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Softwire WG                                                       J. Qin
Internet-Draft                                                       ZTE
Intended status: Standards Track                            M. Boucadair
Expires: May 3, 2012                                      France Telecom
                                                                 T. Tsou
                                               Huawei Technologies (USA)
                                                        October 31, 2011


            DHCPv6 Options for IPv6 DS-Lite Multicast Prefix
             draft-qin-softwire-multicast-prefix-option-01

Abstract

   This document defines Dynamic Host Configuration Protocol version 6
   (DHCPv6) Options for multicast transition solutions, aiming to convey
   the IPv6 prefixes to be used to build unicast and multicast IPv4-
   embedded IPv6 addresses.

   These options can be in particular used in the context of DS-Lite,
   Stateless A+P and other IPv4-IPv6 interconnection techniques.

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 May 3, 2012.

Copyright Notice

   Copyright (c) 2011 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



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   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.


Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . . . 3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
   3.  PREFIX64 DHCPv6 Option  . . . . . . . . . . . . . . . . . . . . 4
     3.1.  Option Format . . . . . . . . . . . . . . . . . . . . . . . 4
     3.2.  M_PREFIX64 Sub-option . . . . . . . . . . . . . . . . . . . 4
     3.3.  U_PREFIX64 Sub-option . . . . . . . . . . . . . . . . . . . 5
   4.  Client Behaviour  . . . . . . . . . . . . . . . . . . . . . . . 6
   5.  Server Behaviour  . . . . . . . . . . . . . . . . . . . . . . . 6
   6.  Security Considerations . . . . . . . . . . . . . . . . . . . . 7
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 7
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 8
     9.1.  Normative References  . . . . . . . . . . . . . . . . . . . 8
     9.2.  Informative References  . . . . . . . . . . . . . . . . . . 8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . . 9


























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1.  Introduction

   [I-D.ietf-softwire-dslite-multicast] and several other solutions
   (e.g., [I-D.ietf-softwire-mesh-multicast],
   [I-D.venaas-behave-mcast46], etc.) are proposed for the delivery of
   multicast services in the context of transition to IPv6.  Even these
   solutions may have different applicable use cases, they all use
   specific IPv6 addresses to embed IPv4 addresses, for both the
   multicast group addresses
   [I-D.boucadair-behave-64-multicast-address-format], and the multicast
   source addresses [RFC6052].

   This document defines DHCPv6 options [RFC3315] to convey the IPv6
   prefixes (a.k.a., PREFIX64) to be used for constructing these IPv4-
   embedded IPv6 addresses.

   These options can be in particular used in the context of DS-Lite
   [RFC6333], Stateless A+P [RFC6346] and other IPv4-IPv6
   interconnection techniques.

1.1.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].


2.  Terminology

   This document makes use of the following terms:

   o  IPv4-embedded IPv6 address: is an IPv6 address which embeds a 32
      bit-encoded IPv4 address [RFC6052].  An IPv4-embedded IPv6 address
      can be unicast or multicast address.

   o  PREFIX64: is a dedicated IPv6 prefix for building IPv4-embedded
      IPv6 addresses.  A PREFIX64 can be of unicast or multicast.

   o  M_PREFIX64: denotes a multicast PREFIX64.  It may belong to the
      SSM range (i.e., ff3x::/32 [RFC4607]) or ASM range.

   o  U_PREFIX64: denotes a unicast PREFIX64 for building the IPv4-
      embedded IPv6 addresses of multicast sources in SSM mode.








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3.  PREFIX64 DHCPv6 Option

   OPTION_PREFIX64 is defined to convey the IPv6 prefix(es) to use to
   synthesize IPv4-embbedded IPv6 addresses.  This option MAY enclose
   one or more sub-options.

3.1.  Option Format

   Figure 1 shows the format of the OPTION_PREFIX64 DHCPv6 option.

      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_PREFIX64        |         option-length         |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                          sub-option                           |
     .                                                               .
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                              ...                              |
     .                                                               .
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                       preferred-lifetime                      |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                         valid-lifetime                        |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     option-code: OPTION_PREFIX64 (TBD)

     option-length: The length of enclosed sub-option(s) + 8 in octets

     sub-option: One or several sub-obtions. Two sub-codes are defined
                 in this document:
                    (1) SUB_OPTION_M_PREFIX64
                    (2) SUB_OPTION_U_PREFIX64

     preferred-lifetime: The preferred lifetime for the IPv6 prefix(es)
     in the sub-option(s), expressed in units of seconds.

     valid-lifetime: The valid lifetime for the IPv6 prefix(es)
     in the sub-option(s), expressed in units of seconds.

                Figure 1: DHCPv6 Option Format for PREFIX64

3.2.  M_PREFIX64 Sub-option

   This sub-option (Figure 2) is defined to convey the IPv6 multicast
   prefix to use to synthesize the IPv4-embedded IPv6 addresses of the
   multicast groups [I-D.boucadair-behave-64-multicast-address-format].
   The conveyed multicast IPv6 prefix MAY belong to the SSM range (i.e.,



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   ff3x::/32 [RFC4607]) or ASM range.

     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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |    SUB_OPTION_M_PREFIX64      |       sub-option-length       |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    | prefix-length |                 reserved                      |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                                                               |
    |             M_PREFIX64 (IPv6 multicast prefix)                |
    |                                                               |
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

    sub-option-code: SUB_OPTION_M_PREFIX64 (TBD)

    sub-option-len: 20 in octets

    prefix-length: the length of M_PREFIX64 in bits

    M_PREFIX64: the multicast prefix for constructing the IPv4-embedded
                IPv6 addresses of multicast groups. It MAY belong to
                SSM or ASM address range.

             Figure 2: DHCPv6 Sub-option Format for M_PREFIX64

3.3.  U_PREFIX64 Sub-option

   This sub-option (Figure 3) is defined to convey the IPv6 unicast
   prefix to be used in SSM mode for constructing the IPv4-embedded IPv6
   addresses of the multicast sources.  It is also used to extract the
   IPv4 address from received multicast data flows (e.g.,
   [I-D.ietf-softwire-dslite-multicast]).  The address synthesis MUST
   follow the guidelines documented at [RFC6052].

















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      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    SUB_OPTION_U_PREFIX64      |       sub-option-length       |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     | prefix-length |                 reserved                      |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     |              U_PREFIX64 (IPv6 unicast prefix)                 |
     |                                                               |
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     sub-option-code: SUB_OPTION_U_PREFIX64 (TBD)

     sub-option-len: 20 in octets

     prefix-length: the length of U_PREFIX64 in bits

     U_PREFIX64: the unicast prefix for constructing the IPv4-embedded
     IPv6 addresses of the multicast sources in SSM mode

             Figure 3: DHCPv6 Sub-option Format for U_PREFIX64


4.  Client Behaviour

   To retrieve the IPv6 prefixes to use to synthesize unicast and
   multicast IPv4-embedded IPv6 addresses, the DHCPv6 client MUST
   include OPTION_PREFIX64 in its OPTION_ORO.

   If the DHCPv6 client receives more than one OPTION_PREFIX64 option
   from the DHCPv6 server, only the first instance of that option MUST
   be used.

   When OPTION_PREFIX64 option is received from the DHCPv6 server, at
   most three sub-options MAY be included.

   The prefix conveyed in SUB_OPTION_U_PREFIX64 is used to synthesize
   unicast IPv4-embedded IPv6 addresses as specified in [RFC6052].

   The prefix conveyed in SUB_OPTION_M_PREFIX64 is used to synthesize
   multicast IPv4-embedded IPv6 addresses as specified in
   [I-D.boucadair-behave-64-multicast-address-format].


5.  Server Behaviour

   A DHCPv6 server MUST NOT reply with a value for the OPTION_PREFIX64



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   if the DHCPv6 client has not explicitly included OPTION_PREFIX64 in
   its OPTION_ORO.

   If OPTION_PREFIX64 option is requested by the DHCPv6 client, the
   DHCPv6 server MUST NOT send more than one OPTION_PREFIX64 option in
   the response.

   One or two SUB_OPTION_M_PREFIX64 sub-options MAY be enclosed in
   OPTION_PREFIX64 DHCPv6 option.  In particular, if only SSM or ASM
   mode is supported, only one SUB_OPTION_M_PREFIX64 sub-option MUST be
   returned to the requesting client.  If both SSM and ASM mode are
   supported, two SUB_OPTION_M_PREFIX64 sub-options MUST be returned.

   When two SUB_OPTION_M_PREFIX64 sub-options are present, one
   SUB_OPTION_M_PREFIX64 sub-option MUST convey an IPv6 prefix in SSM
   range and the other one MUST enclose an IPv6 prefix in the ASM range.

   If the IPv6 multicast prefix conveyed in SUB_OPTION_M_PREFIX64 is an
   SSM prefix, U_PREFIX64 sub-option MUST also be present.


6.  Security Considerations

   The security considerations in [RFC3315] are to be considered.


7.  Acknowledgements

   TBD


8.  IANA Considerations

   A new DHCPv6 option:

      OPTION_PREFIX64

   and two sub-options:

      SUB_OPTION_M_PREFIX64,

      SUB_OPTION_U_PREFIX64

   need to be assigned by IANA.


9.  References




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9.1.  Normative References

   [I-D.boucadair-behave-64-multicast-address-format]
              Boucadair, M., Qin, J., Lee, Y., Venaas, S., Li, X., and
              M. Xu, "IPv4-Embedded IPv6 Multicast Address Format",
              draft-boucadair-behave-64-multicast-address-format-03
              (work in progress), October 2011.

   [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.

   [RFC4607]  Holbrook, H. and B. Cain, "Source-Specific Multicast for
              IP", RFC 4607, August 2006.

   [RFC6052]  Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X.
              Li, "IPv6 Addressing of IPv4/IPv6 Translators", RFC 6052,
              October 2010.

9.2.  Informative References

   [I-D.ietf-softwire-dslite-multicast]
              Wang, Q., Qin, J., Boucadair, M., Jacquenet, C., and Y.
              Lee, "Multicast Extensions to DS-Lite Technique in
              Broadband Deployments",
              draft-ietf-softwire-dslite-multicast-00 (work in
              progress), September 2011.

   [I-D.ietf-softwire-mesh-multicast]
              Xu, M., Cui, Y., Yang, S., Wu, J., Metz, C., and G.
              Shepherd, "Softwire Mesh Multicast",
              draft-ietf-softwire-mesh-multicast-01 (work in progress),
              October 2011.

   [I-D.venaas-behave-mcast46]
              Venaas, S., Asaeda, H., SUZUKI, S., and T. Fujisaki, "An
              IPv4 - IPv6 multicast translator",
              draft-venaas-behave-mcast46-02 (work in progress),
              December 2010.

   [RFC6333]  Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual-
              Stack Lite Broadband Deployments Following IPv4
              Exhaustion", RFC 6333, August 2011.

   [RFC6346]  Bush, R., "The Address plus Port (A+P) Approach to the



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              IPv4 Address Shortage", RFC 6346, August 2011.


Authors' Addresses

   Jacni Qin
   ZTE
   Shanghai,
   China

   Phone: +86 1391 8619 913
   Email: jacni@jacni.com


   Mohamed Boucadair
   France Telecom
   Rennes,   35000
   France

   Phone:
   Email: mohamed.boucadair@orange.com


   Tina Tsou
   Huawei Technologies (USA)
   2330 Central Expressway
   Santa Clara, CA  95050
   USA

   Phone: +1 408 330 4424
   Email: tina.tsou.zouting@huawei.com




















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