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Versions: (draft-jiang-softwire-map-radius) 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14

Softwire                                                   S. Jiang, Ed.
Internet-Draft                              Huawei Technologies Co., Ltd
Intended status: Standards Track                              Y. Fu, Ed.
Expires: August 4, 2018                                            CNNIC
                                                                  B. Liu
                                            Huawei Technologies Co., Ltd
                                                               P. Deacon
                                                      IEA Software, Inc.
                                                                  C. Xie
                                                           China Telecom
                                                                   T. Li
                                                     Tsinghua University
                                                            M. Boucadair
                                                                  Orange
                                                        January 31, 2018


    RADIUS Attribute for Softwire Address plus Port based Mechanisms
                   draft-ietf-softwire-map-radius-14

Abstract

   IPv4-over-IPv6 transition mechanisms provide both IPv4 and IPv6
   connectivity services simultaneously during the IPv4/IPv6 co-existing
   period.  The Dynamic Host Configuration Protocol for IPv6 (DHCPv6)
   options have been defined to configure Customer Edge (CE) in MAP-E,
   MAP-T, Lightweight 4over6 and PREFIX64 option for Multicast Basic
   Bridging BroadBand (mB4) in multicast scenarios.  However, in many
   networks, the configuration information may be stored in an
   Authentication Authorization and Accounting (AAA) server, while user
   configuration information is mainly provided by the Broadband Network
   Gateway (BNG) through the DHCPv6 protocol.  This document defines two
   new Remote Authentication Dial In User Service (RADIUS) attributes
   that carry CE or mB4 configuration information from an AAA server to
   BNG.

Status of This Memo

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

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

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any



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   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 August 4, 2018.

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
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Configuration process with RADIUS . . . . . . . . . . . . . .   4
   4.  Attributes  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     4.1.  Softwire46-Configuration Attribute  . . . . . . . . . . .   7
     4.2.  S46 Container Options . . . . . . . . . . . . . . . . . .   8
     4.3.  Sub Options for S46 Container Option  . . . . . . . . . .   9
       4.3.1.  S46-Rule Sub Option . . . . . . . . . . . . . . . . .   9
       4.3.2.  S46-BR Sub Option . . . . . . . . . . . . . . . . . .  10
       4.3.3.  S46-DMR Sub Option  . . . . . . . . . . . . . . . . .  11
       4.3.4.  S46-V4V6Bind Sub Option . . . . . . . . . . . . . . .  12
       4.3.5.  S46-PORTPARAMS Sub Option . . . . . . . . . . . . . .  13
     4.4.  Sub Options for S46-Rule Sub Option . . . . . . . . . . .  13
       4.4.1.  Rule-IPv6-Prefix Sub Option . . . . . . . . . . . . .  13
       4.4.2.  Rule-IPv4-Prefix Sub Option . . . . . . . . . . . . .  14
       4.4.3.  EA Length Sub Option  . . . . . . . . . . . . . . . .  15
     4.5.  Sub Options for S46-v4v6Bind Sub Option . . . . . . . . .  15
       4.5.1.  The IPv4-address Sub Option . . . . . . . . . . . . .  15
       4.5.2.  The Bind-IPv6-Prefix Sub Option . . . . . . . . . . .  15
     4.6.  Sub Options for S46-PORTPARAMS Sub Option . . . . . . . .  16
       4.6.1.  The PSID-offset Sub Option  . . . . . . . . . . . . .  16
       4.6.2.  The PSID-len Sub Option . . . . . . . . . . . . . . .  17
       4.6.3.  The PSID Sub Option . . . . . . . . . . . . . . . . .  17
     4.7.  Softwire46 Sub Options Encapsulation  . . . . . . . . . .  17
     4.8.  Softwire46-Priority Attribute . . . . . . . . . . . . . .  18
     4.9.  Softwire46-Multicast Attribute  . . . . . . . . . . . . .  18



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       4.9.1.  ASM-Prefix64 TLV  . . . . . . . . . . . . . . . . . .  20
       4.9.2.  SSM-Prefix64 TLV  . . . . . . . . . . . . . . . . . .  21
       4.9.3.  U-Prefix64 TLV  . . . . . . . . . . . . . . . . . . .  22
     4.10. Table of attributes . . . . . . . . . . . . . . . . . . .  23
   5.  Diameter Considerations . . . . . . . . . . . . . . . . . . .  24
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  24
     6.1.  S46 Mechanisms and Their Identifying Option Codes . . . .  25
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  25
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  26
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  26
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  26
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  27
   Additional Authors  . . . . . . . . . . . . . . . . . . . . . . .  29
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  30

1.  Introduction

   Recently providers have started to deploy IPv6 and consider how to
   transit to IPv6.  Many IPv4 service continuity mechanisms based on
   the Address plus Port (A+P) [RFC6346] have been proposed for running
   IPv4 over IPv6-only infrastructure.  Mapping of Address and Port with
   Encapsulation (MAP-E)[RFC7597] and Mapping of Address and Port using
   Translation (MAP-T)[RFC7599] are stateless mechanisms for running
   IPv4 over IPv6-only infrastructure.  Lightweight 4over6 [RFC7596] is
   a hub-and-spoke IPv4-over-IPv6 tunneling mechanism, with complete
   independence of IPv4 and IPv6 addressing.  MAP-E, MAP-T, and
   Lightweight 4over6 Customer Edge (CE) devices may be provisionned by
   mans of Dynamic Host Configuration Protocol for IPv6 (DHCPv6)
   [RFC3315].  In particualr, the CE uses DHCPv6 options to discover the
   Border Relay (BR) and retrieve Softwire46 (S46) configurations.

   [RFC8114] specifies a generic solution for delivery of IPv4 multicast
   services to IPv4 clients over an IPv6 multicast network.  The
   solution applies also for lw4o6 and MAP-E.  [RFC8115] defines a
   DHCPv6 PREFIX64 option to convey the IPv6 prefixes to be used for
   constructing IPv4-embedded IPv6 addresses to inform the mB4 element
   of the PREFIX64.  The following lists the multicast-related
   information that needs to be provisioned:

   o  ASM Multicast Prefix64: the IPv6 multicast prefix to be used to
      synthesize the IPv4-embedded IPv6 addresses of the multicast
      groups in the Any-Source Multicast (ASM) mode.

   o  SSM Multicast Prefix64: the IPv6 multicast prefix to be used to
      synthesize the IPv4-embedded IPv6 addresses of the multicast
      groups in the Source-Specific Multicast (SSM) [RFC4607] mode.





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   o  Unicast Prefix64: the IPv6 unicast prefix to be used in SSM mode
      for constructing the IPv4-embedded IPv6 addresses representing the
      IPv4 multicast sources in the IPv6 domain.  Unicast Prefix64 may
      also be used to extract the IPv4 address from the received
      multicast data flows.  The address mapping follows the guidelines
      documented in [RFC6052].

   In many networks, user configuration information may be stored in an
   Authentication, Authorization, and Accounting (AAA) server.
   Currently, the AAA servers communicate using the Remote
   Authentication Dial In User Service (RADIUS) [RFC2865] protocol.  In
   a fixed line broadband network, a Broadband Network Gateway (BNG)
   acts as the access gateway of users.  The BNG is assumed to embed a
   DHCPv6 server function that allows it to locally handle any DHCPv6
   requests initiated by hosts.

   Since the S46 configuration information is stored in an AAA servers
   and user configuration information is mainly transmitted through
   DHCPv6 protocol between the BNGs and hosts/CEs, new RADIUS attributes
   are needed to propagate the information from the AAA servers to BNGs.
   The RADIUS attributes designed in this document are especially for
   the MAP-E[RFC7597], MAP-T[RFC7599] and Lightweight 4over6[RFC7596],
   providing enough information to form the correspondent DHCPv6
   configuration options[RFC7598].  At the Section 4.9, a new RADIUS
   attribute is defined to be used for carrying the Multicast-Prefixes-
   64, based on the equivalent DHCPv6 option already specified in
   [RFC8115].

2.  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 terms DS-Lite multicast Basic Bridging BroadBand element (mB4)
   and the DS-Lite multicast Address Family Transition Router element
   (mAFTR) are defined in [RFC8114] .

3.  Configuration process with RADIUS

   The Figure 1 below illustrates how the RADIUS protocol and DHCPv6 co-
   operate to provide CE with MAP configuration information.  The BNG
   acts as a RADIUS client and DHCPv6 server.








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  CE                              BNG                         AAA Server
  |                                |                               |
  |-------1.DHCPv6 Solicit-------> |                               |
  | (ORO w/container option code)  |                               |
  |                                |-------2.Access-Request------->|
  |                                | (S46-Configuration attribute  |
  |                                |and/or S46-Multicast attribute)|
  |                                |<------3.Access-Accept---------|
  |<---4.DHCPv6 Advertisement----- | (S46-Configuration attribute  |
  |      (container option)        |and/or S46-Multicast attribute)|
  |-------5.DHCPv6  Request------> |                               |
  |      (container Option)        |                               |
  |<------6.DHCPv6 Reply---------- |                               |
  |      (container option)        |                               |
  |                                |                               |
                 DHCPv6                            RADIUS

    Figure 1: the cooperation between DHCPv6 and RADIUS combining with
                           RADIUS authentication

   1.  First, the CE may initiate a DHCPv6 Solicit message that includes
   an Option Request option(6) [RFC3315] with the S46 Container option
   codes as defined in[RFC7598].  As described in [RFC7598],
   OPTION_S46_CONT_MAPE should be included for MAP-E[RFC7597],
   OPTION_S46_CONT_MAPT for MAP-T [RFC7599], and OPTION_S46_CONT_LW for
   Lightweight 4over6 [RFC7596].  For the multicast case,
   OPTION_V6_PREFIX64 should be included for the delivery of multicast
   services in the context of transition to IPv6.  Note however, that
   the ORO (Option Request option) with the S46 Container option code
   could be optional if the network was planned as being S46-enabled as
   default.

   2.  When the BNG receives the Solicit message, it should initiate a
   radius Access-Request message, in which an User-Name attribute (1)
   should be filled by a CE MAC address or interface-id or both, to the
   RADIUS server and a User-password attribute (2) should be filled by
   the shared password that has been preconfigured on the DHCPv6 server,
   requesting authentication as defined in [RFC2865] with the
   corresponding Softwire46-Configuration Attribute or
   Softwire46-Multicast Attribute , which will be defined in the next
   Section.

   3.  If the authentication request is approved by the AAA server, an
   Access-Accept message MUST be acknowledged with the corresponding
   Softwire46-Configuration Attribute or Softwire46-Multicast Attribute.






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   4.  After receiving the Access-Accept message with the corresponding
   Attribute, the BNG SHOULD respond to the DHCPv6 Client (CE) with an
   Advertisement message.

   5.  After receiving the Advertise message, the CE MAY request for the
   corresponding S46 Container option, by including the S46 Container
   option in the Request message.

   6.  After receiving the client's Request message, containing the
   corresponding S46 Container option, the BNG SHOULD reply to the CE
   with the message containing the S46 Container option.  The
   recommended format of the MAC address is defined as Calling-Station-
   Id (Section 3.20 in [RFC3580] without the SSID (Service Set
   Identifier) portion.

   For Lightweight 4over6 [RFC7596], the subscriber's binding state
   should be synchronized between the AAA server and lwAFTR.  If the
   bindings are pre-configured statically, in both the AAA server and
   lwAFTR, an AAA server does not need to configure the lwAFTR anymore.
   Otherwise, if the bindings are locally created on-demand in an AAA
   server, it should inform the lwAFTR with the subscriber's binding
   state, in order to synchronize the binding information of the lwB4
   with the lwAFTR.

   The authorization operation could also be done independently after
   the authentication process.  In such a scenario, after the
   authentication operation, the client MAY initiate a DHCPv6 Request
   message that includes the corresponding S46 Container options.
   Similar to the above scenario, the ORO with the corresponding S46
   Container option code in the initial DHCPv6 request could be optional
   if the network was planned as being S46-enabled by default.  When the
   BNG receives the DHCPv6 Request, it SHOULD initiate the radius
   Access-Request message, which MUST contain a Service-Type attribute
   (6) with the value Authorize Only (17), the corresponding
   Softwire46-Configuration Attribute, and a State attribute obtained
   from the previous authentication process according to [RFC5080].  If
   the authorization request is approved by an AAA server, an Access-
   Accept message MUST be acknowledged with the corresponding
   Softwire46-Configuration Attribute.  The BNG SHOULD then send the
   DHCPv6 Reply message containing the S46 Container option.

   In both the above-mentioned scenarios, Message-authenticator (type
   80) [RFC2869] SHOULD be used to protect both Access-Request and
   Access-Accept messages.

   If the BNG does not receive the corresponding
   Softwire46-Configuration Attribute in the Access-Accept message it
   MAY fallback to a pre-configured default S46 configuration, if any.



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   If the BNG does not have any pre-configured default S46
   configuration, or if the BNG receives an Access-Reject, then S46
   connection cannot be established.

   As specified in [RFC3315], section 18.1.4, "Creation and Transmission
   of Rebind Messages ", if the DHCPv6 server to which the DHCPv6 Renew
   message was sent at time T1 has not responded by time T2, the CE
   (DHCPv6 client) SHOULD enter the Rebind state and attempt to contact
   any available server.  In this situation, the secondary BNG receiving
   the DHCPv6 message MUST initiate a new Access-Request message towards
   the AAA server.  The secondary BNG MAY include the
   Softwire46-Configuration Attribute in its Access-Request message.

4.  Attributes

   This section defines the Softwire46-Configuration Attribute,
   Softwire46-Priority Attribute, and Softwire46-Multicast Attribute.
   The attribute design follows [RFC6158] and refers to [RFC6929].

   The Softwire46-Configuration Attribute carries the configuration
   information for MAP-E, MAP-T, and Lightweight 4over6.  The
   configuration information for each S46 mechanism is carried in the
   corresponding S46 Container option.  Different sub options are
   required for each type of S46 Container option.  The RADIUS attribute
   for Dual-Stack Lite [RFC6333] is defined in [RFC6519].

   A client may be capable of supporting several different S46
   mechanisms.  Depending on the deployment scenario, a client might
   request for more than one S46 mechanism at a time.  The
   Softwire46-Priority Attribute contains information allowing the
   client to prioritize which mechanism to use, corresponding to
   OPTION_S46_PRIORITY defined in [RFC8026].

   The Softwire46-Multicast Attirbute conveys the IPv6 prefixes to be
   used in [RFC8114] to synthesize IPv4-embedded IPv6 addresses.  The
   BNG SHALL use the IPv6 prefixes returned in the RADIUS
   Softwire46-Multicast Attirbute to populate the DHCPv6 PREFIX64 Option
   [RFC8115].

4.1.  Softwire46-Configuration Attribute

   The Softwire46-Configuration Attribute can only encapsulate S46
   Container Option(s).  The Softwire46-Configuration Attribute is
   structured as follows:







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    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      Type     |    Length     |                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
   |                                                               |
   +             S46 Container Option(s)                           +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     Type
       TBD
     Length
       2 + the length of the S46 Container option(s)
       specified in octets
     S46 Container Option (s)
       A variable field that may contains one or more S46 Container
       option(s), defined in Section 4.2.

4.2.  S46 Container Options

   The S46 Container Option can only be encapsulated in the
   Softwire46-Configuration Attribute.  Depending on the deployment
   scenario, a client might request for more than one transition
   mechanism at a time, there MUST be at least one S46 Container option
   encapsulated in one Softwire46-Configuration Attribute.  There MUST
   be at most one instance of each type of S46 Container Option
   encapsulated in one Softwire46-Configuration Attribute.

                                                 /
                        /                       | 1.Rule-IPv6-Prefix
                       |                        |   Sub Option
                       | 1.S46-Rule Sub Option--+ 2.Rule-IPv4-Prefix
                       |                        |   Sub Option
                       | 2.S46-BR Sub Option    | 3.EA Length Sub
 S46 Container Option--+ 3.S46-DMR Sub Option    \  Option
                       |
                       |                             /1.IPv4-address
                       |                            |   Sub Option
                       | 4.S46-v4v6Bind Sub Option--| 2.Bind-IPv6-Prefix
                       |                             \  Sub Option
                       |                               /1.PSID-offset
                       |                              |   Sub Option
                       | 5.S46-PORTPARAMS Sub Option--| 2.PSID-len
                       |                              |   Sub Option
                        \                              \3.PSID Sub
                                                          Option

                 Figure 2: S46 Container Option Hierarchy



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   There are three types of S46 Container Options, namely MAP-E
   Container Option, MAP-T Container Option, Lightweight 4over6
   Container Option.  Each type of S46 Container Option contains a
   number of sub options, defined in Section 4.3.  The hierarchy of the
   S46 Container Option is shown in Figure 2.  Section 4.5 describes
   which Sub Options are mandatory, optional, or not permitted for each
   defined S46 Container Option.

   There are three types of S46-Rule Sub Options, namely Basic Mapping
   Rule, Forwarding Mapping Rule, Basic and Forwarding Mapping Rule.
   Each type of S46-Rule Sub Option also contains a number of Sub
   Options.  The Rule-IPv6-Prefix Sub Option is necessary for every type
   of S46-Rule Sub Option.  It should appear for once and only once.

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      Type     |    Length     |                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
   |                                                               |
   +                         Sub Options                           +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      Type
        TBD1 MAP-E Container Option
        TBD2 MAP-T Container Option
        TBD3 Lightweight 4over6 Container Option
      Length
        2 + the length of the Sub Options specified in octets
      Sub Option
        A variable field that contains necessary sub options defined
        in Section 4.3 and zero or several optional sub options,
        defined in Section 4.4.

    NOTE: The Type values for each S46 Container Option are the same
    as the S46-option-code values of the corresponding S46 Mechanisms
    specified in Section 6.1.

4.3.  Sub Options for S46 Container Option

4.3.1.  S46-Rule Sub Option

   The S46-Rule Sub Option can only be encapsulated in the MAP-E
   Container Option or the MAP-T Container Option.  Depending on
   deployment scenario, one Basic Mapping Rule and zero or more
   Forwarding Mapping Rules MUST be included in one MAP-E Container
   Option or MAP-T Container Option.




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   Each type of S46-Rule Sub Option also contains a number of sub
   options, including Rule-IPv6-Prefix Sub Option, Rule-IPv4-Prefix Sub
   Option, and EA Length Sub Option.  The structure of the sub options
   for S46-Rule Sub Option is defined in section 4.4.

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     SubType   |    SubLen     |                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
   |                                                               |
   +                         Sub Options                           +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      SubType
        1 Basic Mapping Rule (Not Forwarding Mapping Rule)
        2 Forwarding Mapping Rule (Not Basic Mapping Rule)
        3 Basic & Forwarding Mapping Rule
      SubLen
        2 + the length of the Sub Options specified in octets
      Sub Option
        A variable field that contains sub options defined in
        Section 4.4.

4.3.2.  S46-BR Sub Option

   The S46-BR Sub Option an only be encapsulated in the MAP-E Container
   Option or the Lightweight 4over6 Container Option.  There MUST be at
   least one S46-BR Sub Option included in each MAP-E Container Option
   or Lightweight 4over6 Container Option.





















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    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    SubType    |    SubLen     |                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
   |                                                               |
   |                        BR-ipv6-address                        |
   |                                                               |
   +                               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      SubType
         4 (SubType number, for the S46-BR sub option)
      SubLen
         18 (the length of the S46-BR sub option)
      BR-ipv6-address
         a fixed-length field of 16 octets that specifies the IPv6
         address for the S46 BR.

4.3.3.  S46-DMR Sub Option

   The S46-DMR Sub Option can only appear in the MAP-T Container Option.
   There MUST be exactly one S46-DMR Sub Option included in one MAP-T
   Container Option.


























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    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    SubType    |    SubLen     |    Reserved   |dmr-prefix6-len|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        dmr-ipv6-prefix                        |
   |                       (variable length)                       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      SubType
         5 (SubType number, for the S46-DMR Sub Option)
      SubLen
         4 + length of dmr-ipv6-prefix specified in octets
      Reserved
         This field is reserved. It should be set to all zero.
      dmr-prefix6-len
         8 bits long; expresses the bitmask length of the IPv6
         prefix specified in the dmr-ipv6-prefix field. Allowed
         values range from 0 to 96.
      dmr-ipv6-prefix
         a variable-length field specifying the IPv6 prefix or address
         for the BR. This field is right-padded with zeros to the
         nearest octet boundary when dmr-prefix6-len is not divisible
         by 8.

4.3.4.  S46-V4V6Bind Sub Option

   The S46-V4V6Bind Sub Option can only be encapsulated in the
   Lightweight 4over6 Container Option.  There MUST be at most one
   S46-V4V6Bind Sub Option included in each Lightweight 4over6 Container
   Option.

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     SubType   |    SubLen     |                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
   |                                                               |
   +                         Sub Options                           +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      SubType
        6 (SubType number, for the S46-V4V6Bind sub option)
      SubLen
        2 + the length of the Sub Options specified in octets
      Sub Option
        A variable field that contains sub options defined in
        Section 4.5.



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4.3.5.  S46-PORTPARAMS Sub Option

   The S46-PORTPARAMS Sub Option specifies optional port set information
   that MAY be provided to CEs.  The S46-PORTPARAMS sub option can be
   included optionally by each type of S46 Container Option.

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     SubType   |    SubLen     |                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
   |                                                               |
   +                         Sub Options                           +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      SubType
        7 (SubType number, for the S46-PORTPARAMS Sub Option)
      SubLen
        2 + the length of the Sub Options specified in octets
      Sub Option
        A variable field that contains sub options defined in
        Section 4.6.

4.4.  Sub Options for S46-Rule Sub Option

4.4.1.  Rule-IPv6-Prefix Sub Option

   The Rule-IPv6-Prefix Sub Option is necessary for every S46-RULE sub
   option.  There MUST be exactly one S46-IPv6-Prefix Sub Option
   encapsulated in each type of S46-Rule Sub Option.

   The IPv6 Prefix sub option is followed the framed IPv6 prefix
   designed in [RFC3162].


















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    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    SubType    |    SubLen     |   Reserved    |ruleprefix6-len|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   |                        rule-ipv6-prefix                       |
   |                                                               |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      SubType
         8 (SubType number, for the Rule-IPv6-Prefix Sub Option)
      SubLen
         20 (the length of the Rule-IPv6-Prefix Sub Option)
      Reserved
         This field is reserved. It always set to zero. This field
         is one octet in length.
      ruleprefix6-len
         the length of IPv6 prefix, specified in the rule-ipv6-prefix
         field, expressed in bits.
      rule-ipv6-prefix
         a 128-bits field that specifies an IPv6 prefix that appears
         in a MAP rule.

4.4.2.  Rule-IPv4-Prefix Sub Option

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    SubType    |    SubLen     |   Reserved    |  prefix4-len  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       rule-ipv4-prefix                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      SubType
         9 (SubType number, for the Rule-IPv4-Prefix Sub Option)
      SubLen
         8 (the length of the Rule-IPv4-Prefix Sub Option)
      Reserved
         This field is reserved. It always set to zero. This field
         is one octet in length.
      Prefix4-len
         the length of IPv4 prefix, specified in the rule-ipv4-prefix
         field, expressed in bits.
      rule-ipv4-prefix
         a 32-bits field that specifies an IPv4 prefix that appears
         in a MAP rule.





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4.4.3.  EA Length Sub Option

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    SubType    |    SubLen     |             EA-len            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      SubType
         10 (SubType number, for the EA Length Sub Option)
      SubLen
         4 (the length of the EA Length Sub Option)
      EA-len
         16 bits long field that specifies the Embedded-Address (EA)
         bit length.  Allowed values range from 0 to 48.

4.5.  Sub Options for S46-v4v6Bind Sub Option

4.5.1.  The IPv4-address Sub Option

   The IPv4-address Sub Option MAY be used to specify the full or shared
   IPv4 address of the CE.

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    SubType    |    SubLen     |            ipv4-address       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           ipv4-address        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      SubType
         11 (SubType number, for the IPv4-address Sub Option)
      SubLen
         6 (the length of the Rule-IPv4-Prefix Sub Option)
      ipv4-address
         a 32-bits field that specifies an IPv4 address that appears
         in the V4V6Bind Option

4.5.2.  The Bind-IPv6-Prefix Sub Option

   The IPv6 prefix field specified in this field is used by the CE to
   identify the correct prefix to use for the tunnel source.










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    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    SubType    |    SubLen     |   Reserved    |bindprefix6-len|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   |                        bind-ipv6-prefix                       |
   |                        (variable length)                      |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      SubType
         12 (SubType number, for the Bind-IPv6-Prefix Sub Option)
      SubLen
         20 (the length of the Bind-IPv6-Prefix Sub Option)
      Reserved
         This field is reserved. It always set to zero. This field
         is one octet in length.
      bindprefix6-len
         8 bits long; expresses the bitmask length of the IPv6 prefix
         specified in the bind-ipv6-prefix field. Allowed values range
         from 0 to 96.
      bind-ipv6-prefix
         a variable-length field specifying the IPv6 prefix or address
         for the S46 CE. This field is right-padded with zeros to the
         nearest octet boundary when bindprefix6-len is not divisible
         by 8.

4.6.  Sub Options for S46-PORTPARAMS Sub Option

4.6.1.  The PSID-offset Sub Option

    0                   1                   2
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    SubType    |    SubLen     |   PSID-Offset |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      SubType
         13 (SubType number, for the PSID-offset Sub Option)
      SubLen
         3 (the length of the PSID-offset Sub Option)
      PSID Offset
         8 bits long field that specifies the numeric value for the
         S46 algorithm's excluded port range/ offset bits (a bits),
         as per Section 5.1 of RFC7597. Allowed values are between
         0 and 15. Default values for this field are specific to the
         Softwire mechanism being implemented and are defined in the
         relevant specification document.




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4.6.2.  The PSID-len Sub Option

    0                   1                   2
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    SubType    |    SubLen     |    PSID-len   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      SubType
         14 (SubType number, for the PSID-len Sub Option)
      SubLen
         3 (the length of the PSID-len Sub Option)
      PSID-len
         8 bits long; specifies the number of significant bits in
         the PSID field. (also known as 'k'). When set to 0, the
         PSID field is to be ignored. After the first 'a' bits,
         there are k bits in the port number representing valid
         of PSID. Subsequently, the address sharing ratio would
         be 2 ^k.

4.6.3.  The PSID Sub Option

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    SubType    |    SubLen     |             PSID              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      SubType
         15 (SubType number, for the PSID Sub Option)
      SubLen
         4 (the length of the PSID Sub Option)
      PSID (Port-set ID)
         Explicit 16-bit (unsigned word) PSID value.  The PSID value
         algorithmically identifies a set of ports assigned to a CE.
         The first k-bits on the left of this 2-octets field is the
         PSID value. The remaining (16-k) bits on the right are
         padding zeros.

4.7.  Softwire46 Sub Options Encapsulation

   The table below shows which encapsulated Sub Options are mandatory,
   optional, or not permitted for each defined S46 Container Option.










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   +----------------+-------+-------+--------------------+
   | Sub Option     | MAP-E | MAP-T | Lightweight 4over6 |
   +----------------+-------+-------+--------------------+
   | S46-BR         |   M   |  N/P  |          M         |
   +----------------+-------+-------+--------------------+
   | S46-Rule       |   M   |   M   |         N/P        |
   +----------------+-------+-------+--------------------+
   | S46-DMR        |  N/P  |   M   |         N/P        |
   +----------------+-------+-------+--------------------+
   | S46-V4V6Bind   |  N/P  |  N/P  |          O         |
   +----------------+-------+-------+--------------------+
   | S46-PORTPARAMS |   O   |   O   |          O         |
   +----------------+-------+-------+--------------------+

   M - Mandatory, O - Optional, N/P - Not Permitted

4.8.  Softwire46-Priority Attribute

   The S46-Priority Attribute is structured as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      Type     |    Length     |       S46-option-code         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |             ...               |       S46-option-code         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Type
         TBD
      Length
         2 + the length of the S46-option-code(s) specified in octets
      S46-option-code
         16-bit IANA-registered option code of the DHCPv6 option that
         is used to identify the softwire mechanisms. S46 mechanisms
         are prioritized in the appearance order of the
         S46-option-code(s) in the Softwire46-Priority Attribute.
         A Softwire46-Priority  Attribute MUST contain at least one
         S46-option-code. The option codes of the corresponding S46
         mechanisms are listed in Section 6.1.

4.9.  Softwire46-Multicast Attribute

   The Softwire46-Multicast attribute conveys the IPv6 prefixes to be
   used in [RFC8114] to synthesize IPv4-embedded IPv6 addresses.  The
   BNG SHALL use the IPv6 prefixes returned in the RADIUS
   Softwire46-Multicast attribute to populate the DHCPv6 PREFIX64 Option
   [RFC8115].



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   This attribute MAY be used in Access-Request packets as a hint to the
   RADIUS server, for example, if the BNG is pre-configured with
   Softwire46-Multicast, these prefixes MAY be inserted in the
   attribute.  The RADIUS server MAY ignore the hint sent by the BNG,
   and it MAY assign a different Softwire46-Multicast attribute.

   The Softwire46-Multicast Attribute MAY appear in an Access-Accept
   packet.  It MAY also appear in an Access-Request packet.

   The Softwire46-Multicast Attribute MAY appear in a CoA-Request
   packet.

   The Softwire46-Multicast Attribute MAY appear in an Accounting-
   Request packet.

   The Softwire46-Multicast Attribute MUST NOT appear in any other
   RADIUS packet.

   This attribute is of type "TLV" as defined in the RADIUS Protocol
   Extensions [RFC6929].  It contains some sub-attributes:

   o  The Softwire46-Multicast Attribute MAY contain the ASM-Prefix64
      TLV (see Section 4.9.1).

   o  The Softwire46-Multicast Attribute MAY contain the SSM-Prefix64
      TLV (see Section 4.9.2).

   o  The Softwire46-Multicast Attribute MAY contain the U-Prefix64 TLV
      (see Section 4.9.3).

   The Softwire46-Multicast Attribute MUST include the ASM-Prefix64 TLV
   or the SSM-Prefix64 TLV, and it MAY include both.

   The U-Prefix64 TLV MUST be present when the SSM-Prefix64 TLV is
   present.  The U-Prefix64 TLV MAY be present when the ASM-Prefix64 TLV
   is present.

   The format of the Softwire46-Multicast Attribute is shown in
   Figure 3.

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      Type     |     Length    | Extended-Type |    Value ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                                 Figure 3




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   Type

      241 (To be confirmed by IANA).

   Length

      This field indicates the total length in bytes of all fields of
      this attribute, including the Type, Length, Extended-Type, and the
      entire length of the embedded TLVs.

   Extended-Type

      TBD1.

   Value

      This field contains a set of TLVs as follows:

      ASM-Prefix64 TLV

         This TLV contains the ASM IPv6 prefix.  Refer to Section 4.9.1.

      SSM-Prefix64 TLV

         This TLV contains the SSM IPv6 prefix.  Refer to Section 4.9.2.

      U-Prefix64 TLV

         This TLV contains the IPv4 prefix used for address translation
         [RFC6052].  Refer to Section 4.9.3.

   Softwire46-Multicast Attribute is associated with the following
   identifier: 241.Extended-Type(TBDx).

4.9.1.  ASM-Prefix64 TLV

   The format of ASM-Prefix64 TLV is shown in Figure 4.














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    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   TLV-Type    |   Reserved    | Prefix-Length |ASM Prefix64 ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        ... ASM Prefix64 ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        ... ASM Prefix64 ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        ... ASM Prefix64                                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                                 Figure 4

   TLV-Type

      1

   Reserved

      This field is reserved.  It always set to zero.  This field is one
      octet in length.

   Length

      The length of the prefix, in bits.

   ASM Prefix64

      IPv6 prefix.  This field specifies the IPv6 multicast prefix to be
      used to synthesize the IPv4-embedded IPv6 addresses of the
      multicast groups in the ASM mode.  The conveyed multicast IPv6
      prefix MUST belong to the ASM range.

4.9.2.  SSM-Prefix64 TLV

   The format of SSM-Prefix64 TLV is shown in Figure 5.














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    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   TLV-Type    |    Reserved   |Prefix-Length | SSM Prefix64 ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        ... SSM Prefix64 ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        ... SSM Prefix64 ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        ... SSM Prefix64                                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                                 Figure 5

   TLV-Type

      2

   Reserved

      This fiel is reserved.  It always set to zero.  This field is one
      octet in length.

   Length

      The length of the prefix, in bits.

   SSM Prefix64

      IPv6 prefix.  This field specifies the IPv6 multicast prefix to be
      used to synthesize the IPv4-embedded IPv6 addresses of the
      multicast groups in the SSM mode.  The conveyed multicast IPv6
      prefix MUST belong to the SSM range.

4.9.3.  U-Prefix64 TLV

   The format of U-Prefix64 TLV is shown in Figure 6.














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    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   TLV-Type    |  Reserved     | Prefix-Length |Unicast Prefix64
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        ... Unicast Prefix64 ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        ... Unicast Prefix64 ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        ... Unicast Prefix64                                       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                                 Figure 6

   TLV-Type

      3

   Reserved

      This fiel is reserved.  It always set to zero.  This field is one
      octet in length.

   Length

      The length of the prefix, in bits.

   Unicast Prefix64

      IPv6 prefix.  This field identifies the IPv6 unicast prefix to be
      used in SSM mode for constructing the IPv4-embedded IPv6 addresses
      representing the IPv4 multicast sources in the IPv6 domain.  It
      may also be used to extract the IPv4 address from the received
      multicast data flows.

4.10.  Table of attributes

   The following table provides a guide to which attributes may be found
   in which kinds of packets, and in what quantity.












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   Request Accept Reject Challenge Accounting  #  Attribute
                                    Request
    0-1     0-1     0      0         0-1      TBD1 Softwire46-
                                                   Configuration
    0-1     0-1     0      0         0-1      TBD2 Softwire46-
                                                   Priority
    0-1     0-1     0      0         0-1      TBD3 Softwire46-
                                                   Multicast
    0-1     0-1     0      0         0-1      1    User-Name
    0-1     0       0      0         0        2    User-Password
    0-1     0-1     0      0         0-1      6    Service-Type
    0-1     0-1     0-1    0-1       0-1      80   Message-
                                                   Authenticator

   The following table defines the meaning of the above table entries.

   0     This attribute MUST NOT be present in packet.
   0+    Zero or more instances of this attribute MAY be present in
         packet.
   0-1   Zero or one instance of this attribute MAY be present in
         packet.
   1     Exactly one instance of this attribute MUST be present in
         packet.

5.  Diameter Considerations

   S46 Configuration using Diameter [RFC6733] is specified in [RFC7678].

6.  IANA Considerations

   This document requires the assignment of two new RADIUS Attribute
   Type in the "Radius Types" registry (currently located at
   http://www.iana.org/assignments/radius-types for the following
   attributes:

   o  Softwire46-Configuration Attribute TBD1

   o  Softwire46-Priority Attribute TBD2

   o  Softwire46-Multicast Attribute TBD3

   IANA should allocate the numbers from the standard RADIUS Attributes
   space using the "IETF Review" policy [RFC5226].








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6.1.  S46 Mechanisms and Their Identifying Option Codes

   The Softwire46-Priority Attribute defines a 16-bit S46-option-code
   field, for which IANA is to create and maintain a new registry
   entitled "Option Codes Permitted in the Softwire46-Priority
   Attribute".  This document requires IANA to register four option
   codes of the Softwire46 mechanisms permitted to be included in the
   Softwire46-Priority Attribute.  Additional options may be added to
   this list in the future using the IETF Review process described in
   Section 4.1 of [RFC5226].

   The following table shows the option codes that are required and the
   S46 mechanisms that they represent.  The option code for DS-Lite is
   derived from the IANA allocated RADIUS Attribute Type value for DS-
   Lite [RFC6519].  The option codes for MAP-E, MAP-T and Lightweight
   4over6 need to be determined.  The option codes for MAP-E, MAP-T, and
   Lightweight 4over6 should also be used as the option Type values for
   the MAP-E, MAP-T, and Lightweight 4over6 Container Options defined in
   Section 4.2.

             +-------------+------------------+-----------+
             | Option Code |  S46 Mechanism   | Reference |
             +-------------+------------------+-----------+
             |     TBD1    |       MAP-E      |  RFC7597  |
             +-------------+------------------+-----------+
             |     TBD2    |       MAP-T      |  RFC7599  |
             +-------------+------------------+-----------+
             |     TBD3    |Lightweight 4over6|  RFC7596  |
             +-------------+------------------+-----------+
             |     144     |     DS-Lite      |  RFC6519  |
             +--------------------------------+-----------+

                  Table 1: Option Codes to S46 Mechanisms

7.  Security Considerations

   Known security vulnerabilities of the RADIUS protocol are discussed
   in [RFC2607], [RFC2865], and[RFC2869].  Use of IPsec [RFC4301] for
   providing security when RADIUS is carried in IPv6 is discussed in
   [RFC3162].

   A malicious user may use MAC address spoofing on the shared password
   that has been preconfigured on the DHCPv6 server to get unauthorized
   configuration information.

   Security considerations for MAP specific between the MAP CE and the
   BNG are discussed in [RFC7597].  Security considerations for
   Lightweight 4over6 are discussed in [RFC7596].  Security



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   considerations for DHCPv6-Based S46 Prioritization Mechanism are
   discussed in [RFC8026].  Furthermore, generic DHCPv6 security
   mechanisms can be applied DHCPv6 intercommunication between the CE
   and the BNG.

   Security considerations for the Diameter protocol are discussed in
   [RFC6733].

8.  Acknowledgements

   The authors would like to thank the valuable comments made by Peter
   Lothberg, Wojciech Dec, Ian Farrer, Suresh Krishnan, Qian Wang, Wei
   Meng and Cui Wang for this document.  This document was merged with
   draft-sun-softwire-lw4over6-radext-01 and draft-wang-radext-
   multicast-radius-ext-00, thanks to everyone who contributed to this
   draft.

   This document was produced using the xml2rfc tool [RFC7991].

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,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC2865]  Rigney, C., Willens, S., Rubens, A., and W. Simpson,
              "Remote Authentication Dial In User Service (RADIUS)",
              RFC 2865, DOI 10.17487/RFC2865, June 2000,
              <https://www.rfc-editor.org/info/rfc2865>.

   [RFC3162]  Aboba, B., Zorn, G., and D. Mitton, "RADIUS and IPv6",
              RFC 3162, DOI 10.17487/RFC3162, August 2001,
              <https://www.rfc-editor.org/info/rfc3162>.

   [RFC3315]  Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins,
              C., and M. Carney, "Dynamic Host Configuration Protocol
              for IPv6 (DHCPv6)", RFC 3315, DOI 10.17487/RFC3315, July
              2003, <https://www.rfc-editor.org/info/rfc3315>.

   [RFC4607]  Holbrook, H. and B. Cain, "Source-Specific Multicast for
              IP", RFC 4607, DOI 10.17487/RFC4607, August 2006,
              <https://www.rfc-editor.org/info/rfc4607>.






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   [RFC5080]  Nelson, D. and A. DeKok, "Common Remote Authentication
              Dial In User Service (RADIUS) Implementation Issues and
              Suggested Fixes", RFC 5080, DOI 10.17487/RFC5080, December
              2007, <https://www.rfc-editor.org/info/rfc5080>.

   [RFC6052]  Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X.
              Li, "IPv6 Addressing of IPv4/IPv6 Translators", RFC 6052,
              DOI 10.17487/RFC6052, October 2010,
              <https://www.rfc-editor.org/info/rfc6052>.

   [RFC6158]  DeKok, A., Ed. and G. Weber, "RADIUS Design Guidelines",
              BCP 158, RFC 6158, DOI 10.17487/RFC6158, March 2011,
              <https://www.rfc-editor.org/info/rfc6158>.

   [RFC6929]  DeKok, A. and A. Lior, "Remote Authentication Dial In User
              Service (RADIUS) Protocol Extensions", RFC 6929,
              DOI 10.17487/RFC6929, April 2013,
              <https://www.rfc-editor.org/info/rfc6929>.

   [RFC8026]  Boucadair, M. and I. Farrer, "Unified IPv4-in-IPv6
              Softwire Customer Premises Equipment (CPE): A DHCPv6-Based
              Prioritization Mechanism", RFC 8026, DOI 10.17487/RFC8026,
              November 2016, <https://www.rfc-editor.org/info/rfc8026>.

   [RFC8114]  Boucadair, M., Qin, C., Jacquenet, C., Lee, Y., and Q.
              Wang, "Delivery of IPv4 Multicast Services to IPv4 Clients
              over an IPv6 Multicast Network", RFC 8114,
              DOI 10.17487/RFC8114, March 2017,
              <https://www.rfc-editor.org/info/rfc8114>.

   [RFC8115]  Boucadair, M., Qin, J., Tsou, T., and X. Deng, "DHCPv6
              Option for IPv4-Embedded Multicast and Unicast IPv6
              Prefixes", RFC 8115, DOI 10.17487/RFC8115, March 2017,
              <https://www.rfc-editor.org/info/rfc8115>.

9.2.  Informative References

   [RFC2607]  Aboba, B. and J. Vollbrecht, "Proxy Chaining and Policy
              Implementation in Roaming", RFC 2607,
              DOI 10.17487/RFC2607, June 1999,
              <https://www.rfc-editor.org/info/rfc2607>.

   [RFC2869]  Rigney, C., Willats, W., and P. Calhoun, "RADIUS
              Extensions", RFC 2869, DOI 10.17487/RFC2869, June 2000,
              <https://www.rfc-editor.org/info/rfc2869>.






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   [RFC3580]  Congdon, P., Aboba, B., Smith, A., Zorn, G., and J. Roese,
              "IEEE 802.1X Remote Authentication Dial In User Service
              (RADIUS) Usage Guidelines", RFC 3580,
              DOI 10.17487/RFC3580, September 2003,
              <https://www.rfc-editor.org/info/rfc3580>.

   [RFC4301]  Kent, S. and K. Seo, "Security Architecture for the
              Internet Protocol", RFC 4301, DOI 10.17487/RFC4301,
              December 2005, <https://www.rfc-editor.org/info/rfc4301>.

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", RFC 5226,
              DOI 10.17487/RFC5226, May 2008,
              <https://www.rfc-editor.org/info/rfc5226>.

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

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

   [RFC6519]  Maglione, R. and A. Durand, "RADIUS Extensions for Dual-
              Stack Lite", RFC 6519, DOI 10.17487/RFC6519, February
              2012, <https://www.rfc-editor.org/info/rfc6519>.

   [RFC6733]  Fajardo, V., Ed., Arkko, J., Loughney, J., and G. Zorn,
              Ed., "Diameter Base Protocol", RFC 6733,
              DOI 10.17487/RFC6733, October 2012,
              <https://www.rfc-editor.org/info/rfc6733>.

   [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>.







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   [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>.

   [RFC7678]  Zhou, C., Taylor, T., Sun, Q., and M. Boucadair,
              "Attribute-Value Pairs for Provisioning Customer Equipment
              Supporting IPv4-Over-IPv6 Transitional Solutions",
              RFC 7678, DOI 10.17487/RFC7678, October 2015,
              <https://www.rfc-editor.org/info/rfc7678>.

   [RFC7991]  Hoffman, P., "The "xml2rfc" Version 3 Vocabulary",
              RFC 7991, DOI 10.17487/RFC7991, December 2016,
              <https://www.rfc-editor.org/info/rfc7991>.

Additional Authors





























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   Qiong Sun
   China Telecom
   Beijing  China
   Email: sunqiong@ctbri.com.cn

   Qi Sun
   Tsinghua University
   Department of Computer Science, Tsinghua University
   Beijing 100084
   P.R.China
   Phone: +86-10-6278-5822
   Email: sunqibupt@gmail.com

   Cathy Zhou
   Huawei Technologies
   Bantian, Longgang District
   Shenzhen 518129
   Email: cathy.zhou@huawei.com

   Tina Tsou
   Huawei Technologies(USA)
   2330 Central Expressway
   Santa Clara, CA 95050
   USA
   Email: Tina.Tsou.Zouting@huawei.com

   ZiLong Liu
   Tsinghua University
   Beijing 100084
   P.R.China
   Phone: +86-10-6278-5822
   Email: liuzilong8266@126.com

   Yong Cui
   Tsinghua University
   Beijing 100084
   P.R.China
   Phone: +86-10-62603059
   Email: yong@csnet1.cs.tsinghua.edu.cn


Authors' Addresses









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   Sheng Jiang
   Huawei Technologies Co., Ltd
   Q14, Huawei Campus, No.156 Beiqing Road
   Hai-Dian District, Beijing, 100095
   P.R. China

   Email: jiangsheng@huawei.com


   Yu Fu
   CNNIC
   No.4 South 4th Street, Zhongguancun
   Hai-Dian District, Beijing, 100190
   P.R. China

   Email: fuyu@cnnic.cn


   Bing Liu
   Huawei Technologies Co., Ltd
   Q14, Huawei Campus, No.156 Beiqing Road
   Hai-Dian District, Beijing, 100095
   P.R. China

   Email: leo.liubing@huawei.com


   Peter Deacon
   IEA Software, Inc.
   P.O. Box 1170
   Veradale, WA  99037
   USA

   Email: peterd@iea-software.com


   Chongfeng Xie
   China Telecom
   Beijing
   P.R. China

   Email: xiechf.bri@chinatelecom.cn









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   Tianxiang Li
   Tsinghua University
   Beijing  100084
   P.R.China

   Email: peter416733@gmail.com


   Mohamed Boucadair
   Orange
   Rennes, 35000
   France

   Email: mohamed.boucadair@orange.com





































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