Dual Stack Hosts using the "Bump-In-the-Stack" Technique (BIS)
RFC 2767

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Network Working Group                                       K. Tsuchiya
Requests for Comments: 2767                                  H. Higuchi
Category: Informational                                     Y. Atarashi
                                                                Hitachi
                                                          February 2000

     Dual Stack Hosts using the "Bump-In-the-Stack" Technique (BIS)

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2000).  All Rights Reserved.

Abstract

   In the especially initial stage of the transition from IPv4 to IPv6,
   it is hard to provide a complete set of IPv6 applications.  This memo
   proposes a mechanism of dual stack hosts using the technique called
   "Bump-in-the-Stack" in the IP security area. The mechanism allows the
   hosts to communicate with other IPv6 hosts using existing IPv4
   applications.

1. Introduction

   RFC1933 [TRANS-MECH] specifies transition mechanisms, including dual
   stack and tunneling, for the initial stage. Hosts and routers with
   the transition mechanisms are also developed. But there are few
   applications for IPv6 [IPV6] as compared with IPv4 [IPV4] in which a
   great number of applications are available. In order to advance the
   transition smoothly, it is highly desirable to make the availability
   of IPv6 applications increase to the same level as IPv4.
   Unfortunately, however, this is expected to take a very long time.

   This memo proposes a mechanism of dual stack hosts using the
   technique called "Bump-in-the-Stack" [BUMP] in the IP security area.
   The technique inserts modules, which snoop data flowing between a
   TCP/IPv4 module and network card driver modules and translate IPv4
   into IPv6 and vice versa, into the hosts, and makes them self-
   translators. When they communicate with the other IPv6 hosts, pooled
   IPv4 addresses are assigned to the IPv6 hosts internally, but the
   IPv4 addresses never flow out from them. Moreover, since the
   assignment is automatically carried out using DNS protocol, users do

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RFC 2767               Dual Stack Hosts using BIS          February 2000

   not need to know whether target hosts are IPv6 ones. That is, this
   allows them to communicate with other IPv6 hosts using existing IPv4
   applications; thus it seems as if they were dual stack hosts with
   applications for both IPv4 and IPv6. So they can expand the territory
   of dual stack hosts.  Furthermore they can co-exist with other
   translators because their roles are different.

   This memo uses the words defined in [IPV4], [IPV6], and [TRANS-MECH].

2. Components

   Dual stack hosts defined in RFC1933 [TRANS-MECH] need applications,
   TCP/IP modules and addresses for both IPv4 and IPv6. The proposed
   hosts in this memo have 3 modules instead of IPv6 applications, and
   communicate with other IPv6 hosts using IPv4 applications. They are a
   translator, an extension name resolver and an address mapper.

   Figure 1 illustrates the structure of the host in which they are
   installed.

         +----------------------------------------------------------+
         |  +----------------------------------------------------+  |
         |  | IPv4 applications                                  |  |
         |  +----------------------------------------------------+  |
         |  +----------------------------------------------------+  |
         |  | TCP/IPv4                                           |  |
         |  |        +-------------------------------------------+  |
         |  |        |  +-----------+  +---------+  +------------+  |
         |  |        |  | extension |  | address |  | translator |  |
         |  |        |  | name      |  | mapper  |  +------------+  |
         |  |        |  | resolver  |  |         |  +------------+  |
         |  |        |  |           |  |         |  | IPv6       |  |
         |  +--------+  +-----------+  +---------+  +------------+  |
         |  +----------------------------------------------------+  |
         |  | Network card drivers                               |  |
         |  +----------------------------------------------------+  |
         +----------------------------------------------------------+
         +----------------------------------------------------------+
         |    Network cards                                         |
         +----------------------------------------------------------+

               Figure. 1 Structure of the proposed dual stack host

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RFC 2767               Dual Stack Hosts using BIS          February 2000

2.1 Translator