Internet DRAFT - draft-chen-softwire-gw-init-4over6

draft-chen-softwire-gw-init-4over6







Network Working Group                                            Y. Chen
Internet-Draft                                                     J. Wu
Intended status: Standards Track                     Tsinghua University
Expires: March 01, 2014                                          X. Tang
                                                                 G. Zhou
                                         China Unicom Research Institute
                                                         August 28, 2013


                  Gateway-Initiated 4over6 Deployment
                 draft-chen-softwire-gw-init-4over6-02

Abstract

   Gateway-Initiated 4over6 is a variant of Lightweight 4over6.  A
   Lightweight B4 in Lightweight 4over6 mechanism is a router which acts
   as a tunnel initiator for the IPv4-in-IPv6 tunnel.  This mechanism
   mainly focuses on the scenario in which an IPv4 address and related
   configuration information is configured to the device behind
   Lightweight B4.  Gateway-Initiated 4over6 uses the full IPv4 address
   rather than a shared address.  This enables an unmodified end server
   or host that is behind a Lightweight B4 to get access to the IPv4
   Internet through an IPv6 network.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
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   This Internet-Draft will expire on March 01, 2014.

Copyright Notice

   Copyright (c) 2013 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



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   (http://trustee.ietf.org/license-info) in effect on the date of
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Requirements Language . . . . . . . . . . . . . . . . . . . .   3
   4.  GI-4over6 Architecture  . . . . . . . . . . . . . . . . . . .   3
   5.  GI-4over6 in ICP Network  . . . . . . . . . . . . . . . . . .   4
     5.1.  Static Configuration to Establish Tunnel  . . . . . . . .   4
     5.2.  Dynamic Configuration to Establish Tunnel . . . . . . . .   5
   6.  4over6 Gateway Data Plane Behaviors . . . . . . . . . . . . .   5
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   In typical use case of Lightweight 4over6 (Lw4over6)
   ([I-D.ietf-softwire-lw4over6]), IPv4 address (and available port set)
   is provisioned to the Lightweight B4 (LwB4), the tunnel initiator.
   However, there are some cases in which IPv4 address and related
   configuration are not be provisioned to LwB4, but the end device
   behind it.  There is a typical scenario in this case, that is
   Lw4over6 is used in an Internet Content Provider (ICP) network, and
   the device behind LwB4 is an ICP server.

   Gateway-Initiated 4over6 (GI-4over6) is a variant of Lw4over6.  It
   mainly focuses on the scenario in which an IPv4 address and related
   configuration information is provisioned to the device behind LwB4.
   Provisioning full address is preferred to provisioning shared address
   (port-restricted address) in GI-4over6.  It enables an unmodified
   IPv4 device that behind the LwB4 to get access to IPv4 Internet
   through IPv6 network.

2.  Terminology

   This document uses the terms defined in [I-D.ietf-softwire-lw4over6].




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   The other terms used are defined as follows:

   o  End device:     The device in the IPv4 network behind the 4over6
                      gateway.  It can be an IPv4-only or a dual-stack
                      device.

   o  End server:     The end device in an ICP network is supposed to
                      be an end server.

   o  4over6 gateway: The dual-stack gateway device located at the border
                      of both IPv4 and IPv6 networks.  It should be
                      configured with an IPv4 address and the IPv6 address
                      of LwAFTR, and act as the LwB4 on the data plane.


3.  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].

4.  GI-4over6 Architecture

   The general architecture of GI-4over6 is illustrated as Figure 1.
   The 4over6 gateway is a dual-stack gateway device which establishes
   IPv4-in-IPv6 tunnel with the Lightweight Address Family Transition
   Router (LwAFTR) and performs the LwB4 function on data plane.  The
   LwAFTR is a dual-stack border router deployed at the edge of the IPv6
   network and the Internet.  The IPv4 network can be either an ICP
   network, or a customer network of an ISP.  The IPv6 network can be
   either an ICP access network or an ISP access network.  Either or
   both of these networks could be dual-stack.


   +---------------------+          +-------------------------+
   | +-------------+   +-+----------+-+                     +-+--------+   +----------+
   | |             |   |    4over6    | IPv4-in-IPv6 tunnel |          |   |          |
   | | End device  +---+    Gateway   |=====================|  LwAFTR  +---+ Internet |
   | |             |   |    (LwB4)    |                     |          |   |          |
   | +-------------+   +-+----------+-+     IPv6 Network    +-+--------+   +----------+
   |    IPv4 network     |          |                         |
   +---------------------+          +-------------------------+


   Figure 1 GI-4over6 Architecture


   The 4over6 gateway is configured with an public IPv4 address on its



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   "left" side, an IPv6 address on its "right" side, either by static
   (in ICP network) or dynamic (in customer network) way.  It is also
   configured with the IPv6 address of LwAFTR as the address of the
   tunnel endpoint.  Each end device has a public IPv4 address with all
   ports (0-65535) available, hence there is no need to implement NAPT44
   on the 4over6 gateway.

   One typical scenario of this framework is that using Lw4over6 in an
   ICP network.  There might be other similar scenarios, and they could
   be included in this document in the future.

5.  GI-4over6 in ICP Network

   Considering an ISP that plans to update its network to IPv6, one of
   the major issues it may be faced with is the update of its ICP
   network.  If the ICP network is to be updated to run IPv6, the server
   in the network should also be updated to support IPv6.  Obviously it
   is not trivial to update upper layer service running on the server to
   support a network layer protocol.  It's ideal if the ICP access
   network is updated to IPv6, but still capable of providing the server
   with access to IPv4 Internet, meanwhile the ICP network (and the
   servers inside) stay unmodified.

   In this scenario, the end server has already been configured with a
   full public IPv4 address, and it's expected to stay unchanged during
   the update of the network.  It has also been configured with other
   IPv4 related configurations like the network mask of the IPv4 ICP
   network, the IPv4 address of DNS server, etc.

   The 4over6 gateway has already been configured with the routing to
   the end server.  It MUST establish the IPv4-in-IPv6 tunnel with the
   LwAFTR, in order to forward the IPv4 traffics between the end server
   and the IPv4 Internet.  The establishment of the IPv4-in-IPv6 tunnel
   could be done either by static - the most likely way - or dynamic
   configuration.

5.1.  Static Configuration to Establish Tunnel

   The LwAFTR is statically configured with the binding of the public
   IPv4 address of the end server, the available port set (0-65535), and
   IPv6 address of the 4over6 gateway in its binding table statically.

   In a more general case, the addresses of servers behind the same
   4over6 gateway can aggregate.  And as the 4over6 gateway and the
   LwAFTR are both managed by the ISP, people who configure the LwAFTR
   are usually aware of the routing to the ICP network behind the 4over6
   gateway.  Hence the LwAFTR can be configured with the following
   binding: the network prefix of the ICP network, the available port



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   set (0-65535), and IPv6 address of the 4over6 gateway.

5.2.  Dynamic Configuration to Establish Tunnel

   Dynamic configuration could be adopted in case the static
   configuration is not feasible or practical.

   The 4over6 gateway MUST inform the LwAFTR of all of its IPv4 routing
   information (i.e. the whole IPv4 routing table).  The detail of this
   process could be clarified in related draft in future.

   Once the LwAFTR received the routing information from the 4over6
   gateway, it should add the entry(s) into its binding table, with the
   given routing information.  The binding may looks like: the ICP
   network prefix, available port set (0-65535), the IPv6 address of the
   4over6 gateway.

6.  4over6 Gateway Data Plane Behaviors

   The 4over6 gateway must perform the LwB4 function on the data plane.
   The data plane behavior of 4over6 gateway uses the description in
   section 5.2 of [I-D.ietf-softwire-lw4over6].  However, there is no
   need to implement NAPT44 function on 4over6 gateway, because each end
   server behind the 4over6 gateway has a public IPv4 address with all
   ports available.

7.  Security Considerations

   TBD

8.  IANA Considerations

   This document does not include an IANA request.

9.  References

9.1.  Normative References

   [I-D.ietf-softwire-lw4over6]
              Cui, Y., Sun, Q., Boucadair, M., Tsou, T., Lee, Y., and I.
              Farrer, "Lightweight 4over6: An Extension to the DS-Lite
              Architecture", draft-ietf-softwire-lw4over6-01 (work in
              progress), July 2013.

9.2.  Informative References

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



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Authors' Addresses

   Yuchi Chen
   Tsinghua University
   Department of Computer Science, Tsinghua University
   Beijing  100084
   P.R.China

   Phone: +86 10 6278 5822
   Email: chenycmx@gmail.com


   Jianping Wu
   Tsinghua University
   Department of Computer Science, Tsinghua University
   Beijing  100084
   P.R.China

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


   Xiongyan Tang
   China Unicom Research Institute
   33 Erlong Road, Xicheng District
   Beijing  100032
   P.R.China

   Phone: +86 10 6652 2558
   Email: tangxy@chinaunicom.cn


   Guangtao Zhou
   China Unicom Research Institute
   9 Shouti South Road, Haidian District
   Beijing  100048
   P.R.China

   Phone: +86 10 6789 9600
   Email: zhouguangtao@chinaunicom.cn











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