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Versions: 00 01 02 03 04 05 06 07 draft-ietf-dhc-dhcp4o6-saddr-opt

Softwire WG                                                    I. Farrer
Internet-Draft                                       Deutsche Telekom AG
Intended status: Standards Track                                  Q. Sun
Expires: January 1, 2015                                          Y. Cui
                                                     Tsinghua University
                                                           June 30, 2014


                DHCPv4 over DHCPv6 Source Address Option
                draft-fsc-softwire-dhcp4o6-saddr-opt-00

Abstract

   DHCPv4 over DHCPv6 [I-D.ietf-dhc-dhcpv4-over-dhcpv6] describes a
   mechanism for dynamically configuring IPv4 over an IPv6-only network.
   For DHCPv4 over DHCPv6 to function with some IPv4-over-IPv6 softwire
   mechanisms, the operator must obtain information about the IPv4
   address and Port Set ID allocated to the DHCP 4o6 client, as well as
   the /128 IPv6 prefix that the client will use as the source of IPv4-
   in-IPv6 tunnel.  This memo defines a DHCPv6 container option and two
   DHCPv6 sub-options, to communicate the source tunnel IPv6 address
   between the DHCP 4o6 client and server.  It is designed to work in
   conjunction with the IPv4 address allocation process.

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 January 1, 2015.

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



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   (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.  Requirements Language . . . . . . . . . . . . . . . . . . . .   3
   3.  Solution Overview . . . . . . . . . . . . . . . . . . . . . .   3
   4.  IPv6/IPv4 Binding Message Flow  . . . . . . . . . . . . . . .   4
   5.  DHCPv6 Options  . . . . . . . . . . . . . . . . . . . . . . .   5
     5.1.  DHCPv4 over DHCPv6 Source Address Hint Option . . . . . .   5
     5.2.  DHCPv4 over DHCPv6 Source Address Option  . . . . . . . .   6
     5.3.  DHCPv4 over DHCPv6 Softwire Container Option  . . . . . .   6
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   7
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   7
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   Deterministic IPv4-over-IPv6 transition technologies are prescriptive
   in the location of the tunnel endpoint within the home network.  The
   tunnel endpoint should usually be configured on either the home
   gateway device, or sourced from a specific IPv6 tunnel prefix
   allocated to the home network (and in some cases, both).
   [I-D.ietf-softwire-map-dhcp] describes a DHCPv6 based mechanism for
   provisioning these deterministic softwires.

   This document describes a mechanism to inform the service provider of
   the binding between the dynamically allocated IPv4 address and Port
   Set ID (learnt through DHCPv4 over DHCPv6) and the IPv6 address that
   the Softwire Initiator will use for accessing IPv4-over-IPv6
   services.  It is used with DHCPv4 over DHCPv6
   [I-D.ietf-dhc-dhcpv4-over-dhcpv6] message flows to communicate the
   binding over the IPv6-only network.  The service provider can then
   use this binding information to provision other functional elements
   in their network accordingly (such as the border router).

   The mechanism allows much more flexibility in the location of the
   IPv4-over-IPv6 tunnel endpoint, as the IPv6 address is dynamically



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   signalled back to the service provider.  The DHCP 4o6 client and
   tunnel client could be run on end devices attached to any routable
   IPv6 prefix allocated to an end-user, located anywhere within an
   arbitrary home network topology.

   This memo describes extensions to [I-D.ietf-softwire-map-dhcp] to
   enable the provisioning and tunnel management of softwire initiators
   configured through DHCPv4 over DHCPv6.

   Current mechanisms suitable for extending to incorporate DHCPv4 over
   DHCPv6 with dynamic IPv4 address leasing include
   [I-D.ietf-softwire-map] and [I-D.ietf-softwire-lw4over6].

2.  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].

3.  Solution Overview

   The solution described in this document extends the Softwire46
   container approach in [I-D.ietf-softwire-map-dhcp] by defining a new
   container type: OPTION_S46_CONT_DHCP4O6.  The container is used to
   carry the sub-options necessary for softwire configuration.  A client
   can indicate its support for dynamic softwire configuration by
   including the OPTION_S46_CONT_DHCP4O6 option code within the Option
   Request Option.

   Two new DHCPv6 sub-options are also described in this memo:
   OPTION_DHCP4O6_SADDR_HINT and OPTION_DHCP4O6_SADDR.  They are
   intended to be used alongside the normal IPv4 address allocation
   message flow in the context of DHCPv4 over DHCPv6
   [I-D.ietf-dhc-dhcpv4-over-dhcpv6].

   It is a two-way communication process.  The OPTION_DHCP4O6_SADDR_HINT
   is used by the DHCP 4o6 server to optionally indicate to the client a
   preferred IPv6 prefix for binding the received IPv4 configuration and
   sourcing tunnel traffic.  This may be necessary if there are multiple
   IPv6 prefixes in use in the customer network, or if the specific
   IPv4-over-IPv6 transition mechanism requires the use of a particular
   prefix for any reason.  When the client has selected the IPv6 address
   to bind the IPv4 configuration to, it passes the address back to the
   DHCP 4o6 server through OPTION_DHCP4O6_SADDR.

   A softwire client also requires an address or addresses for the
   Border Router (softwire tunnel concentrator).  This is used as the
   destination address for the client IPv4-in-IPv6 encapsulated traffic.



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   Section 4.2 of [I-D.ietf-softwire-map-dhcp] describes the
   OPTION_S46_BR option.  This option SHOULD be included as an
   encapsulated option within OPTION_S46_CONT_DHCP4O6.

   This mechanism MUST be used with DHCPv4 over DHCPv6.  The DHCP client
   MUST request the 4o6 Server Address option first to get DHCPv4 over
   DHCPv6 enabled, as in [I-D.ietf-dhc-dhcpv4-over-dhcpv6].  Then the
   OPTION_S46_CONT_DHCP4O6 MAY be included in DHCPv4-query and
   DHCPv4-response messages.

4.  IPv6/IPv4 Binding Message Flow

   The following diagram shows the client/server message flow and how
   the container OPTION_S46_CONT_DHCP4O6 and its sub-options are used.
   In each step, the relevant DHCPv4 message is given above the arrow
   and the relevant options below the arrow.  The DHCPv4 messages are
   encapsulated in DHCPv4-query or DHCPv4-response message, and those
   options are included in the 'options' filed of the DHCPv4-query or
   DHCPv4-response message.

        DHCP 4o6                                              DHCP 4o6
         Client                                                Server
           |                      DHCPDISCOVER                    |
    Step 1 |----------------------------------------------------->|
           |         ORO with OPTION_S46_CONT_DHCP4O6             |
           |                                                      |
           |                        DHCPOFFER                     |
    Step 2 |<-----------------------------------------------------|
           |   OPTION_S46_CONT_DHCP4O6 containing OPTION_S46_BR,  |
           |   OPTION_DHCP4O6_SADDR_HINT (cipv6-prefix-hint with  |
           |   service provider's preferred prefix)               |
           |                                                      |
           |                       DHCPREQUEST                    |
    Step 3 |----------------------------------------------------->|
           |   OPTION_S46_CONT_DHCP4O6 containing OPTION_S46_BR,  |
           |   OPTION_DHCP4O6_SADDR (cipv6-bound-prefix with      |
           |   client's bound /128 IPv6 address)                  |
           |                                                      |
           |                         DHCPACK                      |
    Step 4 |<-----------------------------------------------------|
           |   OPTION_S46_CONT_DHCP4O6 containing OPTION_S46_BR,  |
           |   OPTION_DHCP4O6_SADDR (cipv6-bound-prefix with      |
           |   client's bound /128 IPv6 prefix)                   |
           |                                                      |


                      IPv6/IPv4 Binding Message Flow




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   The DHCP 4o6 Server and Client MAY implement the
   OPTION_S46_CONT_DHCP4O6 option and its sub-options.  A client that
   intends to dynamically configure softwires SHOULD include the code of
   OPTION_S46_CONT_DHCP4O6 in the ORO when it sends a DHCPDISCOVER
   message.  If so, this container option MUST be present along with
   relevant sub-options in all future DHCPv4 over DHCPv6 transactions.
   The OPTION_S46_BR SHOULD be included in the container.

   When a DHCP 4o6 Server replies with a DHCPOFFER message, it SHOULD
   include the OPTION_S46_CONT_DHCP4O6 option with the OPTION_S46_BR,
   but it MAY include the OPTION_DHCP4O6_SADDR_HINT.  The
   OPTION_DHCP4O6_SADDR_HINT is used by the server to indicate a
   preferred prefix that the client should use to bind IPv4
   configuration to.  If received this sub-option, the client MUST
   perform a longest prefix match between cipv6-prefix-hint and all
   prefixes configured on the device.  The selected prefix MUST then be
   used to bind the received IPv4 configuration to.  Otherwise, the
   client can select any valid /128 IPv6 prefix.

   The OPTION_DHCP4O6_SADDR is used by the client to inform the DHCP 4o6
   Server of the IPv6 prefix that it has bound the IPv4 configuration
   to.  The client MUST put the selected IPv6 address into this sub-
   option and include the OPTION_S46_CONT_DHCP4O6 in the DHCPv4-response
   message when it sends the DHCPREQUEST message.

5.  DHCPv6 Options

5.1.  DHCPv4 over DHCPv6 Source Address Hint 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_DHCP4O6_SADDR_HINT   |         option-length         |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |cipv6-boundlen |                                               |
        +-+-+-+-+-+-+-+-+          cipv6-bound-prefix                   .
        .                          (variable length)                    .
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   o  option-code: OPTION_DHCP4O6_SADDR_HINT (TBA1)
   o  option-length: 2 + length of cipv6-prefix-hint, specified in
      bytes.
   o  cipv6-hintlen: 8-bit field expressing the bit mask length of the
      IPv6 prefix specified in cipv6-prefix-hint.
   o  cipv6-prefix-hint: The IPv6 prefix that the server uses to
      indicate the preferred prefix that the client should use to bind
      IPv4 configuration to.



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5.2.  DHCPv4 over DHCPv6 Source Address Option

   The format of DHCPv4 over DHCPv6 Source address option is defined 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
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |     OPTION_DHCP4O6_SADDR      |         option-length         |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |                                                               |
        +                        cipv6-src-address                      +
        .                           (128 bits)                          .
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   o  option-code: OPTION_DHCP4O6_SADDR (TBA2)
   o  option-length: 16.
   o  cipv6-src-address: The IPv6 address that the client is using to
      bind the allocated IPv4 configuration to.

5.3.  DHCPv4 over DHCPv6 Softwire Container Option

   The DHCP 4o6 Container option specifies the container used to group
   the relevant options and parameters for configuring the client.

         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_DHCP4O6    |         option-length         |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |                                                               |
        |           encapsulated-options (variable length)              |
        .                                                               .
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   o  option-code: OPTION_S46_CONT_DHCP4O6 (TBA3)
   o  option-length: 2 + length of encapsulated options (specified in
      bytes)
   o  encapsulated-options: options for configuring the DHCP 4o6
      Softwire client.

6.  Security Considerations

   TBD





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7.  IANA Considerations

   IANA is requested to allocate the DHCPv6 option code:
   OPTION_DHCP4O6_SADDR_HINT, OPTION_DHCP4O6_SADDR and
   OPTION_S46_CONT_DHCP4O6.

8.  Acknowledgements

9.  References

9.1.  Normative References

   [I-D.ietf-dhc-dhcpv4-over-dhcpv6]
              Sun, Q., Cui, Y., Siodelski, M., Krishnan, S., and I.
              Farrer, "DHCPv4 over DHCPv6 Transport", draft-ietf-dhc-
              dhcpv4-over-dhcpv6-09 (work in progress), June 2014.

   [I-D.ietf-softwire-map-dhcp]
              Mrugalski, T., Troan, O., Farrer, I., Perreault, S., Dec,
              W., Bao, C., leaf.yeh.sdo@gmail.com, l., and X. Deng,
              "DHCPv6 Options for configuration of Softwire Address and
              Port Mapped Clients", draft-ietf-softwire-map-dhcp-07
              (work in progress), March 2014.

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

9.2.  Informative References

   [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-lw4over6-10 (work
              in progress), June 2014.

   [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-10
              (work in progress), January 2014.

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




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Authors' Addresses

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

   Email: ian.farrer@telekom.de


   Qi Sun
   Tsinghua University
   Beijing  100084
   P.R. China

   Phone: +86-10-6278-5822
   Email: sunqi@csnet1.cs.tsinghua.edu.cn


   Yong Cui
   Tsinghua University
   Beijing  100084
   P.R. China

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
























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