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Versions: 00 01 02                                                      
Internet Engineering Task Force                              M. Mawatari
Internet-Draft                          Japan Internet Exchange Co.,Ltd.
Intended status: Informational                              M. Kawashima
Expires: May 3, 2012                            NEC AccessTechnica, Ltd.
                                                                C. Byrne
                                                            T-Mobile USA
                                                        October 31, 2011


       464XLAT: Combination of Stateful and Stateless Translation
                   draft-mawatari-softwire-464xlat-02

Abstract

   This document describes a method (464XLAT) for IPv4 connectivity
   across IPv6 network by combination of stateful translation and
   stateless translation. 464XLAT is a simple technique to provide IPv4
   access service while avoiding encapsulation by using twice IPv4/IPv6
   translation standardized in [RFC6145] and [RFC6146].

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
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must



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   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.  Network Architecture . . . . . . . . . . . . . . . . . . . . .  4
     4.1.  Wireline Network Architecture  . . . . . . . . . . . . . .  4
     4.2.  Wireless 3GPP Network Architecture . . . . . . . . . . . .  5
   5.  Applicability  . . . . . . . . . . . . . . . . . . . . . . . .  5
     5.1.  Wireline Network Applicability . . . . . . . . . . . . . .  5
     5.2.  Wireless 3GPP Network Applicability  . . . . . . . . . . .  6
   6.  Implementation Considerations  . . . . . . . . . . . . . . . .  6
     6.1.  IPv6 Address Format  . . . . . . . . . . . . . . . . . . .  6
     6.2.  DNS Proxy Implementation . . . . . . . . . . . . . . . . .  7
     6.3.  IPv6 Fragment Header Consideration . . . . . . . . . . . .  7
     6.4.  Auto Prefix Assignment . . . . . . . . . . . . . . . . . .  7
   7.  Deployment Considerations  . . . . . . . . . . . . . . . . . .  7
   8.  Security Considerations  . . . . . . . . . . . . . . . . . . .  8
   9.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  8
   10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . .  8
   11. References . . . . . . . . . . . . . . . . . . . . . . . . . .  9
     11.1. Normative References . . . . . . . . . . . . . . . . . . .  9
     11.2. Informative References . . . . . . . . . . . . . . . . . .  9
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10






















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1.  Introduction

   The IANA unallocated IPv4 address pool was exhasuted on February 3,
   2011.  It is likely that each RIR's unallocated IPv4 address pool
   will exhaust in the near future.  In this situation, it will be
   difficult for many networks to assign IPv4 address to end users
   despite substantial IPv4 connectivity required for mobile devices,
   smart-grid, and cloud nodes.

   This document describes an IPv4 over IPv6 solution as one of the
   measures of IPv4 address extension and encouragement of IPv6
   deployment.

   The 464XLAT method described in this document uses twice IPv4/IPv6
   translation standardized in [RFC6145] and [RFC6146].  It does not
   require DNS64 [RFC6147], but it may use DNS64.  It is also possible
   to provide single IPv4/IPv6 translation service, which will be needed
   in the near future.  This feature is one of the advantages, because
   it can be an encouragement to gradually transition to IPv6.


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

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

   CLAT:   CLAT is Customer side translator(XLAT).  A stateless
           translator complies with [RFC6145] that performs 1:1
           translation.  It algorithmically translates private IPv4
           address to global IPv6 address, and vice versa.  It has also
           IPv6 router function that can forward IPv6 packet for IPv6
           hosts in end-user network.  Furthermore, it has DNS Proxy
           function with IPv6 transport that provides name resolution
           for IPv4 hosts and IPv6 hosts in end-user network.  The
           presence of DNS64 [RFC6147] and any port mapping algorithm
           are not required.






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4.  Network Architecture

   464XLAT method is shown in the following figure.

4.1.  Wireline Network Architecture


                                  ----
                                 | 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





















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4.2.  Wireless 3GPP Network Architecture


                                   ----
                                  | 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


5.  Applicability

5.1.  Wireline Network Applicability

   When ISP has IPv6 access network infrastructure and 464XLAT, ISP can
   provide IPv4 service to end users.

   If the IXP or another provider operates the PLAT, all ISPs have to do
   is to deploy IPv6 access network.  All ISPs do not need IPv4
   facilities.  They can migrate quickly their operation to an IPv6-only
   environment.  Incidentally, Japan Internet Exchange(JPIX) is
   providing 464XLAT trial service since July 2010.




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5.2.  Wireless 3GPP Network Applicability

   In pre-release 9 3GPP networks, GSM and UMTS networks must signal and
   support both IPv4 and IPv6 PDP attachments to access IPv4 and IPv6
   network destinations.  This is generally not operationally viable
   since much of the network cost is derived from the number of PDP
   attachments, both in terms of licenses from the network hardware
   vendors and in terms of actual hardware resources required to support
   and maintain the PDP signaling and mobility events.  This has been
   one of the operational challenges of bringing IPv6 to mobile
   networks, it simply costs more from the network provider perspective
   and does not result in any new revenues, since customers are not
   willing to pay for IPv6 access.

   Now that both global and private IPv4 addresses are scarce to the
   extent that it is a substantial business risk and limiting growth in
   many areas, the mobile network providers must support IPv6 address
   which solve the IP address scarcity issue, but it is not feasible to
   simply turn on additional IPv6 PDP network attachments since that
   does not solve the near-term IPv4 scarcity issues and at it also
   increases cost.  The most logical path forward is to replace IPv6
   with IPv4 and replace the common NAT44 with NAT64 and DNS64.
   Extensive live network testing with hundreds of friendly-users has
   shown that IPv6-only network attachments for mobile devices covers
   over 90% of the common use-cases in Symbian and Android mobile
   operating systems.  The remaining 10% of use-cases do not work
   because the application requires an IPv4 socket or the application
   references an IPv4-literal.

   464XLAT in combination with NAT64 and DNS64 allows 90% of the
   applications to continue to work with single translation while at the
   sametime facilitating legacy IPv4-only applications by providing a
   private IPv4 address and IPv4 route on the host for the applications
   to reference and bind to.  Traffic sourced from the IPv4 interface is
   immediately routed the NAT46 CLAT function and passed to the IPv6-
   only mobile network and destine to the PLAT NAT64.


6.  Implementation Considerations

6.1.  IPv6 Address Format

   IPv6 address format in 464XLAT is presented in the following format.








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       +-----------------------------------------------+---------------+
       |              XLAT prefix(96)                  |    IPv4(32)   |
       +-----------------------------------------------+---------------+

                      IPv6 Address Format for 464XLAT

   Source address and destination address have IPv4 address embedded in
   the low-order 32 bits of the IPv6 address.  The format is defined in
   Section 2.2 of [RFC6052].  However, 464XLAT does not use the Well-
   Known Prefix "64:ff9b::/96".

6.2.  DNS Proxy Implementation

   CLAT perform DNS Proxy for IPv4 hosts and IPv6 hosts in end-user
   network.  It MUST provide name resolution with IPv6 transport.  It
   does not need DNS64 [RFC6147] function.

6.3.  IPv6 Fragment Header Consideration

   In the 464XLAT environment, the PLAT and CLAT SHOULD include an IPv6
   Fragment Header, since IPv4 host does not set the DF bit.  However,
   the IPv6 Fragment Header has been shown to cause operational
   difficulties in practice due to limited firewall fragmentation
   support, etc.  Therefore, the PLAT and CLAT may provide a
   configuration function that allows the PLAT and CLAT not to include
   the Fragment Header for the non-fragmented IPv6 packets.  At any
   rate, both behaviors SHOULD match.

6.4.  Auto Prefix Assignment

   Source IPv6 prefix assignment in CLAT is via DHCPv6 prefix delegation
   or another method.  Destination IPv6 prefix assignment in CLAT is via
   some method. (e.g., DHCPv6 option, TR-069, DNS, HTTP,
   [I-D.ietf-behave-nat64-discovery-heuristic], etc.)


7.  Deployment Considerations

   Even if the Internet access provider for consumers is different from
   the PLAT provider (another Internet access provider or Internet
   exchange provider, etc.), 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
       source address and IPv4 destination address from translated IPv6
       packet header, so it can implement traffic engineering based on
       IPv4 source address and IPv4 destination address (e.g. traffic
       monitoring for each IPv4 destination address, packet filtering



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       for each IPv4 destination address, etc.).  The Tunneling methods
       do not have such a advantage, without any deep packet inspection
       for visualizing 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 method
       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 method have two capabilities.  One is a IPv6 -> IPv4 ->
   IPv6 translation for sharing global IPv4 addresses, another is a IPv4
   -> IPv6 translation for reaching IPv6 only servers from IPv4 only
   clients that can not support IPv6.  IPv4 only clients will remain for
   a while.


8.  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].  And furthermore, the CLAT SHOULD perform Bogon
   filter, and SHOULD have IPv6 firewall function as a IPv6 router.  It
   is useful function for native IPv6 packet and translated IPv6 packet.
   The CLAT SHOULD check IPv6 packet received from WAN interface.  If
   the packet is invalid prefix (i.e., it is not XLAT prefix), then
   SHOULD silently drop the packet.  In addition, the CLAT SHOULD check
   IPv4 packet after the translation.  If the packet is not match
   private IPv4 address of LAN, then SHOULD silently drop the packet.


9.  IANA Considerations

   This document has no actions for IANA.


10.  Acknowledgements

   The authors would like to thank JPIX NOC members and Seiichi Kawamura
   for their helpful comments.


11.  References




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11.1.  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.

11.2.  Informative References

   [I-D.ietf-behave-nat64-discovery-heuristic]
              Savolainen, T. and J. Korhonen, "Discovery of a Network-
              Specific NAT64 Prefix using a Well-Known Name",
              draft-ietf-behave-nat64-discovery-heuristic-03 (work in
              progress), October 2011.

   [I-D.ietf-v6ops-3gpp-eps]
              Korhonen, J., Soininen, J., Patil, B., Savolainen, T.,
              Bajko, G., and K. Iisakkila, "IPv6 in 3GPP Evolved Packet
              System", draft-ietf-v6ops-3gpp-eps-08 (work in progress),
              September 2011.

   [I-D.murakami-softwire-4v6-translation]
              Murakami, T., Chen, G., Deng, H., Dec, W., and S.
              Matsushima, "4via6 Stateless Translation",
              draft-murakami-softwire-4v6-translation-00 (work in
              progress), July 2011.

   [I-D.xli-behave-divi]
              Bao, C., Li, X., Zhai, Y., and W. Shang, "dIVI: Dual-
              Stateless IPv4/IPv6 Translation", draft-xli-behave-divi-04
              (work in progress), October 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.



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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  98105
   USA

   Email: cameron.byrne@t-mobile.com























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