Internet DRAFT - draft-li-softwire-dslite-intra-domain

draft-li-softwire-dslite-intra-domain






softwire                                                           Z. Li
Internet-Draft                                              China Mobile
Intended status: Standards Track                                 Q. Zhao
Expires: April 26, 2012                                         X. Huang
                                                                   Y. Ma
                                         Beijing University of Posts and
                                                      Telecommunications
                                                        October 24, 2011


                 DS-Lite Intra-Domain Automatic Tunnel
                draft-li-softwire-dslite-intra-domain-00

Abstract

   This document specifies an automatic tunneling mechanism for
   providing IPv4 connectivity service to IPv6 end users in the same DS-
   Lite domain.  Key aspects include stateless operation and algorithmic
   mapping between IPv4 addresses and IPv6 tunnel endpoints.

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 26, 2012.

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
   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



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   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.  Requirements Language . . . . . . . . . . . . . . . . . . . . . 3
   3.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
   4.  Configuration . . . . . . . . . . . . . . . . . . . . . . . . . 4
     4.1.  CPE Configuration . . . . . . . . . . . . . . . . . . . . . 4
     4.2.  CGN Configuration . . . . . . . . . . . . . . . . . . . . . 4
   5.  Algorithmic Mapping Rules . . . . . . . . . . . . . . . . . . . 4
     5.1.  From a CPE tunnel address to a Domain IPv6 prefix . . . . . 5
     5.2.  From a CPE tunnel address to a Domain IPv4 prefix . . . . . 5
     5.3.  From a CPE tunnel address to a CPE IPv4 prefix  . . . . . . 5
     5.4.  From an IPv4 address to a CPE tunnel address  . . . . . . . 5
   6.  CPE and CGN behaviors . . . . . . . . . . . . . . . . . . . . . 6
     6.1.  CPE reception of an IPv4 packet . . . . . . . . . . . . . . 6
     6.2.  CPE reception of an IPv6 packet . . . . . . . . . . . . . . 6
     6.3.  CGN reception of an IPv4 packet . . . . . . . . . . . . . . 7
     6.4.  CGN reception of an IPv6 packet . . . . . . . . . . . . . . 7
   7.  Security Considerations . . . . . . . . . . . . . . . . . . . . 7
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 7
     9.1.  Normative References  . . . . . . . . . . . . . . . . . . . 7
     9.2.  Informative References  . . . . . . . . . . . . . . . . . . 7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . . 7






















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1.  Introduction

   DS-Lite [RFC6333] technology is used to deploy IPv6 following IPv4
   exhaustion in service provider networks.  It enables a broadband
   service provider to share IPv4 addresses among customers by combining
   IPv4-in-IPv6 tunnel and NAT44 translation.

   From the view of network topology, DS-Lite is a good solution to
   "Hubs and Spokes" problem [RFC4925] since all the IPv4 traffic from
   B4 will be concentrated at AFTR even if all the IPv4 traffic are
   between two adjacent B4 devices.  But, there are huge IPv4 traffic
   demands among end users.  Many applications such as Instant Messenger
   are providing directly end-to-end highspeed transport when they find
   corresponding users are adjacent, instead of relaying the traffic by
   remote server.

   Current DS-Lite technology concentrates all end users' IPv4 traffic
   in IPv4-in-IPv6 tunnels at AFTR and AFTR relays IPv4 traffic among
   different tunnels.  It delays packet delivery among adjacent users,
   aggravates additional workload on AFTR or CGN and involves redundant
   forwarding path.

   This document introduces the concept of domain to DS-Lite technology.
   A DS-Lite domain consists of many home gateways or CPEs with B4
   function and one CGN with AFTR function.  IPv4 packets encapsulated
   by DS-Lite follow the IPv6 routing topology within the SP network
   between CPEs or between CPE and CGN.  From the view of network
   topology, CPE-to-CPE IPv4 traffic in an IPv6 domain is a "Mesh"
   problem [RFC4925].  This document introduces intra-domain automatic
   tunnel technology to solve it.


2.  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].


3.  Terminology

   DS-Lite domain (Domain): A set of DS-Lite CPEs and CGN connected to
   the same virtual DS-Lite link.  An SP may deploy DS-Lite within a
   single DS-Lite domain or across multiple DS-Lite domains.

   DS-Lite CPE (CPE): The home gateway with B4 function.

   DS-Lite CGN (CGN): The tunnel concentrate points with AFTR funtion.



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   CPE IPv4 prefix: The IPv4 prefix of the CPE.  It is derived from the
   CPE tunnel address.  CPE IPv4 prefix is the subset of Domain IPv4
   prefix and can be assigned to LAN side.

   CPE tunnel address: The IPv6 address on the B4 interface of CPE.  It
   is combined by Domain IPv6 prefix and CPE IPv4 prefix.

   CGN tunnel address: The IPv6 address on the AFTR interface of CGN.
   It may be any global IPv6 address.

   Domain IPv4 prefix: A part of or all of IPv4 private address space
   shared among different service providers.  It is non-overlapping in a
   DS-Lite Domain.

   Domain IPv6 prefix: A part of global IPv6 address space.  It differs
   among different DS-Lite Domains and keeps the same within a DS-Lite
   Domain.


4.  Configuration

   For a given DS-Lite domain, the CPE and CGN MUST be configured with a
   set of mapping rules and tunnel addresses.  The configuration MUST be
   consistent for all CPEs and CGN within a given DS-Lite domain.

   A mapping rules consists of the following elements: a CPE tunnel
   address, a Domain IPv6 prefix length, a Domain IPv4 prefix length, a
   CPE IPv4 prefix length.  See section 5 for detailed description of
   mapping rules.

4.1.  CPE Configuration

   The CPE can obtain necessary parameters via DHCPv6 [RFC3315]
   protocols with new options.  Generally, CPE needs an independent IPv6
   address via DHCPv6 to access native IPv6 Internet.  Besides, CPE
   needs mapping rules and CGN tunnel address from DHCPv6 options to
   access IPv4 Internet.  Also, these parameters can be manually
   configured on CPE.

4.2.  CGN Configuration

   The CGN should be configured with CGN tunnel address at least.


5.  Algorithmic Mapping Rules






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5.1.  From a CPE tunnel address to a Domain IPv6 prefix

   When a mapping rule is received, CPE will extract necessary
   parameters from it.  Domain IPv6 prefix is calculated by CPE tunnel
   address and Domain IPv6 prefix length.

   <----------------     CPE tunnel address (128)     ---------------->
   +------------------------------+--------------------+--------+-----+
   |      Domain IPv6 Prefix      | Domain IPv4 Prefix | CPE ID |  0  |
   +------------------------------+--------------------+--------+-----+
   <- Domain IPv6 Prefix length ->

        Figure 1: From a CPE tunnel address to a Domain IPv6 prefix

5.2.  From a CPE tunnel address to a Domain IPv4 prefix

   When a mapping rule is received, CPE will extract necessary
   parameters from it.  Domain IPv4 prefix is calculated by CPE tunnel
   address and Domain IPv4 prefix length.

   <----------------     CPE tunnel address (128)     ---------------->
   +--------------------+------------------------------+--------+-----+
   | Domain IPv6 Prefix |      Domain IPv4 Prefix      | CPE ID |  0  |
   +--------------------+------------------------------+--------+-----+
                        <- Domain IPv4 Prefix length ->

        Figure 2: From a CPE tunnel address to a Domain IPv6 prefix

5.3.  From a CPE tunnel address to a CPE IPv4 prefix

   When a mapping rule is received, CPE will extract necessary
   parameters from it.  CPE IPv4 prefix is calculated by CPE tunnel
   address and CPE IPv4 prefix length.

   <----------------     CPE tunnel address (128)     ---------------->
   +------------------------+------------------------+----------+-----+
   |   Domain IPv6 Prefix   |   Domain IPv4 Prefix   |  CPE ID  |  0  |
   +------------------------+------------------------+----------+-----+
                            <-     CPE IPv4 Prefix length     ->

        Figure 3: From a CPE tunnel address to a Domain IPv6 prefix

5.4.  From an IPv4 address to a CPE tunnel address

   When a packet destined for hosts intra-domain is received, the
   destination IPv4 address will be mapped to the CPE tunnel address of
   destination host.  The Domain IPv6 Prefix has been calculated out
   from mapping rule during initialization.  The CPE IPv4 Prefix length



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   keeps the same in a DS-Lite domain.  The CPE IPv4 Prefix can be
   calculated by destination IPv4 address and CPE IPv4 Prefix length.

                            <-     CPE IPv4 Prefix length     ->
   +------------------------+-----------------------------------+-----+
   |   Domain IPv6 Prefix   |          CPE IPv4 Prefix          |  0  |
   +------------------------+-----------------------------------+-----+
   <----------------     CPE tunnel address (128)     ---------------->

        Figure 4: From a CPE tunnel address to a Domain IPv6 prefix


6.  CPE and CGN behaviors

6.1.  CPE reception of an IPv4 packet

   Step 1:

   CPE calculates destination CPE IPv4 prefix by CPE IPv4 Prefix length
   and the IPv4 destination address in the received IPv4 packet.  Then
   CPE compares it with the Domain IPv4 prefix.

   If the destination CPE IPv4 prefix is a part of Domain IPv4 prefix,
   the IPv4 packet will be encapsulated in intra-domain automatic IPv4-
   in-IPv6 tunnel.  The source IPv6 address is source CPE tunnel address
   and the destination IPv6 address is calculated as descibed in section
   5.4.  An automatic tunnel will be established between source CPE and
   destination CPE bypassing CGN.

   If the destination CPE IPv4 prefix is out of Domain IPv4 prefix, CPE
   proceeds to step2.

   Step 2:

   The IPv4 packet will be encapsulated in primitive DS-Lite IPv4-in-
   IPv6 tunnel.  The source IPv6 address is source CPE tunnel address
   and the destination IPv6 address is the CGN tunnel address.

6.2.  CPE reception of an IPv6 packet

   Step 1:

   CPE decapsulates the IPv6 packet and forwards the IPv4 packets to
   destination host.







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6.3.  CGN reception of an IPv4 packet

   The same with existing AFTR mechanisms.

6.4.  CGN reception of an IPv6 packet

   The same with existing AFTR mechanisms.


7.  Security Considerations

   TBD.


8.  IANA Considerations

   This document makes no request of IANA.

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


9.  References

9.1.  Normative References

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

9.2.  Informative References

   [RFC3315]  Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,
              and M. Carney, "Dynamic Host Configuration Protocol for
              IPv6 (DHCPv6)", RFC 3315, July 2003.

   [RFC4925]  Li, X., Dawkins, S., Ward, D., and A. Durand, "Softwire
              Problem Statement", RFC 4925, July 2007.

   [RFC6333]  Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual-
              Stack Lite Broadband Deployments Following IPv4
              Exhaustion", RFC 6333, August 2011.










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Authors' Addresses

   Zhenqiang Li
   China Mobile
   Unit2, Dacheng Plaza, No. 28 Xuanwumenxi Ave, Xicheng District
   Beijing  100053
   P.R. China

   Email: lizhenqiang@chinamobile.com


   Qin Zhao
   Beijing University of Posts and Telecommunications
   Information Network Center, No. 10 Xitucheng Road, Haidian District
   Beijing  100876
   P.R. China

   Email: zhaoqin@bupt.edu.cn


   Xiaohong Huang
   Beijing University of Posts and Telecommunications
   Information Network Center, No. 10 Xitucheng Road, Haidian District
   Beijing  100876
   P.R. China

   Email: huangxh@bupt.edu.cn


   Yan Ma
   Beijing University of Posts and Telecommunications
   Information Network Center, No. 10 Xitucheng Road, Haidian District
   Beijing  100876
   P.R. China

   Email: mayan@bupt.edu.cn















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