |  +--rw rfc8415-srv:pref-value?   uint8
         |     +--rw rfc8415-srv:auth-option
         |     |  +--rw rfc8415-srv:protocol?           uint8
         |     |  +--rw rfc8415-srv:algorithm?          uint8
         |     |  +--rw rfc8415-srv:rdm?                uint8



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         |     |  +--rw rfc8415-srv:replay-detection?   uint64
         |     |  +--rw rfc8415-srv:auth-information?   string
         |     +--rw rfc8415-srv:server-unicast-option
         |     |  +--rw rfc8415-srv:server-address?
         |     |          inet:ipv6-address
         |     +--rw rfc8415-srv:status-code-option
         |     |  +--rw rfc8415-srv:status-code?      uint16
         |     |  +--rw rfc8415-srv:status-message?   string
         |     +--rw rfc8415-srv:rapid-commit-option!
         |     +--rw rfc8415-srv:vendor-specific-information-option
         |     |  +--rw rfc8415-srv:vendor-specific-information-option-
    instances*
         |     |          [enterprise-number]
         |     |     +--rw rfc8415-srv:enterprise-number     uint32
         |     |     +--rw rfc8415-srv:vendor-option-data*
         |     |             [sub-option-code]
         |     |        +--rw rfc8415-srv:sub-option-code    uint16
         |     |        +--rw rfc8415-srv:sub-option-data?   string
         |     +--rw rfc8415-srv:reconfigure-message-option
         |     |  +--rw rfc8415-srv:msg-type?   uint8
         |     +--rw rfc8415-srv:reconfigure-accept-option!
         |     +--rw rfc8415-srv:info-refresh-time-option
         |     |  +--rw rfc8415-srv:info-refresh-time?
         |     |          dhcpv6-common:timer-seconds32
         |     +--rw rfc8415-srv:sol-max-rt-option
         |     |  +--rw rfc8415-srv:sol-max-rt-value?
         |     |          dhcpv6-common:timer-seconds32
         |     +--rw rfc8415-srv:inf-max-rt-option
         |        +--rw rfc8415-srv:inf-max-rt-value?
         |                dhcpv6-common:timer-seconds32
         +--rw class-selector
         +--rw network-ranges
            +--rw option-set-id*               leafref
            +--rw valid-lifetime?
            |       dhcpv6-common:timer-seconds32
            +--rw renew-time?
            |       dhcpv6-common:timer-seconds32
            +--rw rebind-time?
            |       dhcpv6-common:timer-seconds32
            +--rw preferred-lifetime?
            |       dhcpv6-common:timer-seconds32
            +--rw rapid-commit?                boolean
            +--rw network-range* [network-range-id]
            |  +--rw id                    uint32
            |  +--rw description           string
            |  +--rw network-prefix        inet:ipv6-prefix
            |  +--rw option-set-id*        leafref
            |  +--rw valid-lifetime?



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            |  |       dhcpv6-common:timer-seconds32
            |  +--rw renew-time?
            |  |       dhcpv6-common:timer-seconds32
            |  +--rw rebind-time?
            |  |       dhcpv6-common:timer-seconds32
            |  +--rw preferred-lifetime?
            |  |       dhcpv6-common:timer-seconds32
            |  +--rw rapid-commit?         boolean
            |  +--rw address-pools
            |  |  +--rw address-pool* [pool-id]
            |  |     +--rw pool-id               uint32
            |  |     +--rw pool-prefix           inet:ipv6-prefix
            |  |     +--rw start-address
            |  |     |       inet:ipv6-address-no-zone
            |  |     +--rw end-address
            |  |     |       inet:ipv6-address-no-zone
            |  |     +--rw max-address-count
            |  |     |       dhcpv6-common:threshold
            |  |     +--rw option-set-id*        leafref
            |  |     +--rw valid-lifetime?
            |  |     |       dhcpv6-common:timer-seconds32
            |  |     +--rw renew-time?
            |  |     |       dhcpv6-common:timer-seconds32
            |  |     +--rw rebind-time?
            |  |     |       dhcpv6-common:timer-seconds32
            |  |     +--rw preferred-lifetime?
            |  |     |       dhcpv6-common:timer-seconds32
            |  |     +--rw rapid-commit?         boolean
            |  |     +--rw host-reservations
            |  |     |  +--rw host-reservation* [reserved-addr]
            |  |     |     +--rw client-duid?          binary
            |  |     |     +--rw reserved-addr
            |  |     |     |       inet:ipv6-address
            |  |     |     +--rw option-set-id*        leafref
            |  |     |     +--rw valid-lifetime?
            |  |     |     |       dhcpv6-common:timer-seconds32
            |  |     |     +--rw renew-time?
            |  |     |     |       dhcpv6-common:timer-seconds32
            |  |     |     +--rw rebind-time?
            |  |     |     |       dhcpv6-common:timer-seconds32
            |  |     |     +--rw preferred-lifetime?
            |  |     |     |       dhcpv6-common:timer-seconds32
            |  |     |     +--rw rapid-commit?         boolean
            |  |     +--ro active-leases
            |  |        +--ro total-count        uint64
            |  |        +--ro allocated-count    uint64
            |  |        +--ro active-lease* [leased-address]
            |  |           +--ro leased-address



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            |  |           |       inet:ipv6-address
            |  |           +--ro client-duid?          binary
            |  |           +--ro iaid                  uint32
            |  |           +--ro allocation-time?
            |  |           |       yang:date-and-time
            |  |           +--ro last-renew-rebind?
            |  |           |       yang:date-and-time
            |  |           +--ro preferred-lifetime?
            |  |           |       dhcpv6-common:timer-seconds32
            |  |           +--ro valid-lifetime?
            |  |           |       dhcpv6-common:timer-seconds32
            |  |           +--ro lease-t1?
            |  |           |       dhcpv6-common:timer-seconds32
            |  |           +--ro lease-t2?
            |  |                   dhcpv6-common:timer-seconds32
            |  +--rw prefix-pools {prefix-delegation}?
            |     +--rw prefix-pool* [pool-id]
            |        +--rw pool-id                     uint32
            |        +--rw pool-prefix
            |        |       inet:ipv6-prefix
            |        +--rw client-prefix-length        uint8
            |        +--rw max-pd-space-utilization
            |        |       dhcpv6-common:threshold
            |        +--rw option-set-id*              leafref
            |        +--rw valid-lifetime?
            |        |       dhcpv6-common:timer-seconds32
            |        +--rw renew-time?
            |        |       dhcpv6-common:timer-seconds32
            |        +--rw rebind-time?
            |        |       dhcpv6-common:timer-seconds32
            |        +--rw preferred-lifetime?
            |        |       dhcpv6-common:timer-seconds32
            |        +--rw rapid-commit?               boolean
            |        +--rw host-reservations
            |        |  +--rw prefix-reservation* [reserved-prefix]
            |        |  |  +--rw client-duid?           binary
            |        |  |  +--rw reserved-prefix
            |        |  |  |       inet:ipv6-prefix
            |        |  |  +--rw reserved-prefix-len?   uint8
            |        |  +--rw option-set-id*        leafref
            |        |  +--rw valid-lifetime?
            |        |  |       dhcpv6-common:timer-seconds32
            |        |  +--rw renew-time?
            |        |  |       dhcpv6-common:timer-seconds32
            |        |  +--rw rebind-time?
            |        |  |       dhcpv6-common:timer-seconds32
            |        |  +--rw preferred-lifetime?
            |        |  |       dhcpv6-common:timer-seconds32



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            |        |  +--rw rapid-commit?         boolean
            |        +--ro active-leases
            |           +--ro total-count        uint64
            |           +--ro allocated-count    uint64
            |           +--ro active-lease* [leased-prefix]
            |              +--ro leased-prefix
            |              |       inet:ipv6-prefix
            |              +--ro client-duid?          binary
            |              +--ro iaid                  uint32
            |              +--ro allocation-time?
            |              |       yang:date-and-time
            |              +--ro last-renew-rebind?
            |              |       yang:date-and-time
            |              +--ro preferred-lifetime?
            |              |       dhcpv6-common:timer-seconds32
            |              +--ro valid-lifetime?
            |              |       dhcpv6-common:timer-seconds32
            |              +--ro lease-t1?
            |              |       dhcpv6-common:timer-seconds32
            |              +--ro lease-t2?
            |                      dhcpv6-common:timer-seconds32
            +--ro solicit-count?               uint32
            +--ro advertise-count?             uint32
            +--ro request-count?               uint32
            +--ro confirm-count?               uint32
            +--ro renew-count?                 uint32
            +--ro rebind-count?                uint32
            +--ro reply-count?                 uint32
            +--ro release-count?               uint32
            +--ro decline-count?               uint32
            +--ro reconfigure-count?           uint32
            +--ro information-request-count?   uint32

      rpcs:
        +---x delete-address-lease
        |  +---w input
        |  |  +---w lease-address-to-delete    inet:ipv6-address
        |  +--ro output
        |     +--ro return-message?   string
        +---x delete-prefix-lease
           +---w input
           |  +---w lease-prefix-to-delete    inet:ipv6-prefix
           +--ro output
              +--ro return-message?   string

      notifications:
        +---n address-pool-utilization-threshold-exceeded
        |  +--ro pool-id?                   leafref



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        |  +--ro total-address-count        uint64
        |  +--ro max-address-count          uint64
        |  +--ro allocated-address-count    uint64
        +---n prefix-pool-utilization-threshold-exceeded
        |       {prefix-delegation}?
        |  +--ro pool-id                     leafref
        |  +--ro max-pd-space-utilization    leafref
        |  +--ro pd-space-utilization?       uint64
        +---n invalid-client-detected
        |  +--ro duid?          binary
        |  +--ro description?   string
        +---n decline-received
        |  +--ro duid?                 binary
        |  +--ro declined-resources* []
        |     +--ro (resource-type)?
        |        +--:(declined-address)
        |        |  +--ro address?   inet:ipv6-address
        |        +--:(declined-prefix)
        |           +--ro prefix?    inet:ipv6-prefix
        +---n non-success-code-sent
           +--ro status-code    uint16
           +--ro duid?          binary

               Figure 1: DHCPv6 Server Data Module Structure

   Descriptions of important nodes:

   *  dhcpv6-node-type: The different functional DHCPv6 elements each
      have their relevant identities.

   *  dhcpv6-server: This container holds the server's DHCPv6 specific
      configuration.

   *  server-duid: Each server must have a DUID (DHCP Unique Identifier)
      to identify itself to clients.  A DUID consists of a two-octet
      type field and an arbitrary length (of no more than 128-bytes)
      content field.  Currently there are four defined types of DUIDs in
      [RFC8415] and [RFC6355]: DUID-LLT, DUID-EN, DUID-LL, and DUID-
      UUID.  DUID-Unknown is used for arbitrary DUID formats which do
      not follow any of these defined types.  'active-duid' is a read-
      only field that the server's current DUID can be retrieved from.
      The DUID definitions are imported from the 'ietf-
      dhcpv6-common.yang' module.

   *  vendor-config: This container is provided as a location for
      additional implementation specific YANG nodes for the
      configuration of the device to be augmented.  See Appendix B for
      an example of such a module.



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   *  option-sets: The server can be configured with multiple option-
      sets.  These are groups of DHCPv6 options with common parameters
      which will be supplied to clients on request.  The 'option-set-id'
      field is used to reference an option-set elsewhere in the server's
      configuration.

   *  option-set: Holds configuration parameters for DHCPv6 options.
      The initial set of definitions are contained in the module 'ietf-
      dhcpv6-options-rfc8415-server.yang' and are augmented into the
      server module at this point.  Other DHCPv6 option modules can be
      augmented here as required.

   *  class-selector: This is provided as a location for additional
      implementation specific YANG nodes for vendor specific class
      selector nodes to be augmented.  See Appendix C for an example of
      this.

   *  network-ranges: This module uses a hierarchical model for the
      allocation of addresses and prefixes.  At the top level 'network-
      ranges' holds global configuration parameters.  Under this, a list
      of 'network-ranges' can be defined.  Inside 'network-rages',
      'address-pools' (for IA_NA and IA_TA allocations), and 'prefix-
      pools' (for IA_PD allocation) are defined.  Finally within the
      pools, specific host-reservations are held.

   *  prefix-pools: Defines pools to be used for prefix delegation to
      clients.  As prefix delegation is not supported by all DHCPv6
      server implementations, it is enabled by a feature statement.

   Information about notifications:

   *  address/prefix-pool-utilization-threshold-exceeded: Raised when
      number of leased addresses or prefixes exceeds the configured
      usage threshold.

   *  invalid-client-detected: Raised when the server detects an invalid
      client.  A description of the error that has generated the
      notification can be included.

   *  decline-received: Raised when a DHCPv6 Decline message is received
      from a client.

   *  non-success-code-sent: Raised when a status message is raised for
      an error.

   Information about RPCs





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   *  delete-address-lease: Allows the deletion of a lease for an
      individual IPv6 address from the server's lease database.

   *  delete-prefix-lease: Allows the deletion of a lease for an
      individual IPv6 prefix from the server's lease database.

2.2.  DHCPv6 Relay Tree Diagram

   The tree diagram in Figure 2 provides an overview of the DHCPv6 relay
   module.  The tree also includes the augmentations of the relevant
   option definitions from Section 3.5 and the common functions module
   Section 3.7.

       module: ietf-dhcpv6-relay
         +--rw dhcpv6-node-type?   identityref
         +--rw dhcpv6-relay
            +--rw relay-if* [if-name]
            |  +--rw if-name
            |  |       if:interface-ref
            |  +--rw destination-addresses*
            |  |       inet:ipv6-address
            |  +--rw link-address?                         binary
            |  +--rw relay-options
            |  +--ro solicit-received-count?               uint32
            |  +--ro advertise-sent-count?                 uint32
            |  +--ro request-received-count?               uint32
            |  +--ro confirm-received-count?               uint32
            |  +--ro renew-received-count?                 uint32
            |  +--ro rebind-received-count?                uint32
            |  +--ro reply-sent-count?                     uint32
            |  +--ro release-received-count?               uint32
            |  +--ro decline-received-count?               uint32
            |  +--ro reconfigure-sent-count?               uint32
            |  +--ro information-request-received-count?   uint32
            |  +--ro unknown-message-received-count?       uint32
            |  +--ro unknown-message-sent-count?           uint32
            |  +--ro discarded-message-count?              uint32
            |  +--rw prefix-delegation! {prefix-delegation}?
            |     +--ro pd-leases* [ia-pd-prefix]
            |        +--ro ia-pd-prefix           inet:ipv6-prefix
            |        +--ro last-renew?            yang:date-and-time
            |        +--ro client-peer-address?   inet:ipv6-address
            |        +--ro client-duid?           binary
            |        +--ro server-duid?           binary
            +--ro relay-forward-sent-count?               uint32
            +--ro relay-forward-received-count?           uint32
            +--ro relay-reply-received-count?             uint32
            +--ro relay-forward-unknown-sent-count?       uint32



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            +--ro relay-forward-unknown-received-count?   uint32
            +--ro discarded-message-count?                uint32

         rpcs:
           +---x clear-prefix-entry
           |  +---w input
           |  |  +---w lease-prefix    inet:ipv6-prefix
           |  +--ro output
           |     +--ro return-message?   string
           +---x clear-client-prefixes
           |  +---w input
           |  |  +---w client-duid    binary
           |  +--ro output
           |     +--ro return-message?   string
           +---x clear-interface-prefixes
              +---w input
              |  +---w interface    if:interface-ref
              +--ro output
                 +--ro return-message?   string

         notifications:
           +---n relay-event
              +--ro topology-change
                 +--ro relay-if-name?
                 |       -> /dhcpv6-relay/relay-if/if-name
                 +--ro last-ipv6-addr?   inet:ipv6-address

                Figure 2: DHCPv6 Relay Data Module Structure

   Descriptions of important nodes:

   *  dhcpv6-node-type: The different functional DHCPv6 elements each
      have their relevant identities.

   *  dhcpv6-relay: This container holds the relay's DHCPv6 specific
      configuration.

   *  relay-if: As a relay may have multiple client-facing interfaces,
      they are configured in a list.  The if-name leaf is the key and is
      an interface-ref to the applicable interface defined by the 'ietf-
      interfaces' YANG module.

   *  destination-addresses: Defines a list of IPv6 addresses that
      client messages will be relayed to.  May include unicast or
      multicast addresses.

   *  link-address: Configures the value that the relay will put into
      the link-address field of Relay-Forward messages.



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   *  prefix-delegation: As prefix delegation is not supported by all
      DHCPv6 relay implementations, it is enabled by this feature
      statement where required.

   *  pd-leases: Contains read-only nodes for holding information about
      active delegated prefix leases.

   *  relay-options: As with the Server module, DHCPv6 options that can
      be sent by the relay are augmented here.

   Information about notifications:

   *  topology-changed: Raised when the topology of the relay agent is
      changed, e.g. a client facing interface is reconfigured.

   Information about RPCs

   *  clear-prefix-lease: Allows the removal of a delegated lease entry
      from the relay.

   *  clear-client-prefixes: Allows the removal of all of the delegated
      lease entries for a single client (referenced by client DUID) from
      the relay.

   *  clear-interface-prefixes: Allows the removal of all of the
      delegated lease entries from an interface on the relay.

2.3.  DHCPv6 Client Tree Diagram

   The tree diagram in Figure 3 provides an overview of the DHCPv6
   client module.  The tree also includes the augmentations of the
   relevant option definitions from Section 3.6 and the common functions
   module Section 3.7.

     module: ietf-dhcpv6-client
       +--rw dhcpv6-node-type?   identityref
       +--rw dhcpv6-client
          +--rw client-if* [if-name]
             +--rw if-name
             |       if:interface-ref
             +--rw type-code?                           uint16
             +--rw (duid-type)?
             |  +--:(duid-llt)
             |  |  +--rw duid-llt-hardware-type?        uint16
             |  |  +--rw duid-llt-time?                 yang:timeticks
             |  |  +--rw duid-llt-link-layer-address?
             |  |          yang:mac-address
             |  +--:(duid-en)



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             |  |  +--rw duid-en-enterprise-number?     uint32
             |  |  +--rw duid-en-identifier?            string
             |  +--:(duid-ll)
             |  |  +--rw duid-ll-hardware-type?         uint16
             |  |  +--rw duid-ll-link-layer-address?
             |  |          yang:mac-address
             |  +--:(duid-uuid)
             |  |  +--rw uuid?                          yang:uuid
             |  +--:(duid-unstructured)
             |     +--rw data?                          binary
             +--ro active-duid?                         binary
             +--rw client-configured-options
             +--rw ia-na* [iaid]
             |  +--rw iaid             uint32
             |  +--rw ia-na-options
             |  +--ro lease-state
             |     +--ro ia-na-address?        inet:ipv6-address
             |     +--ro preferred-lifetime?
             |     |       dhcpv6-common:timer-seconds32
             |     +--ro valid-lifetime?
             |     |       dhcpv6-common:timer-seconds32
             |     +--ro lease-t1?
             |     |       dhcpv6-common:timer-seconds32
             |     +--ro lease-t2?
             |     |       dhcpv6-common:timer-seconds32
             |     +--ro allocation-time?      yang:date-and-time
             |     +--ro last-renew-rebind?    yang:date-and-time
             |     +--ro server-duid?          binary
             +--rw ia-ta* [iaid]
             |  +--rw iaid             uint32
             |  +--rw ia-ta-options
             |  +--ro lease-state
             |     +--ro ia-ta-address?        inet:ipv6-address
             |     +--ro preferred-lifetime?
             |     |       dhcpv6-common:timer-seconds32
             |     +--ro valid-lifetime?
             |     |       dhcpv6-common:timer-seconds32
             |     +--ro allocation-time?      yang:date-and-time
             |     +--ro last-renew-rebind?    yang:date-and-time
             |     +--ro server-duid?          binary
             +--rw ia-pd* [iaid]
             |  +--rw iaid             uint32
             |  +--rw ia-pd-options
             |  +--ro lease-state
             |     +--ro ia-pd-prefix?         inet:ipv6-prefix
             |     +--ro preferred-lifetime?
             |     |       dhcpv6-common:timer-seconds32
             |     +--ro valid-lifetime?



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             |     |       dhcpv6-common:timer-seconds32
             |     +--ro lease-t1?
             |     |       dhcpv6-common:timer-seconds32
             |     +--ro lease-t2?
             |     |       dhcpv6-common:timer-seconds32
             |     +--ro allocation-time?      yang:date-and-time
             |     +--ro last-renew-rebind?    yang:date-and-time
             |     +--ro server-duid?          binary
             +--ro solicit-count?                       uint32
             +--ro advertise-count?                     uint32
             +--ro request-count?                       uint32
             +--ro confirm-count?                       uint32
             +--ro renew-count?                         uint32
             +--ro rebind-count?                        uint32
             +--ro reply-count?                         uint32
             +--ro release-count?                       uint32
             +--ro decline-count?                       uint32
             +--ro reconfigure-count?                   uint32
             +--ro information-request-count?           uint32

       notifications:
         +---n invalid-ia-detected
         |  +--ro iaid           uint32
         |  +--ro description?   string
         +---n retransmission-failed
         |  +--ro failure-type    enumeration
         +---n unsuccessful-status-code
         |  +--ro status-code    uint16
         |  +--ro server-duid    binary
         +---n server-duid-changed
            +--ro new-server-duid         binary
            +--ro previous-server-duid    binary
            +--ro lease-ia-na?
            |       -> /dhcpv6-client/client-if/ia-na/iaid
            +--ro lease-ia-ta?
            |       -> /dhcpv6-client/client-if/ia-ta/iaid
            +--ro lease-ia-pd?
                    -> /dhcpv6-client/client-if/ia-pd/iaid

               Figure 3: DHCPv6 Client Data Module Structure

   Descriptions of important nodes:

   *  dhcpv6-node-type: The different functional DHCPv6 elements each
      have their relevant identities.

   *  dhcpv6-client: This container holds the client's DHCPv6 specific
      configuration.



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   *  client-if: As a client may have multiple interfaces requesting
      configuration over DHCP, they are configured in a list.  The if-
      name leaf is the key and is an interface-ref to the applicable
      interface defined by the 'ietf-interfaces' YANG module.

   *  client-duid: Each DHCP client must have a DUID (DHCP Unique
      Identifier) to identify itself to clients.  A DUID consists of a
      two-octet type field and an arbitrary length (of no more than
      128-bytes) content field.  Currently there are four defined types
      of DUIDs in [RFC8415]: DUID-LLT, DUID-EN, DUID-LL, and DUID-UUID.
      DUID-Unknown is used for arbitrary DUID formats which do not
      follow any of these defined types. 'active-duid' is a read-only
      field that the client's current DUID can be retrieved from.  The
      DUID definitions are imported from the 'ietf-dhcpv6-common.yang'
      module.  DUID is configured under the 'client-if' to allow a
      client to have different DUIDs for each interface if required.

   *  ia-na, ia-ta, ia-pd: Contains configuration nodes relevant for
      requesting one or more of each of the lease types.  Also contains
      read only nodes related to active leases.

   Information about notifications:

   *  invalid-ia-detected: Raised when the identity association of the
      client can be proved to be invalid.  Possible conditions include:
      duplicated address, illegal address, etc.

   *  retransmission-failed: Raised when the retransmission mechanism
      defined in [RFC8415] has failed.

3.  DHCPv6 YANG Modules

3.1.  DHCPv6 Server YANG Module

   This module imports typedefs from [RFC6991], [RFC8343].

   <CODE BEGINS> file ietf-dhcpv6-server.yang

   module ietf-dhcpv6-server {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-dhcpv6-server";
     prefix "dhcpv6-server";

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



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     import ietf-yang-types {
       prefix yang;
       reference
         "RFC 6991: Common YANG Data Types";
     }

     import ietf-dhcpv6-common {
       prefix dhcpv6-common;
       reference
         "To be updated on publication";
     }

     import ietf-netconf-acm {
       prefix nacm;
       reference
         "RFC 8341: Network Configuration Access Control Model";
     }

     organization "DHC WG";
     contact
       "cuiyong@tsinghua.edu.cn
       lh.sunlinh@gmail.com
       ian.farrer@telekom.de
       sladjana.zechlin@telekom.de
       hezihao9512@gmail.com
       godfryd@isc.org";

     description "This YANG module defines components for the
       configuration and management of DHCPv6 servers.

       Copyright (c) 2018 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 8513; see
       the RFC itself for full legal notices.";

     revision 2020-12-01 {
       description "Version update for draft -12 publication.";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang-12";
     }




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     revision 2020-05-26 {
       description "Version update for draft -11 publication and
         to align revisions across the different modules.";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang-11";
     }

     revision 2019-12-02 {
       description "Major reworking of the module.";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang-10";
     }

     revision 2018-09-04 {
       description "";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang";
     }

     revision 2018-03-04 {
       description "Resolved most issues on the DHC official
         github";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang";
     }

     revision 2017-12-22 {
       description "Resolve most issues on Ian's github.";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang";
     }

     revision 2017-11-24 {
       description "First version of the separated server specific
         YANG model.";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang";
     }

     /*
      * Identities
      */

     identity server {
       description "DHCPv6 server identity.";
       base "dhcpv6-common:dhcpv6-node";
     }

     leaf dhcpv6-node-type {
       description "Type for a DHCPv6 server.";
       type identityref {
         base "dhcpv6-common:dhcpv6-node";
       }
     }



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     /*
      * Features
      */

     feature prefix-delegation {
       description "Denotes that the server implements DHCPv6 prefix
         delegation.";
     }

     /*
      * Groupings
      */

     grouping resource-config {
       description "Nodes that are reused at multiple levels in the
         DHCPv6 server's addressing hierarchy.";
       leaf-list option-set-id {
         type leafref {
           path "/dhcpv6-server/option-sets/option-set/option-set-id";
         }
         description "The ID field of relevant set of DHCPv6 options
           (option-set) to be provisioned to clients of this
           network-range.";
       }
       leaf valid-lifetime {
         type dhcpv6-common:timer-seconds32;
         description "Valid lifetime for the Identity Association
           (IA).";
       }
       leaf renew-time {
         type dhcpv6-common:timer-seconds32;
         description "Renew (T1) time.";
       }
       leaf rebind-time {
         type dhcpv6-common:timer-seconds32;
         description "Rebind (T2) time.";
       }
       leaf preferred-lifetime {
         type dhcpv6-common:timer-seconds32;
         description "Preferred lifetime for the Identity Association
           (IA).";
       }
       leaf rapid-commit {
         type boolean;
         description "A value of 1 specifies that the pool supports
           client-server exchanges involving two messages.";
       }
     }



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     grouping lease-information {
       description "Binding information for each client that has
         been allocated an IPv6 address or prefix.";
       leaf client-duid {
         description "Client DUID.";
         type binary;
       }
       leaf iaid {
         type uint32;
         mandatory true;
         description "Client's IAID";
       }
       leaf allocation-time {
         description "Time and date that the lease was made.";
         type yang:date-and-time;
       }
       leaf last-renew-rebind {
         description "Time of the last successful renew or
           rebind.";
         type yang:date-and-time;
       }
       leaf preferred-lifetime {
         description "The preferred lifetime expressed in
           seconds.";
         type dhcpv6-common:timer-seconds32;
       }
       leaf valid-lifetime {
         description "The valid lifetime for the leased prefix
           expressed in seconds.";
         type dhcpv6-common:timer-seconds32;
       }
       leaf lease-t1 {
         description "The time interval after which the client
           should contact the server from which the addresses
           in the IA_NA were obtained to extend the lifetimes
           of the addresses assigned to the IA_PD.";
         type dhcpv6-common:timer-seconds32;
       }
       leaf lease-t2 {
         description "The time interval after which the client
           should contact any available server to extend
           the lifetimes of the addresses assigned to the
           IA_PD.";
         type dhcpv6-common:timer-seconds32;
       }
     }

     grouping message-stats {



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       description "Counters for DHCPv6 messages.";
       leaf solicit-count {
         config "false";
         type uint32;
         description "Number of Solicit (1) messages received.";
       }
       leaf advertise-count {
         config "false";
         type uint32;
         description "Number of Advertise (2) messages sent.";
       }
       leaf request-count {
         config "false";
         type uint32;
         description "Number of Request (3) messages received.";
       }
       leaf confirm-count {
         config "false";
         type uint32;
         description "Number of Confirm (4) messages received.";
       }
       leaf renew-count {
         config "false";
         type uint32;
         description "Number of Renew (5) messages received.";
       }
       leaf rebind-count {
         config "false";
         type uint32;
         description "Number of Rebind (6) messages received.";
       }
       leaf reply-count {
         config "false";
         type uint32;
         description "Number of Reply (7) messages sent.";
       }
       leaf release-count {
         config "false";
         type uint32;
         description "Number of Release (8) messages received.";
       }
       leaf decline-count {
         config "false";
         type uint32;
         description "Number of Decline (9) messages received.";
       }
       leaf reconfigure-count {
         config "false";



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         type uint32;
         description "Number of Reconfigure (10) messages sent.";
       }
       leaf information-request-count {
         config "false";
         type uint32;
         description "Number of Information-request (11) messages
           received.";
       }
     }

     /*
      * Data Nodes
      */

     container dhcpv6-server {
       container server-duid {
         description "DUID of the server.";
         uses dhcpv6-common:duid;
       }
       container vendor-config {
         description "This container provides a location for
           augmenting vendor or implementation specific
           configuration nodes.";
       }
       container option-sets {
         description "A server may allow different option sets
           to be configured for clients matching specific parameters
           such as topological location or client type. The
           'option-set' list is a set of options and their
           contents that will be returned to clients.";
         list option-set {
           key option-set-id;
           description "YANG definitions for DHCPv6 options are
             contained in separate YANG modules and augmented to this
             container as required.";
           leaf option-set-id {
             type uint32;
             description "Option set identifier.";
           }
           leaf description {
             type string;
             description "An optional field for storing additional
               information relevant to the option set.";
           }
         }
       }




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       container class-selector {
         description "DHCPv6 servers use a 'class-selector' function
           in order to identify and classify incoming client messages
           so that they can be given the correct configuration.
           The mechanisms used for implementing this function vary
           greatly between different implementations such that they
           are not possible to include in this module. This container
           provides a location for server implementors to augment
           their own class-selector YANG.";
       }

       container network-ranges {
         description "This model is based on an address and parameter
           allocation hierarchy.  The top level is 'global' - which
           is defined as the container for all network-ranges. Under
           this are the individual network-ranges.";
         uses resource-config;
         list network-range {
           key network-range-id;
           description "Network-ranges are identified by the
             'network-range-id' key.";
           leaf id {
             type uint32;
             mandatory true;
             description "Equivalent to subnet ID.";
           }
           leaf description {
             type string;
             mandatory true;
             description "Description for the network range.";
           }
           leaf network-prefix {
             type inet:ipv6-prefix;
             mandatory true;
             description "Network prefix.";
           }
           uses resource-config;
           container address-pools {
             description "Configuration for the DHCPv6 server's
               address pools.";
             list address-pool {
               key pool-id;
               description "List of address pools for allocation to
                 clients, distinguished by 'pool-id'.";
               leaf pool-id {
                 type uint32;
                 mandatory true;
                 description "Unique identifier for the pool.";



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               }
               leaf pool-prefix {
                 type inet:ipv6-prefix;
                 mandatory true;
                 description "IPv6 prefix for the pool.";
               }
               leaf start-address {
                 type inet:ipv6-address-no-zone;
                 mandatory true;
                 description "Start IPv6 address for the pool.";
               }
               leaf end-address {
                 type inet:ipv6-address-no-zone;
                 mandatory true;
                 description "End IPv6 address for the pool.";
               }
               leaf max-address-count {
                 type dhcpv6-common:threshold;
                 mandatory true;
                 description "Maximum number of addresses that can
                   be simultaneously allocated from this pool.";
               }
               uses resource-config;
               container host-reservations {
                 description "Configuration for host reservations from
                   the address pool.";
                 list host-reservation {
                   key reserved-addr;
                   leaf client-duid {
                     type binary;
                     description "Client DUID for the reservation.";
                   }
                   leaf reserved-addr {
                     type inet:ipv6-address;
                     description "Reserved IPv6 address.";
                   }
                   uses resource-config;
                 }
               }
               container active-leases {
                 description "Holds state related to active client
                   leases.";
                 config false;
                 leaf total-count {
                   type uint64;
                   mandatory true;
                   description "The total number of addresses in the
                     pool.";



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                 }
                 leaf allocated-count {
                   type uint64;
                   mandatory true;
                   description "The number of addresses or prefixes
                     in the pool that are currently allocated.";
                 }
                 list active-lease {
                   key leased-address;
                   leaf leased-address {
                     type inet:ipv6-address;
                   }
                   uses lease-information;
                 }
               }
             }
           }
           container prefix-pools {
             description "Configuration for the DHCPv6 server's
               prefix pools.";
             if-feature prefix-delegation;
             list prefix-pool {
               key pool-id;
               description "List of prefix pools for allocation to
                 clients, distinguished by 'pool-id'.";
               leaf pool-id {
                 type uint32;
                 mandatory true;
                 description "Unique identifier for the pool.";
               }
               leaf pool-prefix {
                 type inet:ipv6-prefix;
                 mandatory true;
                 description "IPv6 prefix for the pool.";
               }
               leaf client-prefix-length {
                 type uint8;
                 mandatory true;
                 description "Length of the prefixes that will be
                   delegated to clients.";
               }
               leaf max-pd-space-utilization {
                 type dhcpv6-common:threshold;
                 mandatory true;
                 description "Maximum percentage utilization of the
                   prefix pool in this pool.";
               }
               uses resource-config;



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               container host-reservations {
                 description "Configuration for host reservations
                   from the prefix pool.";
                 list prefix-reservation {
                   description "reserved prefix reservation";
                   key reserved-prefix;
                   leaf client-duid {
                     type binary;
                     description "Client DUID for the reservation.";
                   }
                   leaf reserved-prefix {
                     type inet:ipv6-prefix;
                     description "Reserved IPv6 prefix";
                   }
                   leaf reserved-prefix-len {
                     type uint8;
                     description "Reserved IPv6 prefix length.";
                   }
                 }
                 uses resource-config;
               }
               container active-leases {
                 description "Holds state related to for active client
                   prefix leases.";
                 config false;
                 leaf total-count {
                   type uint64;
                   mandatory true;
                   description "The total number of prefixes in
                     the pool.";
                 }
                 leaf allocated-count {
                   type uint64;
                   mandatory true;
                   description "The number of prefixes in the pool
                     that are currently allocated.";
                 }
                 list active-lease {
                   key leased-prefix;
                   leaf leased-prefix {
                     type inet:ipv6-prefix;
                   }
                   uses lease-information;
                 }
               }
             }
           }
         }



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         uses message-stats;
       }
     }

     /*
      * Notifications
      */

     notification address-pool-utilization-threshold-exceeded {
       description "Notification sent when the address pool
         utilization exceeds the configured threshold.";
       leaf pool-id {
         type leafref {
           path "/dhcpv6-server/network-ranges/network-range/address-poo
   ls/address-pool/pool-id";
         }
       }
       leaf total-address-count {
         type uint64;
         mandatory true;
         description "Count of the total addresses in the pool.";
       }
       leaf max-address-count {
         type uint64;
         mandatory true;
         description "Maximum count of addresses that can be allocated
           in the pool. This value may be less than count of total
           addresses.";
       }
       leaf allocated-address-count {
         type uint64;
         mandatory true;
         description "Count of allocated addresses in the pool.";
       }
     }

     notification prefix-pool-utilization-threshold-exceeded {
       description "Notification sent when the prefix pool
         utilization exceeds the configured threshold.";
       if-feature prefix-delegation;
       leaf pool-id {
         type leafref {
           path "/dhcpv6-server/network-ranges/network-range/prefix-pool
   s/prefix-pool/pool-id";
         }
         mandatory true;
       }
       leaf max-pd-space-utilization {



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         description "PD space utilization threshold.";
         type leafref {
           path "/dhcpv6-server/network-ranges/network-range/prefix-pool
   s/prefix-pool/max-pd-space-utilization";
         }
         mandatory true;
       }
       leaf pd-space-utilization {
         description "Current PD space utilization";
         type uint64;
       }
     }

     notification invalid-client-detected {
       description "Notification sent when the server detects an
         invalid client.";
       leaf duid {
         description "Client DUID.";
         type binary;
       }
       leaf description {
         type string;
         description "Description of the event (e.g. and error code or
           log message).";
       }
     }

     notification decline-received {
       description "Notification sent when the server has received a
         Decline (9) message from a client.";
       leaf duid {
         description "Client DUID.";
         type binary;
       }
       list declined-resources {
         description "List of declined addresses and/or prefixes.";
         choice resource-type {
           case declined-address {
             leaf address {
               type inet:ipv6-address;
             }
           }
           case declined-prefix {
             leaf prefix {
               type inet:ipv6-prefix;
             }
           }
         }



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       }
     }

     notification non-success-code-sent {
       description "Notification sent when the server responded
         to a client with non-success status code.";
       leaf status-code {
         type uint16;
         mandatory true;
         description "Status code returned to the client.";
       }
       leaf duid {
         description "Client DUID.";
         type binary;
       }
     }

     /*
      * RPCs
      */

     rpc delete-address-lease {
       nacm:default-deny-all;
       description "Deletes a client's active address lease from the
         server's lease database. Note, this will not cause the address
         to be revoked from the client, and the lease may be refreshed
         or renewed by the client.";
       input {
         leaf lease-address-to-delete {
           type inet:ipv6-address;
             mandatory true;
           description "IPv6 address of an active lease that will be
             deleted from the server.";
         }
       }
       output {
         leaf return-message {
           type string;
           description "Response message from the server.";
         }
       }
     }
     rpc delete-prefix-lease {
       nacm:default-deny-all;
       description "Deletes a client's active prefix lease from the
         server's lease database. Note, this will not cause the prefix
         to be revoked from the client, and the lease may be refreshed
         or renewed by the client.";



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       input {
         leaf lease-prefix-to-delete {
           type inet:ipv6-prefix;
             mandatory true;
           description "IPv6 prefix of an active lease that will be
             deleted from the server.";
         }
       }
       output {
         leaf return-message {
           type string;
           description "Response message from the server.";
         }
       }
     }
   }


   <CODE ENDS>

3.2.  DHCPv6 Relay YANG Module

   This module imports typedefs from [RFC6991], [RFC8343].

   <CODE BEGINS> file ietf-dhcpv6-relay.yang

   module ietf-dhcpv6-relay {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-dhcpv6-relay";
     prefix "dhcpv6-relay";

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

     import ietf-yang-types {
       prefix yang;
       reference
         "RFC 6991: Common YANG Data Types";
     }

     import ietf-dhcpv6-common {
       prefix dhcpv6-common;
       reference
         "To be updated on publication";
     }



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

     import ietf-netconf-acm {
       prefix nacm;
       reference
         "RFC 8341: Network Configuration Access Control Model";
     }

     organization
       "IETF DHC (Dynamic Host Configuration) Working group";

     contact
       "cuiyong@tsinghua.edu.cn
       lh.sunlinh@gmail.com
       ian.farrer@telekom.de
       sladjana.zechlin@telekom.de
       hezihao9512@gmail.com
       godfryd@isc.org";

     description
       "This YANG module defines components necessary for the
       configuration and management of DHCPv6 relays.

       Copyright (c) 2018 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 8513; see
       the RFC itself for full legal notices.";

     revision 2020-12-01 {
       description "Version update for draft -12 publication.";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang-12";
     }

     revision 2020-05-26 {
       description "Version update for draft -11 publication and
         to align revisions across the different modules.";



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       reference "I-D: draft-ietf-dhc-dhcpv6-yang-11";
     }

     revision 2019-09-20 {
       description "";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang-10";
     }

     revision 2018-03-04 {
       description "Resolved most issues on the DHC official
         github";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang";
     }

     revision 2017-12-22 {
       description
         "Resolve most issues on Ians Github.";
       reference
         "I-D: draft-ietf-dhc-dhcpv6-yang";
     }

     revision 2017-11-24 {
       description
         "First version of the separated relay specific
         YANG model.";
       reference
         "I-D: draft-ietf-dhc-dhcpv6-yang";
     }

     /*
      * Identities
      */

     identity relay {
       description "DHCPv6 relay agent identity.";
       base "dhcpv6-common:dhcpv6-node";
     }

     leaf dhcpv6-node-type {
       description "Type for a DHCPv6 relay.";
       type identityref {
         base "dhcpv6-common:dhcpv6-node";
       }
     }

     /*
      * Features
      */



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     feature prefix-delegation {
       description "Enable if the relay functions as a delegating router
         for DHCPv6 prefix delegation.";
     }

     /*
      * Groupings
      */

     grouping pd-lease-state {
       description "State data for the relay.";
       list pd-leases {
         config false;
         key ia-pd-prefix;
         description "Information about an active IA_PD prefix
           delegation.";
        leaf ia-pd-prefix {
           description "Prefix that is delegated.";
           type inet:ipv6-prefix;
         }
         leaf last-renew {
           description "Time of the last successful refresh or renew
             of the delegated prefix.";
           type yang:date-and-time;
         }
         leaf client-peer-address {
           description "Peer-address of the client.";
           type inet:ipv6-address;
         }
         leaf client-duid {
           description "DUID of the leasing client.";
           type binary;
         }
         leaf server-duid {
           description "DUID of the delegating server.";
           type binary;
         }
       }
     }

     grouping message-statistics {
       description "Contains counters for the different DHCPv6
         message types.";
       leaf solicit-received-count {
         config "false";
         type uint32;
         description "Number of Solicit (1) messages received.";
       }



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       leaf advertise-sent-count {
         config "false";
         type uint32;
         description "Number of Advertise (2) messages sent.";
       }
       leaf request-received-count {
         config "false";
         type uint32;
         description "Number of Request (3) messages received.";
       }
       leaf confirm-received-count {
         config "false";
         type uint32;
         description "Number of Confirm (4) messages received.";
       }
       leaf renew-received-count {
         config "false";
         type uint32;
         description "Number of Renew (5) messages received.";
       }
       leaf rebind-received-count {
         config "false";
         type uint32;
         description "Number of Rebind (6) messages received.";
       }
       leaf reply-sent-count {
         config "false";
         type uint32;
         description "Number of Reply (7) messages received.";
       }
       leaf release-received-count {
         config "false";
         type uint32;
         description "Number of Release (8) messages sent.";
       }
       leaf decline-received-count {
         config "false";
         type uint32;
         description "Number of Decline (9) messages sent.";
       }
       leaf reconfigure-sent-count {
         config "false";
         type uint32;
         description "Number of Reconfigure (10) messages sent.";
       }
       leaf information-request-received-count {
         config "false";
         type uint32;



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         description "Number of Information-request (11) messages
           received.";
       }
       leaf unknown-message-received-count {
         config "false";
         type uint32;
         description
           "Number of messages of unknown type that have been
              received.";
       }
       leaf unknown-message-sent-count {
         config "false";
         type uint32;
         description
           "Number of messages of unknown type that have been sent.";
       }
       leaf discarded-message-count {
         config "false";
         type uint32;
         description
           "Number of messages that have been discarded for any
              reason.";
       }
     }

     grouping global-statistics {
       leaf relay-forward-sent-count {
         config "false";
         type uint32;
         description "Number of Relay-forward (12) messages sent.";
       }
       leaf relay-forward-received-count {
         config "false";
         type uint32;
         description "Number of Relay-forward (12) messages received.";
       }
       leaf relay-reply-received-count {
         config "false";
         type uint32;
         description "Number of Relay-reply (13) messages received.";
       }
       leaf relay-forward-unknown-sent-count {
         config "false";
         type uint32;
         description "Number of Relay-forward (12) messages containing
           a message of unknown type sent.";
       }
       leaf relay-forward-unknown-received-count {



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         config "false";
         type uint32;
         description "Number of Relay-forward (12) messages containing
           a message of unknown type received.";
       }
       leaf discarded-message-count {
         config "false";
         type uint32;
         description "Number of messages that have been discarded
           for any reason.";
       }
     }

     /*
      * Data Nodes
      */

     container dhcpv6-relay {
       description
         "This container contains the configuration data nodes for
         the relay.";
       list relay-if {
         key if-name;
         leaf if-name {
           type if:interface-ref;
         }
         leaf-list destination-addresses {
           type inet:ipv6-address;
           description "Each DHCPv6 relay agent may be configured with
             a list of destination addresses for relayed messages.
             The list may include unicast addresses, multicast addresses
             or other valid addresses.";
         }
         leaf link-address {
           description "An address that may be used by the server
             to identify the link on which the client is located.";
           type binary {
             length "0..16";
           }
         }
         container relay-options {
           description "Definitions for DHCPv6 options that can be sent
             by the relay are augmented to this location from other YANG
             modules as required.";
         }
         uses message-statistics;
         container prefix-delegation {
           description "Controls and holds state information for prefix



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             delegation.";
           presence "Enables prefix delegation for this interface.";
           if-feature prefix-delegation;
           uses pd-lease-state;
         }
       }
       uses global-statistics;
     }

     /*
      * Notifications
      */

     notification relay-event {
       description
         "DHCPv6 relay event notifications.";
       container topology-change {
         description "Raised if the entry for and interface with DHCPv6
           related configuration or state is removed from
           if:interface-refs.";
         leaf relay-if-name {
           description "Name of the interface that has been removed.";
           type leafref {
             path "/dhcpv6-relay/relay-if/if-name";
           }
         }
         leaf last-ipv6-addr {
           type inet:ipv6-address;
           description "Last IPv6 address configured on the interface.";
         }
       }
     }

     /*
      * RPCs
      */

     rpc clear-prefix-entry {
       nacm:default-deny-all;
       description "Clears an entry for an active delegated prefix
         from the relay.";
       input {
         leaf lease-prefix {
           type inet:ipv6-prefix;
           mandatory true;
           description "IPv6 prefix of an active lease entry that will b
   e
             deleted from the relay.";



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         }
       }
       output {
         leaf return-message {
           type string;
           description "Response message from the relay.";
         }
       }
     }
     rpc clear-client-prefixes {
       nacm:default-deny-all;
       description "Clears all active prefix entries for a single client
   .";
       input {
         leaf client-duid {
           type binary;
           mandatory true;
           description "DUID of the client .";
         }
       }
       output {
         leaf return-message {
           type string;
           description "Response message from the relay.";
         }
       }
     }
     rpc clear-interface-prefixes {
       nacm:default-deny-all;
       description "Clears all delegated prefix bindings from an
         interface on the relay.";
       input {
         leaf interface {
           type if:interface-ref;
           mandatory true;
           description "Reference to the relay interface that will have
             all active prefix delegation bindings deleted.";
         }
       }
       output {
         leaf return-message {
           type string;
           description "Response message from the relay.";
         }
       }
     }
   }
   <CODE ENDS>



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3.3.  DHCPv6 Client YANG Module

   This module imports typedefs from [RFC6991], [RFC8343].

   <CODE BEGINS> file ietf-dhcpv6-client.yang

   module ietf-dhcpv6-client {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-dhcpv6-client";
     prefix "dhcpv6-client";

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

     import ietf-yang-types {
       prefix yang;
       reference
         "RFC 6991: Common YANG Data Types";
     }

     import ietf-dhcpv6-common {
       prefix dhcpv6-common;
       reference
         "To be updated on publication";
     }

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

     organization "DHC WG";
     contact
       "cuiyong@tsinghua.edu.cn
       wangh13@mails.tsinghua.edu.cn
       lh.sunlinh@gmail.com
       ian.farrer@telekom.de
       sladjana.zechlin@telekom.de
       hezihao9512@gmail.com
       godfryd@isc.org";

     description
       "This YANG module defines components necessary for the
       configuration and management of DHCPv6 clients.



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       Copyright (c) 2018 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 8513; see
       the RFC itself for full legal notices.";

     revision 2020-12-01 {
       description "Version update for draft -12 publication.";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang-12";
     }

     revision 2020-05-26 {
       description "Version update for draft -11 publication and
         to align revisions across the different modules.";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang-11";
     }

     revision 2019-09-20 {
       description "";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang-10";
     }

     revision 2018-09-04 {
       description "";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang";
     }

     revision 2018-03-04 {
       description "Resolved most issues on the DHC official github";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang";
     }

     revision 2017-12-22 {
       description "Resolve most issues on Ian's Github.";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang";
     }

     revision 2017-11-24 {
       description "First version of the separated client specific
         YANG model.";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang";



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     }

     /*
      * Identities
      */

     identity client {
       base "dhcpv6-common:dhcpv6-node";
       description "DHCPv6 client identity.";
     }

     leaf dhcpv6-node-type {
       description "Type for a DHCPv6 client.";
       type identityref {
         base "dhcpv6-common:dhcpv6-node";
       }
     }


     /*
      * Groupings
      */

     grouping message-statistics {
       description "Counters for DHCPv6 messages.";
       leaf solicit-count {
         config "false";
         type uint32;
         description "Number of Solicit (1) messages sent.";
       }
       leaf advertise-count {
         config "false";
         type uint32;
         description "Number of Advertise (2) messages received.";
       }
       leaf request-count {
         config "false";
         type uint32;
         description "Number of Request (3) messages sent.";
       }
       leaf confirm-count {
         config "false";
         type uint32;
         description "Number of Confirm (4) messages sent.";
       }
       leaf renew-count {
         config "false";
         type uint32;



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         description "Number of Renew (5) messages sent.";
       }
       leaf rebind-count {
         config "false";
         type uint32;
         description "Number of Rebind (6) messages sent.";
       }
       leaf reply-count {
         config "false";
         type uint32;
         description "Number of Reply (7) messages received.";
       }
       leaf release-count {
         config "false";
         type uint32;
         description "Number of Release (8) messages sent.";
       }
       leaf decline-count {
         config "false";
         type uint32;
         description "Number of Decline (9) messages sent.";
       }
       leaf reconfigure-count {
         config "false";
         type uint32;
         description "Number of Reconfigure (10) messages received.";
       }
       leaf information-request-count {
         config "false";
         type uint32;
         description "Number of Information-request (11) messages
           sent.";
       }
     }

     /*
      * Data Nodes
      */

     container dhcpv6-client {
       description "DHCPv6 client configuration and state.";
       list client-if {
         key if-name;
         description "The list of interfaces that the client will be
           requesting DHCPv6 configuration for.";
         leaf if-name {
           type if:interface-ref;
           mandatory true;



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           description "Reference to the interface entry that
             the requested configuration is relevant to.";
         }
         uses dhcpv6-common:duid;
         container client-configured-options {
           description "Definitions for DHCPv6 options that can be be
             sent by the client are augmented to this location from
             other YANG modules as required.";
         }
         list ia-na {
           key iaid;
           description "Configuration relevant for an IA_NA.";
           reference "RFC8415: Dynamic Host Configuration Protocol
             for IPv6 (DHCPv6).";
           leaf iaid {
             type uint32;
             description "A unique identifier for this IA_NA.";
           }
           container ia-na-options {
             description "An augmentation point for additional options
               that the client will send in the IA_NA-options field
               of OPTION_IA_NA.";
           }
           container lease-state {
             config "false";
             description "Information about the active IA_NA lease.";
             leaf ia-na-address {
               description "Address that is currently leased.";
               type inet:ipv6-address;
             }
             leaf preferred-lifetime {
               description "The preferred lifetime for the leased
                 address expressed in units of seconds.";
               type dhcpv6-common:timer-seconds32;
             }
             leaf valid-lifetime {
               description "The valid lifetime for the leased address
                 expressed in units of seconds.";
               type dhcpv6-common:timer-seconds32;
             }
             leaf lease-t1 {
               description "The time interval after which the client
                 should contact the server from which the addresses
                 in the IA_NA were obtained to extend the lifetimes
                 of the addresses assigned to the IA_NA.";
               type dhcpv6-common:timer-seconds32;
             }
             leaf lease-t2 {



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               description "The time interval after which the client
                 should contact any available server to extend
                 the lifetimes of the addresses assigned to the IA_NA.";
               type dhcpv6-common:timer-seconds32;
             }
             leaf allocation-time {
               description "Time and date that the address was first
                 leased.";
               type yang:date-and-time;
             }
             leaf last-renew-rebind {
               description "Time of the last successful renew or rebind
                 of the leased address.";
               type yang:date-and-time;
             }
             leaf server-duid {
               description "DUID of the leasing server.";
               type binary;
             }
           }
         }
         list ia-ta {
           key iaid;
           description "Configuration relevant for an IA_TA.";
           reference "RFC8415: Dynamic Host Configuration Protocol for
             IPv6 (DHCPv6).";
             leaf iaid {
               type uint32;
               description "The unique identifier for this IA_TA.";
             }
           container ia-ta-options {
             description "An augmentation point for additional options
               that the client will send in the IA_TA-options field
               of OPTION_IA_TA.";
           }
           container lease-state {
             config "false";
             description "Information about an active IA_TA lease.";
             leaf ia-ta-address {
               description "Address that is currently leased.";
               type inet:ipv6-address;
             }
             leaf preferred-lifetime {
               description "The preferred lifetime for the leased
                 address expressed in units of seconds.";
               type dhcpv6-common:timer-seconds32;
             }
             leaf valid-lifetime {



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               description "The valid lifetime for the leased address
                 expressed in units of seconds.";
               type dhcpv6-common:timer-seconds32;
             }
             leaf allocation-time {
               description "Time and date that the address was first
                 leased.";
               type yang:date-and-time;
             }
             leaf last-renew-rebind {
               description "Time of the last successful renew or rebind
                 of the address.";
               type yang:date-and-time;
             }
             leaf server-duid {
               description "DUID of the leasing server.";
               type binary;
             }
           }
         }
         list ia-pd {
           key iaid;
           reference "RFC8415: Dynamic Host Configuration Protocol for
             IPv6 (DHCPv6).";
           description "Configuration relevant for an IA_PD.";
           leaf iaid {
             type uint32;
             description "The unique identifier for this IA_PD.";
           }
           container ia-pd-options {
             description "An augmentation point for additional options
               that the client will send in the IA_PD-options field
               of OPTION_IA_TA.";
           }
           container lease-state {
             config "false";
             description "Information about an active IA_PD delegated
               prefix.";
             leaf ia-pd-prefix {
               description "Delegated prefix that is currently leased.";
               type inet:ipv6-prefix;
             }
             leaf preferred-lifetime {
               description "The preferred lifetime for the leased prefix
                 expressed in units of seconds.";
               type dhcpv6-common:timer-seconds32;
             }
             leaf valid-lifetime {



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               description "The valid lifetime for the leased prefix
                 expressed in units of seconds.";
               type dhcpv6-common:timer-seconds32;
             }
             leaf lease-t1 {
               description "The time interval after which the client
                 should contact the server from which the addresses
                 in the IA_NA were obtained to extend the lifetimes
                 of the addresses assigned to the IA_PD.";
               type dhcpv6-common:timer-seconds32;
             }
             leaf lease-t2 {
               description "The time interval after which the client
                 should contact any available server to extend
                 the lifetimes of the addresses assigned to the IA_PD.";
               type dhcpv6-common:timer-seconds32;
             }
             leaf allocation-time {
               description "Time and date that the prefix was first
                 leased.";
               type yang:date-and-time;
             }
             leaf last-renew-rebind {
               description "Time of the last successful renew or rebind
                 of the delegated prefix.";
               type yang:date-and-time;
             }
             leaf server-duid {
               description "DUID of the delegating server.";
               type binary;
             }
           }
         }
         uses message-statistics;
       }
     }

     /*
      * Notifications
      */

     notification invalid-ia-detected {
       description "Notification sent when the identity association
         of the client can be proved to be invalid. Possible conditions
         include a duplicate or otherwise illegal address.";
       leaf iaid {
         type uint32;
         mandatory true;



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         description "IAID";
       }
       leaf description {
         type string;
         description "Description of the event.";
       }
     }

     notification retransmission-failed {
       description "Notification sent when the retransmission mechanism
         defined in [RFC8415] is unsuccessful.";
       leaf failure-type {
         type enumeration {
           enum "MRC-exceeded" {
             description "Maximum retransmission count exceeded.";
           }
           enum "MRD-exceeded" {
             description "Maximum retransmission duration exceeded.";
           }
         }
         mandatory true;
         description "Description of the failure.";
       }
     }

     notification unsuccessful-status-code {
       description "Notification sent when the client receives a message
         that includes an unsuccessful Status Code option.";
       leaf status-code {
         type uint16;
         mandatory true;
         description "Unsuccessful status code received by a client.";
       }
       leaf server-duid {
         description "DUID of the server sending the unsuccessful
           error code.";
         mandatory true;
         type binary;
       }
     }

     notification server-duid-changed {
       description "Notification sent when the client receives a lease
         from a server with different DUID to the one currently stored
         by the client.";
       leaf new-server-duid {
         description "DUID of the new server.";
         mandatory true;



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         type binary;
       }
       leaf previous-server-duid {
         description "DUID of the previous server.";
         mandatory true;
         type binary;
       }
       leaf lease-ia-na {
         description "Reference to the IA_NA lease.";
         type leafref {
           path "/dhcpv6-client/client-if/ia-na/iaid";
         }
       }
       leaf lease-ia-ta {
         description "Reference to the IA_TA lease.";
         type leafref {
           path "/dhcpv6-client/client-if/ia-ta/iaid";
         }
       }
       leaf lease-ia-pd {
         description "Reference to the IA_PD lease.";
         type leafref {
           path "/dhcpv6-client/client-if/ia-pd/iaid";
         }
       }
     }
   }
   <CODE ENDS>

3.4.  RFC8415 Server Options YANG Module

   This module imports typedefs from [RFC6991].

   <CODE BEGINS> file ietf-dhcpv6-options-rfc8415-server.yang

   module ietf-dhcpv6-options-rfc8415 {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-dhcpv6-options-8415-ser
   ver";
     prefix "rfc8415-srv";

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

     import ietf-dhcpv6-common {



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       prefix dhcpv6-common;
       reference
         "To be updated on publication";
     }

     import ietf-dhcpv6-server {
       prefix dhcpv6-server;
       reference
         "To be updated on publication";
     }

     organization "DHC WG";
     contact
       "cuiyong@tsinghua.edu.cn
       wangh13@mails.tsinghua.edu.cn
       lh.sunlinh@gmail.com
       ian.farrer@telekom.de
       sladjana.zechlin@telekom.de
       hezihao9512@gmail.com";

     description "This YANG module contains DHCPv6 options defined
       in RFC8415 that can be used by DHCPv6 servers.";

     revision 2020-12-01 {
       description "Version update for draft -12 publication.";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang-12";
     }

     revision 2020-11-19 {
       description "Separated into a client specific set of options.";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang-12";
     }

     revision 2020-05-26 {
       description "Version update for draft -11 publication and
         to align revisions across the different modules.";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang-11";
     }

     revision 2019-06-07 {
       description "Major reworking to only contain RFC8415 options.
         if-feature for each option removed. Removed groupings
           of features by device or combination of devices. Added ";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang";
     }

     revision 2018-09-04 {
       description "";



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       reference "I-D: draft-ietf-dhc-dhcpv6-yang";
     }

     revision 2018-03-04 {
       description "Resolved most issues on the DHC official
         github";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang";
     }

     revision 2017-12-22 {
       description "Resolve most issues on Ian's github.";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang";
     }

     revision 2017-11-24 {
       description "First version of the separated DHCPv6 options
         YANG model.";
       reference "I-D:draft-ietf-dhc-dhcpv6-yang";
     }

     /*
      * Groupings
      */

     grouping preference-option-group {
       container preference-option {
         description "OPTION_PREFERENCE (7) Preference Option";
         reference "RFC8415: Dynamic Host Configuration Protocol for
           IPv6 (DHCPv6)";
         leaf pref-value {
           type uint8;
           description "The preference value for the server in this
             message. A 1-octet unsigned integer.";
         }
       }
     }

     grouping auth-option-group {
       container auth-option {
         description "OPTION_AUTH (11) Authentication Option";
         reference "RFC8415: Dynamic Host Configuration Protocol
           for IPv6 (DHCPv6)";
         leaf protocol {
           type uint8;
           description "The authentication protocol used in this
             Authentication option.";
         }
         leaf algorithm {



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           type uint8;
           description "The algorithm used in the authentication
             protocol.";
         }
         leaf rdm {
           type uint8;
           description "The replay detection method used
             in this Authentication option.";
         }
         leaf replay-detection {
           type uint64;
           description "The replay detection information for the RDM.";
         }
         leaf auth-information {
           type string;
           description "The authentication information, as specified
             by the protocol and algorithm used in this Authentication
             option.";
         }
       }
     }

     grouping server-unicast-option-group {
       container server-unicast-option {
         description "OPTION_UNICAST (12) Server Unicast Option";
         reference "RFC8415: Dynamic Host Configuration Protocol for
           IPv6 (DHCPv6)";
         leaf server-address {
           type inet:ipv6-address;
           description "The 128-bit address to which the client
             should send messages delivered using unicast.";
         }
       }
     }

     grouping status-code-option-group {
       container status-code-option {
         description "OPTION_STATUS_CODE (13) Status Code Option.";
         reference "RFC8415: Dynamic Host Configuration Protocol
           for IPv6 (DHCPv6)";
         leaf status-code {
           type uint16;
           description "The numeric code for the status encoded
             in this option. See the Status Codes registry at
             <https://www.iana.org/assignments/dhcpv6-parameters>
             for the current list of status codes.";
         }
         leaf status-message {



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           type string;
           description "A UTF-8 encoded text string suitable for
             display to an end user. MUST NOT be null-terminated.";
         }
       }
     }

     grouping rapid-commit-option-group {
       container rapid-commit-option {
         presence "Enable sending of this option";
         description "OPTION_RAPID_COMMIT (14) Rapid Commit Option.
           The presence node is used to enable the option.";
         reference "RFC8415: Dynamic Host Configuration Protocol for
           IPv6 (DHCPv6)";
       }
     }

     grouping vendor-specific-information-option-group {
       container vendor-specific-information-option {
         description "OPTION_VENDOR_OPTS (17) Vendor-specific
           Information Option";
         reference "RFC8415: Dynamic Host Configuration Protocol
           for IPv6 (DHCPv6)";
         list vendor-specific-information-option-instances {
           key enterprise-number;
           description "The vendor specific information option allows
             for multiple instances in a single message. Each list entry
               defines the contents of an instance of the option.";
           leaf enterprise-number {
             type uint32;
             description "The vendor's registered Enterprise Number,
                         as maintained by IANA.";
           }
           list vendor-option-data {
             key sub-option-code;
             description "Vendor options, interpreted by vendor-specific
               client/server functions.";
             leaf sub-option-code {
               type uint16;
               description "The code for the sub-option.";
             }
             leaf sub-option-data {
               type string;
               description "The data area for the sub-option.";
             }
           }
         }
       }



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     }

     grouping reconfigure-message-option-group {
       container reconfigure-message-option {
         description "OPTION_RECONF_MSG (19) Reconfigure Message
           Option.";
         reference "RFC8415: Dynamic Host Configuration Protocol for
           IPv6 (DHCPv6)";
         leaf msg-type {
           type uint8;
           description "5 for Renew message, 6 for Rebind message,
                       11 for Information-request message.";
         }
       }
     }

     grouping reconfigure-accept-option-group {
       container reconfigure-accept-option {
         presence "Enable sending of this option";
         description "OPTION_RECONF_ACCEPT (20)  Reconfigure Accept
           Option.
           A client uses the Reconfigure Accept option to announce to
           the server whether the client is willing to accept
           Reconfigure messages, and a server uses this option to tell
           the client whether or not to accept Reconfigure messages.
           In the absence of this option, the default behavior is that
           the client is unwilling to accept Reconfigure messages.
           The presence node is used to enable the option.";
         reference "RFC8415: Dynamic Host Configuration Protocol
           for IPv6 (DHCPv6)";
       }
     }

     grouping info-refresh-time-option-group {
       container info-refresh-time-option {
         description "OPTION_INFORMATION_REFRESH_TIME (32)
           Information Refresh Time option.";
         reference "RFC8415: Dynamic Host Configuration Protocol for
           IPv6 (DHCPv6)";
         leaf info-refresh-time {
           type dhcpv6-common:timer-seconds32;
           description "Time duration relative to the current time,
                       expressed in units of seconds.";
         }
       }
     }

     grouping sol-max-rt-option-group {



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       container sol-max-rt-option {
         description "OPTION_SOL_MAX_RT (82) sol max rt option";
         reference "RFC8415: Dynamic Host Configuration Protocol for
           IPv6 (DHCPv6)";
         leaf sol-max-rt-value {
           type dhcpv6-common:timer-seconds32;
           description "sol max rt value";
         }
       }
     }

     grouping inf-max-rt-option-group {
       container inf-max-rt-option {
         description "OPTION_INF_MAX_RT (83) inf max rt option";
         reference "RFC8415: Dynamic Host Configuration Protocol for
           IPv6 (DHCPv6)";
         leaf inf-max-rt-value {
           type dhcpv6-common:timer-seconds32;
           description "inf max rt value";
         }
       }
     }

     /*
      * Augmentations
      */

     augment "/dhcpv6-server:dhcpv6-server/dhcpv6-server:option-sets/dhc
   pv6-server:option-set" {
       when "../../../dhcpv6-server:dhcpv6-node-type='dhcpv6-server:serv
   er'";
       uses preference-option-group;
       uses auth-option-group;
       uses server-unicast-option-group;
       uses status-code-option-group;
       uses rapid-commit-option-group;
       uses vendor-specific-information-option-group;
       uses reconfigure-message-option-group;
       uses reconfigure-accept-option-group;
       uses info-refresh-time-option-group;
       uses sol-max-rt-option-group;
       uses inf-max-rt-option-group;
     }
   }
   <CODE ENDS>






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3.5.  RFC8415 Relay Options YANG Module

   This module imports typedefs from [RFC6991].

   <CODE BEGINS> file ietf-dhcpv6-options-rfc8415-server.yang

   module ietf-dhcpv6-options-rfc8415 {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-dhcpv6-options-8415-ser
   ver";
     prefix "rfc8415-srv";

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

     import ietf-dhcpv6-common {
       prefix dhcpv6-common;
       reference
         "To be updated on publication";
     }

     import ietf-dhcpv6-server {
       prefix dhcpv6-server;
       reference
         "To be updated on publication";
     }

     organization "DHC WG";
     contact
       "cuiyong@tsinghua.edu.cn
       wangh13@mails.tsinghua.edu.cn
       lh.sunlinh@gmail.com
       ian.farrer@telekom.de
       sladjana.zechlin@telekom.de
       hezihao9512@gmail.com";

     description "This YANG module contains DHCPv6 options defined
       in RFC8415 that can be used by DHCPv6 servers.";

     revision 2020-12-01 {
       description "Version update for draft -12 publication.";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang-12";
     }

     revision 2020-11-19 {



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       description "Separated into a client specific set of options.";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang-12";
     }

     revision 2020-05-26 {
       description "Version update for draft -11 publication and
         to align revisions across the different modules.";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang-11";
     }

     revision 2019-06-07 {
       description "Major reworking to only contain RFC8415 options.
         if-feature for each option removed. Removed groupings
           of features by device or combination of devices. Added ";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang";
     }

     revision 2018-09-04 {
       description "";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang";
     }

     revision 2018-03-04 {
       description "Resolved most issues on the DHC official
         github";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang";
     }

     revision 2017-12-22 {
       description "Resolve most issues on Ian's github.";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang";
     }

     revision 2017-11-24 {
       description "First version of the separated DHCPv6 options
         YANG model.";
       reference "I-D:draft-ietf-dhc-dhcpv6-yang";
     }

     /*
      * Groupings
      */

     grouping preference-option-group {
       container preference-option {
         description "OPTION_PREFERENCE (7) Preference Option";
         reference "RFC8415: Dynamic Host Configuration Protocol for
           IPv6 (DHCPv6)";



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         leaf pref-value {
           type uint8;
           description "The preference value for the server in this
             message. A 1-octet unsigned integer.";
         }
       }
     }

     grouping auth-option-group {
       container auth-option {
         description "OPTION_AUTH (11) Authentication Option";
         reference "RFC8415: Dynamic Host Configuration Protocol
           for IPv6 (DHCPv6)";
         leaf protocol {
           type uint8;
           description "The authentication protocol used in this
             Authentication option.";
         }
         leaf algorithm {
           type uint8;
           description "The algorithm used in the authentication
             protocol.";
         }
         leaf rdm {
           type uint8;
           description "The replay detection method used
             in this Authentication option.";
         }
         leaf replay-detection {
           type uint64;
           description "The replay detection information for the RDM.";
         }
         leaf auth-information {
           type string;
           description "The authentication information, as specified
             by the protocol and algorithm used in this Authentication
             option.";
         }
       }
     }

     grouping server-unicast-option-group {
       container server-unicast-option {
         description "OPTION_UNICAST (12) Server Unicast Option";
         reference "RFC8415: Dynamic Host Configuration Protocol for
           IPv6 (DHCPv6)";
         leaf server-address {
           type inet:ipv6-address;



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           description "The 128-bit address to which the client
             should send messages delivered using unicast.";
         }
       }
     }

     grouping status-code-option-group {
       container status-code-option {
         description "OPTION_STATUS_CODE (13) Status Code Option.";
         reference "RFC8415: Dynamic Host Configuration Protocol
           for IPv6 (DHCPv6)";
         leaf status-code {
           type uint16;
           description "The numeric code for the status encoded
             in this option. See the Status Codes registry at
             <https://www.iana.org/assignments/dhcpv6-parameters>
             for the current list of status codes.";
         }
         leaf status-message {
           type string;
           description "A UTF-8 encoded text string suitable for
             display to an end user. MUST NOT be null-terminated.";
         }
       }
     }

     grouping rapid-commit-option-group {
       container rapid-commit-option {
         presence "Enable sending of this option";
         description "OPTION_RAPID_COMMIT (14) Rapid Commit Option.
           The presence node is used to enable the option.";
         reference "RFC8415: Dynamic Host Configuration Protocol for
           IPv6 (DHCPv6)";
       }
     }

     grouping vendor-specific-information-option-group {
       container vendor-specific-information-option {
         description "OPTION_VENDOR_OPTS (17) Vendor-specific
           Information Option";
         reference "RFC8415: Dynamic Host Configuration Protocol
           for IPv6 (DHCPv6)";
         list vendor-specific-information-option-instances {
           key enterprise-number;
           description "The vendor specific information option allows
             for multiple instances in a single message. Each list entry
               defines the contents of an instance of the option.";
           leaf enterprise-number {



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             type uint32;
             description "The vendor's registered Enterprise Number,
                         as maintained by IANA.";
           }
           list vendor-option-data {
             key sub-option-code;
             description "Vendor options, interpreted by vendor-specific
               client/server functions.";
             leaf sub-option-code {
               type uint16;
               description "The code for the sub-option.";
             }
             leaf sub-option-data {
               type string;
               description "The data area for the sub-option.";
             }
           }
         }
       }
     }

     grouping reconfigure-message-option-group {
       container reconfigure-message-option {
         description "OPTION_RECONF_MSG (19) Reconfigure Message
           Option.";
         reference "RFC8415: Dynamic Host Configuration Protocol for
           IPv6 (DHCPv6)";
         leaf msg-type {
           type uint8;
           description "5 for Renew message, 6 for Rebind message,
                       11 for Information-request message.";
         }
       }
     }

     grouping reconfigure-accept-option-group {
       container reconfigure-accept-option {
         presence "Enable sending of this option";
         description "OPTION_RECONF_ACCEPT (20)  Reconfigure Accept
           Option.
           A client uses the Reconfigure Accept option to announce to
           the server whether the client is willing to accept
           Reconfigure messages, and a server uses this option to tell
           the client whether or not to accept Reconfigure messages.
           In the absence of this option, the default behavior is that
           the client is unwilling to accept Reconfigure messages.
           The presence node is used to enable the option.";
         reference "RFC8415: Dynamic Host Configuration Protocol



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           for IPv6 (DHCPv6)";
       }
     }

     grouping info-refresh-time-option-group {
       container info-refresh-time-option {
         description "OPTION_INFORMATION_REFRESH_TIME (32)
           Information Refresh Time option.";
         reference "RFC8415: Dynamic Host Configuration Protocol for
           IPv6 (DHCPv6)";
         leaf info-refresh-time {
           type dhcpv6-common:timer-seconds32;
           description "Time duration relative to the current time,
                       expressed in units of seconds.";
         }
       }
     }

     grouping sol-max-rt-option-group {
       container sol-max-rt-option {
         description "OPTION_SOL_MAX_RT (82) sol max rt option";
         reference "RFC8415: Dynamic Host Configuration Protocol for
           IPv6 (DHCPv6)";
         leaf sol-max-rt-value {
           type dhcpv6-common:timer-seconds32;
           description "sol max rt value";
         }
       }
     }

     grouping inf-max-rt-option-group {
       container inf-max-rt-option {
         description "OPTION_INF_MAX_RT (83) inf max rt option";
         reference "RFC8415: Dynamic Host Configuration Protocol for
           IPv6 (DHCPv6)";
         leaf inf-max-rt-value {
           type dhcpv6-common:timer-seconds32;
           description "inf max rt value";
         }
       }
     }

     /*
      * Augmentations
      */

     augment "/dhcpv6-server:dhcpv6-server/dhcpv6-server:option-sets/dhc
   pv6-server:option-set" {



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       when "../../../dhcpv6-server:dhcpv6-node-type='dhcpv6-server:serv
   er'";
       uses preference-option-group;
       uses auth-option-group;
       uses server-unicast-option-group;
       uses status-code-option-group;
       uses rapid-commit-option-group;
       uses vendor-specific-information-option-group;
       uses reconfigure-message-option-group;
       uses reconfigure-accept-option-group;
       uses info-refresh-time-option-group;
       uses sol-max-rt-option-group;
       uses inf-max-rt-option-group;
     }
   }
   <CODE ENDS>

3.6.  RFC8415 Client Options YANG Module

   This module imports typedefs from [RFC6991].

   <CODE BEGINS> file ietf-dhcpv6-options-rfc8415-client.yang

   module ietf-dhcpv6-options-rfc8415 {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-dhcpv6-options-8415-cli
   ent";
     prefix "rfc8415-cli";

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

     import ietf-dhcpv6-common {
       prefix dhcpv6-common;
       reference
         "To be updated on publication";
     }

     import ietf-dhcpv6-client {
       prefix dhcpv6-client;
       reference
         "To be updated on publication";
     }

     organization "DHC WG";



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     contact
       "cuiyong@tsinghua.edu.cn
       wangh13@mails.tsinghua.edu.cn
       lh.sunlinh@gmail.com
       ian.farrer@telekom.de
       sladjana.zechlin@telekom.de
       hezihao9512@gmail.com";

     description "This YANG module contains DHCPv6 options defined
       in RFC8415 that can be used by DHCPv6 clients.";

     revision 2020-12-01 {
       description "Version update for draft -12 publication.";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang-12";
     }

     revision 2020-11-19 {
       description "Separated into a client specific set of options.";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang-12";
     }

     revision 2020-05-26 {
       description "Version update for draft -11 publication and
         to align revisions across the different modules.";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang-11";
     }

     revision 2019-06-07 {
       description "Major reworking to only contain RFC8415 options.
         if-feature for each option removed. Removed groupings
           of features by device or combination of devices. Added ";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang";
     }

     revision 2018-09-04 {
       description "";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang";
     }

     revision 2018-03-04 {
       description "Resolved most issues on the DHC official
         github";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang";
     }

     revision 2017-12-22 {
       description "Resolve most issues on Ian's github.";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang";



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     }

     revision 2017-11-24 {
       description "First version of the separated DHCPv6 options
         YANG model.";
       reference "I-D:draft-ietf-dhc-dhcpv6-yang";
     }

     /*
      * Groupings
      */

     grouping option-request-option-group {
       container option-request-option {
         description "OPTION_ORO (6) Option Request Option. A client
           MUST include an Option Request option in a Solicit, Request,
                Renew, Rebind, or Information-request message to inform
                  the server about options the client wants the server t
   o send
                  to the client.";
         reference "RFC8415: Dynamic Host Configuration Protocol for
           IPv6 (DHCPv6)";
         leaf-list oro-option {
           description "List of options that the client is requesting,
                       identified by option code";
           type uint16;
         }
       }
     }

     grouping status-code-option-group {
       container status-code-option {
         description "OPTION_STATUS_CODE (13) Status Code Option.";
         reference "RFC8415: Dynamic Host Configuration Protocol
           for IPv6 (DHCPv6)";
         leaf status-code {
           type uint16;
           description "The numeric code for the status encoded
             in this option. See the Status Codes registry at
             <https://www.iana.org/assignments/dhcpv6-parameters>
             for the current list of status codes.";
         }
         leaf status-message {
           type string;
           description "A UTF-8 encoded text string suitable for
             display to an end user. MUST NOT be null-terminated.";
         }
       }



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     }

     grouping rapid-commit-option-group {
       container rapid-commit-option {
         presence "Enable sending of this option";
         description "OPTION_RAPID_COMMIT (14) Rapid Commit Option.
           The presence node is used to enable the option.";
         reference "RFC8415: Dynamic Host Configuration Protocol for
           IPv6 (DHCPv6)";
       }
     }

     grouping user-class-option-group {
       container user-class-option {
         description "OPTION_USER_CLASS (15) User Class Option";
         reference "RFC8415: Dynamic Host Configuration Protocol
           for IPv6 (DHCPv6)";
         list user-class-data {
           key user-class-datum-id;
           min-elements 1;
           description "The user classes of which the client
             is a member.";
           leaf user-class-datum-id {
             type uint8;
             description "User class datum ID";
           }
           leaf user-class-datum {
             type string;
             description "Opaque field representing a User Class
               of which the client is a member.";
           }
         }
       }
     }

     grouping vendor-class-option-group {
       container vendor-class-option {
         description "OPTION_VENDOR_CLASS (16) Vendor Class Option";
         reference "RFC8415: Dynamic Host Configuration Protocol
           for IPv6 (DHCPv6)";
         list vendor-class-option-instances {
           key enterprise-number;
           description "The vendor class option allows for multiple
             instances in a single message. Each list entry defines
             the contents of an instance of the option.";
           leaf enterprise-number {
             type uint32;
             description "The vendor's registered Enterprise Number



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               as maintained by IANA.";
           }
           list vendor-class {
             key vendor-class-datum-id;
             description "The vendor classes of which the client is
               a member.";
             leaf vendor-class-datum-id {
               type uint8;
               description "Vendor class datum ID";
             }
             leaf vendor-class-datum {
               type string;
               description "Opaque field representing a vendor class
                 of which the client is a member.";
             }
           }
         }
       }
     }

     grouping vendor-specific-information-option-group {
       container vendor-specific-information-option {
         description "OPTION_VENDOR_OPTS (17) Vendor-specific
           Information Option";
         reference "RFC8415: Dynamic Host Configuration Protocol
           for IPv6 (DHCPv6)";
         list vendor-specific-information-option-instances {
           key enterprise-number;
           description "The vendor specific information option allows
             for multiple instances in a single message. Each list entry
               defines the contents of an instance of the option.";
           leaf enterprise-number {
             type uint32;
             description "The vendor's registered Enterprise Number,
                         as maintained by IANA.";
           }
           list vendor-option-data {
             key sub-option-code;
             description "Vendor options, interpreted by vendor-specific
               client/server functions.";
             leaf sub-option-code {
               type uint16;
               description "The code for the sub-option.";
             }
             leaf sub-option-data {
               type string;
               description "The data area for the sub-option.";
             }



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           }
         }
       }
     }

     grouping reconfigure-accept-option-group {
       container reconfigure-accept-option {
         presence "Enable sending of this option";
         description "OPTION_RECONF_ACCEPT (20)  Reconfigure Accept
           Option.
           A client uses the Reconfigure Accept option to announce to
           the server whether the client is willing to accept
           Reconfigure messages, and a server uses this option to tell
           the client whether or not to accept Reconfigure messages.
           In the absence of this option, the default behavior is that
           the client is unwilling to accept Reconfigure messages.
           The presence node is used to enable the option.";
         reference "RFC8415: Dynamic Host Configuration Protocol
           for IPv6 (DHCPv6)";
       }
     }

     /*
      * Augmentations
      */

     augment "/dhcpv6-client:dhcpv6-client/dhcpv6-client:client-if/dhcpv
   6-client:client-configured-options" {
       when "../../../dhcpv6-client:dhcpv6-node-type='dhcpv6-client:clie
   nt'";
       uses option-request-option-group;
       uses status-code-option-group;
       uses rapid-commit-option-group;
       uses user-class-option-group;
       uses vendor-class-option-group;
       uses vendor-specific-information-option-group;
       uses reconfigure-accept-option-group;
     }
   }
   <CODE ENDS>

3.7.  DHCPv6 Common YANG Module

   This module imports typedefs from [RFC6991].







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   <CODE BEGINS> file ietf-dhcpv6-common.yang

   module ietf-dhcpv6-common {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-dhcpv6-common";
     prefix "dhcpv6-common";

     import ietf-yang-types {
       prefix yang;
       reference
         "RFC 6991: Common YANG Data Types";
     }

     organization "DHC WG";
     contact
       "yong@csnet1.cs.tsinghua.edu.cn
       lh.sunlinh@gmail.com
       ian.farrer@telekom.de
       sladjana.zechlin@telekom.de
       hezihao9512@gmail.com";

     description "This YANG module defines common components
       used for the configuration and management of DHCPv6.";

     revision 2020-12-01 {
       description "Version update for draft -12 publication.";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang-12";
     }

     revision 2020-05-26 {
       description "Version update for draft -11 publication and
         to align revisions across the different modules.";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang-11";
     }

     revision 2018-09-04 {
       description "";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang";
     }

     revision 2018-01-30 {
       description "Initial revision";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang";
     }

     typedef threshold {
       type union {
         type uint16 {



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           range 0..100;
         }
         type enumeration {
           enum "disabled" {
             description "No threshold";
           }
         }
       }
       description "Threshold value in percent";
     }

     typedef timer-seconds32 {
       type uint32 {
         range "1..4294967295";
       }
       units "seconds";
       description
         "Timer value type, in seconds (32-bit range).";
     }

     identity dhcpv6-node {
       description "Abstract base type for DHCPv6 functional nodes";
     }

     /*
      * Groupings
      */

     grouping duid {
       description "Each server and client has only one DUID (DHCP
         Unique Identifier). The DUID here identifies a unique
         DHCPv6 server for clients.  DUID consists of a two-octet
         type field and an arbitrary length (no more than 128 bytes)
         content field.  Currently there are four defined types of
         DUIDs in RFC8415 and RFC6355 - DUID-LLT, DUID-EN, DUID-LL
         and DUID-UUID.  DUID-unstructured represents DUIDs which
         do not follow any of the defined formats.";
       reference "RFC8415: Section 11 and RFC6355: Section 4";
       leaf type-code {
         type uint16;
         default 65535;
         description "Type code of this DUID.";
       }
       choice duid-type {
         default duid-unstructured;
         description "Selects the format of the DUID.";
         case duid-llt {
           description "DUID Based on Link-layer Address Plus Time



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             (Type 1 - DUID-LLT).";
           reference "RFC8415 Section 11.2";
           leaf duid-llt-hardware-type {
             type uint16;
             description "Hardware type as assigned by IANA (RFC826).";
           }
           leaf duid-llt-time {
             type yang:timeticks;
             description "The time that the DUID is generated
               represented in seconds since midnight (UTC),
               January 1, 2000, modulo 2^32.";
           }
           leaf duid-llt-link-layer-address {
             type yang:mac-address;
             description "Link-layer address as described in RFC2464.";
           }
         }
         case duid-en {
           description "DUID Assigned by Vendor Based on Enterprise
             Number (Type 2 - DUID-EN).";
           reference "RFC8415 Section 11.3";
           leaf duid-en-enterprise-number {
             type uint32;
             description "Vendor's registered Private Enterprise Number
               as maintained by IANA.";
           }
           leaf duid-en-identifier {
             type string;
             description "Identifier, unique to the device.";
           }
         }
         case duid-ll {
           description "DUID Based on Link-layer Address
             (Type 3 - DUID-LL).";
           reference "RFC8415 Section 11.4";
           leaf duid-ll-hardware-type {
             type uint16;
             description "Hardware type, as assigned by IANA (RFC826).";
           }
           leaf duid-ll-link-layer-address {
             type yang:mac-address;
             description "Link-layer address, as described in RFC2464";
           }
         }
         case duid-uuid {
           description "DUID Based on Universally Unique Identifier
             (Type 4 - DUID-UUID).";
           reference "RFC6335 Definition of the UUID-Based Unique



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             Identifier";
           leaf uuid {
             type yang:uuid;
             description "A Universally Unique Identifier in the string
               representation, defined in RFC4122. The canonical
               representation uses lowercase characters.";
           }
         }
         case duid-unstructured {
           description "DUID which does not follow any of the other
             structures, expressed as bytes.";
           leaf data {
             type binary;
             description "The bits to be used as the identifier.";
           }
         }
       }
       leaf active-duid {
         config "false";
         description "The DUID which is currently in use.";
         type binary;
       }
     }
   }
   <CODE ENDS>

4.  Security Considerations

   The YANG modules defined in this document are 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.

   All data nodes defined in the YANG modules which can be created,
   modified, and deleted (i.e., config true, which is the default) are
   considered sensitive.  Write operations (e.g., edit-config) to these
   data nodes without proper protection can have a negative effect on
   network operations.






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   As the RPCs for deleting/clearing active address and prefix entries
   in the server and relay modules are particularly sensitive, these use
   'nacm:default-deny-all'.

   An attacker who is able to access the DHCPv6 server can undertake
   various attacks, such as:

   *  Denial of service attacks, based on re-configuring messages to a
      rogue DHCPv6 server.

   *  Various attacks based on re-configuring the contents of DHCPv6
      options.  E.g., changing the address of a the DNS server supplied
      in a DHCP option to point to a rogue server.

   An attacker who is able to access the DHCPv6 relay can undertake
   various attacks, such as:

   *  Re-configuring the relay's destination address to send messages to
      a rogue DHCPv6 server.

   *  Deleting information about a client's delegated prefix, causing a
      denial of service attack as traffic will no longer be routed to
      the client.

   Some of the readable data nodes in this 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 subtrees and data nodes can
   be misused to track the activity of a host:

   *  Re-configuring the relay's destination address to send messages to
      a rogue DHCPv6 server.

   *  Information the server holds about clients with active leases:
      (dhcpv6-server/network-ranges/network-range/ address-pools/
      address-pool/active-leases)

   *  Information the relay holds about clients with active leases:
      (dhcpv6-relay/relay-if/prefix-delegation/)

   Security considerations related to DHCPv6 are discussed in [RFC8415].

   Security considerations given in [RFC7950] are also applicable here.

5.  IANA Considerations

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



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   name:           ietf-dhcpv6
   namespace:      urn:ietf:params:xml:ns:yang:ietf-dhcpv6-common
   prefix:         dhcpv6
   reference:      TBD

   name:           ietf-dhcpv6
   namespace:      urn:ietf:params:xml:ns:yang:ietf-dhcpv6-server
   prefix:         dhcpv6
   reference:      TBD

   name:           ietf-dhcpv6
   namespace:      urn:ietf:params:xml:ns:yang:ietf-dhcpv6-client
   prefix:         dhcpv6
   reference:      TBD

   name:           ietf-dhcpv6
   namespace:      urn:ietf:params:xml:ns:yang:ietf-dhcpv6-relay
   prefix:         dhcpv6
   reference:      TBD

   name:           ietf-dhcpv6
   namespace:
                   urn:ietf:params:xml:ns:yang:ietf-dhcpv6-options-
                   rfc8415-server
   prefix:         dhcpv6
   reference:      TBD

   name:           ietf-dhcpv6
   namespace:
                   urn:ietf:params:xml:ns:yang:ietf-dhcpv6-options-
                   rfc8415-relay
   prefix:         dhcpv6
   reference:      TBD

   name:           ietf-dhcpv6
   namespace:
                   urn:ietf:params:xml:ns:yang:ietf-dhcpv6-options-
                   rfc8415-client
   prefix:         dhcpv6
   reference:      TBD

6.  Acknowledgments

   The authors would like to thank Qi Sun, Lishan Li, Sladjana Zoric,
   Tomek Mrugalski, Marcin Siodelski, and Bing Liu for their valuable
   comments and contributions to this work.





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7.  Contributors

   The following individuals contributed to this effort:

           Hao Wang
           Tsinghua University
           Beijing 100084
           P.R. China
           Phone: +86-10-6278-5822
           Email: wangh13@mails.tsinghua.edu.cn

           Ted Lemon
           Nomium, Inc
           950 Charter St.
           Redwood City, CA 94043
           USA
           Email: Ted.Lemon@nomium.com

           Bernie Volz
           Cisco Systems, Inc.
           1414 Massachusetts Ave
           Boxborough, MA 01719
           USA
           Email: volz@cisco.com


8.  References

8.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC6355]  Narten, T. and J. Johnson, "Definition of the UUID-Based
              DHCPv6 Unique Identifier (DUID-UUID)", RFC 6355,
              DOI 10.17487/RFC6355, August 2011,
              <https://www.rfc-editor.org/info/rfc6355>.

   [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>.







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   [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>.

   [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>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [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>.

   [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>.

   [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>.

   [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>.

   [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>.





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   [RFC8415]  Mrugalski, T., Siodelski, M., Volz, B., Yourtchenko, A.,
              Richardson, M., Jiang, S., Lemon, T., and T. Winters,
              "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)",
              RFC 8415, DOI 10.17487/RFC8415, November 2018,
              <https://www.rfc-editor.org/info/rfc8415>.

8.2.  Informative References

   [RFC3319]  Schulzrinne, H. and B. Volz, "Dynamic Host Configuration
              Protocol (DHCPv6) Options for Session Initiation Protocol
              (SIP) Servers", RFC 3319, DOI 10.17487/RFC3319, July 2003,
              <https://www.rfc-editor.org/info/rfc3319>.

Appendix A.  Example of Augmenting Additional DHCPv6 Option Definitions

   The following section provides a example of how the DHCPv6 option
   definitions can be extended for additional options.  It is expected
   that additional specification documents will be published in the
   future for this.

   The example defines YANG models for OPTION_SIP_SERVER_D (21) and
   OPTION_SIP_SERVER_D (22) defined in [RFC3319].  The overall structure
   is as follows:

   *  A separate grouping is used for each option.

   *  The name of the option is taken from the registered IANA name for
      the option, with an '-option' suffix added.

   *  The description field is taken from the relevant option code name
      and number.

   *  The reference section is the number and name of the RFC in which
      the DHCPv6 option is defined.

   *  The remaining fields match the fields in the DHCP option.  They
      are in the same order as defined in the DHCP option.  Where-ever
      possible, the format that is defined for the DHCP field should be
      matched by the relevant YANG type.

   *  Fields which can have multiple entries or instances are defined
      using list or leaf-list nodes.

   Below the groupings for option definitions, augment statements are
   used to add the option definitions for use in the relevant DHCP
   element's module (server, relay and/or client).  If an option is
   relevant to more than one element type, then an augment statement for
   each element is used.



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   <CODE BEGINS> file example-dhcpv6-options-rfc3319-server.yang

   module example-dhcpv6-options-rfc3319 {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:example-dhcpv6-options-rfc33
   19";
     prefix "rfc3319";

     import ietf-inet-types {
       prefix inet;
     }

     import ietf-dhcpv6-server {
       prefix dhcpv6-server;
     }

     organization "DHC WG";
     contact
       "ian.farrer@telekom.de
       godfryd@isc.org";

     description "This YANG module contains DHCPv6 options defined
       in RFC3319 that can be used by DHCPv6 servers.";

     revision 2020-12-01 {
       description "Version update for draft -12 publication.";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang-12";
     }

     revision 2020-05-26 {
       description "Version update for draft -11 publication and
         to align revisions across the different modules.";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang-11";
     }

     revision 2019-10-18 {
       description "Initial version.";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang";
     }

     /*
      * Groupings
      */

     grouping sip-server-domain-name-list-option-group {
       container sip-server-domain-name-list-option {
         description "OPTION_SIP_SERVER_D (21) SIP Servers Domain Name
           List";



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         reference "RFC3319: Dynamic Host Configuration Protocol
           (DHCPv6) Options for Session Initiation Protocol (SIP)
           Servers";
         list sip-server {
           key sip-serv-id;
           description "sip server info";
           leaf sip-serv-id {
             type uint8;
             description "sip server id";
           }
           leaf sip-serv-domain-name {
             type inet:domain-name;
             description "sip server domain name";
           }
         }
       }
     }

     grouping sip-server-address-list-option-group {
       container sip-server-address-list-option {
         description "OPTION_SIP_SERVER_A (22) SIP Servers IPv6 Address
           List";
         reference "RFC3319: Dynamic Host Configuration Protocol
           (DHCPv6) Options for Session Initiation Protocol (SIP)
           Servers";
         list sip-server {
           key sip-serv-id;
           description "sip server info";
           leaf sip-serv-id {
             type uint8;
             description "sip server id";
           }
           leaf sip-serv-addr {
             type inet:ipv6-address;
             description "sip server addr";
           }
         }
       }
     }

     /*
      * Augmentations
      */

     augment "/dhcpv6-server:dhcpv6-server/dhcpv6-server:option-sets/dhc
   pv6-server:option-set" {
       when "../../../dhcpv6-server:dhcpv6-node-type='dhcpv6-server:serv
   er'";



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       uses sip-server-domain-name-list-option-group;
       uses sip-server-address-list-option-group;
     }
   }
   <CODE ENDS>

   The correct location to augment the new option definition(s) will
   vary according to the specific rules defined for the use of that
   specific option.  E.g. for options which will be augmented into the
   ietf-dhcpv6-server module, in many cases, these will be augmented to:

   '/dhcpv6-server:dhcpv6-server/dhcpv6-server:option-sets/\ dhcpv6-
   server:option-set'

   so that they can be defined within option sets.  However, there are
   some options which are only applicable for specific deployment
   scenarios and in these cases it may be more logical to augment the
   option group to a location relevant for the option.

   One example for this could be OPTION_PD_EXCLUDE (67).  This option is
   only relevant in combination with a delegated prefix which contains a
   specific prefix.  In this case, the following location for the
   augmentation may be more suitable:

   '/dhcpv6-server:dhcpv6-server/dhcpv6-server:network-ranges/\ dhcpv6-
   server:network-range/dhcpv6-server:prefix-pools/\ dhcpv6-
   server:prefix-pool"

Appendix B.  Example Vendor Specific Server Configuration Module

   This section shows how to extend the server YANG module defined in
   this document with vendor specific configuration nodes, e.g.,
   configuring access to a lease storage database.

   The example module defines additional server attributes such as name
   and description.  Storage for leases is configured using a lease-
   storage container.  It allows storing leases in one of three options:
   memory (memfile), MySQL and PosgreSQL.  For each case, the necessary
   configuration parameters are provided.

   At the end there is an augment statement which adds the vendor
   specific configuration defined in "dhcpv6-server-config:config" under
   '/dhcpv6-server:config/dhcpv6-server:vendor-config' mount point.








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   <CODE BEGINS> file example-dhcpv6-server-config.yang

   module example-dhcpv6-server-config {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:example-dhcpv6-server-config
   ";
     prefix "dhcpv6-server-config";

     import ietf-inet-types {
       prefix inet;
     }

     import ietf-interfaces {
       prefix if;
     }

     import ietf-dhcpv6-server {
       prefix dhcpv6-server;
     }

     organization "DHC WG";
     contact
       "cuiyong@tsinghua.edu.cn
       lh.sunlinh@gmail.com
       ian.farrer@telekom.de
       sladjana.zechlin@telekom.de
       hezihao9512@gmail.com";

     description "This YANG module defines components for the
       configuration and management of vendor/implementation specific
       DHCPv6 server functionality. As this functionality varies
       greatly between different implementations, the module
       provided as an example only.";

     revision 2020-12-01 {
       description "Version update for draft -12 publication.";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang-12";
     }

     revision 2020-05-26 {
       description "Version update for draft -11 publication and
         to align revisions across the different modules.";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang-11";
     }

     revision 2019-06-04 {
       description "";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang";



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     }

     /*
      * Groupings
      */

     grouping config {
       description "Parameters necessary for the configuration of a
         DHCPv6 server";
       container serv-attributes {
         description "Contains basic attributes necessary for running a
           DHCPv6 server.";
         leaf name {
           type string;
           description "Name of the DHCPv6 server.";
         }
         leaf description {
           type string;
           description "Description of the DHCPv6 server.";
         }
         leaf ipv6-listen-port {
           type uint16;
           default 547;
           description "UDP port that the server will listen on.";
         }
         choice listening-interfaces {
           default all-interfaces;
           description "Configures which interface or addresses the
             server will listen for incoming messages on.";
           case all-interfaces {
             container all-interfaces {
             presence true;
             description "Configures the server to listen for
               incoming messages on all IPv6 addresses (unicats and
               multicast) on all of its network interfaces.";
             }
           }
           case interface-list {
             leaf-list interfaces {
               type if:interface-ref;
               description "List of interfaces that the server will
                 listen for incoming messages on. Messages addressed
                 to any valid IPv6 address (unicast and multicast) will
                 be received.";
             }
           }
           case address-list {
             leaf-list address-list {



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               type inet:ipv6-address;
               description "List of IPv6 address(es) that the server
                 will listen for incoming messages on.";
             }
           }
         }
         leaf-list interfaces-config {
           type if:interface-ref;
           default "if:interfaces/if:interface/if:name";
           description "A leaf list to denote which one or more
             interfaces the server should listen on.";
         }
         container lease-storage {
           description "Configures how the server will stores leases.";
           choice storage-type {
             description "The type storage that will be used for lease
               information.";
             case memfile {
               description "Configuration for storing leases information
                 in a CSV file.";
               leaf memfile-name {
                 type string;
                 description "Specifies the absolute location
                   of the lease file. The format of the string follow
                   the semantics of the relevant operating system.";
               }
               leaf memfile-lfc-interval {
                 type uint64;
                 description "Specifies the interval in seconds,
                   at which the server will perform a lease file cleanup
                   (LFC).";
               }
             }
             case mysql {
               leaf mysql-name {
                 type string;
                 description "Name of the database.";
               }
               choice mysql-host {
                 case mysql-server-hostname {
                   leaf mysql-hostname {
                     type inet:domain-name;
                     default "localhost";
                     description "If the database is located on a
                       different system to the DHCPv6 server, the
                         domain name can be specified.";
                   }
                 }



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                 case mysql-server-address {
                   leaf mysql-address {
                     type inet:ip-address;
                     default "::";
                     description "Configure the location of the
                       database using an IP (v6 or v6) literal
                       address";
                   }
                 }
               }
               leaf mysql-username {
                 type string;
                 description "User name of the account under which the
                   server will access the database.";
               }
               leaf mysql-password {
                 type string;
                 description "Password of the account under which
                   the server will access the database.";
               }
               leaf mysql-port {
                 type inet:port-number;
                 default 5432;
                 description "If the database is located on a different
                   system, the port number may be specified.";
               }
               leaf mysql-lfc-interval {
                 type uint64;
                 description "Specifies the interval in seconds,
                   at which the server will perform a lease file cleanup
                   (LFC).";
               }
               leaf mysql-connect-timeout {
                 type uint64;
                 description "Defines the timeout interval for
                   connecting to the database. A longer interval can
                   be specified if the database is remote.";
               }
             }
             case postgresql {
               choice postgresql-host {
                 case postgresql-server-hostname {
                   leaf postgresql-hostname {
                     type inet:domain-name;
                     default "localhost";
                     description "If the database is located on a
                       different system to the DHCPv6 server, the
                       domain name can be specified.";



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                   }
                 }
                 case postgresql-server-address {
                   leaf postgresql-address {
                     type inet:ip-address;
                     default "::";
                     description "Configure the location of the database
                       using an IP (v6 or v6) literal address";
                   }
                 }
               }
               leaf postgresql-username {
                 type string;
                 description "User name of the account under which
                   the server will access the database";
               }
               leaf postgresql-password {
                 type string;
                 description "Password of the account under which
                   the server will access the database";
               }
               leaf postgresql-port {
                 type inet:port-number;
                 default 5432;
                 description "If the database is located on a different
                   system, the port number may be specified";
               }
               leaf postgresql-lfc-interval {
                 type uint64;
                 description "Specifies the interval in seconds,
                   at which the server will perform a lease file cleanup
                   (LFC)";
               }
               leaf postgresql-connect-timeout {
                 type uint64;
                 description "Defines the timeout interval for
                   connecting to the database. A longer interval can
                   be specified if the database is remote.";
               }
             }
           }
         }
       }
     }

     /*
      * Augmentations
      */



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     augment "/dhcpv6-server:dhcpv6-server/dhcpv6-server:vendor-config"
   {
       uses dhcpv6-server-config:config;
     }
   }
   <CODE ENDS>

Appendix C.  Example definition of class selector configuration

   The module "example-dhcpv6-class-selector" provides an example of how
   vendor specific class selection configuration can be modelled and
   integrated with the "ietf-dhcpv6-server" module defined in this
   document.

   The example module defines "client-class-names" with associated
   matching rules.  A client can be classified based on "client-id",
   "interface-id" (ingress interface of the client's messages), packets
   source or destination address, relay link address, relay link
   interface-id and more.  Actually, there are endless methods for
   classifying clients.  So this standard does not try to provide full
   specification for class selection, it only shows an example how it
   can be defined.

   At the end of the example augment statements are used to add the
   defined class selector rules into the overall DHCPv6 addressing
   hierarchy.  This is done in two main parts:

   *  The augmented class-selector configuration in the main DHCPv6
      Server configuration.

   *  client-class leafrefs augmented to "network-range", "address-pool"
      and "pd-pool", pointing to the "client-class-name" that is
      required.

   The mechanism is as follows: class is associated to client based on
   rules and then client is allowed to get address(es)/prefix(es) from
   given network-range/pool if the class name matches.

   <CODE BEGINS> file example-dhcpv6-class-selector.yang

   module example-dhcpv6-class-selector {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:example-dhcpv6-class-selecto
   r";
     prefix "dhcpv6-class-selector";

     import ietf-inet-types {
       prefix inet;



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     }

     import ietf-interfaces {
       prefix if;
     }

     import ietf-dhcpv6-common {
       prefix dhcpv6-common;
     }

     import ietf-dhcpv6-server {
       prefix dhcpv6-server;
     }

     organization "DHC WG";
     contact
       "yong@csnet1.cs.tsinghua.edu.cn
       lh.sunlinh@gmail.com
       ian.farrer@telekom.de
       sladjana.zechlin@telekom.de
       hezihao9512@gmail.com";

     description "This YANG module defines components for the definition
       and configuration of the client class selector function for a
       DHCPv6 server.  As this functionality varies greatly between
       different implementations, the module provided as an example
       only.";

     revision 2020-12-01 {
       description "Version update for draft -12 publication.";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang-12";
     }

     revision 2020-05-26 {
       description "Version update for draft -11 publication and
         to align revisions across the different modules.";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang-11";
     }

     revision 2019-06-13 {
       description "";
       reference "I-D: draft-ietf-dhc-dhcpv6-yang";
     }

     /*
      * Groupings
      */




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     grouping client-class-id {
       description "Definitions of client message classification for
         authorization and assignment purposes.";
       leaf client-class-name {
         type string;
         description "Unique Identifier for client class identification
           list entries.";
       }
       choice id-type {
         description "Definitions for different client identifier
           types.";
         mandatory true;
         case client-id-id {
           description "Client class selection based on a string literal
             client identifier.";
           leaf client-id {
             description "String literal client identifier.";
             mandatory true;
             type string;
           }
         }
         case received-interface-id {
           description "Client class selection based on the incoming
             interface of the DHCPv6 message.";
           leaf received-interface {
             description "Reference to the interface entry
               for the incoming DHCPv6 message.";
             type if:interface-ref;
           }
         }
         case packet-source-address-id {
           description "Client class selection based on the source
             address of the DHCPv6 message.";
           leaf packet-source-address {
             description "Source address of the DHCPv6 message.";
             mandatory true;
             type inet:ipv6-address;
           }
         }
         case packet-destination-address-id {
           description "Client class selection based on the destination
             address of the DHCPv6 message.";
           leaf packet-destination-address {
             description "Destination address of the DHCPv6 message.";
             mandatory true;
             type inet:ipv6-address;
           }
         }



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         case relay-link-address-id {
           description "Client class selection based on the prefix
             of the link-address field in the relay agent message
             header.";
           leaf relay-link-address {
             description "Prefix of the link-address field in the relay
               agent message header.";
             mandatory true;
             type inet:ipv6-prefix;
           }
         }
         case relay-peer-address-id {
           description "Client class selection based on the value of the
             peer-address field in the relay agent message header.";
           leaf relay-peer-address {
             description "Prefix of the peer-address field
               in the relay agent message header.";
             mandatory true;
             type inet:ipv6-prefix;
           }
         }
         case relay-interface-id {
           description "Client class selection based on the incoming
             interface-id option.";
           leaf relay-interface {
             description "Reference to the interface entry
               for the incoming DHCPv6 message.";
             type string;
           }
         }
         case user-class-option-id {
           description "Client class selection based on the value of the
             OPTION_USER_CLASS(15) and its user-class-data field.";
           leaf user-class-data {
             description "Value of the enterprise-number field.";
             mandatory true;
             type string;
           }
         }
         case vendor-class-present-id {
           description "Client class selection based on the presence of
             OPTION_VENDOR_CLASS(16) in the received message.";
           leaf vendor-class-present {
             description "Presence of OPTION_VENDOR_CLASS(16)
               in the received message.";
             mandatory true;
             type boolean;
           }



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         }
         case vendor-class-option-enterprise-number-id {
           description "Client class selection based on the value of the
             enterprise-number field in OPTION_VENDOR_CLASS(16).";
           leaf vendor-class-option-enterprise-number {
             description "Value of the enterprise-number field.";
             mandatory true;
             type uint32;
           }
         }
         case vendor-class-option-data-id {
           description "Client class selection based on the value
             of a data field within a vendor-class-data entry
             for a matching enterprise-number field
             in OPTION_VENDOR_CLASS(16).";
           container vendor-class-option-data {
             leaf vendor-class-option-enterprise-number {
               description "Value of the enterprise-number field
                 for matching the data contents.";
               mandatory true;
               type uint32;
             }
             leaf vendor-class-data {
               description "Vendor class data to match.";
               mandatory true;
               type string;
             }
           }
         }
         case remote-id {
           description "Client class selection based on the value
             of Remote-ID .";
           container remote-id {
             leaf vendor-class-option-enterprise-number {
               description "Value of the enterprise-number field
                 for matching the data contents.";
               mandatory true;
               type uint32;
             }
             leaf remote-id {
               description "Remote-ID data to match.";
               mandatory true;
               type string;
             }
           }
         }
         case client-duid-id {
           description "Client class selection based on the value



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             of the received client DUID.";
           uses dhcpv6-common:duid;
         }
       }
     }

     /*
      * Augmentations
      */

     augment "/dhcpv6-server:dhcpv6-server/dhcpv6-server:class-selector"
    {
       container client-classes {
         list class {
           description "List of the client class identifiers applicable
             to clients served by this address pool";
           key client-class-name;
           uses dhcpv6-class-selector:client-class-id;
         }
       }
     }

     augment "/dhcpv6-server:dhcpv6-server/dhcpv6-server:network-ranges/
   dhcpv6-server:network-range" {
       leaf-list client-class {
         type leafref {
           path "/dhcpv6-server:dhcpv6-server/dhcpv6-server:class-select
   or/client-classes/class/client-class-name";
         }
       }
     }

     augment "/dhcpv6-server:dhcpv6-server/dhcpv6-server:network-ranges/
   dhcpv6-server:network-range/dhcpv6-server:address-pools/dhcpv6-server
   :address-pool" {
       leaf-list client-class {
         type leafref {
           path "/dhcpv6-server:dhcpv6-server/dhcpv6-server:class-select
   or/client-classes/class/client-class-name";
         }
       }
     }

     augment "/dhcpv6-server:dhcpv6-server/dhcpv6-server:network-ranges/
   dhcpv6-server:network-range/dhcpv6-server:prefix-pools/dhcpv6-server:
   prefix-pool" {
       leaf-list client-class {
         type leafref {



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           path "/dhcpv6-server:dhcpv6-server/dhcpv6-server:class-select
   or/client-classes/class/client-class-name";
         }
       }
     }
   }
   <CODE ENDS>

Authors' Addresses

   Yong Cui
   Tsinghua University
   Beijing
   100084
   P.R. China

   Phone: +86-10-6260-3059
   Email: cuiyong@tsinghua.edu.cn


   Linhui Sun
   Tsinghua University
   Beijing
   100084
   P.R. China

   Phone: +86-10-6278-5822
   Email: lh.sunlinh@gmail.com


   Ian Farrer
   Deutsche Telekom AG
   TAI, Landgrabenweg 151
   53227 Bonn
   Germany

   Email: ian.farrer@telekom.de


   Sladjana Zechlin
   Deutsche Telekom AG
   CTO-IPT, Landgrabenweg 151
   53227 Bonn
   Germany

   Email: sladjana.zechlin@telekom.de





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   Zihao He
   Tsinghua University
   Beijing
   100084
   P.R. China

   Phone: +86-10-6278-5822
   Email: hezihao9512@gmail.com


   Michal Nowikowski
   Internet Systems Consortium
   Gdansk
   Poland

   Email: godfryd@isc.org



































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