Internet DRAFT - draft-sun-v4tov6

draft-sun-v4tov6






Network Working Group                                             C. Xie
Internet-Draft                                                    Q. Sun
Intended status: Standards Track                                   Q. He
Expires: April 24, 2014                                    China Telecom
                                                                 C. Zhou
                                                     Huawei Technologies
                                                                   X. Li
                                                                  C. Bao
                                                  CERNET Center/Tsinghua
                                                              University
                                                        October 21, 2013


   4to6: The Approach for IPv4-only users to access IPv6-only Content
                          draft-sun-v4tov6-00

Abstract

   Current approaches can not solve the scenario that the users from
   IPv4 Internet to access IPv6-only content.  When IPv6 content are
   becoming more and more popular, it is important to ensure that IPv6-
   only content can be reachable from legacy IPv4-only clients via some
   IPv4-only network.  This document proposes an approach for IPv4-only
   users to access IPv6-only content, and can also achieve address
   sharing in the server side.  It is designed to cover the Scenario 2
   in [RFC6144].

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 24, 2014.

Copyright Notice

   Copyright (c) 2013 IETF Trust and the persons identified as the
   document authors.  All rights reserved.



Xie, et al.              Expires April 24, 2014                 [Page 1]

Internet-Draft      IPv4 user to access IPv6 Content        October 2013


   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
   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.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 4
   3.  Overall solution architecture for IPv4 Internet to access
       IPv6 network  . . . . . . . . . . . . . . . . . . . . . . . . . 4
   4.  The Workflow of 4to6 Solution . . . . . . . . . . . . . . . . . 5
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 7
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 7
     7.1.  Normative References  . . . . . . . . . . . . . . . . . . . 7
     7.2.  Informative References  . . . . . . . . . . . . . . . . . . 8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . . 8



























Xie, et al.              Expires April 24, 2014                 [Page 2]

Internet-Draft      IPv4 user to access IPv6 Content        October 2013


1.  Introduction

   Currently, IPv4 addresses for servers are also facing address
   shortage problem.  When IPv4 addresses are becoming a more scarce
   resource, it will cost more for content providers to keep using so
   many IPv4 addresses as today.  Besides, the upcoming new
   applications, e.g. cloud computing, etc., are consuming more and more
   IPv4 addresses.  Therefore, it is better for content provider to
   upgrade to IPv6 directly.

   Scenario 2 in [RFC6144] is important for this use case.  Not only
   could servers move directly to IPv6 without trudging through a
   difficult transition period, but they could do so without risk of
   losing connectivity with the IPv4-only Internet.  In addition, when
   address sharing can be achieved, the content providers can further
   save money by requiring less IPv4 addresses and reduce the
   operational complexity by using IPv6 single-stack servers.  For Data
   Center Operators, they can offer service to more ICPs with limited
   IPv4 addresses.

   There are several requirements in the design:

      1.Considering IPv4 address has been a scarce resource, the amount
      of public IPv4 addresses consumed by the translator should be less
      than that the number of IPv6 servers in the IPv6 network.

      2.  It should not require extra modifications on the server-side
      and on the client-side, e.g. by using a dynamic port number in the
      server, implementing a TURN client, etc.

      3.  It should not require modification on existing DNS
      architecture.  Otherwise, it would be difficult to deploy in
      reality.

   Existing solutions have not solved this scenario well.  NAT-
   PT[RFC2766]can be used in this scenario, but it requires a tightly
   coupled DNS Application Level Gateway (ALG) in the translator, and
   have been deprecated by the IETF [RFC4966].  The stateless
   translation solution [RFC6219] can work too, but since each IPv6
   server will consume one IPv4 public address, it is not suitable to
   deploy in situation that operators are running out of IPv4 address.
   [RFC6156] can be used for IPv4 client to communicate with IPv6
   client.  But this requires the IPv4 client and IPv6 client to
   implement a TURN client.  Therefore, it is not suitable for
   C-S(Client-Server) and B-S (Browser-Server) mode.

   [I-D.rfvlb-behave-v6-content-for-v4-clients] can work for IPv4-only
   user to access IPv6 content.  But since it uses private IPv4 address



Xie, et al.              Expires April 24, 2014                 [Page 3]

Internet-Draft      IPv4 user to access IPv6 Content        October 2013


   to mapping the IPv6 server, it can only be used for IPv4 network to
   reach IPv6 network.

   This document is designed for IPv4 Internet to reach IPv6 network.
   It is not a new protocol, but just to make use of existing protocols
   and funtionalities.  It can achieve high IPv4 address sharing ratio
   for IPv6 servers, and there is no impact on the server/client and
   existing DNS architecture.


2.  Terminology

   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].

   Terminology defined in [RFC6144] is used extensively in this
   document.  Besides, this document uses the following terminologies:

   IPv6-converted addresses: IPv4 addresses used to represent IPv6 nodes
   in an IPv4 Internet.  They have an explicit mapping relationship to
   IPv6 addresses.

   IPv6-converted port: The port number used to distinguish the traffic
   destinated to different IPv6 servers from the same IPv4 client.

   NAT46: a stateful IPv4/IPv6 translation functionality.  It is
   consistent with IP/ICMP translation [RFC6145].


3.  Overall solution architecture for IPv4 Internet to access IPv6
    network

   The 4to6 solution is used for IPv4 clients in IPv4 Internet to reach
   IPv6 servers .  It is designed for HTTP applications specially.

   In order to achieve the translation initiated from the IPv4 side, two
   addresses need to be determined by NAT46 translator.  The first one
   is the IPv6-converted address of the IPv6 server, which is is
   selected from the IPv4 address pool configured in NAT46.  The second
   one is the IPv4-converted address for the IPv4 client, which can be
   synthetized using the stateless approach defined in [RFC6052].

   In HTTP, since the traffic can be redirected to a different service
   port, it is able to achieve address sharing for IPv6 servers by using
   distinctive port numbers (denoted as IPv6-converted port) in IPv4
   client's upstream traffic .  Therefore, one IPv4 address can support
   up to thousands of IPv6 servers in theory.



Xie, et al.              Expires April 24, 2014                 [Page 4]

Internet-Draft      IPv4 user to access IPv6 Content        October 2013


   The overall architecture of the 4to6 solution is depicted in the
   following figure.

                 -------     +--------------------+      ------
               //       \\   | +----------------+ |    //      \\
              /           \  | |Redirect Server | |   /          \
+---------+  |  The IPv4   | | +----------------+ |  |  The IPv6  |  +--------+
|  IPv4   |  |  Internet   | |                    |  |   Network  |  |  IPv6  |
| Client  |--+             +-|    +------------+  |--+            +--| Server |
+---------+  |             | |    |   NAT46    |  |  |            |  +--------+
              \           /  |    +------------+  |   \          /
               \\       //   +--------------------+    \\      //
                 -------                                 ------

       Figure 1: Overall solution for IPv4 Internet to IPv6 network

   It consists of several functionalities:

   1.  NAT46: This functionality is consistent with [RFC6145].  It keeps
   the binding table between the IPv6 server address, IPv6 service port,
   IPv6-converted address and IPv6-converted port.  When an IPv4 packet
   initiated from the IPv4 client arrives at the NAT46, NAT46 will
   extract the destination address and the destination port, lookup the
   binding table and then translate it to an IPv6 packet.  It will take
   similar action to the downstream packet from the IPv6 server.

   2.  Redirect Server: A redirect server is used to redirect traffic to
   a different IPv6-converted address and IPv6-converted port.  Since
   the A record for a given IPv6 server is always the IPv4 address of
   the redirect server, the first packet from the IPv4 client will be
   routed to the redirect server.  The redirect server will return IPv6-
   converted address and IPv6-converted port to the client by querying
   from the NAT46.

   In 4to6 solution, only the first TCP flow will be treated by the
   redirect server.  The subsequent traffic will be translated directly
   by the NAT46.


4.  The Workflow of 4to6 Solution

   The workflow of this apporach is as follows:









Xie, et al.              Expires April 24, 2014                 [Page 5]

Internet-Draft      IPv4 user to access IPv6 Content        October 2013


+--------+        +--------+        +--------+       +--------+        +--------+
| IPv4   |        |  DNS   |        |Redirect|       | NAT46  |        |  IPv6  |
| Client |        |        |        | Server |       |        |        | Server |
+--------+        +--------+        +--------+       +--------+        +--------+
    |                  |                 |               |                   |
    | DNS A request    |                 |               |                   |
    | ipv6.example.com |                 |               |                   |
    |----------------->|                 |               |                   |
    | A response with  |                 |               |                   |
    | Redirect Ser Addr|                 |               |                   |
    |<-----------------|                 |               |                   |
    | HTTP GET request, with domain name |               |                   |
    |   in HOST field                    |  Request for  |                   |
    |----------------------------------->| IPv4 Dst Addr | Setup mapping     |
    |                                    |-------------->|  table            |
    |return 302 not found, carry IPv4 dst|Return Add+Port|                   |
    |addr and port in the redirect packet|<--------------|                   |
    |<-----------------------------------|               |                   |
    |  IPv4 HTTP request with new v4 dst addr            |                   |
    |--------------------------------------------------->| Translate to IPv6 |
    |                                                    |------------------>|
    |                                                    |<------------------|
    |<---------------------------------------------------|                   |


                 Figure 2: Workflow of Proxy-lite Approach

   1.  An IPv4 client initiates a DNS query for A record (e.g.
   ipv6.example.com).

   2.  In DNS server, the address of the redirect server is configured
   as the A record for ipv6.example.com and returns to the IPv4 client.

   3.  The IPv4 client sends HTTP GET request.  The domain name (e.g.
   ipv6.example.com) is carried in HOST field.

   4.  The redirect server interprets the domain name, and sends the
   request to get IPv6-converted address to NAT46 (carrying the address
   of IPv4 client and the destination port).  The specific protocol for
   the request is now out of scope.

   5.  NAT46 selects IPv6-converted address and IPv6-converted port by
   lookuping the binding table.  It will also keep the destination port
   in the binding table.

   6.  NAT46 returns the IPv6-converted address and IPv6-converted port
   to redirect server and the redirect server in turn returns IPv6-
   converted address in HTTP redirect packet with HTTP error "302 not



Xie, et al.              Expires April 24, 2014                 [Page 6]

Internet-Draft      IPv4 user to access IPv6 Content        October 2013


   found".

   7.  IPv4 client replaces the destination IPv4 address with the
   returned IPv6-converted address.  The IPv4 traffic is routed to the
   NAT46.

   8.  NAT46 extracts the destination address and destination port in
   the IPv4 traffic.  It will lookup the binding table maintained in
   NAT46 and NAT46 translates the IPv4 packet to IPv6 packet according
   to [RFC6145].


5.  IANA Considerations

   No requirement on IANA.


6.  Acknowledgements

   The authors would like to thank Dan Wing, Fred Baker and Jari Arkko
   for their review and comments.


7.  References

7.1.  Normative References

   [I-D.rfvlb-behave-v6-content-for-v4-clients]
              Rajtar, B., Farrer, I., Ales, V., Li, X., and C. Bao,
              "Framework for accessing IPv6 content for IPv4-only
              clients", draft-rfvlb-behave-v6-content-for-v4-clients-01
              (work in progress), July 2013.

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

   [RFC2766]  Tsirtsis, G. and P. Srisuresh, "Network Address
              Translation - Protocol Translation (NAT-PT)", RFC 2766,
              February 2000.

   [RFC4966]  Aoun, C. and E. Davies, "Reasons to Move the Network
              Address Translator - Protocol Translator (NAT-PT) to
              Historic Status", RFC 4966, July 2007.

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




Xie, et al.              Expires April 24, 2014                 [Page 7]

Internet-Draft      IPv4 user to access IPv6 Content        October 2013


   [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.

   [RFC6156]  Camarillo, G., Novo, O., and S. Perreault, "Traversal
              Using Relays around NAT (TURN) Extension for IPv6",
              RFC 6156, April 2011.

   [RFC6219]  Li, X., Bao, C., Chen, M., Zhang, H., and J. Wu, "The
              China Education and Research Network (CERNET) IVI
              Translation Design and Deployment for the IPv4/IPv6
              Coexistence and Transition", RFC 6219, May 2011.

7.2.  Informative References


Authors' Addresses

   Chongfeng Xie
   China Telecom
   P.R.China

   Phone: 86 10 58552116
   Email: xiechf@ctbri.com.cn


   Qiong Sun
   China Telecom
   P.R.China

   Phone: 86 10 58552936
   Email: sunqiong@ctbri.com.cn


   Qi He
   China Telecom
   P.R.China

   Phone: 86 10 58552332
   Email: heqi@ctbri.com.cn





Xie, et al.              Expires April 24, 2014                 [Page 8]

Internet-Draft      IPv4 user to access IPv6 Content        October 2013


   Cathy Zhou
   Huawei Technologies
   Bantian, Longgang District
   Shenzhen  518129
   P.R. China

   Phone:
   Email: cathy.zhou@huawei.com


   Xing Li
   CERNET Center/Tsinghua University
   Room 225, Main Building
   Beijing  100084
   P.R.China

   Phone: +86 10 6278 5983
   Email: xing@cernet.edu.cn


   Congxiao Bao
   CERNET Center/Tsinghua University
   Room 225, Main Building
   Beijing  100084
   P.R.China

   Phone: +86 10 6278 5983
   Email: congxiao@cernet.edu.cn























Xie, et al.              Expires April 24, 2014                 [Page 9]