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Softwire WG                                                 T. Mrugalski
Internet-Draft                                                       ISC
Intended status: Standards Track                                O. Troan
Expires: September 14, 2014                                        Cisco
                                                               I. Farrer
                                                     Deutsche Telekom AG
                                                            S. Perreault
                                                                Viagenie
                                                                  W. Dec
                                                                   Cisco
                                                                  C. Bao
                                                     Tsinghua University
                                                                  L. Yeh
                                                                   CNNIC
                                                                 X. Deng
                                                         Yingke Law Firm
                                                          March 13, 2014


  DHCPv6 Options for configuration of Softwire Address and Port Mapped
                                Clients
                    draft-ietf-softwire-map-dhcp-07

Abstract

   This document specifies DHCPv6 options, termed Softwire46 options,
   for the provisioning of Softwire46 Customer Edge (CE) devices.
   Softwire46 is a collective term used to refer to architectures based
   on the notion of IPv4 Address+Port (A+P) for providing IPv4
   connectivity across an IPv6 network.

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 September 14, 2014.




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Copyright Notice

   Copyright (c) 2014 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
   2.  Conventions . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Softwire 46 Overview  . . . . . . . . . . . . . . . . . . . .   3
   4.  Common Softwire46 DHCPv6 Options  . . . . . . . . . . . . . .   4
     4.1.  S46 Rule Option . . . . . . . . . . . . . . . . . . . . .   5
     4.2.  S46 BR Option . . . . . . . . . . . . . . . . . . . . . .   6
     4.3.  S46 DMR Option  . . . . . . . . . . . . . . . . . . . . .   7
     4.4.  S46 IPv4/IPv6 Address Binding Option  . . . . . . . . . .   7
     4.5.  S46 Port Parameters Option  . . . . . . . . . . . . . . .   8
   5.  Softwire 46 Container DHCPv6 Options  . . . . . . . . . . . .   9
     5.1.  Softwire46 MAP-E Container Option . . . . . . . . . . . .   9
     5.2.  Softwire46 MAP-T Container Option . . . . . . . . . . . .  10
     5.3.  Softwire46 LightWeight 46 Container Option  . . . . . . .  11
   6.  DHCPv6 Server Behavior  . . . . . . . . . . . . . . . . . . .  11
   7.  DHCPv6 Client Behavior  . . . . . . . . . . . . . . . . . . .  12
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  12
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  13
   10. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  13
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .  13
     11.1.  Normative References . . . . . . . . . . . . . . . . . .  13
     11.2.  Informative References . . . . . . . . . . . . . . . . .  13
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  14

1.  Introduction

   A number of architectural solution proposals discussed in the IETF
   Softwire Working Group use Address and Port (A+P) as their technology
   base for providing IPv4 connectivity to end users using CE devices
   across a service provider's IPv6 network, while allowing for shared
   or dedicated IPv4 addressing of the CEs.




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   An example is Mapping of Address and Port (MAP) defined in
   [I-D.ietf-softwire-map].  The MAP solution consists of one or more
   MAP Border Relay (BR) routers, responsible for stateless forwarding
   between a MAP IPv6 domain and an IPv4 network, and one or more MAP
   Customer Edge (CE) routers, responsible for forwarding between a
   user's private IPv4 network and the MAP IPv6 network domain.
   Collectively, the MAP CE and BR form a domain when configured with
   common service parameters.  This characteristic is common to all of
   the Softwire46 proposals.

   To function in such a domain, a CE needs to be provisioned with the
   appropriate A+P service parameters for that domain.  These consist
   primarily of the CE's IPv4 address and transport layer port-range(s).
   Furthermore, the IPv6 transport mode (i.e. encapsulation or
   translation) needs to be specified.  Provisioning of other IPv4
   configuration information not derived directly from the A+P service
   parameters is not covered in this document.  It is expected that
   provisioning of other IPv4 configuration will continue to use DHCPv4
   [RFC2131].

   This memo specifies a set of DHCPv6 [RFC3315] options to provision
   Softwire46 information to CE routers.  Although the focus is to
   deliver IPv4 service to an end-user network (such as a residential
   home network), it can equally be applied to an individual host acting
   as a CE.  Configuration of the BR is out of scope of this document.

2.  Conventions

   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 RFC 2119 [RFC2119].

3.  Softwire 46 Overview

   This document describes a set of common DHCPv6 options for
   configuring the MAP-E [I-D.ietf-softwire-map], MAP-T
   [I-D.ietf-softwire-map-t] and Lightweight 4over6
   [I-D.ietf-softwire-lw4over6] mechanisms.

   MAP-E, MAP-T and Lightweight 4over6 are essentially providing the
   same functionality: IPv4 service to a CE router over an IPv6 only
   access network.  MAP-E and MAP-T may embed parts of the IPv4 address
   in IPv6 prefixes, thereby supporting many clients with a fixed set of
   mapping rules and mesh mode (direct CE to CE communication).  MAP-E
   and MAP-T CEs may also be provisioned in hub and spoke mode, and in
   1:1 mode (with no embedded address bits).  The difference between
   MAP-E and MAP-T is that they use different means to connect to the
   IPv6 domain.  MAP-E uses RFC2473 [RFC2473] IPv4 over IPv6 tunnelling,



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   while MAP-T uses NAT64 [RFC6145] based translation.  Lightweight
   4over6 is a hub and spoke IPv4 over IPv6 tunneling mechanism, with
   complete independence of IPv4 and IPv6 addressing (zero embedded
   address bits).

   The DHCP options described here tie the provisioning parameters, and
   hence the IPv4 service itself, to the End-user IPv6 prefix lifetime.
   The validity of a softwire's IPv4 address, prefix or shared IPv4
   address, port set and any authorization and accounting are tied to
   the lifetime of its associated End-user IPv6 prefix.

   To support more than one mechanism at a time and to allow for a
   possibility of transition between them, the Option Request Option
   DHCPv6 [RFC3315] function is used.  Each mechanism has a
   corresponding DHCPv6 container option.  A DHCPv6 client can request a
   particular mechanism by including the option code for a particular
   container option in its ORO option.  The provisioning parameters for
   that mechanism are expressed by embedding the common format options
   within the respective container.

   This approach implies that all of the provisioning options MUST
   appear only within the container options.  The client MUST NOT
   request any of the provisioning options directly within an ORO.
   Likewise, the server MUST NOT send the provisioning options directly
   within a DHCPv6 message, without encapsulation in the corresponding
   container option.

   The document is organized with the common sub-options described
   first, followed by the three container options.  Some sub-options are
   mandatory in some containers, some are optional and some are not
   permitted at all.

4.  Common Softwire46 DHCPv6 Options

   The DHCPv6 protocol is used for Softwire46 CE provisioning following
   regular DHCPv6 notions, with the CE assuming the role of a DHCPv6
   client, and the DHCPv6 server providing options following typical
   DHCPv6 server side policies.  The format and usage of the options are
   defined in the following sub-sections.

   Each CE needs to be provisioned with enough information to calculate
   its IPv4 address, IPv4 prefix or shared IPv4 address.  MAP-E and
   MAP-T use the OPTION_S46_RULE, while Lightweight 4over6 uses the
   OPTION_S46_V4V6BIND option.  A CE that needs to communicate outside
   of the A+P domain also needs the address or prefix of the BR.  MAP-E
   and Lightweight 4over6 use the OPTION_S46_BR option to communicate
   the IPv6 address of the BR.  MAP-T forms an IPv6 destination address
   by embedding an IPv4 destination address into the BR's IPv6 prefix



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   conveyed via the OPTION_S46_DMR option.  Optionally, all mechanisms
   can include OPTION_S46_PORTPARAMS to specify parameters and port sets
   for the port range algorithm.

4.1.  S46 Rule Option

   Figure 1 shows the format of the S46 Rule option used for conveying
   the Basic Mapping Rule (BMR) and Forwarding Mapping Rule (FMR).

   A server MAY send more than one S46 Rule Option in a container, if it
   is configured to do so.  Clients MUST NOT send a S46 Rule 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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |        OPTION_S46_RULE        |         option-length         |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |     flags     |     ea-len    |  prefix4-len  | ipv4-prefix   |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                  (continued)                  |  prefix6-len  |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                           ipv6-prefix                         |
     |                       (variable length)                       |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     .                        S46_RULE-options                       .
     .                                                               .
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                         Figure 1: S46 Rule Option

   o  option-code: OPTION_S46_RULE (TBD1)
   o  option-length: length of the option, excluding option-code and
      option-length fields, including length of all encapsulated
      options, expressed in bytes.
   o  flags: 8 bits long field carrying flags applicable to the rule.
      The meaning of specific bits are explained in Figure 2.
   o  ea-len: 8 bits long field that specifies the Embedded-Address (EA)
      bit length.  Allowed values range from 0 to 48.
   o  prefix4-len: 8 bits long field expressing the prefix length of the
      IPv4 prefix specified in the rule-ipv4-prefix field.  Valid values
      0 to 32.
   o  ipv4-prefix: a fixed length 32 bit field that specifies the IPv4
      prefix for the S46 rule.  The bits in the prefix after prefix4-len
      number of bits are reserved and MUST be initialized to zero by the
      sender and ignored by the receiver.
   o  prefix6-len: 8 bits long field expressing the length of the IPv6
      prefix specified in the rule-ipv6-prefix field.



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   o  ipv6-prefix: a variable length field that specifies the IPv6
      domain prefix for the S46 rule.  The field is padded with follow
      up zero bits up to the nearest octet boundary when prefix6-len is
      not divisible by 8.
   o  S46_RULE-options: a variable field that may contain zero or more
      options that specify additional parameters for this S46 rule, e.g.
      a Port Parameter Option.

   The Format of the S46 Rule Flags field is:

                              0 1 2 3 4 5 6 7
                             +-+-+-+-+-+-+-+-+
                             |Reserved     |F|
                             +-+-+-+-+-+-+-+-+

                         Figure 2: S46 Rule Flags

   o  Reserved: 7-bits reserved for future use as flags.
   o  F-Flag: 1 bit field that specifies whether the rule is to be used
      for forwarding (FMR).  If set, this rule is used as a FMR, if not
      set this rule is a BMR.  Note: A BMR rule can also be an FMR rule
      by setting the F flag.  The BMR rule is determined by a match of
      the Rule-IPv6-prefix against the CPE's prefix(es).

   It is expected that in a typical mesh deployment scenario, there will
   be a single BMR, which could also be designated as an FMR using the
   F-Flag.

4.2.  S46 BR Option

   The S46 BR Option is used to convey the IPv6 address of the Border
   Relay.  Figure 4 shows the format of the BR 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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         OPTION_S46_BR         |         option-length         |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                      br-ipv6-address                          |
     |                                                               |
     |                                                               |
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                         Figure 3: S46 DMR Option

   o  option-code: OPTION_S46_BR (TBD2)
   o  option-length: 16



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   o  br-ipv6-address: a fixed length field of 16 octets that specifies
      the IPv6 address for the S46 BR.

   BR redundancy can be implemented by using an anycast address for the
   BR IPv6 address.  Multiple BR options MAY be included in the
   container; this document does not further explore the use of multiple
   BR IPv6 addresses.

4.3.  S46 DMR Option

   The S46 DMR Option is used to convey values for the Default Mapping
   Rule (DMR).  Figure 4 shows the format of the MAP Rule option used
   for conveying a DMR.

      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |        OPTION_S46_DMR         |         option-length         |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |dmr-prefix6-len|            dmr-ipv6-prefix                    |
     +-+-+-+-+-+-+-+-+           (variable length)                   |
     .                                                               .
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                         Figure 4: S46 DMR Option

   o  option-code: OPTION_S46_DMR (TBD3)
   o  option-length: 1 + length of dmr-ipv6-prefix specified in bytes.
   o  dmr-prefix6-len: 8 bits long field expressing the bit mask length
      of the IPv6 prefix specified in the dmr-ipv6-prefix field.
   o  dmr-ipv6-prefix: a variable length field specifying the IPv6
      prefix or address for the S46 BR.  This field is right padded with
      zeros to the nearest octet boundary when dmr-prefix6-len is not
      divisible by 8.

4.4.  S46 IPv4/IPv6 Address Binding Option

   The IPv4 address Option MAY be used to specify the full or shared
   IPv4 address of the CE.  The IPv6 prefix field is used by the CE to
   identify the correct prefix to use for the tunnel source.

      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |      OPTION_S46_V4V6BIND      |         option-length         |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                         ipv4-address                          |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



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     |bindprefix6-len|             bind-ipv6-prefix                  |
     +-+-+-+-+-+-+-+-+             (variable length)                 |
     .                                                               .
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     .                      S46_V4V6BIND-options                     .
     .                                                               .
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

              Figure 5: S46 IPv4/IPv6 Address Binding Option

   o  option-code: OPTION_S46_V4V6BIND (TBD4)
   o  option-length: 4
   o  ipv4-address: A fixed field of 4 octets specifying an IPv4
      address.
   o  bindprefix6-len: 8 bits long field expressing the bit mask length
      of the IPv6 prefix specified in the bind-ipv6-prefix field.
   o  bind-ipv6-prefix: a variable length field specifying the IPv6
      prefix or address for the S46.  This field is right padded with
      zeros to the nearest octet boundary when bindprefix6-len is not
      divisible by 8.
   o  S46_V4V6BIND-options: a variable field that may contain zero or
      more options that specify additional parameters e.g. a Port
      Parameters Option.

4.5.  S46 Port Parameters Option

   The Port Parameters Option specifies optional Rule Port Parameters
   that MAY be provided as part of the Mapping Rule for CEs using the
   MAP algorithm.

   See [I-D.ietf-softwire-map], Section 5.1 for a description of MAP
   algorithm, explaining all of the parameters in detail.

      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |     OPTION_S46_PORTPARAMS     |         option-length         |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |   offset      |    PSID-len   |              PSID             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                   Figure 6: S46 Port Parameters Option

   o  option-code: OPTION_S46_PORTPARAMS (TBD5)
   o  option-length: 4
   o  offset: (PSID offset) 8 bits long field that specifies the numeric
      value for the S46 algorithm's excluded port range/offset bits



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      (A-bits), as per section 5.1.1 of [I-D.ietf-softwire-map].
      Allowed values are between 0 and 15, with the default value being
      6.
   o  PSID-len: Bit length value of 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 the value of the Port Set
      Identifier (PSID).  Consequently, the address sharing ratio would
      be 2^k.
   o  PSID: 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 field contain the PSID value.
      The remaining (16-k) bits on the right are padding zeros.

   When receiving the Port Parameters option with an explicit PSID, the
   client MUST use this explicit PSID in configuring its MAP interface.
   If the conveyed IPv4 address is not 32 bit-long, the option MUST be
   discarded.  The formula for this check is "prefix4-len + ea-len = 32"
   and serves to ensure that the explicit PSID is only applied to
   configurations with a completely formed IPv4 address.

   The OPTION_S46_PORTPARAMS option MUST be encapsulated in a
   OPTION_S46_RULE option or an OPTION_S46_V4V6BIND option.  It MUST NOT
   appear directly within a container option.

5.  Softwire 46 Container DHCPv6 Options

      +-----------------------+-------+-------+--------------------+
      | Option                | MAP-E | MAP-T | Lightweight 4over6 |
      +-----------------------+-------+-------+--------------------+
      | OPTION_S46_RULE       |   M   |   M   |        N/A         |
      | OPTION_S46_BR         |   M   |  N/A  |         M          |
      | OPTION_S46_PORTPARAMS |   O   |   O   |         O          |
      | OPTION_S46_DMR        |  N/A  |   M   |        N/A         |
      | OPTION_S46_V4V6BIND   |  N/A  |  N/A  |         O          |
      +-----------------------+-------+-------+--------------------+

             M - Mandatory, O - Optional, N/A - Not Applicable

                   Table 1: Option to Container Mappings

5.1.  Softwire46 MAP-E Container Option

   The MAP-E Container Option specifies the container used to group all
   rules and optional port parameters for a specified domain.

      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



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     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |        OPTION_S46_CONT_MAPE   |         option-length         |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     .            encapsulated-options (variable length)             .
     .                                                               .
     +---------------------------------------------------------------+

                     Figure 7: MAP-E Container Option

   o  option-code: OPTION_S46_CONT_MAPE (TBD6)
   o  option-length: Length of encapsulated options
   o  encapsulated-options: options associated with this Softwire46
      MAP-E domain.

   The encapsulated options field conveys options specific to this MAP
   Option.  Currently there are two options specified for the
   OPTION_S46_CONT_MAPE option, OPTION_S46_RULE and OPTION_S46_BR.
   There MUST be at least one OPTION_S46_RULE option and at least one
   OPTION_S46_BR.

   Other options applicable to a domain may be defined in the future.  A
   DHCP message MAY include multiple S46 MAPE Container Options
   (representing multiple domains).

5.2.  Softwire46 MAP-T Container Option

   The MAP-T Container Option specifies the container used to group all
   rules and optional port parameters for a specified domain.

      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |     OPTION_S46_CONT_MAPT      |         option-length         |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     .            encapsulated-options (variable length)             .
     .                                                               .
     +---------------------------------------------------------------+

                     Figure 8: MAP-E Container Option

   o  option-code: OPTION_S46_CONT_MAPT (TBD7)
   o  option-length: Length of encapsulated options
   o  encapsulated-options: options associated with this Softwire46
      MAP-T domain.





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   The encapsulated options field conveys options specific to this MAP
   Option.  Currently there are two options specified for the
   OPTION_S46_CONT_MAPT option, OPTION_S46_RULE and OPTION_S46_DMR
   options.  There MUST be at least one OPTION_S46_RULE option and
   exactly one OPTION_S46_DMR.

5.3.  Softwire46 LightWeight 46 Container Option

   The LW46 Container Option specifies the container used to group all
   rules and optional port parameters for a specified domain.

      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |      OPTION_S46_CONT_LW       |         option-length         |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     +            encapsulated-options (variable length)             .
     .                                                               .
     +---------------------------------------------------------------+

                      Figure 9: LW46 Container Option

   o  option-code: OPTION_S46_CONT_LW (TBD8)
   o  option-length: Length of encapsulated options
   o  encapsulated-options: options associated with this Softwire46
      domain.

   The encapsulated options field conveys options specific to this
   Lightweight 4over6 Option.  Currently there are two options specified
   for the OPTION_S46_CONT_LW option, OPTION_S46_V4V6BIND and
   OPTION_S46_BR.  There MUST be at most one OPTION_S46_V4V6BIND option
   and at least one OPTION_S46_BR option.

6.  DHCPv6 Server Behavior

   [RFC3315] Section 17.2.2 describes how a DHCPv6 client and server
   negotiate configuration values using the ORO.  As a convenience to
   the reader, we mention here that by default, a server will not reply
   with a Softwire 46 Container Option if the client has not explicitly
   enumerated one in its Option Request Option.

   A CE router may support several (or all) of the mechanisms mentioned
   here.  In the case where a client requests multiple mechanisms in its
   ORO option, the server SHOULD reply with all the corresponding
   Softwire 46 Container options, enumerated in the Option Request
   Option, the the server is configured for.




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7.  DHCPv6 Client Behavior

   An S46 CE acting as DHCPv6 client will request S46 configuration
   parameters from the DHCPv6 server located in the IPv6 network.  Such
   a client SHOULD include the S46 Container option(s) that it is
   configured for in its ORO in SOLICIT, REQUEST, RENEW, REBIND and
   INFORMATION-REQUEST messages.

   When processing received S46 container options the following
   behaviour is expected:

   o  A client MUST support processing multiple received OPTION_S46_RULE
      options in a container OPTION_S46_CONT_MAPE or
      OPTION_S46_CONT_MAPT option
   o  A client receiving an unsupported S46 option, or an invalid
      parameter value SHOULD discard that S46 Container option and log
      the event.

   The behavior of a client supporting multiple Softwire 46 mechanisms,
   is out of scope of this document.  [I-D.ietf-softwire-unified-cpe]
   describes client behaviour for the prioritization and handling of
   multiple mechanisms simultaneously.

   Note that system implementing CE functionality may have multiple
   network interfaces, and these interfaces may be configured
   differently; some may be connected to networks that call for MAP, and
   some may be connected to networks that are using normal dual stack or
   other means.  The CE system should approach this specification on an
   interface-by-interface basis.  For example, if the CE system is MAP
   capable and is attached to multiple networks that provide the MAP
   Mapping Rule Option, then the CE system MUST configure a MAP service
   (i.e. a translation or encapsulation) for each interface separately
   as each MAP provides IPv4 connectivity for each distinct interface.
   The means to bind a MAP configuration to a given interface in a
   multiple interfaces device are out of scope of this document.

8.  Security Considerations

   Implementation of this document does not present any new security
   issues, but as with all DHCPv6-derived configuration state, it is
   possible that configuration is actually being delivered by a third
   party (Man In The Middle).  As such, there is no basis on which
   access over MAP or lw4o6 can be trusted.  Therefore, softwires should
   not bypass any security mechanisms such as IP firewalls.

   Readers concerned with security of MAP provisioning over DHCPv6 are
   encouraged to read [I-D.ietf-dhc-secure-dhcpv6].




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   Section 11 of [I-D.ietf-softwire-map] discusses security issues of
   the MAP mechanism.

   Section 23 of [RFC3315] discusses DHCPv6-related security issues.

9.  IANA Considerations

   IANA is kindly requested to allocate the following DHCPv6 option
   codes:

      TBD1 for OPTION_S46_RULE
      TBD2 for OPTION_S4_BR
      TBD3 for OPTION_S46_DMR
      TBD4 for OPTION_S46_V4V6BIND
      TBD5 for OPTION_S46_PORTPARAMS
      TBD6 for OPTION_S46_CONT_MAPE
      TBD7 for OPTION_S46_CONT_MAPT
      TBD8 for OPTION_S46_CONT_LW

   All values should be added to the DHCPv6 option code space defined in
   Section 24.3 of [RFC3315].

10.  Acknowledgements

   This document was created as a product of a MAP design team.
   Following people were members of that team: Congxiao Bao, Mohamed
   Boucadair, Gang Chen, Maoke Chen, Wojciech Dec, Xiaohong Deng, Jouni
   Korhonen, Xing Li, Satoru Matsushima, Tomasz Mrugalski, Tetsuya
   Murakami, Jacni Qin, Necj Scoberne, Qiong Sun, Tina Tsou, Dan Wing,
   Leaf Yeh and Jan Zorz.

   The authors would like to thank Bernie Volz and Tom Taylor for their
   insightful comments and suggestions.

11.  References

11.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC3315]  Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,
              and M. Carney, "Dynamic Host Configuration Protocol for
              IPv6 (DHCPv6)", RFC 3315, July 2003.

11.2.  Informative References

   [I-D.ietf-dhc-secure-dhcpv6]



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              Jiang, S. and S. Shen, "Secure DHCPv6 Using CGAs", draft-
              ietf-dhc-secure-dhcpv6-07 (work in progress), September
              2012.

   [I-D.ietf-softwire-lw4over6]
              Cui, Y., Qiong, Q., Boucadair, M., Tsou, T., Lee, Y., and
              I. Farrer, "Lightweight 4over6: An Extension to the DS-
              Lite Architecture", draft-ietf-softwire-lw4over6-03 (work
              in progress), November 2013.

   [I-D.ietf-softwire-map-t]
              Li, X., Bao, C., Dec, W., Troan, O., Matsushima, S., and
              T. Murakami, "Mapping of Address and Port using
              Translation (MAP-T)", draft-ietf-softwire-map-t-04 (work
              in progress), September 2013.

   [I-D.ietf-softwire-map]
              Troan, O., Dec, W., Li, X., Bao, C., Matsushima, S.,
              Murakami, T., and T. Taylor, "Mapping of Address and Port
              with Encapsulation (MAP)", draft-ietf-softwire-map-08
              (work in progress), August 2013.

   [I-D.ietf-softwire-unified-cpe]
              Boucadair, M., Farrer, I., Perreault, S., and S.
              Sivakumar, "Unified IPv4-in-IPv6 Softwire CPE", draft-
              ietf-softwire-unified-cpe-01 (work in progress), May 2013.

   [RFC2131]  Droms, R., "Dynamic Host Configuration Protocol", RFC
              2131, March 1997.

   [RFC2473]  Conta, A. and S. Deering, "Generic Packet Tunneling in
              IPv6 Specification", RFC 2473, December 1998.

   [RFC6145]  Li, X., Bao, C., and F. Baker, "IP/ICMP Translation
              Algorithm", RFC 6145, April 2011.

Authors' Addresses

   Tomasz Mrugalski
   Internet Systems Consortium, Inc.
   950 Charter Street
   Redwood City, CA  94063
   USA

   Phone: +1 650 423 1345
   Email: tomasz.mrugalski@gmail.com
   URI:   http://www.isc.org/




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   Ole Troan
   Cisco Systems, Inc.
   Philip Pedersens vei 1
   Lysaker  1366
   Norway

   Email: ot@cisco.com


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

   Email: ian.farrer@telekom.de


   Simon Perreault
   Viagenie
   246 Aberdeen
   Quebec, QC  G1R 2E1
   Canada

   Phone: +1 418 656 9254
   Email: simon.perreault@viagenie.ca


   Wojciech Dec
   Cisco Systems, Inc.
   The Netherlands

   Email: wdec@cisco.com
   URI:   http://cisco.com


   Congxiao Bao
   CERNET Center/Tsinghua University
   Room 225, Main Building, Tsinghua University
   Beijing  100084
   CN

   Phone: +86 10-62785983
   Email: congxiao@cernet.edu.cn







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   Leaf Y. Yeh
   CNNIC
   4, South 4th Street, Zhong_Guan_Cun
   Beijing  100190
   P. R. China

   Email: leaf.yeh.sdo@gmail.com


   Xiaohong Deng
   Yingke Law Firm
   6 Floor, C Block, DaCheng International Center Chaoyang District
   Beijing  100124
   China

   Phone: +61 3858 3128
   Email: dxhbupt@gmail.com


































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