YANG Modules for IPv4-in-IPv6 Address plus Port (A+P) Softwires
draft-ietf-softwire-yang-12

The information below is for an old version of the document
Document Type Active Internet-Draft (softwire WG)
Last updated 2018-11-04
Replaces draft-sun-softwire-yang
Stream IETF
Intended RFC status Proposed Standard
Formats plain text pdf html bibtex
Stream WG state Submitted to IESG for Publication
Document shepherd Sheng Jiang
Shepherd write-up Show (last changed 2018-08-21)
IESG IESG state Waiting for Writeup
Consensus Boilerplate Yes
Telechat date
Responsible AD Terry Manderson
Send notices to Sheng Jiang <jiangsheng@huawei.com>
IANA IANA review state Version Changed - Review Needed
IANA action state None
Softwire Working Group                                            Y. Cui
Internet-Draft                                       Tsinghua University
Intended status: Standards Track                          I. Farrer, Ed.
Expires: May 9, 2019                                 Deutsche Telekom AG
                                                       M. Boucadair, Ed.
                                                                  Orange
                                                                  Q. Sun
                                                                  L. Sun
                                                     Tsinghua University
                                                              S. Zechlin
                                                     Deutsche Telekom AG
                                                                R. Asati
                                                     Cisco Systems, Inc.
                                                        November 5, 2018

    YANG Modules for IPv4-in-IPv6 Address plus Port (A+P) Softwires
                      draft-ietf-softwire-yang-12

Abstract

   This document defines YANG modules for the configuration and
   operation of IPv4-in-IPv6 softwire Border Relays and Customer
   Premises Equipment for the Lightweight 4over6, Mapping of Address and
   Port with Encapsulation (MAP-E), and Mapping of Address and Port
   using Translation (MAP-T) softwire mechanisms.  It also contains the
   initial version of an IANA-maintained YANG module identifying tunnel
   types.

Editorial Note (To be removed by RFC Editor)

   Please update these statements within this document with the RFC
   number to be assigned to this document:

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

   o  "RFC XXXX: YANG Modules for IPv4-in-IPv6 Address plus Port
      Softwires";

   o  "reference: RFC XXXX"

   Please update the "revision" date of the YANG modules.

Status of This Memo

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

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   This Internet-Draft will expire on May 9, 2019.

Copyright Notice

   Copyright (c) 2018 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
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   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
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Overview of the Modules . . . . . . . . . . . . . . . . . . .   4
     3.1.  Overall Structure . . . . . . . . . . . . . . . . . . . .   4
     3.2.  Additional Components Configuration . . . . . . . . . . .   5
   4.  Softwire CE YANG Tree Diagram . . . . . . . . . . . . . . . .   6
     4.1.  CE Tree Diagram . . . . . . . . . . . . . . . . . . . . .   6
     4.2.  Softwire CE Tree Diagram Description  . . . . . . . . . .   8
   5.  Softwire BR YANG Tree Diagram . . . . . . . . . . . . . . . .   9
     5.1.  BR Tree Diagram . . . . . . . . . . . . . . . . . . . . .   9
     5.2.  Softwire BR Tree Diagram Description  . . . . . . . . . .  13
   6.  IANA Tunnel Type YANG Module  . . . . . . . . . . . . . . . .  13
   7.  Softwire CE YANG Module . . . . . . . . . . . . . . . . . . .  17
   8.  BR Softwire YANG Module . . . . . . . . . . . . . . . . . . .  23
   9.  Common Softwire Element Groups YANG Module  . . . . . . . . .  35
   10. Security Considerations . . . . . . . . . . . . . . . . . . .  44
   11. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  44
   12. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  46
   13. Contributors  . . . . . . . . . . . . . . . . . . . . . . . .  46

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   14. References  . . . . . . . . . . . . . . . . . . . . . . . . .  46
     14.1.  Normative References . . . . . . . . . . . . . . . . . .  46
     14.2.  Informative References . . . . . . . . . . . . . . . . .  48
   Appendix A.  Configuration Examples . . . . . . . . . . . . . . .  49
     A.1.  Configuration Example for a lw4o6 BR Binding-Table  . . .  49
     A.2.  Configuration Example for a MAP-E BR  . . . . . . . . . .  50
     A.3.  lw4o6 CE Configuration Example  . . . . . . . . . . . . .  51
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  55

1.  Introduction

   The IETF softwire working group has developed several IPv4-in-IPv6
   softwire mechanisms to address various deployment contexts and
   constraints.  As a companion to the architectural specification
   documents, this document focuses on the provisioning of address plus
   port (A+P) softwire functional elements: Border Routers (BRs) and
   Customer Premises Equipment (CEs, a.k.a., CPE).  The softwire
   mechanisms covered in this document are Lightweight 4 over 6 (lw4o6)
   [RFC7596], Mapping of Address and Port with Encapsulation (MAP-E)
   [RFC7597], and Mapping of Address and Port using Translation (MAP-T)
   [RFC7599].

   This document focuses on A+P mechanisms; the reader can refer to
   [I-D.ietf-softwire-dslite-yang] for a YANG module for DS-Lite
   [RFC6333].

   This document defines YANG modules [RFC7950] that can be used to
   configure and manage A+P softwire elements using the NETCONF protocol
   [RFC6241] for:

   o  Configuration

   o  Operational State

   o  Notifications

2.  Terminology

   The reader should be familiar with the concepts and terms defined in
   [RFC7596], [RFC7597], [RFC7599], and the YANG data modelling language
   defined in [RFC7950].

   The adopts the Network Management Datastore Architecture (NMDA)
   [RFC8342].  The meaning of the symbols in tree diagrams is defined in
   [RFC8340].

   The document uses the abbrieviation 'BR' as a general term for
   softwire tunnel concentrators, including both MAP Border Routers

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   [RFC7597] and Lightweight 4over6 lWAFTRs [RFC7596].

   For brevity, "algorithm" is used to refer to the "mapping algorithm"
   defined in [RFC7597].

   A network element may support one or multiple instances of a softwire
   mechanism; each of these instances (i.e., binding instances, MAP-E
   instances, or MAP-T instances) may have its own configuration and
   parameters.  The term 'algo-instance' is used to denote both MAP-E
   and MAP-T instances.

3.  Overview of the Modules

3.1.  Overall Structure

   This document specifies the initial version of an IANA-maintained
   module (iana-tunnel-type) to identify a collection of tunnel types
   assigned by IANA (Section 6) [RFC4087][RFC7870][RFC7856].

   Moreover, the document defines the following two YANG modules for the
   configuration and monitoring of softwire functional elements:

   ietf-softwire-ce      Provides configuration and monitoring for
                         softwire CE element.  This module is defined as
                         augments to the interface YANG module
                         [RFC8343].

   ietf-softwire-br      Provides configuration and monitoring for
                         softwire BR element.

   In addition, the following module is defined:

   ietf-softwire-common  Contains groups of common functions that are
                         imported into the CE and BR modules.

   This approach has been taken so that the various modules can be
   easily extended to support additional softwire mechanisms, if
   required.

   Within the BR and CE modules, the YANG "feature" statement is used to
   distinguish which of the different softwire mechanism(s) is relevant
   for a specific element's configuration.  For each module, a choice
   statement 'ce-type' is included for either 'binding' or 'algorithm'.
   'Binding' is used for configuring Lightweight 4over6, whereas
   'algorithm' is used for configuring MAP-T or MAP-E.

   In the 'algo-instances' container, a choice statement 'data-plane' is
   included to specify MAP-E (encapsulation) or MAP-T (translation).

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   Table 1 shows how these choices are used to indicate the desired
   softwire mechanism:

            +--------------------+-----------+---------------+
            |   S46 Mechanism    |  ce-type? |  data-plane?  |
            +--------------------+-----------+---------------+
            | Lightweight 4over6 |  binding  |      n/a      |
            |       MAP-E        | algorithm | encapsulation |
            |       MAP-T        | algorithm |  translation  |
            +--------------------+-----------+---------------+

         Table 1: Softwire Mechanism Choice Statement Enumeration

   NETCONF notifications are also included.

      Note: Earlier versions of this specification combined the softwire
      mechanisms by their associated technologies rather than their
      function in the architecture.  As the document was revised, it
      became apparent that dividing the modules by their role in the
      architecture (CE or BR) was a better approach as this follows the
      intended function and existing implementation approaches more
      closely.

3.2.  Additional Components Configuration

   The softwire modules only aim to provide configuration relevant for
   softwires.  In order to fully provision a CE element, the following
   may also be necessary:

   o  IPv6 forwarding and routing configuration, enabling the CE to
      obtain one or more IPv6 prefixes for softwire usage.  A YANG
      module for routing management is described in [RFC8349].

   o  IPv4 routing configuration, to add one or more IPv4 destination
      prefix(es) reachable via the configured softwire.  A YANG module
      for routing management is described in [RFC8349].

   o  Stateful NAT44/NAPT management, to optionally specify a port set
      (Port Set Identifier (PSID)) along with its length.  A YANG module
      for NAT management is described in [I-D.ietf-opsawg-nat-yang].

   o  Stateless NAT46 management, required by softwire translation based
      mechanisms (i.e., the assignment of a Network-Specific Prefix to
      use for IPv4/IPv6 translation).  A YANG module for NAT management
      is described in [I-D.ietf-opsawg-nat-yang].

   As YANG modules for the above functions are already defined in other
   documents, their functionality is not duplicated here and they should

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   be referred to, as needed.  Appendix A.3 provides XML examples of how
   these modules can be used together.

   The CE must already have minimal IPv6 configuration in place so it is
   reachable by the NETCONF client to obtain softwire configuration.  If
   additional IPv6 specific configuration is necessary, the YANG modules
   defined in [RFC8344] and [RFC8349] may be used.

4.  Softwire CE YANG Tree Diagram

4.1.  CE Tree Diagram

   The CE module provides configuration and monitoring for all of the
   softwire mechanisms covered in this document (i.e., Lightweight
   4over6, MAP-E, and MAP-T).

   This module augments "ietf-interfaces", defined in [RFC8343] with an
   entry for the softwire.  This entry can be referenced to configure
   IPv4 forwarding features for the element.  This entry is added only
   if tunnel type (Section 11) is set to 'aplusp'.

   Figure 1 shows the tree structure of the softwire CE YANG module:

     module: ietf-softwire-ce
       augment /if:interfaces/if:interface:
         +--rw softwire-payload-mtu?   uint16
         +--rw softwire-path-mru?      uint16
         +--rw (ce-type)?
            +--:(binding) {binding-mode}?
            |  +--rw binding-ipv6info?       union
            |  +--rw br-ipv6-addr            inet:ipv6-address
            +--:(algo) {map-e or map-t}?
               +--rw algo-instances
                  +--rw algo-instance* [name]
                     +--rw name                string
                     +--rw enable?             boolean
                     +--rw algo-versioning
                     |  +--rw version?   uint64
                     |  +--rw date?      yang:date-and-time
                     +--rw (data-plane)?
                     |  +--:(encapsulation) {map-e}?
                     |  |  +--rw br-ipv6-addr        inet:ipv6-address
                     |  +--:(translation) {map-t}?
                     |     +--rw dmr-ipv6-prefix?    inet:ipv6-prefix
                     +--rw ea-len              uint8
                     +--rw rule-ipv6-prefix    inet:ipv6-prefix
                     +--rw rule-ipv4-prefix    inet:ipv4-prefix
                     +--rw forwarding          boolean

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       augment /if:interfaces/if:interface/if:statistics:
            +--ro sent-ipv4-packets?
            |       yang:zero-based-counter64
            +--ro sent-ipv4-bytes?
            |       yang:zero-based-counter64
            +--ro sent-ipv6-packets?
            |       yang:zero-based-counter64
            +--ro sent-ipv6-bytes?
            |       yang:zero-based-counter64
            +--ro rcvd-ipv4-packets?
            |       yang:zero-based-counter64
            +--ro rcvd-ipv4-bytes?
            |       yang:zero-based-counter64
            +--ro rcvd-ipv6-packets?
            |       yang:zero-based-counter64
            +--ro rcvd-ipv6-bytes?
            |       yang:zero-based-counter64
            +--ro dropped-ipv4-packets?
            |       yang:zero-based-counter64
            +--ro dropped-ipv4-bytes?
            |       yang:zero-based-counter64
            +--ro dropped-ipv6-packets?
            |       yang:zero-based-counter64
            +--ro dropped-ipv6-bytes?
            |       yang:zero-based-counter64
            +--ro dropped-ipv4-fragments?
            |       yang:zero-based-counter64
            +--ro dropped-ipv4-fragment-bytes?
            |       yang:zero-based-counter64
            +--ro ipv6-fragments-reassembled?
            |       yang:zero-based-counter64
            +--ro ipv6-fragments-bytes-reassembled?
            |       yang:zero-based-counter64
            +--ro out-icmpv4-error-packets?
            |       yang:zero-based-counter64
            +--ro out-icmpv4-error-bytes?
            |       yang:zero-based-counter64
            +--ro out-icmpv6-error-packets?
            |       yang:zero-based-counter64
            +--ro out-icmpv6-error-bytes?
                    yang:zero-based-counter64

       notifications:
         +---n softwire-ce-event {binding-mode}?
            +--ro ce-binding-ipv6-addr-change    inet:ipv6-address

                  Figure 1: Softwire CE YANG Tree Diagram

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4.2.  Softwire CE Tree Diagram Description

   Additional information related to the operation of a CE element is
   provided below:

   o  softwire-payload-mtu: optionally used to set the IPv4 MTU for the
      softwire.  Needed if the softwire implementation is unable to
      correctly calculate the correct IPv4 Maximum Transit Unit (MTU)
      size automatically.

   o  softwire-path-mru: optionally used to set the maximum IPv6
      softwire packet size that can be received, including the
      encapsulation/translation overhead.  Needed if the softwire
      implementation is unable to correctly calculate the correct IPv4
      Maximum Receive Unit (MRU) size automatically [RFC4213].

   o  ce-type: provides a choice statement allowing the binding or
      algorithmic softwire mechanisms to be selected.

   Further details relevant to binding softwire elements are:

   o  binding-ipv6info: used to set the IPv6 binding prefix type to
      identify which IPv6 address to use as the tunnel source.  It can
      be 'ipv6-prefix' or 'ipv6-address'.

   o  br-ipv6-addr: sets the IPv6 address of the remote BR.

   Additional details relevant to some of the important algorithmic
   elements are provided below:

   o  algo-versioning: optionally used to associate a version number
      and/or timestamp to the algorithm.  This can be used for logging/
      data retention purposes [RFC7422].  The version number is selected
      to uniquely identify the algorithm configuration and a new value
      written whenever a change is made to the algorithm or a new algo-
      instance is created.

   o  forwarding: specifies whether the rule can be used as a Forward
      Mapping Rule (FMR).  If not set, this rule is a Basic Mapping Rule
      (BMR) only and must not be used for forwarding.  Refer to
      Section 4.1 of [RFC7598].

   o  ea-len: used to set the length of the Embedded-Address (EA), which
      is defined in the mapping rule for a MAP domain.

   o  data-plane: provides a choice statement for either encapsulation
      (MAP-E) or translation (MAP-T).

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   o  br-ipv6-addr: defines the IPv6 address of the BR.  This
      information is valid for MAP-E.

   o  dmr-ipv6-prefix: defines the Default Mapping Rule (DMR) IPv6
      prefix of the BR.  This information is valid for MAP-T.

   Additional information on the notification node is listed below:

   o  ce-binding-ipv6-addr-change: if the CE's binding IPv6 address
      changes for any reason, the NETCONF client will be notified.

5.  Softwire BR YANG Tree Diagram

5.1.  BR Tree Diagram

   The BR YANG module provides configuration and monitoring for all of
   the softwire mechanisms covered in this document (i.e., Lightweight
   4over6, MAP-E, and MAP-T).

   Figure 2 provides the tree structure of this module:

 module: ietf-softwire-br
     +--rw br-instances
        +--rw (br-type)?
           +--:(binding) {binding-mode}?
           |  +--rw binding
           |     +--rw bind-instance* [name]
           |        +--rw name                       string
           |        +--rw binding-table-versioning
           |        |  +--rw version?   uint64
           |        |  +--rw date?      yang:date-and-time
           |        +--rw softwire-num-max      uint32
           |        +--rw softwire-payload-mtu       uint16
           |        +--rw softwire-path-mru           uint16
           |        +--rw enable-hairpinning?         boolean
           |        +--rw binding-table
           |        |  +--rw binding-entry* [binding-ipv6info]
           |        |     +--rw binding-ipv6info     union
           |        |     +--rw binding-ipv4-addr?
           |        |     |       inet:ipv4-address
           |        |     +--rw port-set
           |        |     |  +--rw psid-offset?   uint8
           |        |     |  +--rw psid-len       uint8
           |        |     |  +--rw psid           uint16
           |        |     +--rw br-ipv6-addr?
           |        |             inet:ipv6-address
           |        +--rw icmp-policy
           |        |  +--rw icmpv4-errors

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           |        |  |  +--rw allow-incoming-icmpv4?    boolean
           |        |  |  +--rw icmpv4-rate?              uint32
           |        |  |  +--rw generate-icmpv4-errors?   boolean
           |        |  +--rw icmpv6-errors
           |        |     +--rw generate-icmpv6-errors?   boolean
           |        |     +--rw icmpv6-rate?              uint32
           |        +--ro traffic-stat
           |           +--ro discontinuity-time       yang:date-and-time
           |           +--ro sent-ipv4-packets?
           |           |       yang:zero-based-counter64
           |           +--ro sent-ipv4-bytes?
           |           |       yang:zero-based-counter64
           |           +--ro sent-ipv6-packets?
           |           |       yang:zero-based-counter64
           |           +--ro sent-ipv6-bytes?
           |           |       yang:zero-based-counter64
           |           +--ro rcvd-ipv4-packets?
           |           |       yang:zero-based-counter64
           |           +--ro rcvd-ipv4-bytes?
           |           |       yang:zero-based-counter64
           |           +--ro rcvd-ipv6-packets?
           |           |       yang:zero-based-counter64
           |           +--ro rcvd-ipv6-bytes?
           |           |       yang:zero-based-counter64
           |           +--ro dropped-ipv4-packets?
           |           |       yang:zero-based-counter64
           |           +--ro dropped-ipv4-bytes?
           |           |       yang:zero-based-counter64
           |           +--ro dropped-ipv6-packets?
           |           |       yang:zero-based-counter64
           |           +--ro dropped-ipv6-bytes?
           |           |       yang:zero-based-counter64
           |           +--ro dropped-ipv4-fragments?
           |           |       yang:zero-based-counter64
           |           +--ro dropped-ipv4-fragment-bytes?
           |           |       yang:zero-based-counter64
           |           +--ro ipv6-fragments-reassembled?
           |           |       yang:zero-based-counter64
           |           +--ro ipv6-fragments-bytes-reassembled?
           |           |       yang:zero-based-counter64
           |           +--ro out-icmpv4-error-packets?
           |           |       yang:zero-based-counter64
           |           +--ro out-icmpv4-error-bytes?
           |           |       yang:zero-based-counter64
           |           +--ro out-icmpv6-error-packets?
           |           |       yang:zero-based-counter64
           |           +--ro out-icmpv6-error-bytes?
           |           |       yang:zero-based-counter64

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           |           +--ro dropped-icmpv4-packets?
           |           |       yang:zero-based-counter64
           |           +--ro dropped-icmpv4-bytes?
           |           |       yang:zero-based-counter64
           |           +--ro hairpin-ipv4-packets?
           |           |       yang:zero-based-counter64
           |           +--ro hairpin-ipv4-bytes?
           |           |       yang:zero-based-counter64
           |           +--ro active-softwire-num?
           |                   uint32
           +--:(algo) {map-e or map-t}?
              +--rw algorithm
                 +--rw algo-instance* [name]
                    +--rw name                string
                    +--rw enable?             boolean
                    +--rw algo-versioning
                    |  +--rw version?   uint64
                    |  +--rw date?      yang:date-and-time
                    +--rw (data-plane)?
                    |  +--:(encapsulation) {map-e}?
                    |  |  +--rw br-ipv6-addr        inet:ipv6-address
                    |  +--:(translation) {map-t}?
                    |     +--rw dmr-ipv6-prefix?    inet:ipv6-prefix
                    +--rw ea-len              uint8
                    +--rw rule-ipv6-prefix    inet:ipv6-prefix
                    +--rw rule-ipv4-prefix    inet:ipv4-prefix
                    +--rw forwarding          boolean
                    +--rw port-set
                    |  +--rw psid-offset?   uint8
                    |  +--rw psid-len       uint8
                    |  +--rw psid           uint16
                    +--ro traffic-stat
                       +--ro discontinuity-time     yang:date-and-time
                       +--ro sent-ipv4-packets?
                       |       yang:zero-based-counter64
                       +--ro sent-ipv4-bytes?
                       |       yang:zero-based-counter64
                       +--ro sent-ipv6-packets?
                       |       yang:zero-based-counter64
                       +--ro sent-ipv6-bytes?
                       |       yang:zero-based-counter64
                       +--ro rcvd-ipv4-packets?
                       |       yang:zero-based-counter64
                       +--ro rcvd-ipv4-bytes?
                       |       yang:zero-based-counter64
                       +--ro rcvd-ipv6-packets?
                       |       yang:zero-based-counter64
                       +--ro rcvd-ipv6-bytes?

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                       |       yang:zero-based-counter64
                       +--ro dropped-ipv4-packets?
                       |       yang:zero-based-counter64
                       +--ro dropped-ipv4-bytes?
                       |       yang:zero-based-counter64
                       +--ro dropped-ipv6-packets?
                       |       yang:zero-based-counter64
                       +--ro dropped-ipv6-bytes?
                       |       yang:zero-based-counter64
                       +--ro dropped-ipv4-fragments?
                       |       yang:zero-based-counter64
                       +--ro dropped-ipv4-fragment-bytes?
                       |       yang:zero-based-counter64
                       +--ro ipv6-fragments-reassembled?
                       |       yang:zero-based-counter64
                       +--ro ipv6-fragments-bytes-reassembled?
                       |       yang:zero-based-counter64
                       +--ro out-icmpv4-error-packets?
                       |       yang:zero-based-counter64
                       +--ro out-icmpv4-error-bytes?
                       |       yang:zero-based-counter64
                       +--ro out-icmpv6-error-packets?
                       |       yang:zero-based-counter64
                       +--ro out-icmpv6-error-bytes?
                               yang:zero-based-counter64

   notifications:
     +---n softwire-binding-instance-event {binding-mode}?
     |  +--ro bind-name?
     |  |       -> /br-instances/binding/bind-instance/name
     |  +--ro invalid-entry*    leafref
     |  +--ro added-entry*      inet:ipv6-address
     |  +--ro modified-entry*   leafref
     +---n softwire-algorithm-instance-event  {map-e, map-t}?
        +--ro algo-name
        |       -> /br-instances/algorithm/algo-instance/name
        +--ro invalid-entry-id*
        |       -> /br-instances/algorithm/algo-instance/name
        +--ro added-entry*
        |       -> /br-instances/algorithm/algo-instance/name
        +--ro modified-entry*
                -> /br-instances/algorithm/algo-instance/name

                      Figure 2: Softwire BR YANG Tree

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5.2.  Softwire BR Tree Diagram Description

   The descriptions for leaves which are common with the CE module are
   provided in Section 4.2.  Descriptions for additional elements are
   provided below:

   o  binding-table-versioning: optionally used to associate a version
      number and/or timestamp to the binding table.  This can be used
      for logging or data retention purposes [RFC7422].  The version
      number is selected to uniquely identify the binding table
      configuration and a new timestamp value written whenever a change
      is made to the contents of the binding table or a new binding
      table list is created.

   o  binding-entry: used to define the binding relationship between
      3-tuples {lwB4's IPv6 address/prefix, the allocated IPv4 address,
      restricted port-set}. For detail information, please refer to
      [RFC7596].

   o  softwire-num-max: used to set the maximum number of softwire
      binding rules that can be created on the lw4o6 element
      simultaneously.  This paramter must not be set to zero because
      this is equivalent to disabling the BR instance.

   o  active-softwire-num: holds the number of softwires currently
      provisioned on the BR element.

   Additional information on some of the important notification nodes is
   listed below:

   o  invalid-entry, added-entry, modified-entry: used to notify the
      NETCONF client that a specific binding entry or MAP rule has
      expired, been invalidated, added, or modified.

6.  IANA Tunnel Type YANG Module

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

   <CODE BEGINS> file "iana-tunnel-type@2018-10-23.yang"

   module iana-tunnel-type {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:iana-tunnel-type";
     prefix iana-tunnel-type;

     import iana-if-type  {
       prefix ift;
       reference

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         "RFC 7224: IANA Interface Type YANG Module";
     }

     organization
       "IANA";
     contact
       "Internet Assigned Numbers Authority

     Postal: ICANN
             12025 Waterfront Drive, Suite 300
             Los Angeles, CA  90094-2536
             United States of America
     Tel:    +1 310 301 5800
     <mailto:iana@iana.org>";

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

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

     revision 2018-10-23 {
       description
         "Initial revision.";
       reference
         "RFC XXXX: YANG Modules for IPv4-in-IPv6 Address plus Port
                    Softwires";
     }

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

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       base ift:tunnel;
       description
         "No intermediate header.";
       reference
         "RFC 4087: IP Tunnel MIB";
      }
      identity gre {
        base ift:tunnel;
        description
          "GRE encapsulation.";
       reference
         "RFC 4087: IP Tunnel MIB";
      }
      identity minimal {
        base ift:tunnel;
        description
          "Minimal encapsulation.";
       reference
         "RFC 4087: IP Tunnel MIB";
      }
      identity l2tp {
        base ift:tunnel;
        description
          "L2TP encapsulation.";
       reference
         "RFC 4087: IP Tunnel MIB";
      }
      identity pptp {
        base ift:tunnel;
        description
          "PPTP encapsulation.";
       reference
         "RFC 4087: IP Tunnel MIB";
      }
      identity l2f {
        base ift:tunnel;
        description
          "L2F encapsulation.";
       reference
         "RFC 4087: IP Tunnel MIB";
      }
      identity udp {
        base ift:tunnel;
        description
          "UDP encapsulation.";
       reference
         "RFC 4087: IP Tunnel MIB";
      }

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      identity atmp {
        base ift:tunnel;
        description
         "ATMP encapsulation.";
       reference
         "RFC 4087: IP Tunnel MIB";
      }
      identity msdp {
        base ift:tunnel;
        description
          "MSDP encapsulation.";
       reference
         "RFC 4087: IP Tunnel MIB";
      }
      identity sixtofour {
        base ift:tunnel;
        description
          "6to4 encapsulation.";
       reference
         "RFC 4087: IP Tunnel MIB";
      }
      identity sixoverfour {
        base ift:tunnel;
        description
          "6over4 encapsulation.";
       reference
         "RFC 4087: IP Tunnel MIB";
      }
      identity isatap {
        base ift:tunnel;
        description
          "ISATAP encapsulation.";
       reference
         "RFC 4087: IP Tunnel MIB";
      }
      identity teredo {
        base ift:tunnel;
        description
          "Teredo encapsulation.";
       reference
         "RFC 4087: IP Tunnel MIB";
      }
      identity iphttps {
        base ift:tunnel;
        description
          "IP over HTTPS (IP-HTTPS) Tunneling Protocol.";
      }
      identity softwiremesh {

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        base ift:tunnel;
        description
          "softwire mesh tunnel.";
        reference
          "RFC 7856: Softwire Mesh Management Information Base (MIB)";
      }
      identity dslite {
        base ift:tunnel;
        description
          "DS-Lite tunnel.";
        reference
          "RFC 7870: Dual-Stack Lite (DS-Lite) Management Information
                     Base (MIB) for Address Family Transition Routers
                    (AFTRs)";
     }
     identity  aplusp {
       base ift:tunnel;
       description
         "A+P encapsulation.";
       reference
         "RFC XXXX: YANG Modules for IPv4-in-IPv6 Address plus Port
                    Softwires";
     }
   }
   <CODE ENDS>

7.  Softwire CE YANG Module

   This module imports the modules defined in [RFC6991], [RFC8343], and
   [RFC7224].  It also imports the 'ietf-softwire-common' module.

<CODE BEGINS>file "ietf-softwire-ce@2018-10-23.yang"

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

  import ietf-inet-types {
    prefix inet;
    reference "Section 4 of RFC 6991";
  }

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

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  import ietf-softwire-common {
    prefix softwire-common;
    reference
      "RFC XXXX: YANG Modules for IPv4-in-IPv6 Address plus Port
                 Softwires";
  }
  import iana-tunnel-type {
    prefix iana-tunnel-type;
    reference
      "RFC XXXX: YANG Modules for IPv4-in-IPv6 Address plus Port
                 Softwires";
  }

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

     Author:  Qi Sun
              <mailto:sunqi.ietf@gmail.com>

     Author:  Linhui Sun
              <mailto:lh.sunlinh@gmail.com>

     Author:  Yong Cui
              <mailto:yong@csnet1.cs.tsinghua.edu.cn>

     Author:  Ian Farrer
              <mailto:ian.farrer@telekom.de>

     Author:  Sladjana Zoric
              <mailto:sladjana.zoric@telekom.de>

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

     Author:  Rajiv Asati
               <mailto:rajiva@cisco.com>";
  description
    "This document defines a YANG module for the configuration and
     management of A+P Softwire Customer Premises Equipment (CEs). It
     covers Lightweight 4over6, MAP-E, and MAP-T mechanisms.

     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

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     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 XXXX; see
     the RFC itself for full legal notices.";

  revision 2018-10-23 {
    description
      "Initial revision.";
    reference
      "RFC XXXX: YANG Modules for IPv4-in-IPv6 Address plus Port
                 Softwires";
  }

  /*
   * Features
   */

  feature binding-mode {
    description
      "Binding is used for configuring the Lightweight 4over6 mechanism.

       Binding based softwire mechanisms are IPv4-over-IPv6 tunnelling
       transition mechanisms specifically intended for complete
       independence between the IPv6 subnet prefix (and IPv6 address)
       and IPv4 address, with or without IPv4 address sharing.

       This is accomplished by maintaining state for each softwire
       (per-subscriber state) in the central Border Relay (BR) and using
       a hub-and-spoke forwarding architecture. In order to delegate the
       NAPT function and achieve IPv4 address sharing, port-restricted
       IPv4 addresses needs to be allocated to CEs.

       This feature indicates that the network element can function as
       one or more binding based softwire instances.";
    reference
      "RFC7596: Lightweight 4over6: An Extension to the Dual-Stack Lite
                Architecture
       RFC7597: Mapping of Address and Port with Encapsulation (MAP-E)
       RFC7599: Mapping of Address and Port using Translation (MAP-T)";
  }

  feature map-e {
    description
      "MAP-E is an IPv6 transition mechanism for transporting IPv4

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       packets across an IPv6 network using IP encapsulation. MAP-E
       allows for a reduction of the amount of centralized state using
       rules to express IPv4/IPv6 address mappings. This introduces an
       algorithmic relationship between the IPv6 subnet and IPv4
       address.

       This feature indicates that the network element can function as
       one or more MAP-E softwire instances.";
    reference
      "RFC7597: Mapping of Address and Port with Encapsulation (MAP-E)";
  }

  feature map-t {
    description
      "MAP-T is an IPv6 transition mechanism for transporting IPv4
       packets across an IPv6 network using IP translation. It leverages
       a double stateless NAT64 based solution as well as the stateless
       algorithmic address & transport layer port mapping algorithm
       defined for MAP-E.

       This feature indicates that the network element can function as
       one or more MAP-T softwire instances.";
    reference
      "RFC7599: Mapping of Address and Port using Translation (MAP-T)";
  }

  // Binding Entry

  grouping binding-entry {
    description
      "The binding BR (Border Relay) maintains an address binding table
       that contains the binding between the CE's IPv6 address,
       the allocated IPv4 address and restricted port-set.";
    leaf binding-ipv6info {
      type union {
        type inet:ipv6-address;
        type inet:ipv6-prefix;
      }
      description
        "The IPv6 information for a binding entry.

         When the IPv6 prefix type is used,
         the IPv6 source address of the CE is constructed
         according to the description in RFC7596.

         If the IPv6 address type is used, the CE can use
         any valid /128 address from a prefix assigned to
         the CE.";

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      reference "Section 5.1 of RFC7596.";
    }
    leaf br-ipv6-addr {
      type inet:ipv6-address;
      mandatory true;
      description
        "The IPv6 address of the binding BR.";
    }
  }

  // configuration and stateful parameters for softwire CE interface

  augment "/if:interfaces/if:interface" {
    when "derived-from(if:type, 'iana-tunnel-type:aplusp')";
    description
      "Softwire CE interface configuration";
    leaf softwire-payload-mtu {
      type uint16;
      units "bytes";
      description
        "The payload IPv4 MTU for the softwire tunnel.";
    }
    leaf softwire-path-mru {
      type uint16;
      units "bytes";
      description
        "The path MRU for the softwire (payload + encapsulation
         overhead).";
      reference
        "RFC 4213: Basic Transition Mechanisms for IPv6 Hosts and
                   Routers";
    }
    choice ce-type {
      description
        "Sets the softwire CE mechanism";
      case binding {
        if-feature "binding-mode";
        description
          "CE binding configuration";
        uses binding-entry;
      }
      case algo {
        if-feature "map-e or map-t";
        description
          "CE algorithm configuration";
        container algo-instances {
          description
            "Collection of MAP-E/MAP-T parameters";

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          list algo-instance {
            key "name";
            description
              "MAP forwarding rule instance for
               MAP-E/MAP-T";
            leaf name {
              type string;
              mandatory true;
              description
                "The name is used to uniquely identify an algorithm
                 instance.

                 This name can be automatically assigned
                 or explicitly configured.";
            }
            uses softwire-common:algorithm-instance;
          }
        }
      }
    }
  }
  augment "/if:interfaces/if:interface/if:statistics" {
    when "derived-from(../if:type, 'iana-tunnel-type:aplusp')";
    description
      "Softwire CE interface statistics.";
    uses softwire-common:traffic-stat;
  }

  /*
   * Notifications
   */

  notification softwire-ce-event {
    if-feature "binding-mode";
    description
      "CE notification";
    leaf ce-binding-ipv6-addr-change {
      type inet:ipv6-address;
      mandatory true;
      description
        "This notification is generated whenever the CE's binding IPv6
         address changes for any reason.";
    }
  }
}
<CODE ENDS>

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8.  BR Softwire YANG Module

   This module imports typedefs from [RFC6991].  It also imports the
   'ietf-softwire-common' module.

<CODE BEGINS>file "ietf-softwire-br@2018-10-23.yang"

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

  import ietf-inet-types {
    prefix inet;
    reference "Section 4 of RFC 6991";
  }
  import ietf-yang-types {
    prefix yang;
    reference "Section 3 of RFC 6991";
  }
  import ietf-softwire-common {
    prefix softwire-common;
    reference
      "RFC XXXX: YANG Modules for IPv4-in-IPv6 Address plus Port
                 Softwires";
  }

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

     Author:  Qi Sun
              <mailto:sunqi.ietf@gmail.com>

     Author:  Linhui Sun
              <mailto:lh.sunlinh@gmail.com>

     Author:  Yong Cui
              <mailto:yong@csnet1.cs.tsinghua.edu.cn>

     Author:  Ian Farrer
              <mailto:ian.farrer@telekom.de>

     Author:  Sladjana Zoric
              <mailto:sladjana.zoric@telekom.de>

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

     Author:  Rajiv Asati
               <mailto:rajiva@cisco.com>";

  description
    "This document defines a YANG module for the configuration and
     management of A+P Softwire Border Routers. It covers Lightweight
     4over6, MAP-E, and MAP-T mechanisms.

     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 XXXX; see
     the RFC itself for full legal notices.";

  revision 2018-10-23 {
    description
      "Initial revision.";
    reference
      "RFC XXXX: YANG Modules for IPv4-in-IPv6 Address plus Port
                 Softwires";
  }

  /*
   * Groupings
   */

  grouping port-set {
    description
      "Describes a set of layer 4 port numbers.

       This may be a simple port range, or use the Port Set
       Identifier (PSID) algorithm to represent a range of transport
       layer ports which will be used by a NAPT.";
    leaf psid-offset {
      type uint8 {
        range "0..16";
      }
      description

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        "The number of offset bits. In Lightweight 4over6,
         the default value is 0 for assigning one contiguous
         port range. In MAP-E/T, the default value is 6,
         which means the system ports (0-1023) are excluded by
         default and the assigned port ranges are distributed across
         the entire port space, depending on either psid-len or the
         number of contiguous ports.";
    }
    leaf psid-len {
      type uint8 {
        range "0..15";
      }
      mandatory true;
      description
        "The length of PSID, representing the sharing
         ratio for an IPv4 address. This, along with ea-len, can
         be used to calculate the number of contiguous ports per
         port range";
    }
    leaf psid {
      type uint16;
      mandatory true;
      description
        "Port Set Identifier (PSID) value, which
         identifies a set of ports algorithmically.";
    }
  }

  grouping binding-entry {
    description
      "The binding BR maintains an address binding table that
       contains the binding between the CE's IPv6 address,
       the allocated IPv4 address and restricted port-set.";
    leaf binding-ipv6info {
      type union {
        type inet:ipv6-address;
        type inet:ipv6-prefix;
      }
      description
        "The IPv6 information for a CE binding entry.
         When the IPv6 prefix type is used,
         the IPv6 source address of the CE is constructed
         according to the description in RFC7596;
         if the IPv6 address type is used, the CE can use
         any valid /128 address from a prefix assigned to
         the CE.";
      reference
        "RFC7596: Lightweight 4over6: An Extension to the Dual-Stack

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                  Lite Architecture";
    }
    leaf binding-ipv4-addr {
      type inet:ipv4-address;
      description
        "The IPv4 address assigned to the binding CE,
         which is used as the IPv4 external address
         for binding CE local NAPT44.";
    }
    container port-set {
      description
        "For Lightweight 4over6, the default value
         for offset should be 0, to configure one contiguous
         port range.";
      uses port-set {
        refine "psid-offset" {
          default "0";
        }
      }
    }
    leaf br-ipv6-addr {
      type inet:ipv6-address;
      description
        "The IPv6 address for binding BR.";
    }
  }

  /*
   * Features
   */

  feature binding-mode {
    description
      "Binding is used for configuring the Lightweight 4over6 mechanism.

       Binding based softwire mechanisms are IPv4-over-IPv6 tunnelling
       transition mechanisms specifically intended for complete
       independence between the IPv6 subnet prefix (and IPv6 address)
       and IPv4 address, with or without IPv4 address sharing.

       This is accomplished by maintaining state for each softwire
       (per-subscriber state) in the central Border Relay (BR) and using
       a hub-and-spoke forwarding architecture. In order to delegate the
       NAPT function and achieve IPv4 address sharing, port-restricted
       IPv4 addresses needs to be allocated to CEs.

       This feature indicates that the network element can function as
       one or more binding based softwire instances.";

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    reference
      "RFC7596: Lightweight 4over6: An Extension to the Dual-Stack Lite
                Architecture
       RFC7597: Mapping of Address and Port with Encapsulation (MAP-E)
       RFC7599: Mapping of Address and Port using Translation (MAP-T)";
  }

  feature map-e {
    description
      "MAP-E is an IPv6 transition mechanism for transporting IPv4
       packets across an IPv6 network using IP encapsulation. MAP-E
       allows for a reduction of the amount of centralized state using
       rules to express IPv4/IPv6 address mappings. This introduces an
       algorithmic relationship between the IPv6 subnet and IPv4
       address.

       This feature indicates that the network element can function as
       one or more MAP-E softwire instances.";
    reference
      "RFC7597: Mapping of Address and Port with Encapsulation (MAP-E)";
  }

  feature map-t {
    description
      "MAP-T is an IPv6 transition mechanism for transporting IPv4
       packets across an IPv6 network using IP translation. It leverages
       a double stateless NAT64 based solution as well as the stateless
       algorithmic address & transport layer port mapping algorithm
       defined for MAP-E.

       This feature indicates that the network element can function as
       one or more MAP-T softwire instances.";
    reference
      "RFC7599: Mapping of Address and Port using Translation (MAP-T)";
  }

  container br-instances {
    description
      "BR instances enabled in a network element.";
    choice br-type {
      description
        "Select binding or algorithmic BR functionality.";
      case binding {
        if-feature "binding-mode";
        container binding {
          description
            "binding mechanism (binding table) configuration.";
          list bind-instance {

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            key "name";
            description
              "A set of binding instances to be configured.";
            leaf name {
              type string;
              mandatory true;
              description
                "The name for the binding BR. It is used to uniquely
                 distinguish a binding instance by its name.";
            }
            container binding-table-versioning {
              description
                "binding table's version";
              leaf version {
                type uint64;
                description
                  "Timestamp when the binding table was activated.

                   A binding instance may be provided with binding
                   entries that may change in time (e.g., increase
                   the size of the port set). When an abuse party
                   presents an external IP address/port, the version
                   of the binding table is important because, depending
                   on the version, a distinct customer may be
                   identified.

                   The timestamp is used as a key to find the
                   appropriate binding table that was put into effect
                   when an abuse occurred. ";
              }
              leaf date {
                type yang:date-and-time;
                description
                  "Timestamp of the binding table";
                reference
                  "RFC7422: Deterministic Address Mapping to Reduce
                            Logging in Carrier-Grade NAT Deployments";
              }
            }
            leaf softwire-num-max {
              type uint32 {
                range "1..max";
              }
              mandatory true;
              description
                "The maximum number of softwires that can be created
                 on the binding BR.";
            }

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            leaf softwire-payload-mtu {
              type uint16;
              units "bytes";
              mandatory true;
              description
                "The payload IPv4 MTU for binding softwire.";
            }
            leaf softwire-path-mru {
              type uint16;
              units "bytes";
              mandatory true;
              description
                "The path MRU for binding softwire.";
              reference
                "RFC4213: Basic Transition Mechanisms for IPv6 Hosts
                          and Routers";
            }
            leaf enable-hairpinning {
              type boolean;
              default "true";
              description
                "Enables/disables support for locally forwarding
                 (hairpinning) traffic between two CEs.";
              reference "Section 6.2 of RFC7596";
            }
            container binding-table {
              description
                "binding table";
              list binding-entry {
                key "binding-ipv6info";
                description
                  "binding entry";
                uses binding-entry;
              }
            }
            container icmp-policy {
              description
                "The binding BR can be configured to process or drop
                 incoming ICMP messages, and to generate outgoing ICMP
                 error messages.";
              container icmpv4-errors {
                description
                  "ICMPv4 error processing configuration";
                leaf allow-incoming-icmpv4 {
                  type boolean;
                  default "true";
                  description
                    "Enables the processing of incoming ICMPv4

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                     packets.";
                  reference
                    "RFC7596: Lightweight 4over6: An Extension to
                              the Dual-Stack Lite Architecture";
                }
                leaf icmpv4-rate {
                  type uint32;
                  description
                    "Rate limit threshold in messages per-second
                     for processing incoming ICMPv4 errors messages";
                }
                leaf generate-icmpv4-errors {
                  type boolean;
                  default "true";
                  description
                    "Enables the generation of outgoing ICMPv4 error
                     messages on receipt of an inbound IPv4 packet
                     with no matching binding table entry.";
                  reference "Seciton 5.2 of RFC7596.";
                }
              }
              container icmpv6-errors {
                description
                  "ICMPv6 error processing configuration";
                leaf generate-icmpv6-errors {
                  type boolean;
                  default "true";
                  description
                    "Enables the generation of ICMPv6 error messages if
                     no matching binding table entry is found for a
                     received packet.";
                  reference "Section 6.2 of RFC7596.";
                }
                leaf icmpv6-rate {
                  type uint32;
                  description
                    "Rate limit threshold in messages per-second
                     for sending ICMPv6 errors messages";
                  reference "Section 9 of RFC7596.";
                }
              }
            }
            container traffic-stat {
              config false;
              description
                "Traffic statistics information for the BR.";
              leaf discontinuity-time {
                type yang:date-and-time;

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                mandatory true;
                description
                  "The time of the most recent occasion on which the BR
                   instance suffered a discontinuity.  This must be
                   initialized when the BR instance is configured
                   or rebooted.";
              }
              uses softwire-common:traffic-stat;
              leaf dropped-icmpv4-packets {
                type yang:zero-based-counter64;
                description
                  "ICMPv4 packets that are dropped as a result
                   of the ICMP policy. Typically, this can be any
                   incoming ICMPv4 packets if ICMPv4 processing is
                   disabled or incoming ICMPv4 packets that exceed
                   the ICMPv4 rate-limit threshold.

                   Discontinuities in the value of this counter can
                   occur at re-initialization of the management
                   system, and at other times as indicated by
                   the value of 'discontinuity-time'.";
              }
              leaf dropped-icmpv4-bytes {
                type yang:zero-based-counter64;
                description
                  "ICMPv4 messages, in bytes, that are dropped as
                   a result of the ICMP policy. Typically, it
                   can be any incoming ICMPv4 packets if ICMPv4
                   processing is disabled or incoming ICMPv4
                   packets that exceed the ICMPv4 rate-limit
                   threshold.

                   Discontinuities in the value of this counter can
                   occur at re-initialization of the management
                   system, and at other times as indicated by
                   the value of 'discontinuity-time'.";
              }
              leaf hairpin-ipv4-packets {
                type yang:zero-based-counter64;
                description
                  "IPv4 packets locally routed between two CEs
                   (hairpinned).

                   Discontinuities in the value of this counter can
                   occur at re-initialization of the management
                   system, and at other times as indicated by
                   the value of 'discontinuity-time'.";
              }

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              leaf hairpin-ipv4-bytes {
                type yang:zero-based-counter64;
                description
                  "IPv4 bytes locally routed between two CEs
                   (hairpinned).

                   Discontinuities in the value of this counter can
                   occur at re-initialization of the management
                   system, and at other times as indicated by
                   the value of 'discontinuity-time'.";
              }
              leaf active-softwire-num {
                type uint32;
                config false;
                description
                  "The number of currently active softwires on the
                   binding instance.

                   Discontinuities in the value of this counter can
                   occur at re-initialization of the management
                   system, and at other times as indicated by
                   the value of 'discontinuity-time'.";
              }
            }
          }
        }
      }
      case algo {
        if-feature "map-e or map-t";
        container algorithm {
          description
            " A set of parameters used for MAP-E/MAP-T.";
          list algo-instance {
            key "name";
            description
              "Instances of algorithm";
            leaf name {
              type string;
              mandatory true;
              description
                "The name is used to uniquely identify an algorithm
                 instance.

                 This name can be automatically assigned
                 or explicitly configured.";
            }
            uses softwire-common:algorithm-instance;
            container port-set {

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              description
                "Indicates a set of ports.";
              uses port-set;
            }
            container traffic-stat {
              config false;
              description
                "Traffic statistics information for the BR.";
              leaf discontinuity-time {
                type yang:date-and-time;
                mandatory true;
                description
                  "The time of the most recent occasion on which the BR
                   instance suffered a discontinuity.  This must be
                   reset to the current date-and-time when the BR
                   instance is configured or rebooted.";
              }
              uses softwire-common:traffic-stat;
            }
          }
        }
      }
    }
  }

  /*
   * Notifications
   */

  notification softwire-binding-instance-event {
    if-feature "binding-mode";
    description
      "Notifications for binding instance when an entry is
       added, modified, or is not valid anymore.";
    leaf bind-name {
      type leafref {
        path "/br-instances/binding/bind-instance/name";
      }
      description
        "The name of the binding-instance that
         generated the notification.";
    }
    leaf-list invalid-entry {
      type leafref {
        path
          "/br-instances/binding/"
          + "bind-instance[name=current()/../bind-name]/"
          + "binding-table/binding-entry/binding-ipv6info";

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      }
      description
        "Notify the client that a specific binding entry has
         expired or is invalid. The binding-ipv6info identifies
         an entry.";
    }
    leaf-list added-entry {
      type inet:ipv6-address;
      description
        "Notify the client that a binding entry has been added.
         The ipv6 address of that entry is the index. The client
         gets other information from the binding BR about the entry
         indexed by that ipv6 address.";
    }
    leaf-list modified-entry {
      type leafref {
        path
          "/br-instances/binding/"
          + "bind-instance[name=current()/../bind-name]/"
          + "binding-table/binding-entry/binding-ipv6info";
      }
      description
        "The binding-table entry that has been modified.";
    }
  }
  notification softwire-algorithm-instance-event {
    if-feature "map-e or map-t";
    description
      "Notifications for algorithm instance when an entry is
       added, modified, or is not valid anymore.";
    leaf algo-name {
      type leafref {
        path "/br-instances/algorithm/algo-instance/name";
      }
      mandatory true;
      description
        "algorithmic instance event.";
    }
    leaf-list invalid-entry {
      type leafref {
        path "/br-instances/algorithm/algo-instance/name";
      }
      description
        "Invalid entry event.";
    }
    leaf-list added-entry {
      type leafref {
        path "/br-instances/algorithm/algo-instance/name";

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      }
      description
        "Added entry.";
    }
    leaf-list modified-entry {
      type leafref {
        path "/br-instances/algorithm/algo-instance/name";
      }
      description
        "Modified entry.";
    }
  }
}
<CODE ENDS>

9.  Common Softwire Element Groups YANG Module

   This module imports typedefs from [RFC6991].

   The following YANG module contains definitions that are used by both
   the softwire CE and softwire BR YANG modules.

<CODE BEGINS>file "ietf-softwire-common@2018-10-23.yang"

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

  import ietf-inet-types {
    prefix inet;
    reference "Section 4 of RFC 6991";
  }
  import ietf-yang-types {
    prefix yang;
    reference "Section 3 of RFC 6991";
  }

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

     Author:  Qi Sun
              <mailto:sunqi.ietf@gmail.com>

     Author:  Linhui Sun

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              <mailto:lh.sunlinh@gmail.com>

     Author:  Yong Cui
              <mailto:yong@csnet1.cs.tsinghua.edu.cn>

     Author:  Ian Farrer
              <mailto:ian.farrer@telekom.de>

     Author:  Sladjana Zoric
              <mailto:sladjana.zoric@telekom.de>

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

     Author:  Rajiv Asati
               <mailto:rajiva@cisco.com>";
  description
    "This document defines a YANG module defining types
     common to all A+P modules.

     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 XXXX; see
     the RFC itself for full legal notices.";

  revision 2018-10-23 {
    description
      "Initial revision.";
    reference
      "RFC XXXX: YANG Modules for IPv4-in-IPv6 Address plus Port
                 Softwires";
  }

  feature map-e {
    description
      "MAP-E is an IPv6 transition mechanism for transporting IPv4
       packets across an IPv6 network using IP encapsulation. MAP-E
       allows for a reduction of the amount of centralized state using
       rules to express IPv4/IPv6 address mappings. This introduces an
       algorithmic relationship between the IPv6 subnet and IPv4

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       address.

       This feature indicates that the network element can function as
       one or more MAP-E softwire instances.";
    reference
      "RFC7597: Mapping of Address and Port with Encapsulation (MAP-E)";
  }

  feature map-t {
    description
      "MAP-T is an IPv6 transition mechanism for transporting IPv4
       packets across an IPv6 network using IP translation. It leverages
       a double stateless NAT64 based solution as well as the stateless
       algorithmic address & transport layer port mapping algorithm
       defined for MAP-E.

       This feature indicates that the network element can function as
       one or more MAP-T softwire instances.";
    reference
      "RFC7599: Mapping of Address and Port using Translation (MAP-T)";
  }

  /*
   * Groupings
   */

  grouping algorithm-instance {
    description
      "A collection of parameters that is used fro MAP-E/MAP-T.";
    leaf enable {
      type boolean;
      description
        "Enable/disable an individual MAP-E or MAP-T rule.";
    }
    container algo-versioning {
      description
        "Version number for this algorithm instance";
      leaf version {
        type uint64;
        description
          "A version number for the mapping algorithm
           rules provided to the algorithm instance";
      }
      leaf date {
        type yang:date-and-time;
        description
          "Timestamp when the algorithm instance was activated.

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           An algorithm instance may be provided with mapping
           rules that may change in time (for example, increase
           the size of the port set). When an abuse party
           presents an external IP address/port, the version
           of the algorithm is important because depending on
           the version, a distinct customer may be identified.

           The timestamp is used as a key to find the appropriate
           algorithm that was put into effect when an abuse
           occurred. ";
        reference
          "RFC7422: Deterministic Address Mapping to Reduce
                    Logging in Carrier-Grade NAT Deployments";
      }
    }
    choice data-plane {
      description
        "Selects MAP-E (encapsulation) or MAP-T
         (translation)";
      case encapsulation {
        if-feature "map-e";
        description
          "encapsulation for MAP-E";
        leaf br-ipv6-addr {
          type inet:ipv6-address;
          mandatory true;
          description
            "The IPv6 address of the MAP-E BR.";
        }
      }
      case translation {
        if-feature "map-t";
        description
          "translation for MAP-T";
        leaf dmr-ipv6-prefix {
          type inet:ipv6-prefix;
          description
            "The IPv6 prefix of the MAP-T BR.";
        }
      }
    }
    leaf ea-len {
      type uint8;
      mandatory true;
      description
        "Embedded Address (EA) bits are the IPv4 EA-bits in the IPv6
         address identifying an IPv4 prefix/address (or part thereof)
         or a shared IPv4 address (or part thereof) and a port-set

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         identifier. The length of the EA-bits is defined as part of
         a MAP rule for a MAP domain.";
    }
    leaf rule-ipv6-prefix {
      type inet:ipv6-prefix;
      mandatory true;
      description
        "The Rule IPv6 prefix defined in the mapping rule.";
    }
    leaf rule-ipv4-prefix {
      type inet:ipv4-prefix;
      mandatory true;
      description
        "The Rule IPv4 prefix defined in the mapping rule.";
    }
    leaf forwarding {
      type boolean;
      mandatory true;
      description
        "This parameter specifies whether the rule may be used for
         forwarding (FMR). If set, this rule is used as an FMR;
         if not set, this rule is a Basic Mapping Rule (BMR) only
         and must not be used for forwarding.";
    }
  }

  grouping traffic-stat {
    description
      "Traffic statistics";
    leaf sent-ipv4-packets {
      type yang:zero-based-counter64;
      description
        "Number of decapsulated and forwarded IPv4 packets.

         Discontinuities in the value of this counter can occur
         at re-initialization of the management system, and at
         other times as indicated by the value of
         'discontinuity-time'.";
    }
    leaf sent-ipv4-bytes {
      type yang:zero-based-counter64;
      description
        "Decapsulated/translated IPv4 traffic sent, in bytes

         Discontinuities in the value of this counter can occur
         at re-initialization of the management system, and at
         other times as indicated by the value of
         'discontinuity-time'.";

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    }
    leaf sent-ipv6-packets {
      type yang:zero-based-counter64;
      description
        "Number of encapsulated IPv6 packets sent.

         Discontinuities in the value of this counter can occur
         at re-initialization of the management system, and at
         other times as indicated by the value of
         'discontinuity-time'.";
    }
    leaf sent-ipv6-bytes {
      type yang:zero-based-counter64;
      description
        "Encapsulated IPv6 traffic sent, in bytes

         Discontinuities in the value of this counter can occur
         at re-initialization of the management system, and at
         other times as indicated by the value of
         'discontinuity-time'.";
    }
    leaf rcvd-ipv4-packets {
      type yang:zero-based-counter64;
      description
        "Number of incoming IPv4 packets at the
         Internet-facing interface.

         Discontinuities in the value of this counter can occur
         at re-initialization of the management system, and at
         other times as indicated by the value of
         'discontinuity-time'.";
    }
    leaf rcvd-ipv4-bytes {
      type yang:zero-based-counter64;
      description
        "IPv4 traffic received for processing, in bytes.

         Discontinuities in the value of this counter can occur
         at re-initialization of the management system, and at
         other times as indicated by the value of
         'discontinuity-time'.";
    }
    leaf rcvd-ipv6-packets {
      type yang:zero-based-counter64;
      description
        "Number of IPv4-in-IPv6 packets received.

         Discontinuities in the value of this counter can occur

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         at re-initialization of the management system, and at
         other times as indicated by the value of
         'discontinuity-time'.";
    }
    leaf rcvd-ipv6-bytes {
      type yang:zero-based-counter64;
      description
        "IPv4-in-IPv6 traffic received, in bytes.

         Discontinuities in the value of this counter can occur
         at re-initialization of the management system, and at
         other times as indicated by the value of
         'discontinuity-time'.";
    }
    leaf dropped-ipv4-packets {
      type yang:zero-based-counter64;
      description
        "Number of IPv4 packets dropped at the
         Internet-facing interface.

         Discontinuities in the value of this counter can occur
         at re-initialization of the management system, and at
         other times as indicated by the value of
         'discontinuity-time'.";
    }
    leaf dropped-ipv4-bytes {
      type yang:zero-based-counter64;
      description
        "IPv4 traffic dropped at the Internet-facing
         interface, in bytes.

         Discontinuities in the value of this counter can occur
         at re-initialization of the management system, and at
         other times as indicated by the value of
         'discontinuity-time'.";
    }
    leaf dropped-ipv6-packets {
      type yang:zero-based-counter64;
      description
        "Number of IPv4-in-IPv6 packets dropped.

         Discontinuities in the value of this counter can occur
         at re-initialization of the management system, and at
         other times as indicated by the value of
         'discontinuity-time'.";
    }
    leaf dropped-ipv6-bytes {
      type yang:zero-based-counter64;

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      description
        "IPv4-in-IPv6 traffic dropped, in bytes.

         Discontinuities in the value of this counter can occur
         at re-initialization of the management system, and at
         other times as indicated by the value of
         'discontinuity-time'.";
    }
    leaf dropped-ipv4-fragments {
      type yang:zero-based-counter64;
      description
        "Number of fragmented IPv4 packets dropped.

         Discontinuities in the value of this counter can occur
         at re-initialization of the management system, and at
         other times as indicated by the value of
         'discontinuity-time'.";
    }
    leaf dropped-ipv4-fragment-bytes {
      type yang:zero-based-counter64;
      description
        "Fragmented IPv4 traffic dropped, in bytes.

         Discontinuities in the value of this counter can occur
         at re-initialization of the management system, and at
         other times as indicated by the value of
         'discontinuity-time'.";
    }
    leaf ipv6-fragments-reassembled {
      type yang:zero-based-counter64;
      description
        "Number of IPv6 fragments successfully reassembled.

         Discontinuities in the value of this counter can occur
         at re-initialization of the management system, and at
         other times as indicated by the value of
         'discontinuity-time'.";
    }
    leaf ipv6-fragments-bytes-reassembled {
      type yang:zero-based-counter64;
      description
        "IPv6 fragments successfully reassembled, in bytes.

         Discontinuities in the value of this counter can occur
         at re-initialization of the management system, and at
         other times as indicated by the value of
         'discontinuity-time'.";
    }

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    leaf out-icmpv4-error-packets {
      type yang:zero-based-counter64;
      description
        "Internally generated ICMPv4 error packets.

         Discontinuities in the value of this counter can occur
         at re-initialization of the management system, and at
         other times as indicated by the value of
         'discontinuity-time'.";
    }
    leaf out-icmpv4-error-bytes {
      type yang:zero-based-counter64;
      description
        "Internally generated ICMPv4 error messages, in bytes.

         Discontinuities in the value of this counter can occur
         at re-initialization of the management system, and at
         other times as indicated by the value of
         'discontinuity-time'.";
    }
    leaf out-icmpv6-error-packets {
      type yang:zero-based-counter64;
      description
        "Internally generated ICMPv6 error packets.

         Discontinuities in the value of this counter can occur
         at re-initialization of the management system, and at
         other times as indicated by the value of
         'discontinuity-time'.";
    }
    leaf out-icmpv6-error-bytes {
      type yang:zero-based-counter64;
      description
        "Internally generated ICMPv6 error messages, in bytes.

         Discontinuities in the value of this counter can occur
         at re-initialization of the management system, and at
         other times as indicated by the value of
         'discontinuity-time'.";
    }
  }
}
<CODE ENDS>

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10.  Security Considerations

   The YANG modules defined in this document is designed to be accessed
   via network management protocols such as NETCONF [RFC6241] or
   RESTCONF [RFC8040].  The lowest NETCONF layer is the secure transport
   layer, and the mandatory-to-implement secure transport is Secure
   Shell (SSH) [RFC6242].  The lowest RESTCONF layer is HTTPS, and the
   mandatory-to-implement secure transport is TLS [RFC8446].

   The NETCONF access control model [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) applied
   to these data nodes without proper protection can negatively affect
   network operations.

11.  IANA Considerations

   This document requests IANA to assign a new tunnel type under
   "tunnelType" sub-registry (under "ifType definitions" registry):

   o  aplusp: A+P Encapsulation [RFCXXXX].

   This document requests IANA to register the following URIs in the
   "IETF XML Registry" [RFC3688]:

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

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

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

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

   This document requests that IANA registers the following YANG modules
   in the "YANG Module Names" registry [RFC6020]:

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            name: iana-tunnel-type
            namespace: urn:ietf:params:xml:ns:yang:iana-tunnel-type
            prefix: iana-tunnel-type
            reference: RFC XXXX

            name: ietf-softwire-ce
            namespace: urn:ietf:params:xml:ns:yang:ietf-softwire-ce
            prefix: softwire-ce
            reference: RFC XXXX

            name: ietf-softwire-br
            namespace: urn:ietf:params:xml:ns:yang:ietf-softwire-br
            prefix: softwire-br
            reference: RFC XXXX

            name: ietf-softwire-common
            namespace: urn:ietf:params:xml:ns:yang:ietf-softwire-common
            prefix: softwire-common
            reference: RFC XXXX

   This document defines the initial version of the IANA-maintained
   iana-tunnel-type YANG module.  IANA is requested to add this note:

      Tunnel type values must not be directly added to the iana-tunnel-
      type YANG module.  They must instead be respectively added to the
      "tunnelType" sub-registry (under "ifType definitions" registry).

   When a tunnel type is added to the "tunnelType" registry, a new
   "identity" statement must be added to the iana-tunnel-type YANG
   module.  The name of the "identity" is the same as the corresponding
   enumeration in the IANAifType-MIB (i.e., IANAtunnelType).  The
   following substatements to the "identity" statement should be
   defined:

   "base":        Contains the name assigned to the tunnel type, in
                  lowercase.

   "description": Replicate the description from the registry.

   "reference":   Replicate the reference from the registry and add the
                  title of the document.

   Unassigned or reserved values are not present in the module.

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

   IANA is requested to add this note to "tunnelType" registry:

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

12.  Acknowledgements

   The authors would like to thank Lishan Li, Bert Wijnen, Giles Heron,
   Ole Troan, Andy Wingo and Leo Tietz for their contributions to this
   work.

   Thanks to Sheng Jiang for the review.

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

13.  Contributors

   The following individual contributed to this document:

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

14.  References

14.1.  Normative References

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

   [RFC6020]  Bjorklund, M., Ed., "YANG - A Data Modeling Language for
              the Network Configuration Protocol (NETCONF)", RFC 6020,
              DOI 10.17487/RFC6020, October 2010,
              <https://www.rfc-editor.org/info/rfc6020>.

   [RFC6241]  Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
              and A. Bierman, Ed., "Network Configuration Protocol
              (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
              <https://www.rfc-editor.org/info/rfc6241>.

   [RFC6242]  Wasserman, M., "Using the NETCONF Protocol over Secure
              Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011,
              <https://www.rfc-editor.org/info/rfc6242>.

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

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

   [RFC7596]  Cui, Y., Sun, Q., Boucadair, M., Tsou, T., Lee, Y., and I.
              Farrer, "Lightweight 4over6: An Extension to the Dual-
              Stack Lite Architecture", RFC 7596, DOI 10.17487/RFC7596,
              July 2015, <https://www.rfc-editor.org/info/rfc7596>.

   [RFC7597]  Troan, O., Ed., Dec, W., Li, X., Bao, C., Matsushima, S.,
              Murakami, T., and T. Taylor, Ed., "Mapping of Address and
              Port with Encapsulation (MAP-E)", RFC 7597,
              DOI 10.17487/RFC7597, July 2015,
              <https://www.rfc-editor.org/info/rfc7597>.

   [RFC7598]  Mrugalski, T., Troan, O., Farrer, I., Perreault, S., Dec,
              W., Bao, C., Yeh, L., and X. Deng, "DHCPv6 Options for
              Configuration of Softwire Address and Port-Mapped
              Clients", RFC 7598, DOI 10.17487/RFC7598, July 2015,
              <https://www.rfc-editor.org/info/rfc7598>.

   [RFC7599]  Li, X., Bao, C., Dec, W., Ed., Troan, O., Matsushima, S.,
              and T. Murakami, "Mapping of Address and Port using
              Translation (MAP-T)", RFC 7599, DOI 10.17487/RFC7599, July
              2015, <https://www.rfc-editor.org/info/rfc7599>.

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

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

   [RFC8341]  Bierman, A. and M. Bjorklund, "Network Configuration
              Access Control Model", STD 91, RFC 8341,
              DOI 10.17487/RFC8341, March 2018,
              <https://www.rfc-editor.org/info/rfc8341>.

   [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>.

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   [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>.

14.2.  Informative References

   [I-D.ietf-opsawg-nat-yang]
              Boucadair, M., Sivakumar, S., Jacquenet, C., Vinapamula,
              S., and Q. Wu, "A YANG Module for Network Address
              Translation (NAT) and Network Prefix Translation (NPT)",
              draft-ietf-opsawg-nat-yang-17 (work in progress),
              September 2018.

   [I-D.ietf-softwire-dslite-yang]
              Boucadair, M., Jacquenet, C., and S. Sivakumar, "A YANG
              Data Model for Dual-Stack Lite (DS-Lite)", draft-ietf-
              softwire-dslite-yang-17 (work in progress), May 2018.

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

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

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

   [RFC7422]  Donley, C., Grundemann, C., Sarawat, V., Sundaresan, K.,
              and O. Vautrin, "Deterministic Address Mapping to Reduce
              Logging in Carrier-Grade NAT Deployments", RFC 7422,
              DOI 10.17487/RFC7422, December 2014,
              <https://www.rfc-editor.org/info/rfc7422>.

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

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

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   [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>.

   [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>.

   [RFC8344]  Bjorklund, M., "A YANG Data Model for IP Management",
              RFC 8344, DOI 10.17487/RFC8344, March 2018,
              <https://www.rfc-editor.org/info/rfc8344>.

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

Appendix A.  Configuration Examples

   The following sections provide examples of how the softwire YANG
   modules can be used for configuring softwire elements.

A.1.  Configuration Example for a lw4o6 BR Binding-Table

   The lwAFTR maintains an address binding table which contains the
   following 3-tuples:

   o  IPv6 Address for a single lwB4

   o  Public IPv4 Address

   o  Restricted port-set

   The entry has two functions: the IPv6 encapsulation of inbound IPv4
   packets destined to the lwB4 and the validation of outbound IPv4-in-
   IPv6 packets received from the lwB4 for de-capsulation.

   Consider an example for the following lw4o6 binding table entry:

   lwB4 Binding IPv6 Address:  2001:db8::1

   lwB4 Binding IPv4 Address:  192.0.2.1

   lwB4 PSID:                  0x34

   lwB4 PSID Length            8

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   BR IPv6 Address:            2001:db8:1::2

       <br-instances>
         <binding>
             <bind-instance>
               <name>mybinding-instance</name>
               <binding-table>
                 <binding-entry>
                   <binding-ipv6info>2001:db8::1</binding-ipv6info>
                   <binding-ipv4-addr>192.0.2.1</binding-ipv4-addr>
                   <port-set>
                     <psid>52</psid>
                     <psid-len>8</psid-len>
                   </port-set>
                   <br-ipv6-addr>2001:db8:1::2</br-ipv6-addr>
                 </binding-entry>
               </binding-table>
               <softwire-num-max>1024</softwire-num-max>
               <softwire-path-mru>1540</softwire-path-mru>
               <softwire-payload-mtu>1500</softwire-payload-mtu>
             </bind-instance>
         </binding>
       </br-instances>

              Figure 3: lw4o6 Binding-Table Configuration XML

A.2.  Configuration Example for a MAP-E BR

   A MAP-E BR is configured with forward mapping rules for the CEs it is
   serving.  In this example (taken from [RFC7597], Appendix A, Example
   2), the following parameters are required:

   o  Rule IPv6 Prefix

   o  Rule IPv4 Prefix

   o  Rule EA-bit bit length

   o  IPv6 Address of MAP-BR

   The mapping rule has two functions: identifying the destination CE
   IPv6 address for encapsulating inbound IPv4 packets and the
   validation of outbound IPv4-in-IPv6 packets received from the CE for
   de-capsulation.

   The transport type for the data plane also needs to be configured for
   encapsulation to enable MAP-E and forwarding needs to be enabled.

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   Consider an example for the following MAP-E Forwarding Mapping Rule:

   Data plane:         encapsulation

   Rule IPv6 Prefix:   2001:db8::/40

   Rule IPv4 Prefix:   192.0.2.0/24

   Rule EA-bit Length: 16

   BR IPv6 Address:    2001:db8:ffff::1

   Figure 4 provides the example MAP-E BR configuration xml.

       <br-instances>
         <algorithm>
           <algo-instance>
             <name>myalgo-instance</name>
             <encapsulation>
               <br-ipv6-addr>2001:db8:ffff::1</br-ipv6-addr>
             </encapsulation>
             <ea-len>16</ea-len>
             <rule-ipv4-prefix>192.0.2.0/24</rule-ipv4-prefix>
             <rule-ipv6-prefix>2001:db8::/40</rule-ipv6-prefix>
             <forwarding>true</forwarding>
             <port-set>
               <psid-offset>6</psid-offset>
               <psid-len>8</psid-len>
             </port-set>
           </algo-instance>
         </algorithm>
       </br-instances>

                   Figure 4: MAP-E FMR Configuration XML

A.3.  lw4o6 CE Configuration Example

   This section provides XML examples for configuring a lw4o6 CE.
   Examples for routing and NAT44 are also provided for convienience.

   Consider an example for the following lw4o6 CE configuration:

   lwB4 Binding IPv6 Address:  2001:db8::1

   lwB4 Binding IPv4 Address:  192.0.2.1

   lwB4 PSID:                  0x34

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   lwB4 PSID Length            8

   BR IPv6 Address:            2001:db8:1::2

   <config xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
     <interfaces xmlns="urn:ietf:params:xml:ns:yang:ietf-interfaces">
       <interface>
         <name>lw4o6-wan</name>
         <type>iana-tunnel-type:aplusp</type>
         <br-ipv6-addr
           xmlns="urn:ietf:params:xml:ns:yang:ietf-softwire-ce">
           2001:db8:1::2
         </br-ipv6-addr>
         <binding-ipv6info
           xmlns="urn:ietf:params:xml:ns:yang:ietf-softwire-ce">
           2001:db8::1
         </binding-ipv6info>
       </interface>
     </interfaces>
   </config>

                   Figure 5: lw4o6 CE Configuration XML

   In the example depicted in Figure 5, the interface name is defined
   for the softwire tunnel.  This name is then referenced by the routing
   configuration for the IPv4 route.  Figure 6 provides an example
   configuration for the CE's IPv4 routing, using the YANG module
   described in [RFC8349].

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<config xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
  <routing xmlns="urn:ietf:params:xml:ns:yang:ietf-routing">
    <control-plane-protocols>
      <control-plane-protocol>
        <type>static</type>
        <name>v4</name>
        <static-routes>
          <ipv4
          xmlns="urn:ietf:params:xml:ns:yang:ietf-ipv4-unicast-routing">
            <route>
              <destination-prefix>0.0.0.0/0</destination-prefix>
              <next-hop>
                <outgoing-interface>lw4o6-wan</outgoing-interface>
              </next-hop>
            </route>
          </ipv4>
        </static-routes>
      </control-plane-protocol>
    </control-plane-protocols>
  </routing>
</config>

               Figure 6: lw4o6 CE Routing Configuration XML

   Figure 7 provides an example configuration for the CE's NAPT44
   function, using the YANG module described in
   [I-D.ietf-opsawg-nat-yang].

 <config xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
   <nat xmlns="urn:ietf:params:xml:ns:yang:ietf-nat">
    <instances>
      <instance>
        <id>1</id>
        <policy>
         <policy-id>1</policy-id>
         <external-ip-address-pool>
           <pool-id>1</pool-id>
           <external-ip-pool>192.0.2.1</external-ip-pool>
         </external-ip-address-pool>
         <port-set-restrict>
           <port-set-algo>
             <psid-offset>6</psid-offset>
             <psid-len>8</psid-len>
             <psid>52</psid>
           </port-set-algo>
         </port-set-restrict>
         <notify-pool-usage>
           <pool-id>1</pool-id>

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           <high-threshold>80</high-threshold>
         </notify-pool-usage>
         </policy>
         <mapping-limits>
          <limit-per-protocol>
           <protocol-id>1</protocol-id>
           <limit>8</limit>
          </limit-per-protocol>
          <limit-per-protocol>
           <protocol-id>6</protocol-id>
           <limit>32</limit>
          </limit-per-protocol>
          <limit-per-protocol>
           <protocol-id>17</protocol-id>
           <limit>16</limit>
          </limit-per-protocol>
         </mapping-limits>
         <mapping-table>
           <mapping-entry>
             <index>1</index>
             <external-src-address>192.0.2.1/32</external-src-address>
             <internal-src-address>192.168.1.0/24</internal-src-address>
             <transport-protocol>6</transport-protocol>
           </mapping-entry>
           <mapping-entry>
             <index>2</index>
             <external-src-address>192.0.2.1/32</external-src-address>
             <internal-src-address>192.168.1.0/24</internal-src-address>
             <transport-protocol>17</transport-protocol>
           </mapping-entry>
           <mapping-entry>
             <index>3</index>
             <external-src-address>192.0.2.1/32</external-src-address>
             <internal-src-address>192.168.1.0/24</internal-src-address>
             <transport-protocol>1</transport-protocol>
           </mapping-entry>
         </mapping-table>
       </instance>
     </instances>
   </nat>
 </config>

                   Figure 7: lw4o6 NAT Configuration XML

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Authors' Addresses

   Yong Cui
   Tsinghua University
   Beijing  100084
   P.R. China

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

   Ian Farrer (editor)
   Deutsche Telekom AG
   CTO-ATI,Landgrabenweg 151
   Bonn, NRW  53227
   Germany

   Email: ian.farrer@telekom.de

   Mohamed Boucadair (editor)
   Orange
   Rennes  35000
   France

   Email: mohamed.boucadair@orange.com

   Qi Sun
   Tsinghua University
   Beijing  100084
   P.R. China

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

   Linhui Sun
   Tsinghua University
   Beijing  100084
   P.R. China

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

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   Sladjana Zechlin
   Deutsche Telekom AG
   Landgrabenweg 151
   Bonn, NRW  53227
   Germany

   Email: sladjana.zechlin@telekom.de

   Rajiv Asati
   Cisco Systems, Inc.
   7025 Kit Creek Rd.
   RTP, NC  27709
   USA

   Email: Rajiva@cisco.com

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