[Docs] [txt|pdf] [Tracker] [WG] [Email] [Diff1] [Diff2] [Nits]

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: April 3, 2015                                            Y. Cui
                                                     Tsinghua University
                                                      September 30, 2014


                DHCPv4 over DHCPv6 Source Address Option
                draft-fsc-softwire-dhcp4o6-saddr-opt-01

Abstract

   DHCPv4 over DHCPv6 [RFC7341] 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
   used 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 April 3, 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



Farrer, et al.            Expires April 3, 2015                 [Page 1]


Internet-Draft            DHCP 4o6 SADDR option           September 2014


   (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  . . . . . . . . . . . . . . . . . . . . . . .   6
     5.1.  DHCPv4 over DHCPv6 Source Address Hint Option . . . . . .   6
     5.2.  DHCPv4 over DHCPv6 Source Address Option  . . . . . . . .   6
     5.3.  DHCPv4 over DHCPv6 Softwire Container Option  . . . . . .   7
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   7
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   7
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   8
   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 such deterministic softwires.

   This document describes a mechanism for informing 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 [RFC7341]
   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,
   e.g. using the client's binding information to synchronise the
   binding table in the border router.





Farrer, et al.            Expires April 3, 2015                 [Page 2]


Internet-Draft            DHCP 4o6 SADDR option           September 2014


   The mechanism allows much more flexibility in the location of the
   IPv4-over-IPv6 tunnel endpoint, as the IPv6 address is dynamically
   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 in this document extends the Softwire46 container
   approach described 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 defined in this memo:
   OPTION_DHCP4O6_SADDR_HINT and OPTION_DHCP4O6_SADDR.  They are
   intended to be used alongside the normal DHCPv4 IPv4 address
   allocation message flow in the context of DHCPv4 over DHCPv6
   [RFC7341].

   The communication of parameters between the client and server is two-
   way: OPTION_DHCP4O6_SADDR_HINT can be (optionally) 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.




Farrer, et al.            Expires April 3, 2015                 [Page 3]


Internet-Draft            DHCP 4o6 SADDR option           September 2014


   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's IPv4-in-IPv6 encapsulated
   traffic.  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 [RFC7341].  Then the OPTION_S46_CONT_DHCP4O6
   MAY be included in DHCPv4-query and DHCPv4-response messages.  If the
   IPv6 source address of the client changes (such as IPv6 lease
   expiration, etc.), the client follows the Section 9 of [RFC7341] to
   reenable the DHCPv4-over-DHCPv6 function.

   If OPTION_S46_CONT_DHCP4O6 is used, the option (as well as any
   suboption(s) it contains) MUST be transported in the DHCPv4-query and
   DHCPv4-response messages [RFC7341].

4.  IPv6/IPv4 Binding Message Flow

   The following diagram shows the client/server message flow and how
   the OPTION_S46_CONT_DHCP4O6 container 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' field of the DHCPv4-query or
   DHCPv4-response message.























Farrer, et al.            Expires April 3, 2015                 [Page 4]


Internet-Draft            DHCP 4o6 SADDR option           September 2014


        DHCP 4o6                                              DHCP 4o6
         Client                                                Server
           |                DHCPDISCOVER (DHCPv4)                 |
    Step 1 |----------------------------------------------------->|
           |     ORO with OPTION_S46_CONT_DHCP4O6 (DHCPv6)        |
           |                                                      |
           |                 DHCPOFFER (DHCPv4)                   |
    Step 2 |<-----------------------------------------------------|
           |   OPTION_S46_CONT_DHCP4O6 containing OPTION_S46_BR,  |
           |   OPTION_DHCP4O6_SADDR_HINT (cipv6-prefix-hint with  |
           |     service provider's preferred prefix) (DHCPv6)    |
           |                                                      |
           |                 DHCPREQUEST (DHCPv4)                 |
    Step 3 |----------------------------------------------------->|
           |   OPTION_S46_CONT_DHCP4O6 containing OPTION_S46_BR,  |
           |    OPTION_DHCP4O6_SADDR (cipv6-bound-prefix with     |
           |     client's bound /128 IPv6 address) (DHCPv6)       |
           |                                                      |
           |                   DHCPACK (DHCPv4)                   |
    Step 4 |<-----------------------------------------------------|
           |   OPTION_S46_CONT_DHCP4O6 containing OPTION_S46_BR,  |
           |    OPTION_DHCP4O6_SADDR (cipv6-bound-prefix with     |
           |      client's bound /128 IPv6 prefix) (DHCPv6)       |
           |                                                      |


                      IPv6/IPv4 Binding Message Flow

   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 option
   code for OPTION_S46_CONT_DHCP4O6 in the DHCPv6 ORO alongside the
   DHCPv4 DHCPDISCOVER message.  This container option MUST be present,
   along with relevant sub-options, in all subsequent DHCPv4 over DHCPv6
   transactions for the lifetime of the IPv4 address lease.
   OPTION_S46_BR SHOULD also be included in the container.

   When a DHCP 4o6 Server replies with a DHCPOFFER message, it SHOULD
   include an OPTION_S46_CONT_DHCP4O6 option containing OPTION_S46_BR.
   It MAY also include 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 this sub-option is received, the client MUST
   perform a longest prefix match between cipv6-prefix-hint and all
   configured prefixes on the device.  If a match is found, then the
   selected prefix MUST then be used to bind the received IPv4
   configuration to.  If the client doesn't receive the sub-option, or




Farrer, et al.            Expires April 3, 2015                 [Page 5]


Internet-Draft            DHCP 4o6 SADDR option           September 2014


   the matching fails, the client can select any valid /128 IPv6 prefix
   to use.

   OPTION_DHCP4O6_SADDR is used by the client to inform the DHCP 4o6
   Server which IPv6 prefix the IPv4 configuration has been bound to.
   The client MUST put the selected IPv6 address into this sub-option
   and include 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-hintlen |                                               |
        +-+-+-+-+-+-+-+-+          cipv6-prefix-hint                   .
        .                          (variable length)                    .
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   o  option-code: OPTION_DHCP4O6_SADDR_HINT (TBA1)
   o  option-length: 1 + 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 indicating the preferred prefix
      for the client to bind the received IPv4 configuration to.

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)                          .
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+





Farrer, et al.            Expires April 3, 2015                 [Page 6]


Internet-Draft            DHCP 4o6 SADDR option           September 2014


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

5.3.  DHCPv4 over DHCPv6 Softwire Container Option

   The DHCP 4o6 Container option carries 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: length of encapsulated-options (specified in bytes)
   o  encapsulated-options: options for configuring the DHCP 4o6
      Softwire client.

6.  Security Considerations

   TBD

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-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-08
              (work in progress), July 2014.



Farrer, et al.            Expires April 3, 2015                 [Page 7]


Internet-Draft            DHCP 4o6 SADDR option           September 2014


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

   [RFC7341]  Sun, Q., Cui, Y., Siodelski, M., Krishnan, S., and I.
              Farrer, "DHCPv4-over-DHCPv6 (DHCP 4o6) Transport", RFC
              7341, August 2014.

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.

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





Farrer, et al.            Expires April 3, 2015                 [Page 8]


Internet-Draft            DHCP 4o6 SADDR option           September 2014


   Yong Cui
   Tsinghua University
   Beijing  100084
   P.R. China

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












































Farrer, et al.            Expires April 3, 2015                 [Page 9]


Html markup produced by rfcmarkup 1.129b, available from https://tools.ietf.org/tools/rfcmarkup/