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v6ops                                                              X. Li
Internet-Draft                                                    C. Bao
Intended status: Informational                                    G. Han
Expires: August 1, 2017                                         M. Sheng
                                                  CERNET Center/Tsinghua
                                                              University
                                                        January 28, 2017


         CERNET deployment of IVI/MAP-T in an IPv6-only network
                  draft-xli-v6ops-cernet-deployment-02

Abstract

   This document presents the China Education and Research Network
   (CERNET)'s IPv4 as a Service (IPv4aaS) design, deployment and
   operation experience.

   The techniques used are IPv4/IPv6 stateless translation both in the
   forms of single translation (IVI, for IPv6-only servers) and double
   translation (MAP-T, for dual-stack clients).

Status of This Memo

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   This Internet-Draft will expire on August 1, 2017.

Copyright Notice

   Copyright (c) 2017 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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   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
     1.1.  Major Motivation . . . . . . . . . . . . . . . . . . . . .  3
     1.2.  IPv4-as-a-Service Requirements . . . . . . . . . . . . . .  3
   2.  Architecture and Methodology . . . . . . . . . . . . . . . . .  4
     2.1.  Major Design Considerations  . . . . . . . . . . . . . . .  4
     2.2.  Regulatory Considerations  . . . . . . . . . . . . . . . .  4
     2.3.  Security Considerations  . . . . . . . . . . . . . . . . .  5
     2.4.  Operational Considerations . . . . . . . . . . . . . . . .  5
       2.4.1.  Subnet for the Servers . . . . . . . . . . . . . . . .  5
       2.4.2.  Subnet for the Clients . . . . . . . . . . . . . . . .  5
     2.5.  End-User Experience Considerations . . . . . . . . . . . .  6
   3.  Design and Deployment  . . . . . . . . . . . . . . . . . . . .  6
     3.1.  Single stateless translation for servers - IVI . . . . . .  6
     3.2.  Double stateless translation for clients - MAP-T . . . . .  7
   4.  Observations and Experiences . . . . . . . . . . . . . . . . .  9
     4.1.  Effects on End-User  . . . . . . . . . . . . . . . . . . .  9
     4.2.  Effects on Internal Staff  . . . . . . . . . . . . . . . .  9
     4.3.  Effects on Business  . . . . . . . . . . . . . . . . . . .  9
   5.  Summary: Post-mortem Report  . . . . . . . . . . . . . . . . .  9
     5.1.  Deviations from IETF Documents . . . . . . . . . . . . . .  9
     5.2.  The Suggestions for the IPv6 Transition  . . . . . . . . . 10
   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 10
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 10
   8.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
     9.1.  Normative References . . . . . . . . . . . . . . . . . . . 10
     9.2.  Informative References . . . . . . . . . . . . . . . . . . 11
















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1.  Introduction

   The China Education and Research Network (CERNET) is an academic
   network in mainland China, with the universities, institutes and
   schools as the customers.  The student population in mainland China
   is about 320 million and there are no enough public IPv4 addresses
   available.  The cloud computing, the mobile Internet and the Internet
   of Things make the IPv4 address exhaustion situation even worse.  Ten
   years ago, we have deployed an IPv6-only backbone named CERNET2 and
   eight years ago, we have developed the IPv4/IPv6 stateless
   translation technology called IVI [RFC6219], which becomes the
   proposed IETF standard of the IPv4/IPv6 stateless translation
   [RFC6145], [RFC6052], etc.  In order to improve the customer
   experience for the IPv4-only applications and application with the
   address literals embedded, we have developed double IPv4/IPv6
   stateless translation technology called dIVI, which becomes the
   mapping address and port with translation (MAP-T) [RFC7599].  This
   document presents our experience of IPv4 as a Service (IPv4aaS), the
   techniques used are IVI [RFC6145], [RFC6052] and [RFC6219] and a
   slightly modified version of MAP-T [RFC7599].

1.1.  Major Motivation

   In order to extend the service in the case of IPv4 address depletion,
   we need to provide IPv6 services and the still keep the ability for
   users to access the global IPv4 Internet.  Therefore, IPv4 as a
   Service (IPv4aaS) is a natural choice for the new campus network
   connected to IPv6-only CERNET2.

1.2.  IPv4-as-a-Service Requirements

   The design requirements for IPv4aaS in CERNET are:

   1.  Deploy IPv6-only single stack network as large as possible in
       order to reduce CAPEX and OPEX.

   2.  The clients should have the same user experience compared with
       the dual-stack network with NAT44.

   3.  The IPv6-only servers should be able to serve the IPv4-only
       clients in the Internet.

   4.  Make the use of the IPv4 public address as much efficient as
       possible.

   5.  Provide a path to allow IPv6-only clients to communicate to the
       IPv4 Internet.




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   6.  For the scalability, resilience and security, prefer stateless
       technologies.

2.  Architecture and Methodology

2.1.  Major Design Considerations

   For CERNET, we have the following situation:

   o  There are two nation-wide backbones, CERNET is an IPv4 backbone
      and CERNET2 is an IPv6-only backbone.

   o  Most of the campus networks are dual stack.  The IPv4 interfaces
      of the border router of the campus networks are connected to
      CERNET and various commodity ISPs.  The IPv6 interfaces of the
      border router of the campus networks are connected to CERNET2.

   o  For special purpose subnets which are providing service for the
      servers, the subnets can be dual stack, IPv4-only or IPv6-only.
      The IPv6-only subnets are recommended.

   o  For general purpose subnets which are providing services for the
      clients (both wired Ethernet and the WLAN with multiple SSID), the
      dual stack is recommended.  Since it is the only way to maximize
      the satisfaction for the users using various operating systems
      (Windows XP, Windows 7/8, OSX, Linux, iOS, Android, etc.) and
      different applications (IPv4-only, dual stack and with address
      literals).

   o  Since we are running an academic network, we encourage users to
      try new technologies and make some part of the network as the
      testbeds.

   o  Ten years experience of deploying IPv6-only CERNET2, we strongly
      believe that the killer application of the IPv6 is the ability to
      communicate the global IPv4 Internet and therefore the translation
      technology should be the first choice.  In addition, due to the
      scalability, security and manageability considerations, the
      stateless technology should be preferred.  Those considerations
      result in the development and deployment of IVI [RFC6145],
      [RFC6052], [RFC6219] and MAP-T [RFC7599].

2.2.  Regulatory Considerations

   The government requires server operators to detect the packet sender
   by source IP (and port) and therefore stateless address mapping
   technologies are preferred.  This will dramatically reduce the volume
   of material required to be held for logging compliance.



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   In addition, the stateless translation technology is preferred, since
   IPv6 addresses in the IPv6 packets everywhere in the network contain
   both the IPv6 and IPv4 address information without the requirement of
   decapsulation.

2.3.  Security Considerations

   From operation point of view, single stack (IPv6-only) is easier for
   ensuring the security compared with the dual stack.

   The stateless mechanism can help for the trace back and identifying
   the source addresses (and port).

   The translation mechanism can help for configuring the access list
   and rate-limiting without decapsulation.

2.4.  Operational Considerations

   The IPv4aaS in CERNET is mainly for deploying new networks.  The
   existing IPv4 and dual stack networks will not be changed.  The
   methods for upgrading the existing networks in order to release the
   public IPv4 addresses will be discussed in future documents.

2.4.1.  Subnet for the Servers

   For subnets for the servers, The IPv6-only subnet with stateless
   translation is recommended.  The configuration is statically
   performed.

2.4.2.  Subnet for the Clients

   For general purpose subnets for the clients, dual stack is
   recommended, with DHCP for the IPv4 and SLAAC for the IPv6.  There is
   no issue for the DNSSEC operation.

   If IPv6-only subnet is required, the configuration should be done via
   DHCPv6 stateful mode with stateless or stateful IPv4/IPv4 translation
   service [RFC6145], [RFC6052], [RFC6146] [RFC6219] and DNS64
   [RFC6147].  Note that there are issues for the DNSSEC operation.

   We don't recommend mixing SLAAC and DHCPv6 stateful in the same
   subnet.

   For the WLAN environment, the users can decide which subnet to use
   among the IPv4-only, the dual stack and the IPv6-only (with
   translation) by selecting different SSIDs.





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2.5.  End-User Experience Considerations

   Due to the public IPv4 address depletion problem, the modern
   applications can fully support NAT44.  Therefore, the end-users will
   be satisfied if the IPv4aaS provides the same service as NAT44 with
   IPv4 address sharing.

   Besides TCP and UDP, concerning other protocols for example ICMP
   (ping), we found that the end-users will be satisfied if the IPv4aaS
   provides the same service as NAT44 with IPv4 address sharing.

3.  Design and Deployment

   Before the IPv4 address depletion, CERNET/CERNET2 has reserved a /17
   public IPv4 address prefix and several /40s IPv6 prefixes for the
   IPv4/IPv6 stateless translation.  The current implementations of both
   IPv6-only servers and dual-stack clients are still using these
   prefix.  The topology is shown in Figure 1.

      ------                        -----           ------
    /        \       -----        /       \       /        \
   |  CERNET  |-----| IVI |------| CERNET2 |--+--|IPv6-only|
    \  IPv4  /       -----        \ IPv6  /   |   \servers /
      ------                        -----     |     ------
                                              |                ------
                                              |   ------     /        \
                                              +--|MAP-T |---|Dual-stack|
                                              |   ------     \clients /
                                              |                ------
                                              |
                                              |                ------
                                              |   ------     /        \
                                              .--|MAP-T |---|Dual-stack|
                                              |   ------     \clients /
                                              |                ------
                                              |


               Figure 1: CERNET/CERNET2 Translation Topology

3.1.  Single stateless translation for servers - IVI

   The single stateless translation for servers using IVI is
   straightforward, as shown in Figure 2.







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            ------                        -----           ------
          /  The   \       -----        /        \      /  The   \
         |  IPv4    |-----| IVI |------|IPv6-only|-----|  IPv6    |
          \Internet/       -----        \servers /      \Internet/
            ------                        -----           ------

                               Figure 2: IVI

   The corresponding IETF documents are [RFC6145], [RFC6052] and
   [RFC6219].

   The authoritive A record is derived from IPv6-only servers AAAA
   recorded and manually configured in the DNS server.

   Thanks to the stateless technology, there are multiple 10G IVI
   translators and load balancing can be easily achieved.

3.2.  Double stateless translation for clients - MAP-T

   The double stateless translation for clients is a modified version of
   MAP-T [RFC7599].  Note that the original MAP-T is as shown in
   Figure 3.





























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         User N
       Private IPv4
      |  Network
      |
   O--+---------------O
   |  | MAP-T CE      |
   | +-----+--------+ |
   | NAPT44|  MAP-T | |
   | +-----+        | +-._   ,-------.                     .------.
   |       +--------+ |   ,-'         `-.                ,-'       `-.
   O------------------O  /              \   O---------O /   Public   \
                        /   IPv6 only    \  |  MAP-T  |/     IPv4     \
                       (    Network       --+  Border +-   Network     )
                        \                /  |  Relay  |\              /
   O------------------O  \              /   O---------O \             /
   |    MAP-T CE      |   ;".         ,-'                `-.       ,-'
   | +-----+--------+ | ,"   `----+--'                      ------'
   | NAPT44|  MAP-T | |,          |
   | +-----+        | +        IPv6 node(s)
   |   |   +--------+ |  (w/ v4-embedded-v6 address)
   O---+--------------O
       |
         User M
       Private IPv4
         Network

                       Figure 3: MAP-T Architecture

   For the campus network environment, there are some modifications for
   the MAP-T

   o  The IPv4 address sharing algorithm in the MAP-T BR is moved into
      MAP-T CE.  Therefore the first translator (IVI in Figure 1) is
      with the public IPv4 sharing ratio=1, and the 1:N address sharing
      function is performed in the second translator (MAPT in Figure 1).

   o  The IPv4-converted IPv6 addresses and IPv4-translatable IPv6
      addresses have the same prefix and prefix length [RFC6052].

   o  There are no additional IPv4 address sharing in NAPT44 of the
      MAP-T CE.

   Based on the measurement statistics, the public IPv4 address sharing
   ratio is configured to 1024.

   The multiple 10G IVI translators are shared with the single
   translation, the MAP-T translators are 1G equipment.  We have
   deployed MAP-T translators in more than 100 campus networks.



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4.  Observations and Experiences

4.1.  Effects on End-User

   For the IVI/MAP-T end-users in more than 100 campus networks, they
   are satisfied with IPv4aaS.  They did not notice that the services
   are provided via IPv4/IPv6 single/double translation.

4.2.  Effects on Internal Staff

   For IPv6-only servers provide IPv4 service via IVI, the management
   software is IPv6-only.  Note that the IPv4 addresses managed in the
   system is a subset in the IPv6 address space and this will
   dramatically reduce the programming load, since there is no need to
   treat IPv4 and IPv6 differently.

   For Dual-stack clients access IPv4 Internet via MAP-T, the management
   software is dual stack.  The existing dual stack user management
   software can be used.  The upper link of the second translator is
   IPv6-only, the IPv6 management software should be developed.  Note
   that the IPv4 addresses managed in the system is a subset in the IPv6
   address space and this will dramatically reduce the programming load,
   since there is no need to treat IPv4 and IPv6 differently.

4.3.  Effects on Business

   The IPv6-only server can provide the service directly for the IPv6
   Internet and to the IPv4 Internet via IVI.  Both CAPEX and OPEX are
   reduced compared with the dual stack.

   The service for the clients is via MAP-T with address sharing ratio
   1024.  This greatly reduce the requirements of the public IPv4
   addresses for deploying new networks.

5.  Summary: Post-mortem Report

   We are satisfied with the IVI/MAP-T deployment for IPv4aaS.  More
   campus networks are expected to move in this direction.

5.1.  Deviations from IETF Documents

   The base specifications the IPv4aaS in the deployment are defined in
   [RFC6145], [RFC6052], [RFC6146], [RFC6219], [RFC6147] and [RFC7599].
   As we discussed in this document, there are enhancements and
   modifications which will be presented in future documents.






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5.2.  The Suggestions for the IPv6 Transition

   Based on ten years experience, we found that IPv4aaS is a good model
   for the IPv6 transition.

   1.  The new networks should be IPv6.

   2.  Use native IPv6 if possible.

   3.  Use single stateless translation (IVI) for the IPv6-only servers
       and clients.

   4.  Use double stateless translation (MAP-T) for the dual-stack
       clients.

   5.  The practical IPv6 transition path should be from double
       translation to single translation and finally to native IPv6.

6.  IANA Considerations

   This specification does not require any IANA actions.

7.  Security Considerations

   There are no other special security considerations.

8.  Acknowledgements

9.  References

9.1.  Normative References

   [RFC6052]  Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X.
              Li, "IPv6 Addressing of IPv4/IPv6 Translators", RFC 6052,
              DOI 10.17487/RFC6052, October 2010,
              <http://www.rfc-editor.org/info/rfc6052>.

   [RFC6145]  Li, X., Bao, C., and F. Baker, "IP/ICMP Translation
              Algorithm", RFC 6145, DOI 10.17487/RFC6145, April 2011,
              <http://www.rfc-editor.org/info/rfc6145>.

   [RFC6146]  Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful
              NAT64: Network Address and Protocol Translation from IPv6
              Clients to IPv4 Servers", RFC 6146, DOI 10.17487/RFC6146,
              April 2011, <http://www.rfc-editor.org/info/rfc6146>.

   [RFC6147]  Bagnulo, M., Sullivan, A., Matthews, P., and I. van
              Beijnum, "DNS64: DNS Extensions for Network Address



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              Translation from IPv6 Clients to IPv4 Servers", RFC 6147,
              DOI 10.17487/RFC6147, April 2011,
              <http://www.rfc-editor.org/info/rfc6147>.

   [RFC7599]  Li, X., Bao, C., Dec, W., Ed., Troan, O., Matsushima, S.,
              and T. Murakami, "Mapping of Address and Port using
              Translation (MAP-T)", RFC 7599, DOI 10.17487/RFC7599,
              July 2015, <http://www.rfc-editor.org/info/rfc7599>.

9.2.  Informative References

   [RFC6144]  Baker, F., Li, X., Bao, C., and K. Yin, "Framework for
              IPv4/IPv6 Translation", RFC 6144, DOI 10.17487/RFC6144,
              April 2011, <http://www.rfc-editor.org/info/rfc6144>.

   [RFC6219]  Li, X., Bao, C., Chen, M., Zhang, H., and J. Wu, "The
              China Education and Research Network (CERNET) IVI
              Translation Design and Deployment for the IPv4/IPv6
              Coexistence and Transition", RFC 6219, DOI 10.17487/
              RFC6219, May 2011,
              <http://www.rfc-editor.org/info/rfc6219>.

Authors' Addresses

   Xing Li
   CERNET Center/Tsinghua University
   Room 225, Main Building, Tsinghua University
   Beijing,   100084
   China

   Phone: +86 10-62785983
   EMail: xing@cernet.edu.cn


   Congxiao Bao
   CERNET Center/Tsinghua University
   Room 225, Main Building, Tsinghua University
   Beijing,   100084
   China

   Phone: +86 10-62785983
   EMail: congxiao@cernet.edu.cn









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   Guoliang Han
   CERNET Center/Tsinghua University
   Room 225, Main Building, Tsinghua University
   Beijing  100084
   CN

   Phone: +86 10-62785983
   EMail: bupthgl@gmail.com


   Maojia Sheng
   CERNET Center/Tsinghua University
   Room 225, Main Building, Tsinghua University
   Beijing  100084
   CN

   Phone: +86 10-62785983
   EMail: ynsfsmj@foxmail.com

































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