v6ops Q. Sun
Internet-Draft C. Xie
Intended status: Informational China Telecom
Expires: November 7, 2011 J. Qin
ZTE
Q. Liu
China Telecom
D. Liu
BII Group
May 6, 2011
Rapid Transition of IPv4 contents to IPv6-accessible
draft-sunq-v6ops-contents-transition-00
Abstract
This document describes one deployment model of NAT64, aiming to
rapidly increase the amount of contents which are IPv6 accessible for
users from IPv6 Internet.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . . 3
2. Deployment Scenario . . . . . . . . . . . . . . . . . . . . . . 4
3. Overall procedure . . . . . . . . . . . . . . . . . . . . . . . 4
4. 5. Deployment Considerations . . . . . . . . . . . . . . . . . 5
4.1. Stateful Translation . . . . . . . . . . . . . . . . . . . 5
4.2. Addressing and mapping . . . . . . . . . . . . . . . . . . 5
4.3. DNS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4.4. Capacity . . . . . . . . . . . . . . . . . . . . . . . . . 5
4.5. Traffic Logging and User Management . . . . . . . . . . . . 5
4.6. ALG . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
7. Security Considerations . . . . . . . . . . . . . . . . . . . . 6
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6
8.1. Normative References . . . . . . . . . . . . . . . . . . . 6
8.2. Informative References . . . . . . . . . . . . . . . . . . 7
Appendix A. Deployment Example . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7
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1. Introduction
The global IPv4 address depletion becomes a reality. Although the
IPv4 to IPv6 transition is considered inevitable, deployments of IPv6
are still quite limited as this document is written. Facing the
pressure of IPv4 address shortage, the operaters may like to provide
services through IPv6 in some wayes. However, compared to the
readiness of operaters' infrastructures, the IPv6 transition on the
content provider and end user sides moves even more slowly.
There have been statements from several popular content providers
that they have turned on, or planned to turn on IPv6 soon, which do
have a beneficial effect on encouraging end users to transit to
IPv6. While given the operational cost and the risk to the
continuity of service delivery, compared to the number of active IPv6
users currently, it is difficult to convince much more content
providers (especially conservative ones and, the great many ones of
small-to-medium size) to immediately enable IPv6 and make their
publically-facing services accessible through IPv6 natively. On the
other hand, from the users' perspective the IPv6 reachability of
resources required for their daily lives is one of the foremost
factors that they concern when making the decision on whether or not
to access Internet using IPv6. It is a chicken or egg dilemma, but
the two perspectives are interdependent. If the transition of one
side passes the point of inflexion, the other side will be speeded up
after. So, more efforts are needed to encourage the IPv6 adoption
and reach the point.
This document describes one deployment model of
[I-D.ietf-behave-v6v4-xlate-stateful], aiming at rapidly increasing
the amount of IPv6 reachable contents for users from IPv6 Internet.
The contents can be still accessible through IPv4. While this must
not be used as a long-term solution, and the native transition of
contents should always be recommended.
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 [RFC2119].
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2. Deployment Scenario
+-----+
| DNS |
+-----+
\
\
+----------------+ +--------------+
| IDC | +-------+ | IPv6 |
| | --- | Xlate | --- | Internet |
| +--------+ | +-------+ +--------------+
| | IPv4 | |
| | Server | | +--------------+
| +--------+ | --------------- | IPv4 |
| | | Internet |
+----------------+ +--------------+
The NAT64 gateway is deployed between the IPv6 Internet and the IPv4
server. An IPv6 prefix is assigned to embed the IPv4 addresses of
the server then form IPv6 addresses (per [RFC6052]) which are used
for AAAA records adding. The route of the IPv6 prefix should be
advertised by the NAT64 gateway to IPv6 Internet. Also, an IPv4
address pool is needed on the Xlate to translate IPv6 packets to
IPv4. Private addresses (e.g. 10/8) may be used.
3. Overall procedure
Before initiating a session, generally an IPv6 user will do a DNS
lookup to get the AAAA records and learn the addresses of the host to
be accessed. In this case, the IPv6 addresses learned through AAAA
records are those translated from the IPv4 addresses of the server.
In this deployment model, the NAT64 gateway will perform the
translation from IPv6 to IPv4, and vice versa. The communication is
initiated by the IPv6 side. When an IPv6 packet arrives, a lookup of
the mapping table will take place to get the IPv4 address used for
translation. If there is no one matched, a new entry will be
created.
1:1 mapping is employed in the context of this deployment model,
which would simplify the packet processing procedure.Then, the
translated packet with private IPv4 address would be sent to the IPv4
server.
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4. 5. Deployment Considerations
4.1. Stateful Translation
The translation functions are specified in
[I-D.ietf-behave-v6v4-xlate-stateful], which allows clients from IPv6
Internet to contact IPv4 server in Data Center.
4.2. Addressing and mapping
To save global IPv4 addresses which become scarce resources, private
blocks, for instance 10.0.0.0/8 can be used by the NAT64 gateway for
Stateful NAT64 operations. Since the scenario of server side is
different from that of client side and considering the capacity of
devices for the scale of traffic in the foreseeable future, we choose
1:1 address mapping (one IPv6 address mapped to one private IPv4
address). In this way, the problems introduced by address sharing
could be avoided and the efficiency of NAT64 operations could be
improved (Refer to Section 4.4 for capacity considerations).
Note that Conflicts might happen when the same private address space
is used for the interconnection of servers internally. (e.g., for
Load Balancing)
An IPv6 prefix is needed to represent the IPv4 servers, and the route
of the prefix should be advertised to the IPv6 Internet.
4.3. DNS
Correspondingly, the AAAA records are needed to serve the end users
from IPv6 Internet. Two methods could be considered: deploying the
DNS64 along with the NAT64 gateway to respond the queries from IPv6
Internet with dynamically formed AAAA records; manually adding AAAA
records based on translated addresses into the authorized name
servers, some auto-configuration tools may be used.
...
4.4. Capacity
In theory, about 16 million sessions can be established
simultaneously if for example the 10.0.0.0/8 block is used for 1:1
stateful NAT64 in the configured-lifetime.
4.5. Traffic Logging and User Management
Traffic logging and user management is important. Since only 1:1
addressing mapping is used in this model, traffic logging system will
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be substaintially simplified to record IPv6 end-user address,
translated IPv4 address, timestamp and lifetime.
The traffic statistics can be used by content providers as a
reference when setting out the timetable of native transition.
4.6. ALG
Only limited ALGs need to be deployed in NAT64 gateway according to
the services provided.
5. Acknowledgements
TBD
6. IANA Considerations
This document includes no request to IANA.
7. Security Considerations
Some malicious attackers can send a large number of IPv6 packets with
different forged source IPv6 addresses, to rapidly deplete the IPv4
address pool, which is a kind of DOS attack.
8. References
8.1. Normative References
[I-D.ietf-behave-v6v4-xlate-stateful]
Bagnulo, M., Matthews, P., and I. Beijnum, "Stateful
NAT64: Network Address and Protocol Translation from IPv6
Clients to IPv4 Servers",
draft-ietf-behave-v6v4-xlate-stateful-12 (work in
progress), July 2010.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC6052] Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X.
Li, "IPv6 Addressing of IPv4/IPv6 Translators", RFC 6052,
October 2010.
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8.2. Informative References
[RFC2629] Rose, M., "Writing I-Ds and RFCs using XML", RFC 2629,
June 1999.
Appendix A. Deployment Example
We have deployed 1:1 addressing mapping NAT64 prototype in Hunan
Province. Currently, there are three content providers covered by
our deployment. Refer to www.2118.com.cn, www.5460.net and
www.118326.com.
...
Authors' Addresses
Qiong Sun
China Telecom
Room 708 No.118, Xizhimenneidajie
Beijing, Xicheng 100035
P.R.China
Phone: 86 10 58552936
Email: sunqiong@ctbri.com.cn
Chongfeng Xie
China Telecom
Room 708 No.118, Xizhimenneidajie
Beijing, Xicheng 100035
P.R.China
Phone: 86 10 58552116
Email: xiechf@ctbri.com.cn
Jacni Qin
ZTE
Shanghai,
China
Phone: +86 1391 861 9913
Email: jacniq@gmail.com
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Qian Liu
China Telecom
ChangSha, Hunan 410011
China
Phone: +86 731 8226 0127
Email: 18973133999@189.cn
Dong Liu
BII Group
Beijing, 100028
China
Phone: +86 138-0103-2487
Email: dliu@biigroup.com
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