Internet DRAFT - draft-mi-softwire-applicable-index-translation
draft-mi-softwire-applicable-index-translation
Softwire Wei Mi, Ed.
Internet-Draft Jingguo Ge
Intended status: Informational IIE/Chinese Academy of Sciences
Expires: June 30, 2016 December 28, 2015
The Applicability Index of Translation
draft-mi-softwire-applicable-index-translation-01
Abstract
The Softwire working group is currently discussing both encapsulation
and translation based stateless IPv4/IPv6 solutions in order to be
able to provide IPv4 connectivity to customers in an IPv6-Only
environment.
The purpose of this document is to describe the basic issues and key
elements of the IPv4/IPv6 translation, and presents its applicability
index that would help the operators decide on the development scheme
for their IPv6 transition.It could lead to significant operational
benefits and potential savings for the operators.
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
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This Internet-Draft will expire on June 30, 2016.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. The Basic Issues and Key elements of Translation Mechanisms . 3
2.1. Basic Issues . . . . . . . . . . . . . . . . . . . . . . 3
2.2. Key Elements . . . . . . . . . . . . . . . . . . . . . . 4
3. Applicability Index of Translation . . . . . . . . . . . . . 5
3.1. Sustainable Index . . . . . . . . . . . . . . . . . . . . 5
3.2. The Support Degree of Business Application Index . . . . 5
3.3. The Preformance Index . . . . . . . . . . . . . . . . . . 5
3.4. The Development Index . . . . . . . . . . . . . . . . . . 6
3.5. The Security Index . . . . . . . . . . . . . . . . . . . 6
4. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . 6
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
7. Security Considerations . . . . . . . . . . . . . . . . . . . 6
8. Informative References . . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
The Softwire working group is currently discussing both encapsulation
and translation based stateless IPv4/IPv6 solutions developed for the
purposes of offering IPv4 connectivity to the customers in an
IPv6-Only environment.
In the all stages of transition from IPv4 to IPv6, IPv4 networks/
hosts and IPv6 networks/hosts are likely to coexist. For the
operators, supporting inter-connection is inevitable. One-time
translation mechanisms emerged as required.
With the IPv6 development, IPv4 Internet has been gradually replaced.
For the low cost, network operators tend to build IPv6 network rather
than dual-stack network. In order to ensure the compatibility of
legacy IPv4 application, IPv4-IPv6-IPv4 double translation scheme is
provided.
Generic mechanism for one-time translation mechanisms are specified
in [RFC2765], [RFC6219], [RFC2766], [RFC6146], [RFC6535], and double
translation mechanisms are specified in [RFC6877], [I-D.ietf-
softwire-map],etc. With the diverse characteristics and transition
requirements of practical networks and the lack of overall transition
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architecture, the selection and deployment of IPv6 transition
mechanisms are very difficult.
In an effort to push forward the IPv6 transition process, this
document describles the basic issues and key elements of translation
mechanisms,and presents the applicability index that would help the
operators decide on the development scheme for their IPv6
transition.It could lead to significant operational benefits and
potential savings for the operators.
2. The Basic Issues and Key elements of Translation Mechanisms
Translation scheme is used to achieve direct communication between
IPv4 and IPv6 networks (or hosts).
2.1. Basic Issues
Its basic operation is to convert the semantics between IPv4 and
IPv6, turning IPv4 packet into IPv6 if the packet is destined to IPv6
network, or turning IPv6 packet into IPv4 if the packet is destined
to IPv4 network.
a. The basic data operation. IPv4-IPv6 packet translation is the
basic data plane operation. It involves network, transport, and
application layer. Thus, the basic operations include address
and port conversion, IP/TCP/UDP protocol field translation, and
application layer translation (address and port conversion when
they appear in application protocol). What is more, to overcome
further diversities in the protocol definition between IPv4 and
IPv6, translation has to take care of issues like fragmentation
and reassembling, path MTU (Maximum Transmission Unit) discovery,
ICMP, etc.
b. The basic control operation. The basic control plane operation
is the address conversion rule: either some special address
scheme needs to be deployed in advance, or dynamic address
bindings have to be built during the translation. Heterogeneous
addressing (learning the in-protocol address of the remote end)
and corresponding routing should be performed based on the
address conversion rule.
c. The translation model. According to the applicable scenarios,
the models of IPv6 translation mechanisms are divided into
application-side, network-side and host-side translation.
According to the address conversion manner, we can also divide
network-side translation mechanisms into stateless translation
and stateful translation.
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2.2. Key Elements
a. Transition equipment. In translation technologies, the
translator is the transition equipments. Usually, network-side
translation happens on the IPv4-IPv6 border, so the translator
would be an AFBR (Address Family Border Router). And host-side
translation happens in the TCP/IP stack of the end host, so the
translator would be host. They should support address and port
conversion, IP/TCP/UDP protocol field translation and also
maintain the state. Thus, translator has requirements in the use
of bandwidth, computing and finding, storage.
b. Address translation. Using specific address conversion rules,
the translator either gets IPv4 address from a specific position
of IPv6 address, or builds the IPv6 address using IPv4 address.
The address conversion rule includes some special address scheme
needs to be deployed in advance, and dynamic address bindings
have to be built during the translation.
c. Other fields translation. Except the source address and
destination address, there are other fields (fragmentation ID,
checksum, ban-fragmentation flag, etc.) in IP/ICMP packets, which
carry specific information. In the IPv4-IPv6 translation
process, the header information of IPv4 packet cannot be lost.
Therefore, translation techniques are required to ensure the
integrity of IPv4 information.
d. State maintenance. In IPv6 transition, the state is available to
only represent a series of attributes mapping relationship among
a communication entity (such as client, server), a communication
path (the connection between communication entities), or a
communication process (control flow and data flow). The IP
address in network layer and ID in transport layer of the
communication entities are the core state which need translation
techniques to maintain.
e. DNS64 and DNS46. The main function of DNS64 and DNS46 is to
realize the bi-directional translation between A and AAAA record.
DNS64 translates the AAAA query from IPv6 hosts into A query when
receiving one, and DNS46 translates the A response for IPv6 hosts
into AAAA response following the IPv4-mapped address rule before
sending one out. There are usually two kinds of implementations:
static configuration DNS records and dynamic translation.
f. Application layer translation. Those applications whose address
and port conversion when they appear in application protocol
cannot work in NAT and IPv4/IPv6 translation environments. Such
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as FTP, SIP, etc. One solution is assist applications to realize
translation work by using the application layer gateway.
3. Applicability Index of Translation
There are applicability index which need to be analyzed by the
operator when choosing which transition technology option they would
like to deploy. The applicability index in terms of sustainable,
applications, performance, development and security. This section
describes some of those considerations.
3.1. Sustainable Index
Sustainable index would include:
a. The scenarios and function of transition represents whether meet
the needs of transitional scenario.
b. Both (a)the coupling degree between IPv4 address and (b) IPv6
address and the reuse rate of IPv4 addresses resource represent
whether promote the deployment and usage of IPv6.
3.2. The Support Degree of Business Application Index
The support degree of business application index would include:
a. The support degree of IPv4 application represents the impact on
the IPv4 business application.
b. The support degree of IPv6 application represents the impact on
the IPv6 business application.
3.3. The Preformance Index
The preformance index would include:
a. The performance requirements of translator can be divided into
(a) the routing information announcement and (b) the space and
time overhead of state maintenance, which represents the capacity
of bandwidth, computing and finding, storage.
b. The routing scalability can be represented by the aggregation of
IPv6 addresses, which represents the impact on the scope of
deployment.
c. Robustness represents the capacity of redundancy backup.
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3.4. The Development Index
The cost of development index would include:
a. Technological and industry maturity represent the support degree
of standard.
b. The update cost can be divided into (a) the impact on application
layer, (b) the impact on network layerand and (c) the impact on
end users layer, which represent the impact on the present
network.
c. The cost of operation, management and maintenance represent the
impact on the operator.
3.5. The Security Index
The security index includes the security issues and concerns.
4. Conclusions
For the consideration of deployment scenarios and address format,
numerous translation mechanisms have been proposed in the past
several years. However, due to a wide range of mechanisms and a lot
of overlap and similar functions, no one translation mechanism can be
used in all transition scenarios.
The applicability index of translation mechanisms described in this
document have highlighted the applicability of all translation
mechanisms to help the operators decide on the development scheme for
their IPv6 transition.
5. Acknowledgements
6. IANA Considerations
This memo includes no request to IANA.
7. Security Considerations
All drafts are required to have a security considerations section.
8. Informative References
[RFC2765] Nordmark, E., "Stateless IP/ICMP Translation Algorithm
(SIIT)", RFC 2765, DOI 10.17487/RFC2765, February 2000,
<http://www.rfc-editor.org/info/rfc2765>.
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[RFC2766] Tsirtsis, G. and P. Srisuresh, "Network Address
Translation - Protocol Translation (NAT-PT)", RFC 2766,
DOI 10.17487/RFC2766, February 2000,
<http://www.rfc-editor.org/info/rfc2766>.
[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>.
[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>.
[RFC6535] Huang, B., Deng, H., and T. Savolainen, "Dual-Stack Hosts
Using "Bump-in-the-Host" (BIH)", RFC 6535,
DOI 10.17487/RFC6535, February 2012,
<http://www.rfc-editor.org/info/rfc6535>.
[RFC6877] Mawatari, M., Kawashima, M., and C. Byrne, "464XLAT:
Combination of Stateful and Stateless Translation",
RFC 6877, DOI 10.17487/RFC6877, April 2013,
<http://www.rfc-editor.org/info/rfc6877>.
Authors' Addresses
Wei Mi (editor)
IIE/Chinese Academy of Sciences
No.89 Minzhuang Road, Haidian District
Beijing 100190
CN
Phone: +86 10-82546356
EMail: miwei@iie.ac.cn
Jingguo Ge
IIE/Chinese Academy of Sciences
No.89 Minzhuang Road, Haidian District
Beijing 100190
CN
Phone: +86 10-82546559
EMail: gejingguo@iie.ac.cn
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