v6ops X. Li
Internet-Draft C. Bao
Intended status: Informational G. Han
Expires: April 20, 2018 M. Sheng
CERNET Center/Tsinghua
University
October 17, 2017
CERNET deployment of IVI/MAP-T in an IPv6-only network
draft-xli-v6ops-cernet-deployment-03
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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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,
<https://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,
<https://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, <https://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,
<https://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, <https://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, <https://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,
<https://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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