Network Working Group                                       N. Matsuhira
Internet-Draft                                           Fujitsu Limited
Intended status: Informational                          February 1, 2010
Expires: August 5, 2010


      Stateless Automatic IPv4 over IPv6 Tunneling: Specification
                     draft-matsuhira-sa46t-spec-00

Abstract

   This document specifies Stateless Automatic IPv4 over IPv6 Tunneling
   (SA46T) base specification.  SA46T makes backbone network to IPv6
   only.  And also, SA46T can stack many IPv4 networks, i.e. the
   networks using same IPv4 (private) addresses, without
   interdependence.  SA46T 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 to IETF in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
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   Drafts.

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   This Internet-Draft will expire on August 5, 2010.

Copyright Notice




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   Copyright (c) 2010 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
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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 BSD License.


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Basic Network Configuration  . . . . . . . . . . . . . . . . .  3
   3.  Basic Function of SA46T  . . . . . . . . . . . . . . . . . . .  4
     3.1.  IPv4 over IPv6 Tunneling . . . . . . . . . . . . . . . . .  4
     3.2.  SA46T address architecture . . . . . . . . . . . . . . . .  5
     3.3.  Route Advertisement  . . . . . . . . . . . . . . . . . . .  6
   4.  SA46T address format . . . . . . . . . . . . . . . . . . . . .  7
     4.1.  Unique Local IPv6 Unicast Address as SA46T address . . . .  7
     4.2.  IPv6 Global Unicast Address as SA46T address . . . . . . .  8
     4.3.  Global SA46T address format  . . . . . . . . . . . . . . .  9
   5.  Stacking IPv4 Networks . . . . . . . . . . . . . . . . . . . . 10
   6.  Redundancy of SA46T  . . . . . . . . . . . . . . . . . . . . . 11
   7.  Example of SA46T Operation . . . . . . . . . . . . . . . . . . 12
     7.1.  Basic SA46T Operation  . . . . . . . . . . . . . . . . . . 12
     7.2.  SA46T Operation with plane ID  . . . . . . . . . . . . . . 13
   8.  Characteristic . . . . . . . . . . . . . . . . . . . . . . . . 16
   9.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 16
   10. Security Considerations  . . . . . . . . . . . . . . . . . . . 16
   11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 16
   12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 17
     12.1. Normative References . . . . . . . . . . . . . . . . . . . 17
     12.2. Informative References . . . . . . . . . . . . . . . . . . 17
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 17












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1.  Introduction

   This document provides Stateless Automatic IPv4 over IPv6 Tunneling
   (SA46T) base specification.

   The basic strategy for IPv6 deployment is dual stack.  Viewing this
   strategy from operational side, operation cost of dual stack is
   higher than single stack operation.  Viewing from future, IPv6 only
   operation is more reasonable rather than IPv4 only operation.
   Therefore IPv6 only operation is desired.

   SA46T makes backbone network to IPv6 only.  And also, SA46T can stack
   many IPv4 networks, i.e. the networks using same IPv4 (private)
   address, without interdependence.

   SA46T is gateway technology, not protocol.


2.  Basic Network Configuration

   Figure 1 shows network configuration with SA46T. The network consists
   of three parts.  Backbone network, stub network, and SA46T.

   Backbone network is operated with IPv6 only.  Stub network has three
   cases.  IPv4 only, Dual Stack (both IPv4 and IPv6), and IPv6 only.

   SA46T connects backbone network and stub network in case IPv4 still
   works in that stub network.  If stub network is IPv6 only, SA46T is
   not needed.

   Campus network, corporate network, and ISP network are the example
   for such network.



















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    /---------------------------------------------------\
    |                                                   |
    |                  Backbone Network                 |
    |                    (IPv6 only)                    |
    |                                                   |
    \---------------------------------------------------/
          |                    |                |
      +-------+            +-------+            |
      | SA46T |            | SA46T |            |
      +-------+            +-------+            |
          |                    |                |
    /--------------\   /--------------\   /--------------\
    |              |   |              |   |              |
    | Stub Network |   | Stub Network |   | Stub Network |
    | (IPv4 only)  |   | (Dual Stack) |   | (IPv6 only)  |
    |              |   |              |   |              |
    \--------------/   \--------------/   \--------------/

                                 Figure 1


3.  Basic Function of SA46T

   SA46T has mainly two function.  One is IPv4 over IPv6 Tunneling, and
   another is advertise route for stub network.

3.1.  IPv4 over IPv6 Tunneling

   SA46T encapsulates IPv4 packet to IPv6 from stub network to backbone
   network, and decapsulates IPv6 packet to IPv4 from backbone network
   to stub network.  Figure 2 shows such movement.


     +---------+-------+       +---------+------+------+
     | data    | IPv4  |  -->  | data    | IPv4 | IPv6 |
     +---------+-------+       +---------+------+------+

     +---------+-------+       +---------+------+------+
     | IPv4    | data  |  <--  | IPv6    | IPv4 | data |
     +---------+-------+       +---------+------+------+


    /--------------\  +-------+  /-----------------\
    | Stub Network |--| SA46T |--| Backbone Network |
    | (IPv4)       |  +-------+  | (IPv6 only       |
    \--------------/             \------------------/

                                 Figure 2



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   SA46T MUST support tunnel MTU discovery[RFC1853].  When encapsulated
   IPv6 Packet size exceed path MTU and inner IPv4 packet have the Don't
   Fragment bit is set, SA46T MUST return ICMP Destination unreachable
   message with Type3 Code4, fragmentation needed and DF set[RFC0792].

   In case IPv6, SA46T just relays IPv6 packet.


     +---------+-------+       +---------+------+
     | data    | IPv6  |  -->  | data    | IPv6 |
     +---------+-------+       +---------+------+

     +---------+-------+       +---------+------+
     | IPv6    | data  |  <--  | IPv6    | data |
     +---------+-------+       +---------+------+


    /--------------\  +-------+  /-----------------\
    | Stub Network |--| SA46T |--| Backbone Network |
    | (IPv6)       |  +-------+  | (IPv6 only       |
    \--------------/             \------------------/

                                 Figure 3

   By IPv4 over IPv6 function, SA46T make backbone network to IPv6 only.

3.2.  SA46T address architecture

   SA46T address is a IPv6 address used in outer IPv6 header which
   encapsulate IPv4 packet by SA46T.

   Figure 4 shows SA46T address architecture


    |  96 - m bits          |          m bits          |     32 bits  |
    +-----------------------+--------------------------+--------------+
    | SA46T address prefix  |  IPv4 network plane ID   | IPv4 address |
    +-----------------------+--------------------------+--------------+

                                 Figure 4

   SA46T address consists of three parts as follows.

   SA46T address prefix

      SA46T address prefix indicates this packet is encapsulated by
      SA46T and MUST be encapsulated by SA46T. This value is
      preconfigured to all SA46T in the networks.



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   IPv4 network plane ID

      IPv4 network plane ID is an identifier of IPv4 network stack over
      IPv6 backbone network.  This value is preconfigured depend on the
      SA46T belong which IPv4 network plane.  For more detail see
      section 5.

   IPv4 address

      IPv4 address in inner IPv4 packet.

   SA46T address is resolved copying IPv4 address in inner IPv4 packet,
   and preconfigured values, SA46T prefix and IPv4 network plane ID.

   Table 1 shows SA46T IPv4 network plane ID length (m) and number of
   plane.

                       +----+----------------------+
                       | m  | # of plane           |
                       +----+----------------------+
                       | 16 | 65536                |
                       | 32 | 4294967296           |
                       | 64 | 18446744073709551616 |
                       +----+----------------------+

                                  Table 1

3.3.  Route Advertisement

   SA46T converts stub network's IPv4 route to SA46T IPv6 route and
   advertises to backbone network.  And reverse direction, SA46T
   converts SA46T IPv6 route to IPv4 route, that advertises other IPv4
   stub networks.

   If IPv4 stub network's prefix length is n, the prefix length of SA46T
   IPv6 route which converts from that IPv4 prefix is 128 - 32 + n.
   Table 2 shows detail value.

             +--------------------+--------------------------+
             | IPv4 prefix length | SA46T IPv6 prefix length |
             +--------------------+--------------------------+
             | /8                 | /104                     |
             | /16                | /112                     |
             | /24                | /120                     |
             +--------------------+--------------------------+

                                  Table 2




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   The IPv4 route for stub network is map to SA46T IPv6 route one to
   one, so number of route of IPv4 is same as number of route of SA46T
   IPv6 route.  Total number of route is same as when backbone network
   operate dual stack, without SA46T.

   In stub network, usual dynamic routing protocol for IPv4 and IPv6 can
   be used such as RIPv2[RFC2453], RIPng[RFC2080], OSPFv2[RFC2328],
   OSPFv3[RFC2740].  Similarly, in backbone network, usual dynamic
   routing protocol for IPv6 can be used such as RIPng[RFC2080],
   OSPFv3[RFC2740].


4.  SA46T address format

   SA46T can be used closely in the backbone network, so SA46T address
   does not be advertised outside of the backbone network, and IPv6
   packet which contains SA46T address does not be forwarded outside of
   the backbone network.

   So, SA46T address format and SA46T address prefix can be decided each
   backbone network.  But for your information, two examples are shown
   as follows.  First one is based on Unique Local IPv4 Unicast Address,
   and the second one is based on IPv6 Global Unicast Address.

   Of course, SA46T can be used in the Internet, or between the ASs.
   This case is discussed shortly in section 4.3.

4.1.  Unique Local IPv6 Unicast Address as SA46T address

   This example is based on Unique Local IPv6 Unicast Address [RFC4193].
   Figure 5 shows Unique Local IPv6 Unicast Address Format.


      | 7 bits |1|  40 bits   |  16 bits  |          64 bits           |
      +--------+-+------------+-----------+----------------------------+
      | Prefix |L| Global ID  | Subnet ID |        Interface ID        |
      +--------+-+------------+-----------+----------------------------+

                                 Figure 5

   Figure 6 shows SA46T address format, using part of Unique Local IPv6
   Unicast Address.









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      | 7 bits |1|  40 bits   |  16 bits  |          64 bits           |
      +--------+-+------------+-----------+------------+---------------+
      | Prefix |L| Global ID  | Subnet ID |  plane ID  | IPv4 address  |
      +--------+-+------------+-----------+------------+---------------+
      <----SA46Tprefix-------------------->

                                 Figure 6

   Where:

   Prefix

      FC00::7 prefix

   L

      Set to 1 (locally assigned)

   Global ID

      indication for SA46T prefix.  Example is 0x5A46 or select from
      pseudo-random value

   Subnet ID

      Reserved for plane ID expansion

   plane ID

      IPv4 network plane ID.  The value 0 should be for the global IPv4
      Internet.

   IPv4 address

      IPv4 address of inner IPv4 packet

4.2.  IPv6 Global Unicast Address as SA46T address

   This example is based on IPv6 Global Unicast Address Format
   [RFC3587].

   Figure 7 shows IPv6 Global Unicast Address Format.









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    | 3 |        45bits         |  16bits   |        64bits            |
    +---+-----------------------+-----------+--------------------------+
    |001| Global routing prefix | subnet id |  Interface ID            |
    +---+-----------------------+-----------+--------------------------+

                                 Figure 7

   Figure 8 shows SA46T address format using part of IPv6 Global Unicast
   Address.


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

                                 Figure 8

   Where:

   Global routing prefix

      global routing prefix

   subnet id

      indication for SA46T prefix.  Example is 0x5A46.

   plane id

      IPv4 network plane ID.  The value 0 should be for the global IPv4
      Internet.

   IPv4 address

      IPv4 address of inner IPv4 packet

4.3.  Global SA46T address format

   SA46T can be used in The Internet, or between AS.  This is achieved
   by recognizing SA46T address format as common address.  Such address
   should be Global SA46T address.

   Global SA46T address format and prefix requires IANA assignment of
   IPv6 address prefix.  Global SA46T address is proposed in
   [I-D.draft-matsuhira-sa46t-gaddr].




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5.  Stacking IPv4 Networks

   SA46T can provide VPN like service to stub networks by using
   different IPv4 network plane ID value.  Table 3 shows example of IPv4
   network plane ID and its usage.

   If backbone network operator provide IPv4 privates network service to
   Organization A, backbone network operator sets IPv4 network plane ID
   value =1 to the SA46T which connects stub network of organization A.
   If there are five stub network of organization A, backbone network
   operator sets same IPv4 network plane ID = 1, to five SA46Ts which
   connect stub network of organization A. If there are one hundred stub
   network of organization B, backbone network operator sets same IPv4
   network plane ID = 2, to one hundred SA46Ts which connect stub
   network of organization B. If a new stub network in organization B
   join, backbone network operator configures same IPv4 network plane ID
   = 2, to the new stub network only, which connect stub network of
   organization B, and no configuration is needed to one hundred SA46Ts
   which are already connected.

   Such configuration, that means same stub network group to same IPv4
   network plane ID value, is simple and easy to understand, so, it is
   expected that possibility of misconfiguration is very low.  And also,
   number of configuration is minimum, that mean, number of
   configuration is same as number of stub networks, and add new stub
   network, configure to new one only.

   Describe above, SA46T can provide VPN like service, for example,
   Intranet or extranet.  And, after IPv4 global address running out,
   some service provider may want to reuse IPv4 private address.  SA46T
   can provide such IPv4 private address networks over single IPv6
   backbone network.  By SA46T, some service providers may reuse IPv4
   private address.


















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   +---------------------+---------------------------------------------+
   | IPv4 network plane  | usage                                       |
   | ID value            |                                             |
   +---------------------+---------------------------------------------+
   | 0                   | IPv4 Internet (Global)                      |
   | 1                   | IPv4 Private network for Organization A     |
   |                     | (Intranet)                                  |
   | 2                   | IPv4 Private network for Organization B     |
   |                     | (Intranet)                                  |
   | 3                   | IPv4 Private network for Group A (Extranet) |
   | 4                   | IPv4 Private network for Group B (Extranet) |
   | 5                   | Net10 reuse network for consumer group A    |
   |                     | (Private address access)                    |
   | 6                   | Net10 reuse network for consumer group B    |
   |                     | (Private address access)                    |
   | 7                   | Net10 reuse network for consumer group C    |
   |                     | (Private address access )                   |
   | ....                | ....                                        |
   +---------------------+---------------------------------------------+

                                  Table 3


6.  Redundancy of SA46T

   SA46T brings no limit for redundancy.  Figure 9 shows such example in
   case two connection between backbone network and stub network.
   Number of link between backbone network and stub network is not
   limited, and different type of link can be used, for example, for
   wire and wireless.

   Configuration of SA46Ts, which connect same stub network, is same.
   That mean same SA46T prefix and same IPv4 network plane ID value.


















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    /---------------------------------------------------\
    |                                                   |
    |                  Backbone Network                 |
    |                    (IPv6 only)                    |
    |                                                   |
    \---------------------------------------------------/
          |         |                  |         |
      +-------+ +-------+          +-------+ +-------+
      | SA46T | | SA46T |          | SA46T | | SA46T |
      +-------+ +-------+          +-------+ +-------+
          |         |                  |         |
    /---------------------\      /---------------------\
    |                     |      |                     |
    |    Stub Network     |      |    Stub Network     |
    |    (IPv4 only)      |      |    (Dual Stack)     |
    |                     |      |                     |
    \---------------------/      \---------------------/

                                 Figure 9


7.  Example of SA46T Operation

7.1.  Basic SA46T Operation

   Figure 10 shows SA46T operation which does not use IPv4 network plane
   ID.  In this example, two stub network is connected to backbone
   network via SA46T. One stub network is 10.1.1.0/24 sub network, and
   the other is 10.1.2.0/24 sub network.

   When SA46T receives IPv4 route advertisement, then SA46T convert this
   IPv4 route to IPv6 route by address resolution to SA46T address, and
   advertise this IPv6 route to backbone network.  When SA46T receives
   IPv6 route advertisements, then SA46T converts this IPv6 route to
   IPv4 route if this IPv6 route is match SA46T address ( same prefix
   with SA46T), and advertise this IPv4 route to stub network.

   In this example.  IPv4 route, 10.1.1.0/24 is converted to IPv6 route,
   <SA46Tprefix>:10.1.1.0/120,and IPv4 route, 10.1.2.0/24 is converted
   to IPv6 route, <SA46Tprefix>:10.1.2.0/120 at SA46T from stub network
   to backbone network.  And, from backbone network to stub network,
   IPv6 route, <SA46Tprefix>:10.1.1.0/120 is converted to IPv4 route,
   10.1.1.0/24, and IPv6 route, <SA46Tprefix>:10.1.2.0/120 is converted
   to IPv4 route, 10.1.2.0/24.







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     /-------------/  +-----+  +------------+  +-----+  +-------------+
     |Stub Network |  |     |  | Backbone   |  |     |  |Stub Network |
     |(10.1.1.0/24)|--|SA46T|--| Network    |--|SA46T|--|(10.1.2.0/24)|
     |             |  |     |  |(IPv6 only) |  |     |  |             |
     --------------/  +-----+  +------------+  +-----+  +-------------+

    [10.1.1.0/24] --->  [<SA46Tprefix>:10.1.1.0/120] ---> [10.1.1.0/24]
    [10.1.2.0/24] <---  [<SA46Tprefix>:10.1.2.0/120] <--- [10.1.2.0/24]


     +---------+----+       +---------+----+----+      +---------+----+
     | data    |IPv4|  -->  | data    |IPv4|IPv6| -->  | data    |IPv4|
     +---------+----+       +---------+----+----+      +---------+----+
     src: 10.1.1.1        src: <SA46Tprefix>:10.1.1.1     src: 10.1.1.1
     dst: 10.1.2.1        dst: <SA46Tprefix>:10.1.2.1     dst: 10.1.2.1

                                 Figure 10

7.2.  SA46T Operation with plane ID

   Figure 11 shows SA46T operation which uses IPv4 network plane ID.  In
   this example, there are two planes, and two stub network in each
   plane is connected to backbone network via SA46T. In each plane, one
   stub network is 10.1.1.0/24 sub network, and the other is 10.1.2.0/24
   sub network, that means same IPv4 address is used in different plane.

   When SA46T receives IPv4 route advertisements, then SA46T converts
   this IPv4 route to IPv6 route by address resolution to SA46T address,
   and advertise this IPv6 route to backbone network.  When SA46T
   receives IPv6 route advertisements, then SA46T converts this IPv6
   route to IPv4 route if this IPv6 route is match SA46T address ( same
   prefix with SA46T), and advertises this IPv4 route to stub network.

   In this example in plane #1.  IPv4 route, 10.1.1.0/24 is converted to
   IPv6 route, <SA46Tprefix><#1>:10.1.1.0/120,and IPv4 route,
   10.1.2.0/24 is converted to IPv6 route, <SA46Tprefix><#1>:10.1.2.0/
   120 at SA46T from stub network to backbone network.  And, from
   backbone network to stub network, IPv6 route, <SA46Tprefix><#
   1>:10.1.1.0/120 is converted to IPv4 route, 10.1.1.0/24, and IPv6
   route, <SA46Tprefix><#1>:10.1.2.0/120 is converted to IPv4 route,
   10.1.2.0/24.

   And also, In this example in plane #2.  IPv4 route, 10.1.1.0/24 is
   converted to IPv6 route, <SA46Tprefix><#2>:10.1.1.0/120,and IPv4
   route, 10.1.2.0/24 is converted to IPv6 route, <SA46Tprefix><#
   2>:10.1.2.0/120 at SA46T from stub network to backbone network.  And,
   from backbone network to stub network, IPv6 route, <SA46Tprefix><#
   2>:10.1.1.0/120 is converted to IPv4 route, 10.1.1.0/24, and IPv6



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   route, <SA46Tprefix><#2>:10.1.2.0/120 is converted to IPv4 route,
   10.1.2.0/24.

   In IPv6 space, address <SA46Tprefix><#1>:10.1.1.1 and address
   <SA46Tprefix><#2>:10.1.1.1 are different address, route
   <SA46Tprefix><#1>:10.1.1.0/120 and route <SA46Tprefix><#2>:10.1.1.0/
   120 are different route, although in IPv4 space, address 10.1.1.1 in
   plane #1 and 10.1.1.1 in plane#2 are same address, route 10.1.1.0/24
   in plane#1 and route 10.1.1.0/24 in plane#2 are same route.










































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                            /------------\
.......<plane#1>............|............|............................
: /-------------\  +-----+  |            |  +-----+ 24 /-------------\ :
: | Stub Network|  |     |  |            |  |     |  | Stub Network| :
: |(10.1.1.0/24)|--|SA46T|--| Backbone   |--|SA46T|--|(10.1.2.0/24)| :
: |             |  |     |  | Network    |  |     |  |             | :
: \-------------/  +-----+  |(IPv6 only) |  +-----+  \-------------/ :
:...........................|............|...........................:
                            |            |
........<plane#2>...........|............|............................
: /-------------\  +-----+  |            |  +-----+  /-------------\ :
: | Stub Network|  |     |  |            |  |     |  | Stub Network| :
: |(10.1.1.0/24)|--|SA46T|--|            |--|SA46T|--|(10.1.2.0/24)| :
: |             |  |     |  |            |  |     |  |             | :
: \-------------/  +-----+  |            |  +-----+  \-------------/ :
:...........................|............|...........................:
                            \------------/


<<plane #1>>

 [10.1.1.0/24] --->[<SA46Tprefix><#1>:10.1.1.0/120] ---> [10.1.1.0/24]
 [10.1.2.0/24] <---[<SA46Tprefix><#1>:10.1.2.0/120] <--- [10.1.2.0/24]

  +---------+----+       +---------+----+----+       +---------+----+
  | data    |IPv4|  -->  | data    |IPv4|IPv6|  -->  | data    |IPv4|
  +---------+----+       +---------+----+----+       +---------+----+
  src: 10.1.1.1       src: <SA46Tprefix><#1>:10.1.1.1    src: 10.1.1.1
  dst: 10.1.2.1       dst: <SA46Tprefix><#1>:10.1.2.1    dst: 10.1.2.1


<<plane#2>>

 [10.1.1.0/24] --->[<SA46Tprefix><#2>:10.1.1.0/120] ---> [10.1.1.0/24]
 [10.1.2.0/24] <---[<SA46Tprefix><#2>:10.1.2.0/120] <--- [10.1.2.0/24]

  +---------+----+       +---------+----+----+      +---------+----+
  | data    |IPv4|  -->  | data    |IPv4|IPv6| -->  | data    |IPv4|
  +---------+----+       +---------+----+----+      +---------+----+
  src: 10.1.1.1       src: <SA46Tprefix><#2>:10.1.1.1    src: 10.1.1.1
  dst: 10.1.2.1       dst: <SA46Tprefix><#2>:10.1.2.1    dst: 10.1.2.1

                                 Figure 11








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8.  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

   o  Can Stack IPv4 Private networks

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

   o  Provide redundancy


9.  IANA Considerations

   This document makes no request of IANA.

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


10.  Security Considerations

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


11.  Acknowledgements

   This document is based on Naoki Matsuhira's original ideas and an
   individual effort of the author.

   Review and encouragement have been provided by many others.
   Particulary Akira Kato at WIDE Project / Keio University and Masanobu
   Katoh at Fujitsu Laboratories Ltd.




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12.  References

12.1.  Normative References

   [I-D.draft-matsuhira-sa46t-gaddr]
              Matsuhira, N., "Stateless Automatic IPv4 over IPv6
              Tunneling: Global SA46T Address Format", January 2010.

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

   [RFC1853]  Simpson, W., "IP in IP Tunneling", RFC 1853, October 1995.

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

   [RFC3587]  Hinden, R., Deering, S., and E. Nordmark, "IPv6 Global
              Unicast Address Format", RFC 3587, August 2003.

   [RFC4193]  Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast
              Addresses", RFC 4193, October 2005.

12.2.  Informative References

   [RFC2080]  Malkin, G. and R. Minnear, "RIPng for IPv6", RFC 2080,
              January 1997.

   [RFC2267]  Ferguson, P. and D. Senie, "Network Ingress Filtering:
              Defeating Denial of Service Attacks which employ IP Source
              Address Spoofing", RFC 2267, January 1998.

   [RFC2328]  Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998.

   [RFC2453]  Malkin, G., "RIP Version 2", STD 56, RFC 2453,
              November 1998.

   [RFC2740]  Coltun, R., Ferguson, D., and J. Moy, "OSPF for IPv6",
              RFC 2740, December 1999.

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










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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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