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Versions: (draft-mawatari-v6ops-464xlat) 00 01 02 03 04 05 06 07 08 09 10 RFC 6877

Internet Engineering Task Force                              M. Mawatari
Internet-Draft                          Japan Internet Exchange Co.,Ltd.
Intended status: BCP                                        M. Kawashima
Expires: January 4, 2013                        NEC AccessTechnica, Ltd.
                                                                C. Byrne
                                                            T-Mobile USA
                                                            July 3, 2012


       464XLAT: Combination of Stateful and Stateless Translation
                      draft-ietf-v6ops-464xlat-05

Abstract

   This document describes an architecture (464XLAT) for providing
   limited IPv4 connectivity across an IPv6-only network by combining
   existing and well-known stateful protocol translation RFC 6146 in the
   core and stateless protocol translation RFC 6145 at the edge. 464XLAT
   is a simple and scalable technique to quickly deploy limited IPv4
   access service to IPv6-only edge networks without encapsulation.

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 4, 2013.

Copyright Notice

   Copyright (c) 2012 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



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   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.  Requirements Language  . . . . . . . . . . . . . . . . . . . .  3
   3.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   4.  Motivation and Uniqueness of 464XLAT . . . . . . . . . . . . .  4
   5.  Network Architecture . . . . . . . . . . . . . . . . . . . . .  4
     5.1.  Wireline Network Architecture  . . . . . . . . . . . . . .  4
     5.2.  Wireless 3GPP Network Architecture . . . . . . . . . . . .  5
   6.  Applicability  . . . . . . . . . . . . . . . . . . . . . . . .  6
     6.1.  Wireline Network Applicability . . . . . . . . . . . . . .  6
     6.2.  Wireless 3GPP Network Applicability  . . . . . . . . . . .  7
   7.  Implementation Considerations  . . . . . . . . . . . . . . . .  7
     7.1.  IPv6 Address Format  . . . . . . . . . . . . . . . . . . .  7
     7.2.  IPv4/IPv6 Address Translation Chart  . . . . . . . . . . .  7
       7.2.1.  Case of enabling only stateless XLATE on CLAT  . . . .  7
       7.2.2.  Case of enabling NAT44 and stateless XLATE on CLAT . .  9
     7.3.  IPv6 Prefix Handling . . . . . . . . . . . . . . . . . . . 11
       7.3.1.  Case of enabling only stateless XLATE on CLAT  . . . . 11
       7.3.2.  Case of enabling NAT44 and stateless XLATE on CLAT . . 11
     7.4.  Traffic Treatment Scenarios  . . . . . . . . . . . . . . . 12
     7.5.  DNS Proxy Implementation . . . . . . . . . . . . . . . . . 12
     7.6.  CLAT in a Gateway  . . . . . . . . . . . . . . . . . . . . 12
     7.7.  CLAT to CLAT communications  . . . . . . . . . . . . . . . 12
   8.  Deployment Considerations  . . . . . . . . . . . . . . . . . . 13
   9.  Security Considerations  . . . . . . . . . . . . . . . . . . . 13
   10. IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 13
   11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 14
   12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14
     12.1. Normative References . . . . . . . . . . . . . . . . . . . 14
     12.2. Informative References . . . . . . . . . . . . . . . . . . 14
   Appendix A.  Examples of IPv4/IPv6 Address Translation . . . . . . 16
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 19












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1.  Introduction

   The IANA unallocated IPv4 address pool was exhausted on February 3,
   2011.  Each RIR's unallocated IPv4 address pool will exhaust in the
   near future.  It will be difficult for many networks to assign IPv4
   addresses to end users, despite substantial IP connectivity growth
   required for fast growing edge networks.

   This document describes an IPv4 over IPv6 solution as one of the
   techniques for IPv4 service extension and encouragement of IPv6
   deployment. 464XLAT is not a one for one replacement of full IPv4
   functionality.  The 464XLAT architecture only supports IPv4 in the
   client server model, where the server has global IPv4 address.  This
   means it is not fit for IPv4 peer-to-peer communication or inbound
   IPv4 connections. 464XLAT builds on IPv6 transport and includes full
   any to any IPv6 communication.

   The 464XLAT architecture described in this document uses IPv4/IPv6
   translation standardized in [RFC6145] and [RFC6146].  It does not
   require DNS64 [RFC6147] since an IPv4 host may simply send IPv4
   packets, including packets to an IPv4 DNS server, which will be
   translated on the CLAT to IPv6 and back to IPv4 on the PLAT. 464XLAT
   networks may use DNS64 [RFC6147] to enable single stateful
   translation [RFC6146] instead of 464XLAT double translation where
   possible.  The 464XLAT architecture encourages IPv6 transition by
   making IPv4 services reachable across IPv6-only networks and
   providing IPv6 and IPv4 connectivity to single-stack IPv4 or IPv6
   servers and peers.

   By combining 464XLAT with BIH [RFC6535], it is also possible to
   provide single IPv4 to IPv6 translation service, which will be needed
   in the future case of IPv6-only servers and peers to be reached from
   legacy IPv4-only hosts across IPv6-only networks.


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 [RFC2119].


3.  Terminology








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   PLAT:   PLAT is Provider side translator(XLAT) that complies with
           [RFC6146].  It translates N:1 global IPv6 packets to global
           IPv4 packets, and vice versa.

   CLAT:   CLAT is Customer side translator(XLAT) that complies with
           [RFC6145].  It algorithmically translates 1:1 private IPv4
           packets to global IPv6 packets, and vice versa.  The CLAT
           function is applicable to a router or an end-node such as a
           mobile phone.  CLAT SHOULD perform router function to
           facilitate packets forwarding through the stateless
           translation even if it is an end-node.  In the case where the
           access network does not allow for a dedicated IPv6 prefix for
           translation, a NAT44 SHOULD be used between the router
           function and the stateless translator function.  The CLAT as
           a common home router or 3G router is expected to perform
           gateway functions such as DHCP server and DNS proxy for local
           clients.  The CLAT does not comply with the sentence "Both
           IPv4-translatable IPv6 addresses and IPv4-converted IPv6
           addresses SHOULD use the same prefix." that is described on
           Section 3.3 in [RFC6052] due to using different IPv6 prefixes
           for CLAT-side and PLAT-side IPv4 addresses.


4.  Motivation and Uniqueness of 464XLAT

   1.  Minimal IPv4 resource requirements, maximum IPv4 efficiency
       through statistical multiplexing

   2.  No new protocols required, quick deployment

   3.  IPv6-only networks are simpler and therefore less expensive to
       operate


5.  Network Architecture

   464XLAT architecture is shown in the following figure.

5.1.  Wireline Network Architecture

   The private IPv4 host on this diagram can reach global IPv4 hosts via
   translation on both CLAT and PLAT.  On the other hand, the IPv6 host
   can reach other IPv6 hosts on the Internet directly without
   translation.  This means that the CPE can not only have the function
   of CLAT but also the function of IPv6 native router for IPv6 native
   traffic.





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                                  ----
                                 | v6 |
                                  ----
                                    |
    ----      |                 .---+---.                    .------.
   | v6 |-----+                /         \                  /        \
    ----      |    ------     /   IPv6    \     ------     /   IPv4   \
              +---| CLAT |---+  Internet   +---| PLAT |---+  Internet  |
    -------   |    ------     \           /     ------     \           /
   |v4p/v6 |--+                `---------'                  `----+----'
    -------   |                                                  |
    -----     |                                                -----
   | v4p |----+                                               | v4g |
    -----     |                                                -----

          <- v4p -> XLAT <--------- v6 --------> XLAT <- v4g ->


     v6  : Global IPv6
     v4p : Private IPv4
     v4g : Global IPv4

                    Figure 1: Wireline Network Topology

5.2.  Wireless 3GPP Network Architecture

   The CLAT function on the UE provides an [RFC1918] address and IPv4
   default route.  The applications on the UE can use the private IPv4
   address for reaching global IPv4 hosts via translation on both CLAT
   and PLAT.  On the other hand, reaching IPv6 hosts (including host
   presented via DNS64 [RFC6147]) does not require the CLAT function on
   the UE.



















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                                   ----
                                  | v6 |
                                   ----
                                     |
                                 .---+---.
                                /         \
                               /   IPv6    \
                              |   Internet  |
                               \           /
      UE / Mobile Phone         `---------'
   +----------------------+          |
   |  ----     |          |      .---+---.                   .------.
   | | v6 |----+          |     /         \                 /        \
   |  ----     |    ------|    / IPv6 PDP  \     ------    /   IPv4   \
   |           +---| CLAT |---+ Mobile Core +---| PLAT |--+  Internet  |
   |           |    ------|    \    GGSN   /     ------    \          /
   |           |          |     \         '                 `----+---'
   |  ------   |          |      `-------'                       |
   | | v4p |---+          |                                    -----
   |  ------   |          |                                   | v4g |
   +----------------------+                                    -----

           <- v4p -> XLAT <--------- v6 --------> XLAT <- v4g ->


     v6  : Global IPv6
     v4p : Private IPv4
     v4g : Global IPv4

                 Figure 2: Wireless 3GPP Network Topology


6.  Applicability

6.1.  Wireline Network Applicability

   When an ISP has IPv6 464XLAT, the ISP can provide outgoing IPv4
   service to end users across an IPv6 access network.  The result is
   that edge network growth is no longer tightly coupled to the
   availability of scarce IPv4 addresses.

   If the IXP or another provider operates the PLAT, the edge ISP is
   only required to deploy an IPv6 access network.  All ISPs do not need
   IPv4 access networks.  They can migrate their access network to a
   simple and highly scalable IPv6-only environment.

   Incidentally, the effectiveness of 464XLAT was confirmed in the WIDE
   camp Spring 2012.  The result is described in



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   [I-D.hazeyama-widecamp-ipv6-only-experience].

6.2.  Wireless 3GPP Network Applicability

   The vast majority of mobile networks are compliant to Pre-Release 9
   3GPP standards.  In Pre-Release 9 3GPP networks, GSM and UMTS
   networks must signal and support both IPv4 and IPv6 Packet Data
   Protocol (PDP) attachments to access IPv4 and IPv6 network
   destinations [RFC6459].  Since there are 2 PDPs required to support 2
   address families, this is double the number of PDPs required to
   support the status quo of 1 address family, which is IPv4.

   464XLAT in combination with stateful translation [RFC6146] and DNS64
   [RFC6147] allows 85% of the Android applications to continue to work
   with single translation or native IPv6 access.  For the remaining 15%
   of applications that require IPv4 connectivity, the CLAT function on
   the UE provides a private IPv4 address and IPv4 default-route on the
   host for the applications to reference and bind to.  Connections
   sourced from the IPv4 interface are immediately routed to the CLAT
   function and passed to the IPv6-only mobile network, destine to the
   PLAT.  In summary, the UE has the CLAT function that does a stateless
   translation [RFC6145], but only when required.  The mobile network
   has a PLAT that does stateful translation [RFC6146].

   464XLAT works with today's existing systems as much as possible.
   464XLAT is compatible with existing network based deep packet
   inspection solutions like 3GPP standardized Policy and Charging
   Control (PCC) [TS.23203].


7.  Implementation Considerations

7.1.  IPv6 Address Format

   IPv6 address format in 464XLAT is defined in Section 2.2 of
   [RFC6052].

7.2.  IPv4/IPv6 Address Translation Chart

7.2.1.  Case of enabling only stateless XLATE on CLAT

   This case should be used when a prefix delegation mechanism such as
   DHCPv6-PD [RFC3633] is available to assign a dedicated translation
   prefix to the CLAT.







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                                           Source IPv4 address
                                          +----------------------------+
                                          | Global IPv4 address        |
                                          | assigned to IPv4 pool@PLAT |
                               +--------+ +----------------------------+
                               |  IPv4  |  Destination IPv4 address
                               | server | +----------------------------+
                               +--------+ | Global IPv4 address        |
                                   ^      | assigned to IPv4 server    |
                                   |      +----------------------------+
                               +--------+
                               |  PLAT  | Stateful XLATE(IPv4:IPv6=1:n)
                               +--------+
                                   ^
                                   |
         Source IPv6 address  (IPv6 cloud)
        +--------------------------------------------------------------+
        | IPv4-Embedded IPv6 address                                   |
        | defined in Section 2.2 of RFC6052                            |
        +--------------------------------------------------------------+
         Destination IPv6 address
        +--------------------------------------------------------------+
        | IPv4-Embedded IPv6 address                                   |
        | defined in Section 2.2 of RFC6052                            |
        +--------------------------------------------------------------+
                              (IPv6 cloud)
                                   ^
                                   |
                               +--------+
                               |        | In the case CLAT has a
                               |        | dedicated IPv6 prefix for
                               |  CLAT  | translation, the CLAT can
                               |        | perform with only Stateless
                               |        | XLATE (IPv4:IPv6=1:1).
                               +--------+
                                   ^       Source IPv4 address
                                   |      +----------------------------+
                               +--------+ | Private IPv4 address       |
                               |  IPv4  | | assigned to IPv4 client    |
                               | client | +----------------------------+
                               +--------+  Destination IPv4 address
                                          +----------------------------+
                                          | Global IPv4 address        |
                                          | assigned to IPv4 server    |
                                          +----------------------------+

               Case of enabling only stateless XLATE on CLAT




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7.2.2.  Case of enabling NAT44 and stateless XLATE on CLAT

   This case should be used when a prefix delegation mechanism is not
   available to assign a dedicated translation prefix to the CLAT.  In
   this case, NAT44 SHOULD be used so that all IPv4 source addresses are
   mapped to a single IPv6 address.













































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                                           Source IPv4 address
                                          +----------------------------+
                                          | Global IPv4 address        |
                                          | assigned to IPv4 pool@PLAT |
                               +--------+ +----------------------------+
                               |  IPv4  |  Destination IPv4 address
                               | server | +----------------------------+
                               +--------+ | Global IPv4 address        |
                                   ^      | assigned to IPv4 server    |
                                   |      +----------------------------+
                               +--------+
                               |  PLAT  | Stateful XLATE(IPv4:IPv6=1:n)
                               +--------+
                                   ^
                                   |
         Source IPv6 address  (IPv6 cloud)
        +--------------------------------------------------------------+
        | IPv4-Embedded IPv6 address                                   |
        | defined in Section 2.2 of RFC6052                            |
        +--------------------------------------------------------------+
         Destination IPv6 address
        +--------------------------------------------------------------+
        | IPv4-Embedded IPv6 address                                   |
        | defined in Section 2.2 of RFC6052                            |
        +--------------------------------------------------------------+
                              (IPv6 cloud)
                                   ^
                                   |
                               +--------+
                               |        | In the case CLAT does not have
                               |        | a dedicated IPv6 prefix for
                               |  CLAT  | translation, the CLAT can
                               |        | perform with NAT44 and
                               |        | Stateless XLATE
                               |        | (IPv4:IPv6=1:1).
                               +--------+
                                   ^       Source IPv4 address
                                   |      +----------------------------+
                               +--------+ | Private IPv4 address       |
                               |  IPv4  | | assigned to IPv4 client    |
                               | client | +----------------------------+
                               +--------+  Destination IPv4 address
                                          +----------------------------+
                                          | Global IPv4 address        |
                                          | assigned to IPv4 server    |
                                          +----------------------------+

            Case of enabling NAT44 and stateless XLATE on CLAT



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7.3.  IPv6 Prefix Handling

7.3.1.  Case of enabling only stateless XLATE on CLAT

   From the delegated DHCPv6 [RFC3633] prefix, a /64 is dedicated to
   source and receive IPv6 packets associated with the stateless
   translation [RFC6145].

   The CLAT MAY discover the Pref64::/n of the PLAT via some method such
   as DHCPv6 option, TR-069, DNS APL RR [RFC3123] or
   [I-D.ietf-behave-nat64-discovery-heuristic].

7.3.2.  Case of enabling NAT44 and stateless XLATE on CLAT

   In the case that DHCPv6-PD [RFC3633] is not available, the CLAT does
   not have dedicated IPv6 prefix for translation.  If the CLAT does not
   have a dedicated IPv6 prefix for translation, the CLAT can perform
   with NAT44 and stateless translation [RFC6145].

   Incoming source IPv4 packets from the LAN of [RFC1918] addresses are
   NAT44 to the CLAT IPv4 host address.  Then, the CLAT will do a
   stateless translation [RFC6145] so that the IPv4 packets from the
   CLAT IPv4 host address are translated to the CLAT WAN IPv6 address as
   described in [RFC6052].

   Its subnet prefix is made of the delegated prefix, completed if
   needed to a /64 by a subnet ID = 0.  Its interface ID is the 464XLAT
   interface ID (Section 10).

   The CLAT MAY discover the Pref64::/n of the PLAT via some method such
   as TR-069, DNS APL RR [RFC3123] or
   [I-D.ietf-behave-nat64-discovery-heuristic].



















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7.4.  Traffic Treatment Scenarios


        +--------+-------------+-----------------------+-------------+
        | Server | Application |   Traffic Treatment   | Location of |
        |        | and Host    |                       | Translation |
        +--------+-------------+-----------------------+-------------+
        |  IPv6  |    IPv6     |    End-to-end IPv6    |    None     |
        +--------+-------------+-----------------------+-------------+
        |  IPv4  |    IPv6     | Stateful Translation  |    PLAT     |
        +--------+-------------+-----------------------+-------------+
        |  IPv4  |    IPv4     |        464XLAT        |  PLAT/CLAT  |
        +--------+-------------+-----------------------+-------------+
        |  IPv6  |    IPv4     | Stateless Translation |    CLAT     |
        +--------+-------------+-----------------------+-------------+

                        Traffic Treatment Scenarios

   The above chart shows most common traffic types and traffic
   treatment.

7.5.  DNS Proxy Implementation

   The CLAT SHOULD implement a DNS proxy as defined in [RFC5625].  The
   case of an IPv4-only node behind CLAT querying an IPv4 DNS server is
   undesirable since it requires both stateful and stateless translation
   for each DNS lookup.  The CLAT SHOULD set itself as the DNS server
   via DHCP or other means and proxy DNS queries for IPv4 and IPv6
   clients.  Using the CLAT enabled home router or UE as a DNS proxy is
   a normal consume gateway function and simplifies the traffic flow so
   that only IPv6 native queries are made across the access network.
   The CLAT SHOULD allow for a client to query any DNS server of its
   choice and bypass the proxy.

7.6.  CLAT in a Gateway

   The CLAT is a stateless translation feature which can be implemented
   in a common home router or mobile phone that has a mobile router
   feature.  The router with CLAT function SHOULD provide common router
   services such as DHCP of [RFC1918] addresses, DHCPv6, and DNS
   service.  The router SHOULD set itself as the DNS server advertised
   via DHCP or other means to the clients so that it may implement the
   DNS proxy function to avoid double translation of DNS request.

7.7.  CLAT to CLAT communications

   While CLAT to CLAT IPv4 communication may work when the client IPv4
   subnets do not overlap, this traffic flow is out of scope. 464XLAT is



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   a hub and spoke architecture focused on enabling IPv4-only services
   over IPv6-only access networks.


8.  Deployment Considerations

   Even if the Internet access provider for consumers is different from
   the PLAT provider (e.g. another internet access provider), it can
   implement traffic engineering independently from the PLAT provider.
   Detailed reasons are below:

   1.  The Internet access provider for consumers can figure out IPv4
       destination address from translated IPv6 packet header, so it can
       implement traffic engineering based on IPv4 destination address
       (e.g. traffic monitoring for each IPv4 destination address,
       packet filtering for each IPv4 destination address, etc.).  The
       tunneling methods do not have such a advantage, without any deep
       packet inspection for processing the inner IPv4 packet of the
       tunnel packet.

   2.  If the Internet access provider for consumers can assign IPv6
       prefix greater than /64 for each subscriber, this 464XLAT
       architecture can separate IPv6 prefix for native IPv6 packets and
       XLAT prefix for IPv4/IPv6 translation packets.  Accordingly, it
       can identify the type of packets ("native IPv6 packets" and
       "IPv4/IPv6 translation packets"), and implement traffic
       engineering based on IPv6 prefix.

   This 464XLAT architecture has two capabilities.  One is a IPv4 ->
   IPv6 -> IPv4 translation for sharing global IPv4 addresses, another,
   if combined with BIH [RFC6535], is a IPv4 -> IPv6 translation for
   reaching IPv6-only servers from IPv4-only clients that can not
   support IPv6.  IPv4-only clients must be support through the long
   period of global transition to IPv6.


9.  Security Considerations

   To implement a PLAT, see security considerations presented in Section
   5 of [RFC6146].

   To implement a CLAT, see security considerations presented in Section
   7 of [RFC6145].  The CLAT MAY comply with [RFC6092].


10.  IANA Considerations

   IANA is requested to reserve a Modified EUI-64 identifier for 464XLAT



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   according to section 2.2.2 of [RFC5342].  Its suggested value is 02-
   00-5E-00-00-00-00-00 to 02-00-5E-0F-FF-FF-FF-FF or 02-00-5E-10-00-00-
   00-00 to 02-00-5E-EF-FF-FF-FF-FF, depending on whether it should be
   taken in reserved or available values.


11.  Acknowledgements

   The authors would like to thank JPIX NOC members, JPIX 464XLAT trial
   service members, Seiichi Kawamura, Dan Drown, Brian Carpenter, Rajiv
   Asati, Washam Fan, Behcet Sarikaya, Jan Zorz, Tatsuya Oishi, Lorenzo
   Colitti, Erik Kline, Ole Troan, Maoke Chen, Gang Chen, Tom Petch, and
   Jouni Korhonen for their helpful comments.  Special acknowledgments
   go to Remi Despres for his plentiful supports and suggestions,
   especially about using NAT44 with IANA's EUI-64 ID.  We also would
   like to thank Fred Baker and Joel Jaeggli for their support.


12.  References

12.1.  Normative References

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

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

   [RFC6144]  Baker, F., Li, X., Bao, C., and K. Yin, "Framework for
              IPv4/IPv6 Translation", RFC 6144, April 2011.

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

   [RFC6146]  Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful
              NAT64: Network Address and Protocol Translation from IPv6
              Clients to IPv4 Servers", RFC 6146, April 2011.

12.2.  Informative References

   [I-D.hazeyama-widecamp-ipv6-only-experience]
              Hazeyama, H., Hiromi, R., Ishihara, T., and O. Nakamura,
              "Experiences from IPv6-Only Networks with Transition
              Technologies in the WIDE Camp Spring 2012",
              draft-hazeyama-widecamp-ipv6-only-experience-01 (work in
              progress), March 2012.




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   [I-D.ietf-behave-nat64-discovery-heuristic]
              Savolainen, T., Korhonen, J., and D. Wing, "Discovery of
              IPv6 Prefix Used for IPv6 Address Synthesis",
              draft-ietf-behave-nat64-discovery-heuristic-10 (work in
              progress), June 2012.

   [RFC1918]  Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and
              E. Lear, "Address Allocation for Private Internets",
              BCP 5, RFC 1918, February 1996.

   [RFC3123]  Koch, P., "A DNS RR Type for Lists of Address Prefixes
              (APL RR)", RFC 3123, June 2001.

   [RFC3633]  Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic
              Host Configuration Protocol (DHCP) version 6", RFC 3633,
              December 2003.

   [RFC5342]  Eastlake, D., "IANA Considerations and IETF Protocol Usage
              for IEEE 802 Parameters", BCP 141, RFC 5342,
              September 2008.

   [RFC5625]  Bellis, R., "DNS Proxy Implementation Guidelines",
              BCP 152, RFC 5625, August 2009.

   [RFC6092]  Woodyatt, J., "Recommended Simple Security Capabilities in
              Customer Premises Equipment (CPE) for Providing
              Residential IPv6 Internet Service", RFC 6092,
              January 2011.

   [RFC6147]  Bagnulo, M., Sullivan, A., Matthews, P., and I. van
              Beijnum, "DNS64: DNS Extensions for Network Address
              Translation from IPv6 Clients to IPv4 Servers", RFC 6147,
              April 2011.

   [RFC6459]  Korhonen, J., Soininen, J., Patil, B., Savolainen, T.,
              Bajko, G., and K. Iisakkila, "IPv6 in 3rd Generation
              Partnership Project (3GPP) Evolved Packet System (EPS)",
              RFC 6459, January 2012.

   [RFC6535]  Huang, B., Deng, H., and T. Savolainen, "Dual-Stack Hosts
              Using "Bump-in-the-Host" (BIH)", RFC 6535, February 2012.

   [TS.23203] 3GPP, "Policy and charging control architecture", 3GPP
              TS 23.203 10.7.0, June 2012.







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Appendix A.  Examples of IPv4/IPv6 Address Translation

   The following are examples of IPv4/IPv6 Address Translation on the
   464XLAT architecture.

   Example 1.  (Case of enabling only stateless XLATE on CLAT)

   In the case that IPv6 prefix greater than /64 is assigned to end
   users by such as DHCPv6-PD [RFC3633], only the function of Stateless
   XLATE should be enabled on CLAT.  Because the CLAT can use dedicated
   a /64 from the assigned IPv6 prefix for Stateless XLATE.








































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      Host & configuration value
   +------------------------------+
   |           IPv4 server        |
   |         [198.51.100.1]       |            IP packet header
   +------------------------------+   +--------------------------------+
                   ^                  | Source IP address              |
                   |                  | [192.0.2.1]                    |
                   |                  | Destination IP address         |
                   |                  | [198.51.100.1]                 |
   +------------------------------+   +--------------------------------+
   |              PLAT            |                   ^
   | IPv4 pool address            |                   |
   | [192.0.2.1 - 192.0.2.100]    |                   |
   | PLAT-side XLATE IPv6 prefix  |                   |
   | [2001:db8:1234::/96]         |                   |
   +------------------------------+   +--------------------------------+
                   ^                  | Source IP address              |
                   |                  | [2001:db8:aaaa::192.168.1.2]   |
                   |                  | Destination IP address         |
                   |                  | [2001:db8:1234::198.51.100.1]  |
   +------------------------------+   +--------------------------------+
   |              CLAT            |                   ^
   | PLAT-side XLATE IPv6 prefix  |                   |
   | [2001:db8:1234::/96]         |                   |
   | CLAT-side XLATE IPv6 prefix  |                   |
   | [2001:db8:aaaa::/96]         |                   |
   +------------------------------+   +--------------------------------+
                   ^                  | Source IP address              |
                   |                  | [192.168.1.2]                  |
                   |                  | Destination IP address         |
                   |                  | [198.51.100.1]                 |
   +------------------------------+   +--------------------------------+
   |          IPv4 client         |
   |        [192.168.1.2/24]      |
   +------------------------------+
   Delegated IPv6 prefix for client: 2001:db8:aaaa::/56





   Example 2.  (Case of enabling NAT44 and stateless XLATE on CLAT)

   In the case that IPv6 prefix /64 is assigned to end users, the
   function of NAT44 and Stateless XLATE should be enabled on CLAT.
   Because the CLAT does not have dedicated IPv6 prefix for translation.





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      Host & configuration value
   +-------------------------------+
   |           IPv4 server         |
   |         [198.51.100.1]        |            IP packet header
   +-------------------------------+   +-------------------------------+
                   ^                   | Source IP address             |
                   |                   | [192.0.2.1]                   |
                   |                   | Destination IP address        |
                   |                   | [198.51.100.1]                |
   +-------------------------------+   +-------------------------------+
   |              PLAT             |                  ^
   | IPv4 pool address             |                  |
   | [192.0.2.1 - 192.0.2.100]     |                  |
   | PLAT-side XLATE IPv6 prefix   |                  |
   | [2001:db8:1234::/96]          |                  |
   +-------------------------------+   +-------------------------------+
                   ^                   | Source IP address             |
                   |                   | [2001:db8:aaaa:200:5e10:0:0]  |
                   |                   | Destination IP address        |
                   |                   | [2001:db8:1234::198.51.100.1] |
   +-------------------------------+   +-------------------------------+
   | CLAT Stateless XLATE function |                  ^
   | - - - - - - - - - - - - - - - |                  |
   | PLAT-side XLATE IPv6 prefix   |                  |
   | [2001:db8:1234::/96]          |                  |
   | CLAT-side XLATE IPv6 prefix   |                  |
   | [2001:db8:aaaa::/64]          |                  |
   | CLAT-side XLATE IPv6 EUI-64 ID|                  |
   | [02-00-5E-10-00-00-00-00]     |                  |
   + - - - - - - - - - - - - - - - +   +-------------------------------+
   |               ^               |   | Source IP address             |
   |               |               |   | [10.255.255.1]                |
   |               |               |   | Destination IP address        |
   |               |               |   | [198.51.100.1]                |
   + - - - - - - - - - - - - - - - +   +-------------------------------+
   | CLAT NAT44 function           |                  ^
   | - - - - - - - - - - - - - - - |                  |
   | NAT44 NATed address           |                  |
   | [10.255.255.1/32]             |                  |
   +-------------------------------+   +-------------------------------+
                   ^                   | Source IP address             |
                   |                   | [192.168.1.2]                 |
                   |                   | Destination IP address        |
                   |                   | [198.51.100.1]                |
   +-------------------------------+   +-------------------------------+
   |          IPv4 client          |
   |        [192.168.1.2/24]       |
   +-------------------------------+



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   Delegated IPv6 prefix for client: 2001:db8:aaaa::/64


Authors' Addresses

   Masataka Mawatari
   Japan Internet Exchange Co.,Ltd.
   KDDI Otemachi Building 19F, 1-8-1 Otemachi,
   Chiyoda-ku, Tokyo  100-0004
   JAPAN

   Phone: +81 3 3243 9579
   Email: mawatari@jpix.ad.jp


   Masanobu Kawashima
   NEC AccessTechnica, Ltd.
   800, Shimomata
   Kakegawa-shi, Shizuoka  436-8501
   JAPAN

   Phone: +81 537 23 9655
   Email: kawashimam@vx.jp.nec.com


   Cameron Byrne
   T-Mobile USA
   Bellevue, Washington  98006
   USA

   Email: cameron.byrne@t-mobile.com




















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