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Network Working Group                                       N. Matsuhira
Internet-Draft                                           Fujitsu Limited
Intended status: Experimental                             April 19, 2011
Expires: October 21, 2011


 Stateless Automatic IPv4 over IPv6 Tunneling with IPv4 Address Sharing
                      draft-matsuhira-sa46t-as-01

Abstract

   This document specifies Stateless Automatic IPv4 over IPv6 Tunneling
   with IPv4 Address Sharing (SA46T-AS) base specification.  SA46T-AS is
   basically the same technology with SA46T, however that have IPv4
   address sharing capability.  SA46T-SA is gateway technology, not
   protocol.

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].

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 October 21, 2011.

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



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   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.  Architecture of SA46T-AS  . . . . . . . . . . . . . . . . . . . 3
   3.  SA46T-AS address format . . . . . . . . . . . . . . . . . . . . 5
   4.  Using SA46T-AS in client server environments  . . . . . . . . . 5
     4.1.  Client environments . . . . . . . . . . . . . . . . . . . . 5
     4.2.  Server environments . . . . . . . . . . . . . . . . . . . . 6
   5.  Port Number Issue . . . . . . . . . . . . . . . . . . . . . . . 7
   6.  Characteristic  . . . . . . . . . . . . . . . . . . . . . . . . 7
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 8
   8.  Security Considerations . . . . . . . . . . . . . . . . . . . . 8
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 8
     9.1.  Normative References  . . . . . . . . . . . . . . . . . . . 8
     9.2.  References  . . . . . . . . . . . . . . . . . . . . . . . . 8
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . . . 9



























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1.  Introduction

   This document provides Stateless Automatic IPv4 over IPv6 Tunneling
   with IPv4 Address Sharing (SA46T-AS) base specification.

   SA46T-AS is basically the same technology with SA46T
   [I-D.draft-matsuhira-sa46t-spec] , however that have IPv4 address
   sharing capability.

   The basic architecture of the SA46T-AS is the same with SA46T, so
   SA46T-AS can provide all of SA46T function, such as making bachbone
   network IPv6 only , or provide many IPv4 network planes over single
   IPv6 backbone network.

   SA46T-AS add IPv4 address sharing function to SA46T. So, SA46T-AS
   enable many host to share single IPv4 global address.

   SA46T is gateway technology, not protocol.


2.  Architecture of SA46T-AS

   Figure 1 shows SA46T address architecture.  SA46T map IPv4 address to
   SA46T address keeping locator - identifier relation.  The n bits
   identifier part of IPv4 address and n bits identifier part of IPv6
   address is the same value, and the 32-n bits locator part in IPv4
   address and 128 - n bits locator part in IPv6 address is the same
   meaning.  So, the meaning of routing information is the same between
   IPv4 space and IPv6 space.






















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    |<------------------------ 128 bits ----------------------------->|
    |<-------------------- 96 bits ------------------->|<-- 32 bits ->|
    |                                                          :      |
    |                                                  +-------:------+
    |                                                  | IPv4 address |
    |                                                  +-------:------+
    |                                                  |<-Loc->:<-ID->|
    |                                                  | 32-n  :  n   |
    |                                                  | bits  : bits |
    |                                                  |       :      |
    |                                                  |       :      |
    |                                                  |       :      |
    |  96 - m bits          |          m bits          |     32 bits  |
    +-----------------------+--------------------------+-------:------+
    | SA46T address prefix  |  IPv4 network plane ID   | IPv4 address |
    +-----------------------+--------------------------+-------:------+
    |<------------- Locator (128 - n bits ) ------------------>:<-ID->|
    |                                                          :  n   |
    |                                                          : bits |

                                 Figure 1

   Figure 2 shows SA46T-AS address architecture.  SA46T-AS address
   consists four parts, SA46T-AS prefix, IPv4 network plane ID, IPv4
   address, and Port number.  That mean SA46T-AS address consists SA46T
   address and port number.


|                      |                |                |         |
|    80 - m bits       |   m bits       |    32 bits     | 16 bits |
+----------------------+----------------+----------------+----:----+
|  SA46T-AS prefix     | IPv4 network   |  IPv4 address  |  port   |
|                      | plane ID       |                | number  |
+----------------------+----------------+----------------+----:----+
|<--------------- Locator (128 -n bits  )-------------------->:<-->|
|                                                             : ID |
|                                                             : (n bits)


                                 Figure 2

   In SA46T, boundary of locator and identifier is in IPv4 address part,
   however in SA46T-AS, boundary of locator and identifier is in port
   number part, that mean, SA46T-AS use upper part of port number as
   locator, and lower part of port number as identifier.






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3.  SA46T-AS address format

   Figure 3 show a example of SA46T-AS address format.  In this example,
   16bits IPv4 network plane ID is used, that provide 65535 IPv4 network
   plane.



  | 3 |        45bits       |  16bits |  16 bits|   32bits   | 16 bits |
  +---+---------------------+---------+---------+------------+---------+
  |001|Global routing prefix|subnet id| plane ID|IPv4 address| Port #  |
  +---+---------------------+---------+----------------------+---------+
  <---SA46T address prefix----------->


                                 Figure 3


4.  Using SA46T-AS in client server environments

4.1.  Client environments

   Figure 4 shows a example of SA46T-AS usage in client environments.
   In this document, NAPT is IPv4 - IPv4 Netowrk address and port number
   translator.  Coopetation with NAPT, SA46T-AS provide IPv4 address
   sharing with different users.

























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    +--------------+
    |              |    +---------+  +--------+     +---------+
    |              +----|SA46T-AS |--|  NAPT  |--+--| Clients |
    |              |    +---------+  +--------+  |  +---------+
    |              |                             |  +---------+
    |              |                             +--| Clients |
    | Backbone     |                             |  +---------+
    |              |                             :
    |              |                             |  +---------+
    |   Network    |                             +--| Clients |
    |              |                                +---------+
    |              |
    |              |    +---------+  +--------+     +---------+
    |              +----|SA46T-AS |--|  NAPT  |--+--| Clients |
    |              |    +---------+  +--------+  |  +---------+
    |              |                             |  +---------+
    |              |                             +--| Clients |
    |              |                             |  +---------+
    |              |                             :
    |              |                             |  +---------+
    |              |                             +--| Clients |
    |              |                                +---------+
    :              :        :             :              :
    |              |    +---------+  +--------+     +---------+
    |              +----|SA46T-AS |--|  NAPT  |--+--| Clients |
    |              |    +---------+  +--------+  |  +---------+
    |              |                             |  +---------+
    |              |                             +--| Clients |
    |              |                             |  +---------+
    |              |                             :
    |              |                             |  +---------+
    |              |                             +--| Clients |
    |              |                                +---------+
    +--------------+


                                 Figure 4

4.2.  Server environments

   Figure 5 shows an example of SA46T-AS usage in server environments.
   In this example, server terminate SA46T-AS tunnel.  This case, Server
   require at least one port number per server, that mean, 128bits host
   route advertise for server access via IPv4.  This case, full access
   is provided via IPv6.






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    +--------------+
    |              |    +------------+
    |              +----|Server with |
    |              |    |SA46T-AS    |
    | Backbone     |    |function    |
    |              |    +------------+
    |              |    +------------+
    |  Network     +----|Server with |
    |              |    |SA46T-AS    |
    |              |    |function    |
    |              |    +------------+
    :              :           :
    |              |    +------------+
    |              +----|Server with |
    |              |    |SA46T-AS    |
    |              |    |function    |
    |              |    +------------+
    +--------------+


                                 Figure 5


5.  Port Number Issue

   SA46T-AS require port number of transport layer.  SA46T-AS can not
   support ICMPv4 [RFC0792].  The function provided by ICMPv4 does not
   work in SA46T-AS environments, such as Path MTU Discovery [RFC1191],
   ping command, etc.


6.  Characteristic

   SA46T has following useful characteristics.

   o  Reduce backbone network operation cost with IPv6 single stack ( at
      least less than Dual Stack)

   o  Can allocate IPv4 address to stub networks, which used in backbone
      network before installing SA46T

   o  Less configuration

   o  No need for special protocol

   o  No dependent Layer 2 network





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   o  Can Stack IPv4 Private networks

   o  Easy stop IPv4 operation in stub network for future ( just remove
      SA46T)

   o  Provide redundancy

   Moreover, SA46T-AS add following characteristsics to SA46T.

   o  Provide IPv4 address sharig function


7.  IANA Considerations

   This document makes no request of IANA.

   Note to RFC Editor: this section may be removed on publication as an
   RFC.


8.  Security Considerations

   SA46T-AS use automatic tunneling technologies.  Security
   consideration related tunneling technologies are discussed in RFC2893
   [RFC2893], RFC2267 [RFC2267], etc.


9.  References

9.1.  Normative References

   [I-D.draft-matsuhira-sa46t-spec]
              Matsuhira, N., "Stateless Automatic IPv4 over IPv6
              Tunneling: Specification".

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

9.2.  References

   [RFC0792]  Postel, J., "Internet Control Message Protocol", STD 5,
              RFC 792, September 1981.

   [RFC1191]  Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191,
              November 1990.

   [RFC2267]  Ferguson, P. and D. Senie, "Network Ingress Filtering:
              Defeating Denial of Service Attacks which employ IP Source



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              Address Spoofing", RFC 2267, January 1998.

   [RFC2893]  Gilligan, R. and E. Nordmark, "Transition Mechanisms for
              IPv6 Hosts and Routers", RFC 2893, August 2000.


Author's Address

   Naoki Matsuhira
   Fujitsu Limited
   17-25, Shinkamata 1-chome, Ota-ku
   Tokyo,   144-8588
   Japan

   Phone: +81-3-6424-6270
   Fax:
   Email: matsuhira@jp.fujitsu.com


































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