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Versions: 00 01 02 03 04 05 draft-ietf-softwire-yang

Softwire Working Group                                            Q. Sun
Internet-Draft                                                   H. Wang
Intended status: Standards Track                                  Y. Cui
Expires: April 8, 2016                               Tsinghua University
                                                               I. Farrer
                                                     Deutsche Telekom AG
                                                            M. Boucadair
                                                          France Telecom
                                                                R. Asati
                                                     Cisco Systems, Inc.
                                                         October 6, 2015


               YANG Data Model for IPv4-in-IPv6 Softwire
                       draft-sun-softwire-yang-04

Abstract

   This document defines a YANG data model for the configuration and
   management of IPv4-in-IPv6 Softwire Border Routers and Customer
   Premises Equipment.  It covers the Lightweight 4over6, MAP-E and
   MAP-T Softwire mechanisms.

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

Status of This Memo

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

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

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

   This Internet-Draft will expire on April 8, 2016.






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Copyright Notice

   Copyright (c) 2015 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
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   3
     1.2.  YANG Tree Diagrams  . . . . . . . . . . . . . . . . . . .   3
     1.3.  YANG Modelling of NAT44 Functionality . . . . . . . . . .   4
   2.  Objectives  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     2.1.  Common  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     2.2.  Lightweight 4over6  . . . . . . . . . . . . . . . . . . .   5
     2.3.  MAP-E . . . . . . . . . . . . . . . . . . . . . . . . . .   5
     2.4.  MAP-T . . . . . . . . . . . . . . . . . . . . . . . . . .   5
   3.  Softwire YANG Tree Diagrams . . . . . . . . . . . . . . . . .   5
     3.1.  Common Tree Diagrams  . . . . . . . . . . . . . . . . . .   5
     3.2.  Lightweight 4over6 Tree Diagrams  . . . . . . . . . . . .   6
     3.3.  MAP-E Tree Diagrams . . . . . . . . . . . . . . . . . . .   8
     3.4.  MAP-T Tree Diagrams . . . . . . . . . . . . . . . . . . .  10
     3.5.  Notifications for Softwire YANG . . . . . . . . . . . . .  12
   4.  Softwire YANG Model . . . . . . . . . . . . . . . . . . . . .  12
   5.  Example of Configure Lw4over6 Binding-Table . . . . . . . . .  30
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  31
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  32
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  32
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  32
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  32
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  33
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  34

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 softwire



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   functional elements: Border Routers (BRs) and Customer Premises
   Equipment (CPEs).

   This document defines a YANG data model that can be used to configure
   and manage IPv4-in-IPv6 Softwire BRs and/or CEs via NETCONF
   protocol[RFC6241].  To ensure interoperability in mixed vendors
   environments, it is important that the models can be easily reused
   between different vendors and implementations.

   There are three different mechanisms in this YANG model.  Each
   specific mechanism has their separate YANG modules respectively:

   o  Lightweight 4over6 [RFC7596]

   o  MAP-E [RFC7597]

   o  MAP-T [RFC7599]

   This model is structured into two root containers:

   1.  Container "softwire-config" holds the collection of YANG
       definitions common to all softwire configuration of BRs and CEs.

   2.  Container "softwire-state" holds YANG definitions for the
       operational state of the Softwire BRs and CEs.

   The model also includes a notification module.  The aim is to notify
   the client that a specific status has been changed.

   This approach has been taken so that the model can be easily extended
   in the future to support additional softwire mechanisms, should this
   be necessary.

1.1.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

   The reader should be familiar with the terms defined in [RFC7596]
   [RFC7597] [RFC7599] , and the YANG data modelling language [RFC6020].

1.2.  YANG Tree Diagrams

   The Softwire YANG tree diagrams provide a concise representation of
   the YANG modules to help the reader understand the module structure.
   The meaning of the symbols in these diagrams are as follows:




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   o  Brackets "[" and "]" enclose list keys.

   o  Braces "{" and "}" enclose feature content.

   o  Parentheses "(" and ")" enclose choice and case nodes, and case
      nodes are also marked with a colon (":").

   o  Symbols after data node names: "?" means an optional node, and "*"
      denotes a list and leaf-list.

   o  Abbreviations before data node names: "rw" means configuration
      data (read-write), and "ro" means state data (read-only).

1.3.  YANG Modelling of NAT44 Functionality

   This documented model does not include NAT-specific provisioning
   parameters other than the external IP address and port set which a
   softwire client may use for NAT44.  Additional NAT-specific
   considerations are out of scope of this document.  A YANG model for
   the configuration and management of NAT gateways is described in
   [I-D.sivakumar-yang-nat].

2.  Objectives

   This document defines a YANG data model that can be used to configure
   and manage BRs and CEs for the following IPv4-in-IPv6 Softwire
   mechanisms: Lightweight 4over6, MAP-E and MAP-T.

   For Lightweight 4over6, the configuration and management information
   of lwB4 and lwAFTR are different.  The lwAFTR needs to maintain a
   binding table of configured lwB4s.  The lwB4 holds the configuration
   for its local tunnel, the lwAFTR address and a NAPT table of active
   translations.

   For the MAP-E and MAP-T, CE and BR both need to maintain the map-rule
   table.  Thus, there is no need to distinguish BR and CE.

2.1.  Common

   The common model abstracts the shared features of different BRs and
   CEs making a single node softwire description for common features.

   The following sections of the document are structured with the root
   of the softwire YANG model (common to all mechanisms) described
   first.  The subsequent sections describe the models relevant to the
   different softwire mechanisms.  All functions are listed, but the
   YANG models use the "feature" statement to distinguish among the
   different softwire mechanisms.



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2.2.  Lightweight 4over6

   Lightweight 4over6 includes two elements: lwAFTR and lwB4.  The
   lwAFTR holds configuration for IPv4-IPv6 address bindings which is
   used for the forwarding of traffic originating from lwB4s.  And the
   lwB4 is configured with the relevant parameters for establishing the
   IPv4 in IPv6 tunnel including an IPv6 address for the lwAFTR and the
   IPv4 configuration for NAPT44.

2.3.  MAP-E

   MAP-E elements (BR and CE) are provisioned with the MAP rules
   necessary for defining MAP domains and forwarding rules.

2.4.  MAP-T

   MAP-T elements (BR and CE) are provisioned with the MAP rules
   necessary for defining MAP domains and forwarding rules.  MAP-T CEs
   an additional "ipv6-prefix" parameter is also configured.

3.  Softwire YANG Tree Diagrams

3.1.  Common Tree Diagrams

   Figure 1 describes the softwire data model which is common to all of
   the different softwire mechanisms listed in Section 1:

      +--rw softwire-config
      |  +--rw description?               string
      |  +--rw lw4over6 {lw4over6}?
      |  |  +--rw lwaftr {lwaftr}?
      |  |  +--rw lwb4 {lwb4}?
      |  +--rw map-e {map-e}?
      |  +--rw map-t {map-t}?
      |
      +--ro softwire-state
         +--ro description?               string
         +--ro lw4over6 {lw4over6}?
         |  +--ro lwaftr {lwaftr}?
         |  +--ro lwb4 {lwb4}?
         +--ro map-e {map-e}?
         +--ro map-t {map-t}?

              Figure 1: Softwire Common Data Model Structure

   The mechanism specific models for lw4over6, MAP-E and MAP-T are
   described in detail in the following sections.




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3.2.  Lightweight 4over6 Tree Diagrams

   Figure 2 defines the softwire data model for Lightweight 4over6 which
   includes lwAFR and lwB4:

module: ietf-softwire
   +--rw softwire-config
   |  +--...
   |  +--rw lw4over6 {lw4over6}?
   |     +--rw lwaftr {lwaftr}?
   |     |  +--rw enable?                          boolean
   |     |  +--rw lwaftr-instances
   |     |     +--rw lwaftr-instance* [id]
   |     |        +--rw id                         uint32
   |     |        +--rw name?                      string
   |     |        +--rw softwire-num-threshold     uint32
   |     |        +--rw tunnel-mtu                 uint16
   |     |        +--rw fragment-mru               uint16
   |     |        +--rw binding-table
   |     |           +--rw binding-entry* [binding-ipv6info]
   |     |              +--rw binding-ipv6info     union
   |     |              +--rw binding-ipv4-addr    inet:ipv4-address
   |     |              +--rw port-set
   |     |              |  +--rw offset            uint8
   |     |              |  +--rw psid              uint16
   |     |              |  +--rw psid-len          uint8
   |     |              +--rw lwaftr-ipv6-addr     inet:ipv6-address
   |     |              +--rw lifetime?            uint32
   |     +--rw lwb4 {lwb4}?
   |        +--rw enable?                          boolean
   |        +--rw lwb4-instances
   |           +--rw lwb4-instance* [binding-ipv6info]
   |              +--rw name?                      string
   |              +--rw tunnel-mtu                 uint16
   |              +--rw fragment-mru               uint16
   |              +--rw b4-ipv6-addr-format        boolean
   |              +--rw binding-ipv6info           union
   |              +--rw binding-ipv4-addr          inet:ipv4-address
   |              +--rw port-set
   |              |  +--rw offset                  uint8
   |              |  +--rw psid                    uint16
   |              |  +--rw psid-len                uint8
   |              +--rw lwaftr-ipv6-addr           inet:ipv6-address
   |              +--rw lifetime?                  uint32
   +--ro softwire-state
      +--...
      +--ro lw4over6 {lw4over6}?
         +--ro lwaftr {lwaftr}?



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         |  +--ro lwaftr-instances
         |     +--ro lwaftr-instance* [id]
         |        +--ro id                         uint32
         |        +--ro name?                      string
         |        +--ro sentPacket?                yang:zero-based-counter64
         |        +--ro sentByte?                  yang:zero-based-counter64
         |        +--ro rcvdPacket?                yang:zero-based-counter64
         |        +--ro rcvdByte?                  yang:zero-based-counter64
         |        +--ro droppedPacket?             yang:zero-based-counter64
         |        +--ro droppedByte?               yang:zero-based-counter64
         |        +--ro active-softwire-num?       uint32
         |        +--ro binding-table
         |           +--ro binding-entry* [binding-ipv6info]
         |              +--ro binding-ipv6info     union
         |              +--ro active?              boolean
         +--ro lwb4 {lwb4}?
            +--ro lwb4-instances
               +--ro lwb4-instance* [binding-ipv6info]
                  +--ro name?                      string
                  +--ro binding-ipv6info           union
                  +--ro sentPacket?                yang:zero-based-counter64
                  +--ro sentByte?                  yang:zero-based-counter64
                  +--ro rcvdPacket?                yang:zero-based-counter64
                  +--ro rcvdByte?                  yang:zero-based-counter64
                  +--ro droppedPacket?             yang:zero-based-counter64
                  +--ro droppedByte?               yang:zero-based-counter64

        Figure 2: Softwire Lightweight 4over6 Data Model Structure

   Some of the important lwAFTR nodes:

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

   o  tunnel-mtu: used to set the value of MTU for the Lightweight
      4over6 tunnel.

   o  fragment-mru: used to set the value of fragment for Lightweight
      4over6 tunnel.

   o  tunnel-num-threshold: used to set the maximum number of tunnels
      that can be created on the lw4over6 device simultaneously.

   o  active-tunnel-num (ro): used to present the number of tunnels
      currently provisioned on the device.




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   o  active (ro): used to show the status of particular binding-entry.

   Some of the important lwB4 nodes:

   o  b4-ipv6-addr-format: indicates the format of lwB4 IPv6 address.
      If set to true, it indicates that the IPv6 source address of the
      lwB4 is constructed according to the description in [RFC7596]; if
      set to false, the lwB4 can use any /128 address from the assigned
      IPv6 prefix.

   o  binding-ipv6info: used to set the IPv6 address type which is
      combined in a binding entry, for a complete address or a prefix.

3.3.  MAP-E Tree Diagrams

   Figure 3 defines the softwire data model for MAP-E:



































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 module: ietf-softwire
    +--rw softwire-config
    |  +--...
    |  +--rw map-e {map-e}?
    |     +--rw enable?                        boolean
    |     +--rw map-e-instances
    |        +--rw map-e-instance* [id]
    |           +--rw id                       uint32
    |           +--rw name?                    string
    |           +--rw map-rules
    |           |  +--rw map-rule* [id]
    |           |     +--rw id                 uint8
    |           |     +--rw forwarding         boolean
    |           |     +--rw rule-ipv6-prefix   inet:ipv6-prefix
    |           |     +--rw rule-ipv4-prefix   inet:ipv4-prefix
    |           |     +--rw port-set
    |           |     |  +--rw offset          uint8
    |           |     |  +--rw psid            uint16
    |           |     |  +--rw psid-len        uint8
    |           |     +--rw ea-len             uint8
    |           +--rw tunnel-mtu               uint16
    |           +--rw fragment-mru             uint16
    |           +--rw br-ipv6-addr             inet:ipv6-address
    +--ro softwire-state
       +--...
       +--ro map-e {map-e}?
          +--ro map-e-instances
             +--ro map-e-instance* [id]
                +--ro id                       int32
                +--ro name?                    string
                +--ro sentPacket?              yang:zero-based-counter64
                +--ro sentByte?                yang:zero-based-counter64
                +--ro rcvdPacket?              yang:zero-based-counter64
                +--ro rcvdByte?                yang:zero-based-counter64
                +--ro droppedPacket?           yang:zero-based-counter64
                +--ro droppedByte?             yang:zero-based-counter64

               Figure 3: Softwire MAP-E Data Model Structure

   Some of the important MAP-E nodes:

   o  forwarding: This parameter specifies whether the rule is to be
      used for forwarding (FMR).  If set, this rule is used as an FMR;
      if not set, this rule is a BMR only and MUST NOT be used for
      forwarding.  See Section 4.1 [RFC7598].

   o  offset: used to set the number of offset bits.




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   o  psid: used to algorithmically identify a set of ports exclusively
      for a specific softwire.

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

   o  tunnel-mtu: used to set the value of MTU for MAP-E tunnel.

   o  fragment-mru: used to the value of fragment for MAP-E tunnel.

   o  stat-count (ro): use to show the numbers of packets and bytes
      information of specific device respectively.

3.4.  MAP-T Tree Diagrams

   Figure 4 defines the softwire data model for MAP-T:



































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   module: ietf-softwire
      +--rw softwire-config
      |  +--...
      |  +--rw map-t {map-t}?
      |     +--rw enable?                         boolean
      |     +--rw map-t-instances
      |        +--rw map-t-instance* [id]
      |           +--rw id                        uint32
      |           +--rw name?                     string
      |           +--rw map-rules
      |           |  +--rw map-rule* [id]
      |           |     +--rw id                  uint8
      |           |     +--rw forwarding          boolean
      |           |     +--rw rule-ipv6-prefix    inet:ipv6-prefix
      |           |     +--rw rule-ipv4-prefix    inet:ipv4-prefix
      |           |     +--rw port-set
      |           |     |  +--rw offset      uint8
      |           |     |  +--rw psid        uint16
      |           |     |  +--rw psid-len    uint8
      |           |     +--rw ea-len              uint8
      |           +--rw dmr-ipv6-prefix?   inet:ipv6-prefix
      +--ro softwire-state
         +--...
         +--ro map-t {map-t}?
            +--ro map-t-instances
               +--ro map-t-instance* [id]
                  +--ro id               int32
                  +--ro name?            string
                  +--ro sentPacket?      yang:zero-based-counter64
                  +--ro sentByte?        yang:zero-based-counter64
                  +--ro rcvdPacket?      yang:zero-based-counter64
                  +--ro rcvdByte?        yang:zero-based-counter64
                  +--ro droppedPacket?   yang:zero-based-counter64
                  +--ro droppedByte?     yang:zero-based-counter64


               Figure 4: Softwire MAP-T Data Model Structure

   Some of the important MAP-T nodes:

   o  dmr-ipv6-prefix: defines the DMR in MAP-T.  This parameter is
      optional when configuring a MAP-T BR.

   o  stat-count (ro): use to show the numbers of packets and bytes
      information of specific device respectively.






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3.5.  Notifications for Softwire YANG

   This section describes the diagram tree for the notifications.  These
   notifications pertain to configuration and monitoring portions of
   specific Softwire mechanisms.  The logic is that, the softwire
   instance notifies the NETCONF client with the index for a mapping
   entry and then the NETCONF client retrieves the related information
   from the operational datastore of that instance.

module: ietf-softwire
notifications:
   +---n softwire-lwaftr-event {lw4over6,lwaftr}?
   |  +--ro lwaftr-id?        -> /softwire-state/lw4over6/lwaftr/.../id
   |  +--ro invalid-entry*    -> /softwire-config/lw4over6/lwaftr/.../binding-table/binding-entry/binding-ipv6info
   |  +--ro added-entry*      inet:ipv6-address
   |  +--ro modified-entry*   -> /softwire-config/lw4over6/lwaftr/.../binding-table/binding-entry/binding-ipv6info
   +---n softwire-lwb4-event {lw4over6,lwb4}?
   |  +--ro lwb4-binding-ipv6-addr-change    inet:ipv6-address
   +---n softwire-map-e-event {map-e}?
   |  +--ro map-e-id            -> /softwire-config/map-e/.../id
   |  +--ro invalid-entry-id*   -> /softwire-config/map-e/.../map-rules/map-rule/id
   |  +--ro added-entry*        uint32
   |  +--ro modified-entry*     -> /softwire-config/map-e/.../map-rules/map-rule/id
   +---n softwire-map-t-event {map-t}?
      +--ro map-t-id            -> /softwire-config/map-t/.../id
      +--ro invalid-entry-id*   -> /softwire-config/map-t/.../map-rules/map-rule/id
      +--ro added-entry*        uint32
      +--ro modified-entry*     -> /softwire-config/map-t/.../map-rules/map-rule/id

           Figure 5: Softwire Notifications Data Model Structure

   Some of the important notification nodes:

   o  invalid-entry, added-entry, modified-entry: used to notify the
      client that a specific binding entry or MAP rule is expired/
      invalid, added, or modified.

   o  lwb4-binding-ipv6-addr-change: use to notify that the lwB4's
      binding-ipv6-address has been changed or the value of the
      'b4-ipv6-addr-format' is "false".

4.  Softwire YANG Model

   This module imports typedefs from [RFC6991].

<CODE BEGINS> file "ietf-softwire@2015-08-31.yang"

module ietf-softwire {



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  namespace "urn:ietf:params:xml:ns:yang:ietf-softwire";
  prefix "softwire";

  import ietf-inet-types {prefix inet; }
  import ietf-yang-types {prefix yang; }

  organization "Softwire Working Group";

  contact
    "
    Qi Sun sunqi.ietf@gmail.com
    Hao Wang wangh13@mails.tsinghua.edu.cn
    Yong Cui yong@csnet1.cs.tsinghua.edu.cn
    Ian Farrer ian.farrer@telekom.de
    Mohamed Boucadair mohamed.boucadair@orange.com
    Rajiv Asati rajiva@cisco.com
    ";

  description
    "This document defines a YANG data model for the configuration and
    management of IPv4-in-IPv6 Softwire Border Routers and Customer
    Premises Equipment. It covers Lightweight 4over6, MAP-E and MAP-T
    Softwire mechanisms.

    Copyright (c) 2014 IETF Trust and the persons identified
    as authors of the code. All rights reserved.
    This version of this YANG module is part of RFC XXX; see the RFC
    itself for full legal notices.";

  revision 2015-09-30 {
    description
      "Version-04: fix YANG syntax; Add flags to map-rule; Remove
                  the map-rule-type element. ";
       reference "tbc";
  }

  revision 2015-04-07 {
    description
      "Version-03: Integrate lw4over6; Updata state nodes; Correct
          grammar errors; Reuse groupings; Update descriptions.
          Simplify the model.";
       reference "tbc";
  }

  revision 2015-02-10 {
    description
      "Version-02: Add notifications.";
       reference "tbc";



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  }


  revision 2015-02-06 {
    description
      "Version-01: Correct grammar errors; Reuse groupings; Update
      descriptions.";
       reference "tbc";
  }

  revision 2015-02-02 {
    description
      "Initial revision.";
       reference "tbc";
  }

/*
 * Features
 */

  feature lw4over6 {
    description
    "Lightweight 4over6 (lw4over6) is an IPv4-over-IPv6 tunnelling
     transition mechanism. Lightweight 4over6 is a solution designed
     specifically for complete independence between IPv6 subnet
     prefix (and /128 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 lwAFTR and
     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.";

   reference
      "I-D.ietf-softwire-lw4over6";
  }

  feature lwaftr {
    if-feature lw4over6;
    description
     "The AFTRs (BRs) for Lightweight 4over6, so-called lwAFTR. This
      feature indicates that a instance functions as a lwAFTR.
      A lwAFTR is an IPv4-in-IPv6 tunnel concentrator that maintains
      per-subscriber IPv4-IPv6 address binding.";
  }

  feature lwb4 {



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    if-feature lw4over6;
    description
      "The B4s (CEs) for Lightweight 4over6, so-called lwB4. This
      feature indicates that a instance functions as a lwB4. A lwB4 is
      an IPv4-in-IPv6 tunnel initiator. It is dual-stack capable node,
      either a directly connected end-host or a CE. It sources IPv4
      conncections using the configured port-set and the public IPv4
      address.";
  }

  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 relationship also allows the option of direct, meshed
      connectivity between users. Alternatively, MAP-E can
      be configured to support IPv4/IPv6 indepent binding.
      This feature indicates the instance functions
      as a MAP-E instance.";
    reference
      "I-D.ietf-softwire-map";
  }

  feature map-t {
    description
     "The Mapping of Address and Port - Translation (MAP-T)
     architecture is a double stateless NAT64 based solution. It uses
     the stateless algorithmic address & transport layer port mapping
     scheme defined in MAP-E. The MAP-T solution differs from MAP-E in
     the use of IPv4-IPv6 translation, rather than encapsulation, as
     the form of IPv6 domain transport. This feature indicates the
     instance functions as a MAP-T instance. ";

   reference
      "I-D.ietf-softwire-map-t";
  }

/*
 * Grouping
 */

  grouping port-set {
    description
      "Use the PSID algorithm to represent a range of transport layer



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      ports.";
    leaf offset {
      type uint8 {
        range 0..16;
      }
     mandatory true;
     description
       "The number of offset bits. In Lightweight 4over6, the defaul
       value is 0 for assigning one contiguous port range. In MAP-E/T,
       the default value is 6, which excludes system ports by default
       and assigns distributed port ranges. If the this parameter is
       larger than 0, the value of offset MUST be greater than 0.";
    }
    leaf psid {
      type uint16;
      mandatory true;
      description
        "Port Set Identifier (PSID) value, which identifies a set
        of ports algorithmically.";
    }
    leaf psid-len {
      type uint8 {
        range 0..16;
      }
      mandatory true;
      description
        "The length of PSID, representing the sharing ratio for an
        IPv4 address.";
    }
  }

  grouping binding-entry {
    description
      "The lwAFTR maintains an address binding table that contains
      thebinding between the lwB4's IPv6 address, the allocated IPv4
      address and restricted port-set.";
    leaf binding-ipv6info {
      type union {
        type inet:ipv6-address;
        type inet:ipv6-prefix;
      }
      mandatory true;
      description
        "The IPv6 information for a binding entry.
         If it's an IPv6 prefix, it indicates that
         the IPv6 source address of the lwB4 is constructed
         according to the description in RFC7596;
         if it's an IPv6 address, it means the lwB4 uses



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         any /128 address from the assigned IPv6 prefix.
         ";
    }
    leaf binding-ipv4-addr {
      type inet:ipv4-address;
      mandatory true;
      description
        "The IPv4 address assigned to the lwB4, which is
         used as the IPv4 external address
         for lwB4 local NAPT44.";
    }
    container port-set {
      description
        "For Lightweight 4over6, the default value
        of offset should be 0, to configure one contiguous
        port range.";
      uses port-set {
        refine offset {
          default "0";
        }
      }
    }
    leaf lwaftr-ipv6-addr {
      type inet:ipv6-address;
          mandatory true;
      description
        "The IPv6 address for lwaftr.";
    }
    leaf lifetime {
      type uint32;
      units seconds;
      description "The lifetime for the binding entry";
    }
  }

/*
  grouping nat-table {

    description
      "Grouping 'nat-table' is not extended. The current mechanism
      isfocusing on the provisioning of external IP address and
      port set; other NAT-specific considerations are out of scope for
      this model.";
  }
*/

  grouping map-instance {
    description "A map-instance could be a MAP-CE or a MAP-BR";



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    leaf id {
      type uint32;
      mandatory true;
      description "MAP Instance ID";
    }
    leaf name {
      type string;
      description "MAP Instance Name";
    }
    container map-rules {
      description
        "A MAP instance could be configured with multiple
        sets of MAP rules";
      list map-rule {
        key "id";

        description
          "A set of parameters describing the mapping between
          an IPv4 prefix, IPv4 address or shared IPv4 address
          and an IPv6 prefix or address.
          Each domain uses a differe mapping rule set.";

        leaf id {
          type uint8;
          description "Rule ID";
        }
                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 BMR only and MUST NOT be used
      for forwarding.";
                }
/*****
        leaf map-rule-type {
          mandatory true;
          type enumeration {
            enum "BMR";
            enum "FMR";
          }
          description
            "The BMR and FMR share the rule format. BMR is used for a node
            to configure itself with IPv4 information retrived from the
            rule. FMR is designed for the in-domain 4-in-6 routing, used
            in mesh mode. A BMR can be FMR in some case. The DMR for map-t
            is defined separately.";



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        }
*****/
        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.";
        }
        container port-set {
          description
            "Port set parameters specify a set of port ranges.
            For MAP, the default value of offset is 6. ";
          uses port-set {
            refine offset {
              default "6";
            }
          }
        }
        leaf ea-len {
          type uint8;
          mandatory true;
          description
            "Embedded Address (EA) bits are the IPv4 EA-bits
             in the IPv6 address identify an IPv4
             prefix/address (or part thereof) or
             a shared IPv4 address (or part thereof)
             and a port-set dentifier.
             The length of the EA-bits is defined as
             part of a MAP rule for a MAP domain.";
        }
      }
    }
  }
  grouping traffic-stat {
    description "Traffic statistics";
    leaf sentPacket {
      type yang:zero-based-counter64;
      description "Number of packets sent.";
    }
    leaf sentByte {
      type yang:zero-based-counter64;
      description "Traffic sent, in bytes";



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    }
    leaf rcvdPacket {
      type yang:zero-based-counter64;
      description "Number of packets received.";
    }
    leaf rcvdByte {
      type yang:zero-based-counter64;
      description "Traffic received, in bytes";
    }
    leaf droppedPacket {
      type yang:zero-based-counter64;
      description "Number of packets dropped.";
    }
    leaf droppedByte {
      type yang:zero-based-counter64;
      description "Traffic dropped, in bytes";
    }
  }


/*
 * Configuration Data Nodes
 */


  container softwire-config {
    description
      "The configuration data for Softwire instances. And the shared
      data describes the softwire data model which is common to all of
      the different softwire mechanisms, such as description.";
    leaf description {
      type string;
      description
        "A textual description of Softwire.";
    }
    container lw4over6 {
      if-feature lw4over6;
      description
        "lw4over6 configuration.";
      container lwaftr {
        if-feature lwaftr;
        description
          "Indicate this instance supports the lwAFTR function. The
          instances advertise the lwaftr feature through the
          capability exchange mechanism when a NETCONF session is
          established.";
        leaf enable {
          type boolean;



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          description
            "Enable/disable the lwAFTR function.";
        }
        container lwaftr-instances {
          description
            "A set of lwAFTRs to be configured.";
          list lwaftr-instance {
            key "id";
          description
            "A set of lwAFTRs to be configured.";
            leaf id {
              type uint32;
              description "An instance identifier.";
            }
            leaf name {
              type string;
              description "The name for the lwaftr.";
            }
            leaf softwire-num-threshold {
              type uint32;
              mandatory true;
              description
                "The maximum number of tunnels that can be created on
                the lwAFTR.";
            }
            leaf tunnel-mtu {
              type uint16;
              mandatory true;
              description
                "The MTU for Lightweight 4over6 tunnel.";
            }
            leaf fragment-mru {
              type uint16;
              mandatory true;
              description
                "The fragmentation MRU for Lightweight 4over6
                tunnel.";
            }
            container binding-table {
              description "id";
              list binding-entry {
                key "binding-ipv6info";
                description "id";
                uses binding-entry;
              }
            }
          }
        }



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      }
      container lwb4 {
        if-feature lwb4;
        description
          "Indicate this instance supports the lwB4 function. The
          instances advertise the lwb4 feature through the
          capability exchange mechanism when a NETCONF session is
          established.";
        leaf enable {
          type boolean;
          description
            "Enable/disable the lwB4 function.";
        }
        container lwb4-instances {
          description
            "A set of lwB4s to be configured.";
          list lwb4-instance {
            key "binding-ipv6info";
            description "id";
            leaf name {
              type string;
              description "The lwb4 name.";
            }
            leaf tunnel-mtu {
              type uint16;
              mandatory true;
              description
                "The MTU for Lightweight 4over6 tunnel.";
            }
            leaf fragment-mru {
              type uint16;
              mandatory true;
              description
                "The fragment MRU for Lightweight 4over6 tunnel.";
            }
            leaf b4-ipv6-addr-format {

              type boolean;
              mandatory true;
              description
               "The format of lwB4 IPv6 address. If set to true, it
               indicates that the IPv6 source address of the lwB4 is
               constructed according to the description in
               [RFC7596]; if set to false, the lwB4
               can use any /128 address from the assigned IPv6
               prefix.";
            }
            uses binding-entry;



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          }
        }
      }
    }
    container map-e {
      if-feature map-e;
      description
        "Indicate the instances support the MAP-E function. The
        instances advertise the map-e feature through the capability
        exchange mechanism when a NETCONF session is established.";
      leaf enable {
        type boolean;
        default "true";
        description
          "Enable/disable the MAP-E function.";
      }
      container map-e-instances {
        description
          "A set of MAP-E instances to be configured,
           applying to BRs and CEs.";
        list map-e-instance {
          key "id";
          description "id";
          uses map-instance;
          leaf tunnel-mtu {
            type uint16;
            mandatory true;
            description
              "The MTU for MAP-E tunnel.";
          }
          leaf fragment-mru {
            type uint16;
            mandatory true;
            description
              "The fragment MRU for MAP-E tunnel.";
          }
          leaf br-ipv6-addr {
            type inet:ipv6-address;
                        mandatory true;
            description
              "The IPv6 address of the MAP-E BR.";
          }
        }
      }
    }
    container map-t {
      if-feature map-t;
      description



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        "Indicate the instances support the MAP-T function. The
        instances advertise the map-t feature through the capability
        exchange mechanism when a NETCONF session is established.";
      leaf enable {
        type boolean;
        default "true";
        description
          "Enable/disable the MAP-T function.";
      }
      container map-t-instances {
        description
          "A set of the MAP-T instances to be configured, a
           pplying to BRs and CEs.";
        list map-t-instance {
          key "id";
          description "id";
          uses map-instance;
          leaf dmr-ipv6-prefix {
            type inet:ipv6-prefix;
            description
              "The IPv6 prefix of the MAP-T BR. ";
          }
        }
      }
    }
  }

/*
 * Operational state Data Nodes
 */

  container softwire-state {
    config false;
    description
      "The operational state data for Softwire instances. ";
    leaf description {
      type string;
      description
        "A textual description of the softwire instances.";
    }
    container lw4over6 {
      if-feature lw4over6;
      description
        "lw4over6 state.";
      container lwaftr {
        if-feature lwaftr;
        config false;
        description



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          "Indicate this instance supports the lwAFTR function. The
          instances advertise the lwaftr feature through the
          capability exchange mechanism when a NETCONF session is
          established.";
        container lwaftr-instances {
          description
            "A set of lwAFTRs.";
          list lwaftr-instance {
            key "id";
            description "id";
            leaf id {
              type uint32;
              description "id";
            }
            leaf name {
              type string;
              description "The name for this lwaftr.";
            }
            uses traffic-stat;
            leaf active-softwire-num {
              type uint32;
              description
                "The number of currently active tunnels on the
                lw4over6 instance.";
            }
            container binding-table {
              description "id";
              list binding-entry {
                key "binding-ipv6info";
                description "An identifier of the binding entry.";
                leaf binding-ipv6info {
                  type union {
                    type inet:ipv6-address;
                    type inet:ipv6-prefix;
                  }
                  mandatory true;
                  description
                    "The IPv6 information used to identify
                      a binding entry. ";
                }
                leaf active {
                  type boolean;
                  description
                    "Status of a specific tunnel.";
                }
              }
            }
          }



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        }
      }


      container lwb4 {
        if-feature lwb4;
        config false;
        description
          "Indicate this instance supports the lwB4 function. The
          instances advertise the lwb4 feature through the
          capability exchange mechanism when a NETCONF session is
          established.";
        container lwb4-instances {
          description
            "Status of the configured lwB4s.";
          list lwb4-instance {
            key "binding-ipv6info";
            description "a lwB4 isntance.";
            leaf name {
              type string;
              description "The lwb4 name.";
            }
            leaf binding-ipv6info {
              type union {
                type inet:ipv6-address;
                type inet:ipv6-prefix;
              }
              mandatory true;
              description
                "The IPv6 information used to identify
                 a binding entry. ";
            }
            uses traffic-stat;
          }
        }
      }
    }

    container map-e {
      if-feature map-e;
      config false;
      description
        "Indicate the instances support the MAP-E function. The
        instances advertise the map-e feature through the capability
        exchange mechanism when a NETCONF session is established.";
      container map-e-instances {
        description
          "Status of MAP-E instance(s).";



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        list map-e-instance {
          key "id";
          description "id";
          leaf id {
            type int32;
            description "id";
          }
          leaf name {
            type string;
            description "The map-e instance name.";

          }
          uses traffic-stat;
        }
      }
    }

    container map-t {
      if-feature map-t;
      config false;
      description
        "Indicate the instances support the MAP-T function. The
        instances advertise the map-t feature through the capability
        exchange mechanism when a NETCONF session is established.";
      container map-t-instances {
        description
          "Status of MAP-T instances.";
        list map-t-instance {
          key "id";
          description "id";
          leaf id {
            type int32;
            description "";
          }
          leaf name {
            type string;
            description "The map-t instance name.";
          }
          uses traffic-stat;
        }
      }
    }
  }

/*
 * Notifications
 */




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  notification softwire-lwaftr-event {
    if-feature lw4over6;
    if-feature lwaftr;
          description "Notification for lwaftr.";

    leaf lwaftr-id {
      type leafref {
        path
          "/softwire-state/lw4over6/lwaftr/lwaftr-instances/"
          + "lwaftr-instance/id";
      }
          description "id";
    }
    leaf-list invalid-entry {
      type leafref {
        path
          "/softwire-config/lw4over6/lwaftr/lwaftr-instances/"
          + "lwaftr-instance[id=current()/../lwaftr-id]/"
          + "binding-table/binding-entry/binding-ipv6info";
      }
      description
        "Notify the client that a specific binding entry has been
        expired/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
          get other information from the lwaftr about the entry
          indexed by that ipv6 address.
          ";
    }
    leaf-list modified-entry {
        type leafref {
          path
            "/softwire-config/lw4over6/lwaftr/lwaftr-instances/"
            + "lwaftr-instance[id=current()/../lwaftr-id]/"
            + "binding-table/binding-entry/binding-ipv6info";
        }
          description "lwaftr";
    }
  }

  notification softwire-lwb4-event {
    if-feature lw4over6;
    if-feature lwb4;
          description "lwB4 notification";



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    leaf lwb4-binding-ipv6-addr-change {
      type inet:ipv6-address;
      mandatory true;
      description
        "The source tunnel IPv6 address of the lwB4.
         If 'b4-ipv6-addr-format' is false, or the lwb4's
         binding-ipv6-address changes for any reason,
         it SHOULD notify the NETCONF client.";
    }
  }

  notification softwire-map-e-event {
    if-feature map-e;
       description "Notifications for MAP-E.";
    leaf map-e-id {
      type leafref {
        path
          "/softwire-config/map-e/map-e-instances/map-e-instance/id";
      }
      mandatory true;
       description "MAP-E event.";
    }
    leaf-list invalid-entry-id {
      type leafref {
        path
          "/softwire-config/map-e/map-e-instances/"
          + "map-e-instance[id=current()/../map-e-id]/map-rules/"
          + "map-rule/id";
      }
       description "Invalid entry event.";
    }
    leaf-list added-entry {
      type uint32;
       description "Added entry.";
    }
    leaf-list modified-entry {
      type leafref {
        path
          "/softwire-config/map-e/map-e-instances/"
          + "map-e-instance[id=current()/../map-e-id]/map-rules/"
          + "map-rule/id";
      }
       description "Modified entry.";
    }
  }

  notification softwire-map-t-event {
    if-feature map-t;



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       description "MAP-T notification";
    leaf map-t-id {
      type leafref {
        path
          "/softwire-config/map-t/map-t-instances/map-t-instance/id";
           }
      mandatory true;
       description "MAP-T ID";
    }
    leaf-list invalid-entry-id {
      type leafref {
        path
          "/softwire-config/map-t/map-t-instances/"
          + "map-t-instance[id=current()/../map-t-id]/map-rules/"
          + "map-rule/id";
           }
       description "Invalid Entry.";
    }
    leaf-list added-entry {
      type uint32;
       description "Added entry";
    }
    leaf-list modified-entry {
      type leafref {
        path
          "/softwire-config/map-t/map-t-instances/"
          + "map-t-instance[id=current()/../map-t-id]/map-rules/"
          + "map-rule/id";
      }
       description "Modified entry";
    }
  }
}


<CODE ENDS>

5.  Example of Configure Lw4over6 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




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   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.

   Requirement: Add an entry that maintain the relationship between
   3-tuples of lwB4 (2001::1) in binding-table, which on the lwAFTR
   (2001::2).  The data value of this 3-tuples are '2001::1',
   '123.1.1.1' and '1234' respectively.

   Here is the example binding-table configuration xml:

     <rpc message-id="101"
       xmlns:nc="urn:params:xml:ns:yang:ietf-softwire:1.0">
   <!-- replace with IANA namespace when assigned. -->
     <edit-config>
       <target>
         <running/>
       </target>
     <softwire-config>
       <lw4over6-aftr>
         <lw4over6-aftr-instances>
           <lw4over6-aftr-instance>
             <aftr-ipv6-addr>2001::2</aftr-ipv6-addr>
             <binding-table>
               <binding-entry>
                 <binding-ipv4-addr>123.1.1.1</binding-ipv4-addr>
                 <port-set>
                   <psid>1234</psid>
                 </port-set>
                 <binding-ipv6-addr>2001::1</binding-ipv6-addr>
                 <active>1</active>
               </binding-entry>
             </binding-table>
           </lw4over6-aftr-instance>
         </lw4over6-aftr-instances>
       </lw4over6-aftr>
     </softwire-config>


            Figure 6: Lw4over6 Binding-Table Configuration XML

6.  Security Considerations

   The YANG module defined in this memo is designed to be accessed via
   the NETCONF protocol [RFC6241].  The lowest NETCONF layer is the
   secure transport layer and the mandatory to implement secure
   transport is SSH [RFC6242].  The NETCONF access control model
   [RFC6536] provides the means to restrict access for particular



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   NETCONF users to a pre-configured subset of all available NETCONF
   protocol operations and content.

   There are a number of data nodes defined in this YANG module which
   are writable/creatable/deletable (i.e. config true, which is the
   default).  These data nodes may be considered sensitive or vulnerable
   in some network environments.  Write operations (e.g. edit-config) to
   these data nodes without proper protection can have a negative effect
   on network operations.  These are the subtrees and data nodes and
   their sensitivity/vulnerability:

      subtrees and data nodes and state why they are sensitive

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

      subtrees and data nodes and state why they are sensitive

7.  IANA Considerations

   A registry for standard YANG modules shall be set up.  This document
   registers one URI for the YANG XML namespace in the IETF XML registry
   [RFC3688].

      URI: urn:ietf:params:xml:ns:yang:softwire

8.  Acknowledgements

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

9.  References

9.1.  Normative References

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

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





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   [RFC6020]  Bjorklund, M., Ed., "YANG - A Data Modeling Language for
              the Network Configuration Protocol (NETCONF)", RFC 6020,
              DOI 10.17487/RFC6020, October 2010,
              <http://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,
              <http://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,
              <http://www.rfc-editor.org/info/rfc6242>.

   [RFC6536]  Bierman, A. and M. Bjorklund, "Network Configuration
              Protocol (NETCONF) Access Control Model", RFC 6536,
              DOI 10.17487/RFC6536, March 2012,
              <http://www.rfc-editor.org/info/rfc6536>.

   [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, <http://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,
              <http://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,
              <http://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, <http://www.rfc-editor.org/info/rfc7599>.

9.2.  Informative References

   [I-D.sivakumar-yang-nat]
              Sivakumar, S., Boucadair, M., and S. <>, "YANG Data Model
              for Network Address Translation (NAT)", draft-sivakumar-
              yang-nat-00 (work in progress), September 2015.




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

Authors' Addresses

   Qi Sun
   Tsinghua University
   Beijing  100084
   P.R. China

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


   Hao Wang
   Tsinghua University
   Beijing  100084
   P.R. China

   Phone: +86-10-6278-5822
   Email: wangh13@mails.tsinghua.edu.cn


   Yong Cui
   Tsinghua University
   Beijing  100084
   P.R. China

   Phone: +86-10-6260-3059
   Email: yong@csnet1.cs.tsinghua.edu.cn


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

   Email: ian.farrer@telekom.de


   Mohamed Boucadair
   France Telecom
   Rennes  35000
   France

   Email: mohamed.boucadair@orange.com



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

   Email: Rajiva@cisco.com












































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