Internet Engineering Task Force S. Matsushima
Internet-Draft Softbank Telecom
Intended status: Informational Y. Yamazaki
Expires: September 30, 2011 Softbank Mobile
C. Sun
M. Yamanishi
J. Jiao
Softbank BB
March 29, 2011
Use case and consideration experiences of IPv4 to IPv6 transition
draft-matsushima-v6ops-transition-experience-02
Abstract
Service Providers will apply their use case when conducting IPv6
transition and determine helpful solutions with the assistance of the
IPv6 transition guideline document. More than one solution is
possible, and decisions must be made from not only the technical
point of view, but also from the economic point of view. This
document describes the conclusions reached by one operator based on
their considerations and their plans for IPv6 transition so as to
assist others who may have similar circumstances.
Status of this Memo
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This Internet-Draft will expire on September 30, 2011.
Copyright Notice
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document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Transition overview and current status . . . . . . . . . . . . 3
3. Experience of IPv4-only Network and Assessment Approach . . . . 3
4. Considerations for IPv6-Only network . . . . . . . . . . . . . 4
5. Considerations for Mobile network . . . . . . . . . . . . . . . 5
6. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . 5
7. Security considerations . . . . . . . . . . . . . . . . . . . . 6
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6
9.1. Normative References . . . . . . . . . . . . . . . . . . . 6
9.2. Informative References . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8
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1. Introduction
IPv4 to IPv6 transition solutions are becoming more converged. Given
the variety of operators involved, various use-case scenarios exist
and efforts are underway to clarify them. Since the first group
addressing IPv6 transition are technically inclined, the economic
analyses needed for creating business plans are often delayed. One
key factor impacting the business plan is architecture. The solution
will be considered and then adopted so as to implement the most
efficient architecture for each operator. In other words, the
Service Provider who wants to ensure long-term viability must place
greater emphasis on the economic impact of IPv6 transition. The
author expect that IETF has great interest in this approach given its
engineering and standardization work. Moreover, sharing the
considerations described in this document would be helpful to
operators who are in similar circumstances.
2. Transition overview and current status
Various transition use-cases have been published.
[I-D.huang-v6ops-v4v6tran-bb-usecase]
[I-D.lee-v6ops-tran-cable-usecase]
[I-D.tsou-v6ops-mobile-transition-guide] [I-D.sunq-v6ops-ivi-sp]
IPv6 transition guideline document
[I-D.arkko-ipv6-transition-guidelines] presents four deployment
models. As our ultimate goal is the IPv6 only network, our strategy
to achieving it is: (1) provide IPv6 connectivity to the existing
IPv4-Only network, (2) build new IPv6-Only network, (3) migrate our
customers from the IPv4-Only network to the IPv6-Only network. Along
with the guideline, we had studied the "Crossing IPv4 Islands" model
in the guideline to realize (1), while performing (2) in parallel.
Subsequently, we started studying the "IPv6-Only Core Network" model
to achieve (3). Research into a deployment model for our mobile
network is now in progress.
3. Experience of IPv4-only Network and Assessment Approach
Our starting point is ensuring that the IPv4-Only network can provide
IPv6 connectivity. Since our final goal is to build a IPv6-only
network and migrate all customers to the network, we will not have to
accommodate new customers beyond current capacity in the existing
IPv4-only network. This means two things for the IPv4-only network;
one, "minimized additional resources will provided to keep the
network" and two, "there is less need to conserve IPv4 addresses in
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the network". As the guideline document pointed out, many "IPv6 over
IPv4 tunneling" solutions have already been developed. Our criterion
for adopting the best solution involves not only technical pros/cons,
but also the cost efficiency of providing IPv6 connectivity to all
customers in the IPv4-only networks.
When the total capital and operational expense of the system is
represented as "Q", and the number of customers that can be served by
the system as "T", the metric of cost efficiency, "S", is given by
the following simple formula:
S=Q/T
We gathered the S values of all candidate products and solutions, and
decided to adopt the solution that had the lowest S value. Ignoring
the price difference between the products, the stateful solutions
have S values that are significantly different from those of the
stateless solutions. In stateful solutions, T is the total number of
system capable sessions divided by the number of sessions per
customer. In stateless solutions, on the other hand, T is the total
amount of system bandwidth capacity divided by the bandwidth
consumption per customer.
From our experience, S(A) < S(B), that is, S(A) is always more
efficient than S(B) (note S(A) is stateless, S(B) is stateful). We
consequently adopt 6rd [RFC5969] for IPv4-only network. As the
guideline document points out, it is not productive to implement an
optimal IPv6 transition system as a temporary solution with goal of
rich functionality. Many service providers hope that by allocating
more resource they can increase network performance, bandwidth
capacity, and the coverage of their network. In other words, we, as
a service provider, want to minimize the resources allocated to such
temporary solutions.
4. Considerations for IPv6-Only network
Our considerations suggest that a stateless solution should be
adopted for the IPv6-only network to minimize overall resource
allocation and to allocate resources to the more productive areas.
In one of IPv6-only network deployment scenario, routing and
addressing lie outside our control except for our own prefix, which
is assigned to the customers who connect to the network. It seems
like relation of operators among wholesale and retail. In that
network, it is difficult to avoid assigning well known and other
operator owned IPv4 prefixes if the stateless solution uses the 32bit
IPv4 address to IPv6 address mapping technique. The solution must
meet the requirements of: (1) The routing path for IPv4 should match
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the optimized IPv6 routing path, (2) It should be capable to share
one IPv4 address among customers since the number of IPv4 addresses
is insufficient, (3) It must be stateless. We will adopt the
solution that satisfies these three requirements. According to
[I-D.sun-intarea-4rd-applicability], there are significant
characteristics in particular these three requirements are satisfied.
It is noted that since some customers require a service which no
address sharing, a non-address sharing solution is also needed, but
this does not need to be the same as the address sharing solution.
The guideline document describes that Dual-Stack-lite
[I-D.ietf-softwire-dual-stack-lite] is recommended only as a
transition solution on the way to the IPv6-only network. Compared to
other deployment scenarios such as crossing IPv4 island and IPv6-only
deployment, there are several candidate solutions for each deployment
model but only one solution for the scenario. It is noted that the
solutions not mentioned in the guideline are discussed in
[I-D.dec-stateless-4v6], which adopt 4rd [I-D.despres-intarea-4rd]
and dIVI [I-D.xli-behave-divi].
5. Considerations for Mobile network
We believe that the requirements explained in the previous section
should be applied to the mobile network as well. [TR23.975], has
clarified the IPv6-only deployment model in the guideline as a IPv6
transition scenario. As [I-D.arkko-ipv6-only-experience] pointed
out, the operators' policy of service quality assurance may require
the solution of avoiding the IPv4 referral issue
[I-D.ietf-behave-v4v6-bih]
It is interesting that stateless address mapping techniques exist for
both encapsulation/decapsulation and translation in the case of IPv4
crossing IPv6-only network model. This means that, the requirements
listed in previous section could be achieved for the mobile network.
6. Conclusions
One of most significant areas that remain to be investigated is the
physical resources of our network. We also need to minimize the
investments needed to secure the IP transition (i.e. the temporary
solutions) because we believe that the ultimate goal of the
transition must be the long-term viability of the Internet and also
the provision of our services. To ensure that, our considerations
yielded the conclusion that the stateless solution should be
specified for all deployment models in the guideline document. It is
recommended that IETF standardize on stateless solutions for not only
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the IPv4-only network, but also both the IPv6-only network and Ipv6-
only deployment models in the guideline.
7. Security considerations
A stateless solution without the appropriate implementation and
operation techniques would be vulnerable to denial of service
attacks, routing loops, spoofing, and other such malicious acts. To
eliminate these security vulnerabilities, a stateless solution, like
6rd, which is capable of validating consistency of IPv6 source
address with IPv4 source address, can be used to avoid these
vulnerabilities, based on its address mapping rule. If a stateless
solution supports IPv4 address sharing, it must take into account the
issues described in [I-D.ietf-intarea-shared-addressing-issues]. If
an operator is concerned about the unnecessary bandwidth consumption
created by unwanted packets from the outside, one recommended
solution is to implement appropriate firewall protection for not only
v4v6 transition solution, but also both native IPv4 and IPv6
networks.
8. Acknowledgements
The authors would like to thank the guideline document of IPv6
transition [I-D.arkko-ipv6-transition-guidelines], which guides us
through the transition way, and has motivated the authors to write
this document. We also would like to thank Miwa Fujii for her
helpful suggestions and supports to share our experience with many
people.
9. References
9.1. Normative 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.
9.2. Informative References
[I-D.arkko-ipv6-only-experience]
Arkko, J. and A. Keranen, "Experiences from an IPv6-Only
Network", draft-arkko-ipv6-only-experience-02 (work in
progress), October 2010.
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[I-D.dec-stateless-4v6]
Dec, W., "Stateless 4Via6 Address Sharing",
draft-dec-stateless-4v6-01 (work in progress), March 2011.
[I-D.despres-intarea-4rd]
Despres, R., Matsushima, S., Murakami, T., and O. Troan,
"IPv4 Residual Deployment across IPv6-Service networks
(4rd) ISP-NAT's made optional",
draft-despres-intarea-4rd-01 (work in progress),
March 2011.
[I-D.huang-v6ops-v4v6tran-bb-usecase]
Huang, C., Li, X., and L. Hu, "Use Case For IPv6
Transition For a Large-Scale Broadband network",
draft-huang-v6ops-v4v6tran-bb-usecase-01 (work in
progress), October 2010.
[I-D.ietf-behave-v4v6-bih]
Huang, B., Deng, H., and T. Savolainen, "Dual Stack Hosts
Using "Bump-in-the-Host" (BIH)",
draft-ietf-behave-v4v6-bih-03 (work in progress),
March 2011.
[I-D.ietf-intarea-shared-addressing-issues]
Ford, M., Boucadair, M., Durand, A., Levis, P., and P.
Roberts, "Issues with IP Address Sharing",
draft-ietf-intarea-shared-addressing-issues-05 (work in
progress), March 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-07 (work
in progress), March 2011.
[I-D.lee-v6ops-tran-cable-usecase]
Lee, Y. and V. Kuarsingh, "IPv6 Transition Cable Access
Network Use Cases", draft-lee-v6ops-tran-cable-usecase-00
(work in progress), October 2010.
[I-D.sun-intarea-4rd-applicability]
Sun, C., Matsushima, S., and J. Jiao, "4rd Applicability
Statement", draft-sun-intarea-4rd-applicability-01 (work
in progress), March 2011.
[I-D.sunq-v6ops-ivi-sp]
Sun, Q., Xie, C., Li, X., Bao, C., and M. Feng,
"Considerations for Stateless Translation (IVI/dIVI) in
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Large SP Network", draft-sunq-v6ops-ivi-sp-02 (work in
progress), March 2011.
[I-D.tsou-v6ops-mobile-transition-guide]
ZOU), T. and T. Taylor, "IPv6 Transition Guide For A Large
Mobile Operator",
draft-tsou-v6ops-mobile-transition-guide-00 (work in
progress), October 2010.
[I-D.xli-behave-divi]
Li, X., Bao, C., and H. Zhang, "Address-sharing stateless
double IVI", draft-xli-behave-divi-01 (work in progress),
October 2009.
[I-D.ymbk-aplusp]
Bush, R., "The A+P Approach to the IPv4 Address Shortage",
draft-ymbk-aplusp-09 (work in progress), February 2011.
[RFC5565] Wu, J., Cui, Y., Metz, C., and E. Rosen, "Softwire Mesh
Framework", RFC 5565, June 2009.
[RFC5969] Townsley, W. and O. Troan, "IPv6 Rapid Deployment on IPv4
Infrastructures (6rd) -- Protocol Specification",
RFC 5969, August 2010.
[TR23.975]
"3GPP, IPv6 migration guidelines",
<http://www.3gpp.org/ftp/specs/html-info/23975.htm>.
Authors' Addresses
Satoru Matsushima
Softbank Telecom
Tokyo Shiodome Building
1-9-1,Higashi-Shibashi,Minato-Ku
Tokyo 105-7322
JAPAN
Email: satoru.matsushima@tm.softbank.co.jp
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Yuji Yamazaki
Softbank Mobile
Tokyo Shiodome Building
1-9-1,Higashi-Shibashi,Minato-Ku
Tokyo 105-7322
JAPAN
Email: yuyamaza@bb.softbank.co.jp
Chunfa Sun
Softbank BB
Tokyo Shiodome Building
1-9-1,Higashi-Shibashi,Minato-Ku
Tokyo 105-7322
JAPAN
Email: c-sun@bb.softbank.co.jp
Masato Yamanishi
Softbank BB
611 Wilshire Blvd., Suite 400
Los Angeles, CA
USA
Email: myamanis@bb.softbank.co.jp
Jie Jiao
Softbank BB
Tokyo Shiodome Building
1-9-1,Higashi-Shibashi,Minato-Ku
Tokyo 105-7322
JAPAN
Email: j-jiao@bb.softbank.co.jp
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