V6OPS Working Group                                               C. Xie
Internet-Draft                                                     C. Li
Intended status: Informational                                     C. Ma
Expires: January 8, 2021                                         Q. Yuan
                                                           China Telecom
                                                            July 7, 2020

          IPv6 development and current status of China Telecom


   The draft presents China Telecom's deployment of IPv6 in multiple
   scenarios for the whole network transition, including the history,
   transition strategy, measurements and challenges.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
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   This Internet-Draft will expire on January 8, 2021.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   2
   3.  Retrospection . . . . . . . . . . . . . . . . . . . . . . . .   2
   4.  IPv6 deployment in multiple scenarios . . . . . . . . . . . .   3
   5.  IPv6 measurement  . . . . . . . . . . . . . . . . . . . . . .   5
   6.  Challenges  . . . . . . . . . . . . . . . . . . . . . . . . .   6
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   7
   9.  Normative References  . . . . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   As one of the 3 operators in China, China Telecom not only provides
   voice, household broadband and mobile services to public customers,
   but also provides leased-line, VPN, IDC and cloud computing services
   to enterprise customers.  Up to now, the quantities of mobile users
   and household users have reached to 308 million and 123 million
   respectively, of which 267 million are LTE/4G users.  With the
   evolution of mobile networks, China Telecom has begun to provide SA-
   based 5G services.  In addition, China Telecom also provides oversea
   services in some regions, for instances, North America, Europe and
   Australia, etc.

   To support the services provisioning for tremendous amount of users
   in different scenarios, a large-scale IP infrastructure has been
   setup and operated.  This document presents IPv6 deployment in the
   large-scale IP infrastructure of China Telecom, including its
   history, deployment strategy, measurements and challenges.

2.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

3.  Retrospection

   China Telecom's IPv6 work can trace back to 2001, considering that
   IPv6 is the future of IP network and IPv4 address will be exhausted
   sooner or later, China Telecom begun to test IPv6 over ADSL network,
   and successfully tunneled through the workflow of IPv4/IPv6 dual-
   stack service in broadband network then.

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   In 2012, IPv6 deployment field-trial for MANs (i.e., Metro Area
   Network) was implemented in Jiangsu and Hunan Provinces, Dual-
   stack([RFC4787]), DS-Lite([RFC6333]) and Lightweight
   4over6([RFC7596]) and IVI([RFC6144]) were tested in the trial.  After
   the field trial IPv6 capability expanded and covered more than 10
   million users.

   Particularly, since Chinese government launched the IPv6 action plan
   in 2017 November, IPv6 commercial deployment was accelerated and
   extended to nearly every part of the network infrastructure,
   including enable IPv6 in the cloud computing platform, which is
   essential for customer to enable IPv6 in their application system.
   After more than two years efforts, comprehensive IPv6 deployment in
   the IP infrastructure have been achieved.

4.  IPv6 deployment in multiple scenarios

   China Telecom's IP infrastructure is an multi-AS system,as
   shown in figure 1,it consists of backbone networks, MANs, IP RAN,
   EPC(i.e., mobile core network of LTE), IDCs, cloud resource pools,

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        .------.                 .-----.                .-----.
       /        \               /       \              /       \
      /  Other   \             / Foreign \            / Foreign \
     (  Domestic  )           ( Operators )          ( Operators )
      \Operators /             \         /            \         /
       \        /               \       /              \       /
        `----- '\               /`-----'                `--+--'
                 \             /                           |
                  \           /                            |
                   \         /                             |
                    \.-----./                           .--+--.
                   /        \                          /       \
                  /          \                        /         \
                 (  ChinaNet  )--------------------- (    CN2    )
                  \          /                        \         /
                   \        /                          \       /
                    `------'\                           /--+--'
                       |     \                         /   |
                       |      \                       /    |
                       |       \                     /     |
                _______|______  \ _________________ /  ____|_________
               |              |  |                 |  |              |
               |     MANs/    |  |    IDCs/Cloud   |  | 4G/5G Mobile |
               |    IPRANs    |  |                 |  | Core Networks|
               +--------------+  +-----------------+  +--------------+

         Figure 1: Overall architecture of network infrastructure

   There are two inter-connected backbone networks, ChinaNet and CN2,
   both have not only nation-wide coverage, but also have some oversea
   POPs.  The two backbones provide high-speed data switching
   domestically and overseas.  MANs, EPCs, IDC and cloud resource pools
   are connected to the two backbones.  ChinaNet is native-IP network,
   which provides high-speed data transfer for wireline and wireless
   broadband Internet-access and communications between different
   regions.  In order to support IPv6 inter-connectivity for other local
   networks, all the routers in ChinaNet have been IPv6-enabled and
   operate in IPv4/IPv6 dual-stack mode.  Different from ChinaNet, CN2
   is a MPLS-based network, which mainly focuses on service provisioning
   to enterprise customers and some services with high-quality
   requirements.  CN2 has enabled 6VPE and 6PE in its equipment,
   therefore, it can provide high-speed IPv6 data switching and IPv6 VPN
   to enterprise customers.

   Currently MANs mainly uses dual-stack approaches, due to the shortage
   of IPv4 address, most users are allocated with private address by
   BRAS/BNGs.  From 2012, multiple types of transition technologies,
   such as Dual-stack, DS-Lite, Lightweight 4over6, and IVI, were

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   evaluated in the field trial, this process is nearly in parallel with
   that of standardization in IETF, and most of the transition
   techniques were in the stage of draft then.  In order to support
   multiple transition techniques, the supportive system of MANs was
   upgraded to support dynamic selection of transition approaches based
   on the type of CPEs and availability of the resource in the network
   locally.  However, due to the fact that most transition techniques do
   not gain commercial support in CPEs, MANs later adopted dual-stack
   approach for household users, and CGN module has been installed in
   BRAS/BNGs for private and public address translation.

   Same to the MANs, EPC of LTE also runs in dual-stack mode.  When IPv6
   deployment in LTE begun in 2015, it was required to switch on the
   IPv6 protocol in the user plane of EPC and each user was allocated
   one /64 Prefix of IPv6 and IPv4 address simultaneously.  It should be
   noted that EPC network of LTE is constructed on the provincial basis,
   and each province has a set of EPC network, so for a given province,
   when IPv6 capability is turned on in the EPC, every user's UE in this
   province can get IPv6 address unless it does not support IPv6.  Since
   IPv6 has good support in the UEs of LTE, IPv6 penetration rate of
   mobile user is higher than that of wireline user.

   IDC is a place to provide stable and broadband networks with high
   performance computers as a service to their customers it is another
   scenario for IPv6.  As the largest IDC providers, China Telecom has
   upgraded all its IDCs to support IPv6.  In addition, China Telecom
   also provides cloud services and products based on the cloud resource
   pools located in different regions of China, currently more than 50
   cloud products are IPv6-capable,e.g., Elastic virtual machine, ELB,
   Cloud desktop, Elastic IP, GPU virtual machine, which makes it
   possible to provide IPv6-based network-cloud-convergence services to

   Regarding to the IPv6 interconnection with other carriers, China
   Telecom has setup IPv6-BGP peers with domestic partners, e.g., China
   Mobile, China Unicom and CERNET, and the total bandwidth reaches to
   5.4 Tbps in 13 inter-connection points, and also setup IPv6 BGP
   connections with some giant global ISPs.

5.  IPv6 measurement

   In order to see how broadly IPv6 is being used in China, a
   measurement system was developed by CAICT (i.e., Chinese Academy of
   Information and Communications Technology).  All the major networks,
   including those of China Telecom, participate in the measurement.
   The metrics that can be measured include user penetration rate,
   traffic volume, end-to-end performance, etc.  The measurement has
   been running continuously and the result can be presented in real

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   From the measurement, it can be seen that the quantity of user who
   are allocated IPv6 address has increased dramatically during the last
   two years.  However, compared with the quantity of user who are
   allocated IPv6 address, the quantity of active user deserves more
   attention, herein, the term of "active IPv6 user" refers to the user
   who have at least one visit of IPv6 content within one month.  Recent
   measurement shows that the rate of active IPv6 users in Mobile
   network is about 79 percent.  However, this metric in wireline
   network is about 30 percent, much lower than that of LTE network.
   This difference is mainly caused by the low rate of IPv6-capble home

   It should be noted that the data in this draft only shows the current
   status, the measurement result changes over time.

6.  Challenges

   Although IPv6 has gained widely deployment in China Telecom and most
   users have been allocated IPv6 addresses, several challenges still
   face operators.  Regarding to the usage of IPv6, traffic volume of
   IPv6 is still much lower than that of IPv4, and the rates of IPv6
   traffic of mobile network and wireline network are about 8.8 percent
   and 2 percent respectively, it is supposed that this is mainly due to
   the reasons below.

   1.  Low rate of IPv6 support in home CPEs: As a matter of fact, a
       portion of home CPEs are not customized by operators.  CPE
       routers can be purchased from online shop and installed at home
       without any allowance of operators, some types do not support
       IPv6 at all.  This factor makes it difficult to improve the
       penetrate rate and IPv6 traffic.  However, there is good news
       that after realizing this problem, the IPv6 community has jointly
       pushed the vendors of CPE router to improve IPv6 support in their

   2.  Slow transition on contents' side:Compared with the transition of
       network operators, the transition of content's side is relatively
       slow.  One reason is that service layer transition depends on the
       IPv6 capability of low-layer infrastructure, such as CDNs and
       IDCs; they are required to support IPv6 in advance.  Another
       reason behind this is that content providers are very concerned
       about the end-to-end performance of the IPv6 networks, so even
       though IPv6 has been implemented in their products, they are
       still very cautious to switch from IPv4 to IPv6 in clients
       software, and the IPv6 coverage is increased step by step based
       on the result of performance test.  One the other side, some OTTs

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       has taken bold step to use IPv6, for instance, the measurement
       show that the rate of IPv6 traffic of Youku, which is one of the
       largest video providers in China, is more than 70 percent.

   Although Challenges lies ahead, China Telecom will persistently push
   forward the deployment and utilization of IPv6.  Take advantages of
   ubiquitous IPv6 deployment, SRv6 field trial has been implemented in
   several use cases, including MAN, Mobile transport network, anti-
   DDOS, etc.  Particularly, IPv6 will be planned to be used in new
   scenarios, such as IOT and network-cloud-convergence, and the
   transition to IPv6-only will be explored in the coming future.

7.  Security Considerations


8.  Acknowledgements

   During the long period, China Telecom's IPv6 deployment has received
   strong support from lots of people, some of them are Xing Li, Fred
   Baker, Latif Ladid, Zhenbin Li, Hui Tian, Shucheng Liu, Geoff Huston,
   Dong Liu, Yan Ma, etc.

9.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,

   [RFC4787]  Audet, F., Ed. and C. Jennings, "Network Address
              Translation (NAT) Behavioral Requirements for Unicast
              UDP", BCP 127, RFC 4787, DOI 10.17487/RFC4787, January
              2007, <https://www.rfc-editor.org/info/rfc4787>.

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

   [RFC6333]  Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual-
              Stack Lite Broadband Deployments Following IPv4
              Exhaustion", RFC 6333, DOI 10.17487/RFC6333, August 2011,

   [RFC7219]  Bagnulo, M. and A. Garcia-Martinez, "SEcure Neighbor
              Discovery (SEND) Source Address Validation Improvement
              (SAVI)", RFC 7219, DOI 10.17487/RFC7219, May 2014,

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   [RFC7596]  Cui, Y., Sun, Q., Boucadair, M., Tsou, T., Lee, Y., and I.
              Farrer, "Lightweight 4over6: An Extension to the Dual-
              Stack Lite Architecture", RFC 7596, DOI 10.17487/RFC7596,
              July 2015, <https://www.rfc-editor.org/info/rfc7596>.

   [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, <https://www.rfc-editor.org/info/rfc7599>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [RFC8200]  Deering, S. and R. Hinden, "Internet Protocol, Version 6
              (IPv6) Specification", STD 86, RFC 8200,
              DOI 10.17487/RFC8200, July 2017,

Authors' Addresses

   Chongfeng Xie
   China Telecom

   Email: xiechf@chinatelecom.cn

   Cong Li
   China Telecom

   Email: licong@chinatelecom.cn

   Chenhao Ma
   China Telecom

   Email: machh@chinatelecom.cn

   Quanxin Yuan
   China Telecom

   Email: yuanqx@chinatelecom.cn

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