Internet DRAFT - draft-yang-v6ops-fast6

draft-yang-v6ops-fast6






Internet Engineering Task Force                                    Y. Wu
Internet-Draft                                                    J. Tan
Intended status: Informational                                     Y. Li
Expires: September 31, 2013                                China Telecom
                                                          March 31, 2013        


Fundamental Architecture of Services Provider's network Transitioning to
                              IPv6 (FAST6)
                       draft-yang-v6ops-fast6-02

Abstract

   The IANA free pool of IPv4 addresses was depleted, IPv6 migration has
   become the most imperative task.  There are many transition
   mechanisms designed for different scenarios, however, some problems
   arosed in the practice.  FAST6, specified in this draft, is based on
   the ideas of native dual stack and address sharing.  It can solves
   the mixed route problem and simplify the planning of private IPv4
   address space by using tunnel technology.  FAST6 is an economical and
   stable technology for smooth network transition.

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 September 31, 2013.

Copyright Notice

   Copyright (c) 2012 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.  Requirements Language  . . . . . . . . . . . . . . . . . .  3
   2.  Terminologies  . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  FAST6 Architecture . . . . . . . . . . . . . . . . . . . . . .  4
     3.1.  FTS  . . . . . . . . . . . . . . . . . . . . . . . . . . .  5
     3.2.  FTN  . . . . . . . . . . . . . . . . . . . . . . . . . . .  5
   4.  FAST6 Tunnel South(FTS)  . . . . . . . . . . . . . . . . . . .  6
     4.1.  Definition . . . . . . . . . . . . . . . . . . . . . . . .  6
     4.2.  Encapsulation  . . . . . . . . . . . . . . . . . . . . . .  6
     4.3.  Fragmentation and Reassembly . . . . . . . . . . . . . . .  6
     4.4.  Discovery  . . . . . . . . . . . . . . . . . . . . . . . .  6
   5.  FAST6 Tunnel Nouth(FTN)  . . . . . . . . . . . . . . . . . . .  6
     5.1.  Definition . . . . . . . . . . . . . . . . . . . . . . . .  6
     5.2.  Encapsulation  . . . . . . . . . . . . . . . . . . . . . .  7
     5.3.  Resource Pool Maintenance  . . . . . . . . . . . . . . . .  7
     5.4.  FAST6 NAT  . . . . . . . . . . . . . . . . . . . . . . . .  7
     5.5.  address mapping table maintenance  . . . . . . . . . . . .  7
   6.  FAST6 Data Flow  . . . . . . . . . . . . . . . . . . . . . . .  8
   7.  FAST6 Deployment . . . . . . . . . . . . . . . . . . . . . . .  9
   8.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 11
   9.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 11
   10. Security Considerations  . . . . . . . . . . . . . . . . . . . 11
   11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
     11.1. Normative References . . . . . . . . . . . . . . . . . . . 12
     11.2. Informative References . . . . . . . . . . . . . . . . . . 12
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14
















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1.  Introduction

   As we known, available transition mechanisms have their
   own drawbacks in practice.  Nowadays, most applications don't
   support IPv6 and the protocol translation technologies, such as
   NAT64 which cannot help in the application level.Therefore it is
   necessary to provide the IPv4 and IPv6 service separately.  However,
   4over6 technology is a risky method for network migration since any
   troubles happen in the IPv6 network will influence the IPv4 service,
   especially in the period when IPv4 flows are dominant in the network.
   Simultaneously, 4over6 technology doesn't help to stimulate
   applications translation of ICPs who are unaware of the well prepared
   IPv6 network.  In the mean time, 6over4 technology is not proper
   for the continuously expanding network.  Native dual stack technology
   can avoid those problems essentially for it can provide dual stack
   service separately, making IPv4 decoupling from IPv6 and providing
   network environment for IPv6 service migration.  However, native dual
   stack is not enough and IP address sharing has to be used when the
   IPv4 addresses were exhausted.

   NAT444 seems to be a good solution except some carrier grade problems
   such as mixed routing (private address routing and public address
   routing), additional unified arrangement of private IPv4 address
   spaces among BNGs and so on.  All these problems will cause overload
   maintenance cost.  This document specifies the FAST6 technology,
   which is aimed at balancing the costs and benefits in service
   provider networks better.  FAST6 is based on native dual-stack.  By
   taking the advantages of tunnel technology and native dual-stack
   technology, FAST6 overcomes carrier grade NAT problems.  It
   stimulates the IPv6 migration and also decouples the IPv4 from IPv6,
   making network transition smoother and guaranteeing the user
   experience effectively.

   This document will first briefly introduce the overall architecture
   of FAST6 and then describe the detailed behaviors of FAST6 elements.
   It will then depict an intuitive example about FAST6 through data
   flow.  At last, we will present the FAST6 implementation in current
   network and show some of its advantages.

1.1.  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].







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2.  Terminologies

   The technology described in this document is known as FAST6.  The
   abbreviation "FAST6" will be used throughout this text.

   FAST6:      Fundamental Architecture of Services Provider's network
               Transitioning to IPv6

   FTN:        FAST6 tunnel North

   FTS:        FAST6 tunnel South.

   Resource Pool:  One of the element in FTN, including address pool,
               Tunnel ID-address pool mapping table, port resource pool.

   FAST6 NAT:  A module use triple-tuple for NAT.

   CR:         Core Router (CR) in a metropolitan area network is the
               egress router of the MAN and connecting to the ISP's
               backbone in upstream and connecting to BRASs for
               downstream.

   BNG:        Broadband Network Gateway, BRAS and SR

   Dual stack: Defined in RFC 4213

   Nat related terminology:  Defined in RFC 1417

   IP-in-IP tunnel:  Defined in RFC 2003


3.  FAST6 Architecture

   FAST6 consists of two functional modules.  One is FTS (FAST6 tunnel
   south) , the other is FTN(FAST6 tunnel north).  FTS is the tunnel
   endpoint present at the user side.  FTN is the tunnel endpoint
   present at the network side.














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                      +-----+-----+ +-----+-----+
                      |  IPv4 host| |  IPv6 host|
                      +-----------+ +-----------+
                            |              |
                    --------|--------------|------
                  /         |              |       \
                 |       Internet          |        |
                  \         |              |       /
                    --------|--------------|------
        |-------------------|--------------|--------------|
        |          +-------------------+   |        FAST6 |
        |          |        FTN        |   |              |
        |          +---------|---------+   |              |
        |                   |||            |              |
        |                   ||| IP in IP Tunnel           |
        |          +-------------------+   |              |
        |          |        FTS        |   |              |
        |          +---------|---------+   |              |
        |                    |             |              |
        |____________________|_____________|______________|
                       +-----+-----+       |
                       |  CPE/ host|-------|
                       +-----------+

                       Figure 1:  FAST6 architecture

3.1.  FTS

   As the tunnel endpoint at user side, FTS is responsible for
   encapsulating private IPv4 packet within a public IPv4 packet to
   establish an IP-in-IP tunnel, or decapsulating private IPv4 packet
   from the tunnel.

3.2.  FTN

   FTN is the tunnel endpoint at network side.  It has four functions:
   encapsulation and decapsulation, address translation, address mapping
   table maintenance, resource pool maintenance.

   From south to north, FTN decapsulates the private IP address packet
   from the tunnel, marking the public IPv4 address as the tunnel ID and
   finding the corresponding IP address pool and port resource in the
   resource pool based on the tunnel ID.  Then FTN replaces the private
   IPv4 address header with the public IPv4 address header and generates
   an address mapping entry.

   From the north to south, FTN searches the address mapping table for
   the corresponding triple tuple ( tunnel ID, private address, port)



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   according to the received public IPv4 address and port.  Then FTN
   forwards the packet to the corresponding tunnel.


4.  FAST6 Tunnel South(FTS)

4.1.  Definition

   As defined above, FTS is a function module used to establish the
   IPv4-in-IPv4 tunnel to FTN, encapsulating and decapsulating the
   packet.

4.2.  Encapsulation

   FTS uses a public IPv4 address to encapsulate the private IPv4
   packet.  The packet encapsulation structure is as below.

                      +-----+-----+-----+-----+-----+-----+
                      |Public IPv4|private IPv4|payload   |
                      +-----------+-----------+-----------+

                    Figure 2: The encapsulation module

   For the encapsulation format and parameters, please refer to RFC2003
   and other encapsulation mode will be considered in the future.

4.3.  Fragmentation and Reassembly

   The encapsulation of IPv4 packet over IPv4 packet will increase 20
   extra bytes in IP headerGBP[not]it is necessary for the service
   provider to manually increase the MTU size for all the links between
   the FTS element and the FTN elements, by at least 20 bytes to
   accommodate both the IPv4 encapsulation header and the IPv4 datagram
   without fragmenting the IPv4 packet.

4.4.  Discovery

   The number of FTSs (the number of the tunnels) is very limited, so
   the IPv4-in-IPv4 tunnel establishment between FTN and FTS can be
   configured manually.


5.  FAST6 Tunnel Nouth(FTN)

5.1.  Definition

   As defined above, FTN has four functions: encapsulation and
   decapsulation, address translation, address mapping table



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   maintenance, resource pool maintenance.

        +----------------------------------------------------+
        |resource pool                                       |
        |  +-------------------+  +----------+ +-----------+ |
        |  |tunnel ID-address pool|address pool| port resource
        |  |mapping table      |  |          | |           | |
        |  +---------|---------+  +-----|----+ +-|---------+ |
        +------------|------------------ /------/------------+
                     |                  /      /
          +------+  +-----------------+/      / +---------------+
          | encap|  |address traslation------/  | mapping table |
          | decap|  |                 |         |               |
          +----- +  +-----------------+         +---------------+

                        Figure 3: FTN architecture

5.2.  Encapsulation

   The encapsulation format of FTN is the same as FTS.  The
   fragmentation and reassembly mode are also the same as FTS.

5.3.  Resource Pool Maintenance

   The resource pool includes the !otunnel ID "C IP address pool!+/-
   mapping table, address pool and port resource pool.  The planning of
   address pool depends on the specific network deployment.  Usually,
   each tunnel ID has its own IP address pool.  In addition, the
   resource pool has to maintain the available port resource and address
   for each address pool.

5.4.  FAST6 NAT

   From south to north, FTN assign a public address and port after
   checking the resource table according to the triple tuple (Tunnel ID,
   private address, port).  From north to south, FTN searches the
   address mapping table after receiving the packet and finds the
   corresponding tunnel ID, private address and port information, then
   forwards the packet to corresponding tunnel.

5.5.  address mapping table maintenance

   From south to north, FTN will generate a network address mapping
   table.  The parameters listed in the entry is in the following order:
   GBP"converted public IPv4 address, converted port, tunnel ID, private
   IPv4 address, port).





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6.  FAST6 Data Flow

   The following picture describes the procedure of accessing internet
   from user end through FAST6.  Users visit the IPv4 internet resources
   through IPv4 network and use IPv6 network to access the IPv6 internet
   resources.

                      +-----+-----+ +-----+-----+
                      |  IPv4 host| |  IPv6 host|
                      +-----------+ +-----------+
                            |              |
                    --------|--------------|-----
                  /         |              |      \
                 |       Internet          |       |
                  \         |              |      /
                    --------|--------------|------
        |--------120.0.0.1--|--------------|--------------|
        |          +-------------------+   |        FAST6 |
        |          |        FTN        |   |              |
        |          +---------|---------+   |              |
        |                   |||            |              |
        |         59.43.0.1 ||| IPv4-in-IPv4 Tunnel       |
        |          +-------------------+   |              |
        |          |        FTS        |   |              |
        |          +---------|---------+   |              |
        |                    |             |              |
        |___________10.0.1.1_|_____________|______________|
                       +-----+-----+       |
                       |  CPE/ host|-------|
                       +-----------+

                         Figure 4: FAST6 Data Flow

   Customer 1 sends a TCP packet with source address 10.0.1.1 and port
   1000 to the ICP server whose address is 198.8.8.8.  When the packet
   arrives at the FTS, FTS encapsulates the private IPv4 packet in a
   public IPv4 header (59.43.0.1) with the destination 59.43.0.2, the
   other end of tunnel.  When the packet arrives at the FTN, FTN
   decapsulates it , checks the corresponding IP address pool based on
   Tunnel ID and chooses 120.0.0.1 and port 2000 to replace the former
   header.  Then FTN generates a mapping
   entryGBP"120.0.0.1,2000,59.43.0.2,10.0.1.1,1000GBP(C).

   From north to south, when FTN receives the packet with the
   destination address 120.0.0.1/2000, it checks the address mapping
   table , finds the
   entryGBP"120.0.0.1,2000,59.43.0.2,10.0.1.1,1000GBP(C)and forwards the
   packet to tunnel established by FTS1 according to the last 3



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   parameters.

              +-----------------+--------------+-----------------+
              |        Datagram | Header field | Contents        |
              +-----------------+--------------+-----------------+
              | IPv4 datagram 1 |     IPv4 Dst | 198.8.8.8       |
              |                 |     IPv4 Src | 10.0.0.1        |
              |                 |      TCP Dst | 80              |
              |                 |      TCP Src | 1000            |
              | --------------- | ------------ | -------------   |
              | IPv4 datagram 2 |IPv4 Dst outer| 59.43.0.2       |
              |                 |IPv4 Src outer| 59.43.0.1       |
              |                 |     IPv4 Dst | 198.8.8.8       |
              |                 |     IPv4 Src | 10.0.0.1        |
              |                 |      TCP Dst | 80              |
              |                 |      TCP Src | 1000            |
              | --------------- | ------------ | -------------   |
              | IPv4 datagram 3 |     IPv4 Dst | 198.8.8..8      |
              |                 |     IPv4 Src | 120.0.0.1       |
              |                 |      TCP Dst | 80              |
              |                 |      TCP Src | 2000            |
              +-----------------+--------------+-----------------+

                 Figure 5: packet header translation table


7.  FAST6 Deployment

   This chapter will briefly introduce the FAST6 deployment in real
   network and some of its advantages.  The following picture only
   depicts IPv4 part of FAST6.The detailed deployment, cutover and
   network transition will be stated in other document.



















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                        +-----+-----+
                        |  IPv4 host|
                        +-----------+
                              |
                      --------|------------
                    /         |             \
                   |       Internet          |
                    \         |             /
                      --------|-------------
                              |
                 +---------------------------+
                 |              CR           |
                 +---|---------|---------|---+
                     |         |         |
                  120.0.0.1  120.0.0.2  120.0.1.1
                 +----------------------------+
                 |            FTN             |
                 +----------------------------+
                 ||         ||       \\
                 ||         ||        \\
         59.43.0.1       59.43.0.3    59.43.0.5
        +------//----BNG1--//----+    + \\---BNG2-----+
        |     ||          ||     |    |  \\           |
        | +--//----+  +--//----+ |    | +-\\-----+    |
        | |  FTS   |  |  FTS   | |    | |  FTS   |    |
        | +---|----+  +---|----+ |    | +--|-----+    |
        +-----|-----------|------+    +----|----------+
         10.0.1.1     10.0.1.2         10.0.1.1
        +-----+-----+  +-----+-----+   +-----+-----+
        |  host1    |  | host2     |   |  host3    |
        +-----------+  +-----------+   +-----------+


                        Figure 6: FAST6 Deployment

   FAST6 is suitable for layer 2 and layer3 access modes.  The FTS
   component can be installed in BNG equipments tunnel interface.  The
   FTN unit is similar to CGN device and can be embedded in the CR as a
   card or deployed as an independent device.

   FAST6 can eliminate the mixed routing problem by establish a tunnel
   from BNG to FTN.  In the mean time, since it uses the public address
   as the tunnel ID to separate different BNGs, the private address pool
   can be overlapped among BNGs, saving the workload for arranging the
   private IPv4 address pool in the whole network uniformly.  Besides,
   since FTS can be configured in the ingress direction of user
   interface on BNG, the tunnel can also isolate the mixed route within
   the device.  This feature fits BNG for providing multiple services



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   which are running behind different address distribution policies (for
   example, private address for common users and public address for VIP
   customers.).

   The IPv4 address used for tunnel encapsulation is different for
   different FTS.  The address pool can be overlapped for each FTS.  FTS
   can be deployed flexibly in centralized and distributed form in the
   network depending on private IPv4 traffic flow amount.  When the FTN
   is distributed, FTN and FTS may probably be in the same card in this
   case, FAST6 is as same as NAT444.

   In addition, FAST6 have some the following advantages:

   (1) Retaining the current access method and customer behaviors,
   modifications of CPE are not required.

   (2) Providing dual stack services for users, no need for protocol
   translation and consequently decreasing the influence on
   applications.

   (3) Easier for troubleshooting.  IPv4 is decoupled from IPv6, so it
   will not be influenced by IPv6.

   (4) Suitable for the initial period of network transition, and it can
   be seamlessly compatible with any other technologies used for later
   stage of transition.


8.  Acknowledgements

   TBD...


9.  IANA Considerations

   This memo includes no request to IANA.


10.  Security Considerations

   This document has no impact on the security properties of specific
   IPv6 transition tools.  When introducing IPv6, it is important to
   ensure that the necessary security capabilities exist on the network
   components even when dealing with IPv6 traffic.  The security issues
   should be considered when deploying any transition technology.  For
   instance, firewall and logging system for illegal activity tracing is
   still a challenge in IPv6 and NAT deployments.




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11.  References

11.1.  Normative References

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

   [min_ref]  authSurName, authInitials., "Minimal Reference", 2012.

11.2.  Informative References

   [I-D.arkko-ipv6-transition-guidelines]
              Arkko, J. and F. Baker, "Guidelines for Using IPv6
              Transition Mechanisms during IPv6 Deployment",
              draft-arkko-ipv6-transition-guidelines-14 (work in
              progress), December 2010.

   [I-D.ietf-behave-lsn-requirements]
              Perreault, S., Yamagata, I., Miyakawa, S., Nakagawa, A.,
              and H. Ashida, "Common requirements for Carrier Grade NATs
              (CGNs)", draft-ietf-behave-lsn-requirements-05 (work in
              progress), November 2011.

   [I-D.ietf-softwire-dual-stack-lite]
              Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual-
              Stack Lite Broadband Deployments Following IPv4
              Exhaustion", draft-ietf-softwire-dual-stack-lite-10 (work
              in progress), May 2011.

   [I-D.kuarsingh-lsn-deployment]
              Kuarsingh, V. and J. Cianfarani, "NAT44/LSN Deployment
              Options and Experiences",
              draft-kuarsingh-lsn-deployment-01 (work in progress),
              January 2011.

   [I-D.shirasaki-nat444]
              Yamagata, I., Shirasaki, Y., Nakagawa, A., Yamaguchi, J.,
              and H. Ashida, "NAT444", draft-shirasaki-nat444-03 (work
              in progress), January 2011.

   [I-D.shirasaki-nat444-isp-shared-addr]
              Shirasaki, Y., Miyakawa, S., Nakagawa, A., Yamaguchi, J.,
              and H. Ashida, "NAT444 addressing models",
              draft-shirasaki-nat444-isp-shared-addr-05 (work in
              progress), January 2011.

   [I-D.yang-v6ops-fast6-tools-selection]
              Yang, G. and C. Huang, "The analysis of tools selection



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              for broadband ISP",
              draft-yang-v6ops-fast6-tools-selection-00 (work in
              progress), May 2011.

   [RFC1661]  Simpson, W., "The Point-to-Point Protocol (PPP)", STD 51,
              RFC 1661, July 1994.

   [RFC1918]  Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and
              E. Lear, "Address Allocation for Private Internets",
              BCP 5, RFC 1918, February 1996.

   [RFC2516]  Mamakos, L., Lidl, K., Evarts, J., Carrel, D., Simone, D.,
              and R. Wheeler, "A Method for Transmitting PPP Over
              Ethernet (PPPoE)", RFC 2516, February 1999.

   [RFC2661]  Townsley, W., Valencia, A., Rubens, A., Pall, G., Zorn,
              G., and B. Palter, "Layer Two Tunneling Protocol "L2TP"",
              RFC 2661, August 1999.

   [RFC3022]  Srisuresh, P. and K. Egevang, "Traditional IP Network
              Address Translator (Traditional NAT)", RFC 3022,
              January 2001.

   [RFC4029]  Lind, M., Ksinant, V., Park, S., Baudot, A., and P.
              Savola, "Scenarios and Analysis for Introducing IPv6 into
              ISP Networks", RFC 4029, March 2005.

   [RFC4213]  Nordmark, E. and R. Gilligan, "Basic Transition Mechanisms
              for IPv6 Hosts and Routers", RFC 4213, October 2005.

   [RFC4241]  Shirasaki, Y., Miyakawa, S., Yamasaki, T., and A.
              Takenouchi, "A Model of IPv6/IPv4 Dual Stack Internet
              Access Service", RFC 4241, December 2005.

   [RFC5569]  Despres, R., "IPv6 Rapid Deployment on IPv4
              Infrastructures (6rd)", RFC 5569, January 2010.

   [RFC5969]  Townsley, W. and O. Troan, "IPv6 Rapid Deployment on IPv4
              Infrastructures (6rd) -- Protocol Specification",
              RFC 5969, August 2010.

   [RFC6036]  Carpenter, B. and S. Jiang, "Emerging Service Provider
              Scenarios for IPv6 Deployment", RFC 6036, October 2010.

   [RFC6146]  Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful
              NAT64: Network Address and Protocol Translation from IPv6
              Clients to IPv4 Servers", RFC 6146, April 2011.




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Authors' Addresses

   Youming Wu
   China Telecom
   109, Zhongshan Ave. West,
   Guangzhou, Tianhe District  510630
   P.R. China

   Phone:
   Email: 13316090389@189.cn

   Jinhua Tan
   China Telecom
   109, Zhongshan Ave. West,
   Guangzhou, Tianhe District  510630
   P.R. China

   Phone:
   Email: 13316097209@189.cn
   
   YangChun Li
   China Telecom
   109, Zhongshan Ave. West,
   Guangzhou, Tianhe District  510630
   P.R. China

   Phone:
   Email: liyc_gsta@189.cn


   



















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