V6OPS B. Carpenter
Internet-Draft Univ. of Auckland
Intended status: Informational S. Jiang
Expires: April 16, 2010 Huawei Technologies Co., Ltd
October 13, 2009
Emerging Service Provider Scenarios for IPv6 Deployment
draft-carpenter-v6ops-isp-scenarios-00
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Abstract
This document describes scenarios that are emerging among Internet
Service Providers for the deployment of IPv6. They are based on
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practical experience so far, as well as current plans and
requirements, but they are not intended as binding recommendations.
[[ NOTE: This a preliminary version with incomplete content. ]]
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Review of existing documents . . . . . . . . . . . . . . . . . 4
3. Review of ISP experience, plans and requirements . . . . . . . 6
4. Lessons from experience and planning . . . . . . . . . . . . . 6
5. Suggested scenarios . . . . . . . . . . . . . . . . . . . . . . 6
6. Gap analysis . . . . . . . . . . . . . . . . . . . . . . . . . 6
7. Security Considerations . . . . . . . . . . . . . . . . . . . . 6
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7
10. Change log . . . . . . . . . . . . . . . . . . . . . . . . . . 7
11. Informative References . . . . . . . . . . . . . . . . . . . . 7
Appendix A. Questionnaire . . . . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9
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1. Introduction
[[ NOTE: This a preliminary version with incomplete content. Later
sections will be filled out after the authors have obtained feedback
from various ISPs. This version is published to clarify our
intention when approaching ISPs for input. ]]
As is well known, the approaching exhaustion of IPv4 address space
will bring about a situation in which Internet Service Providers
(ISPs) are faced with a choice between three major alternatives:
1. Squeeze the use of IPv4 addresses even harder than today, using
smaller and smaller address blocks per customer, and possibly
trading address blocks with other ISPs.
2. Install multiple layers of network address translation, or share
IPv4 addresses by other methods such as address-plus-port mapping
[I-D.ymbk-aplusp], [I-D.boucadair-port-range].
3. Deploy IPv6, and operate IPv4-IPv6 coexistence and interworking
mechanisms.
This document focuses on alternative (3), while recognizing that many
ISPs may be obliged by circumstances to prolong the life of IPv4 by
using (1) or (2) as well.
The document is intended as a guide to useful IPv6 deployment
scenarios. However, it is not a "cookbook" of operational recipes,
and the best choice of scenario will depend on the circumstances of
individual ISPs.
We consider various aspects of IPv6 deployment: addressing, routing,
DNS, management and of course IPv4 coexistence and interworking. We
do not consider application services in detail, but we do discuss
general aspects.
We first review several documents produced in the past by the IETF,
and mention relevant work in progress in the IETF. We then survey
requirements, plans, and practical experience from various ISPs.
Several deployment scenarios that result from that input are then
described; these are not formal recommendations, but are intended as
example scenarios which ISPs may choose to copy or modify to suit
their own technical, economic and regulatory situation. We conclude
with a gap analysis and security considerations.
The reader is assumed to be familiar with IPv6 in general. The
IETF's view of core IPv6 requirements is to be found in [RFC4294]
(currently being updated as [I-D.ietf-6man-node-req-bis]). However,
this does not give a complete view of mechanisms an ISP may need to
deploy, since it considers the requirements for an individual node,
not for a network as a whole.
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2. Review of existing documents
[RFC4029] discusses scenarios for introducing IPv6 into ISP networks,
as the problem was viewed some years ago. The document is still
valuable as a general introduction to the process that an ISP must
design, but it does not consider today's situation where IPv4
addresses have in practical terms run out, and interworking between
IPv6-only and IPv4-only clients and servers must be supported in
addition to basic dual-stack and tunneling scenarios. We can extract
a list of basic issues and needs from RFC4029:
o Customer Premises Equipment (CPE) - must support IPv6, or allow
IPv6-in-IPv4 tunnels. CPE requirements and security are currently
being specified by the IETF [I-D.ietf-v6ops-ipv6-cpe-router],
[I-D.ietf-v6ops-cpe-simple-security].
o Provider Edge Equipment (PE) - ditto.
o ISP backbone (core and border routers, switches if used) - must
support dual stack, or allow IPv6-in-IPv4 tunnels. An alternative
is a newly built IPv6 backbone that allows IPv4-in-IPv6 tunnels.
o Network management and monitoring applications must take IPv6 into
account.
o Customer management (e.g., RADIUS) mechanisms must be able to
supply IPv6 prefixes and other information to customers.
o Accounting and billing mechanisms must support both versions.
o Security mechanisms must support both versions.
The end goal described in RFC4029 is simply a dual-stack ISP
backbone. Today's view is that this is insufficient, as it does not
allow for interworking between IPv6-only and legacy (IPv4-only)
hosts. Indeed, the end goal today might be an IPv6-only ISP
backbone, with some form of legacy IPv4 support.
[RFC4779] discusses deployment in broadband access networks such as
CATV, ADSL and wireless. [RFC5181] deals specifically with IEEE
802.16 access networks. In some access scenarios, the access
protocol allows separately for IPv4 and IPv6, as for DOCSIS-based
CATV and for one variant of IEEE 802.16 [RFC5121]. In other
scenarios, the broadband service is essentially an emulation of raw
Ethernet, as for Wi-Fi, or for another variant of IEEE 802.16
[I-D.ietf-16ng-ip-over-ethernet-over-802-dot-16]. Another issue is
whether the ISP uses MPLS for back-haul from the access network, in
which case the 6PE [RFC4798] mechanism may be appropriate to carry
IPv6.
[RFC4942] covers IPv6 security issues, especially those that are
specific to transition and coexistence scenarios. The main message
for ISPs is that the switch to IPv6 does not mean that IP layer
security issues will go away, and of course security issues that are
not specific to the IP layer will hardly change.
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Also related to security, [RFC4864] discusses what is referred to as
"Local Network Protection", i.e., how the internal structure of a
site network that is not hidden behind a network address translator
can be protected. Although not directly relevant to ISP operations,
this topic does affect the issue of how well an ISP's customers are
protected after they deploy IPv6.
[RFC5211] describes an independent view of a possible sequence of
events for IPv6 adoption in the Internet as a whole, with direct
implications for ISPs. Its main point, perhaps, is that by 2012 it
will be necessary to regard IPv4 networks as the legacy solution.
Although the basic IPv6 standards have long been stable, it should be
noted that considerable work continues in the IETF, particularly to
resolve the issue of highly scalable multihoming support for IPv6
sites, and to resolve the problem of IP layer interworking between
IPv6-only and IPv4-only hosts. Progress continues in various IETF
working groups that may affect ISP scenarios in due course.
o The 6MAN WG maintains the basic IPv6 standards. This work should
have little direct effect on ISPs.
o The V6OPS WG produces documents of direct interest for operational
practice as well as security practice. Current work includes CPE
requirements, CPE security, and Internet Exchange Point practice.
The present document will be discussed in V6OPS.
o The SOFTWIRE WG is working on additional protocols for IP-in-IP
tunnels in an ISP context.
o The BEHAVE WG is working on specifications for NAT64 and DNS64,
methods of supporting access from IPv6-only initiators to reach
IPv4-only services.
o The DHC WG maintains and extends DHCPv6.
o The SHIM6 WG is finalising work on a host-based protocol for IPv6
multihoming, based on the usage of multiple IPv6 prefixes for a
customer connected to multiple ISPs.
o The LISP WG is developing experimental standards for a scalable
tunnel-based routing mechanism which would, if successful, support
an alternative multihoming model.
Readers may find the current documents of these WGs via
<http://www.ietf.org/dyn/wg/charter.html>.
The IETF is not currently discussing IPv6/IPv4 interworking at the
transport or application layers. The former is not generally
considered to be a valuable approach. The latter is considered to be
handled within the original dual-stack model of IPv6 deployment:
either one end of an application session will have dual-stack
connectivity, or a dual-stack intermediary such as an HTTP proxy or
SMTP server will interface to both IPv4-only and IPv6-only hosts.
While valid and useful for many common applications, this approach
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does not solve all possible interworking issues. In any case it does
not require further standards work at the network layer.
3. Review of ISP experience, plans and requirements
[[ NOTE: this section will be filled out when the authors have
received feedback from various ISPs, by means of a questionnaire. ]]
4. Lessons from experience and planning
What was easy, what was difficult, what problems remain.
[[ NOTE: this section will be filled out after the previous section.
]]
5. Suggested scenarios
This document does not make firm recommendations; the circumstances
of each ISP may be different. Rather, it describes several suggested
deployment scenarios that appear, from the analysis above, to have
the best operational characteristics. Each ISP should make its own
choices, according to its own technical, economic and regulatory
environment.
[[ NOTE: this section will be filled out after the previous sections.
It will also discuss changes since the older analyses discussed in
Section 2 ]]
6. Gap analysis
The analysis has shown a certain number of desirable features to be
missing, either in relevant specifications, or in many products.
This section summarizes those gaps.
[[ NOTE: this section will be filled out after the previous sections.
]]
7. Security Considerations
[[ NOTE: this section will be filled out after the previous sections.
]]
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8. IANA Considerations
This document makes no request of the IANA.
9. Acknowledgements
We are grateful to all those ISPs who provided input. Some of them
preferred to remain anonymous. Valuable comments and contributions
were made by ...
This document was produced using the xml2rfc tool [RFC2629].
10. Change log
draft-carpenter-v6ops-isp-scenarios-00: original version, 2009-10-13
11. Informative References
[I-D.boucadair-port-range]
Boucadair, M., Levis, P., Bajko, G., and T. Savolainen,
"IPv4 Connectivity Access in the Context of IPv4 Address
Exhaustion: Port Range based IP Architecture",
draft-boucadair-port-range-02 (work in progress),
July 2009.
[I-D.ietf-16ng-ip-over-ethernet-over-802-dot-16]
Jeon, H., Riegel, M., and S. Jeong, "Transmission of IP
over Ethernet over IEEE 802.16 Networks",
draft-ietf-16ng-ip-over-ethernet-over-802-dot-16-12 (work
in progress), September 2009.
[I-D.ietf-6man-node-req-bis]
Loughney, J. and T. Narten, "IPv6 Node Requirements RFC
4294-bis", draft-ietf-6man-node-req-bis-03 (work in
progress), July 2009.
[I-D.ietf-v6ops-cpe-simple-security]
Woodyatt, J., "Recommended Simple Security Capabilities in
Customer Premises Equipment for Providing Residential
IPv6 Internet Service",
draft-ietf-v6ops-cpe-simple-security-07 (work in
progress), July 2009.
[I-D.ietf-v6ops-ipv6-cpe-router]
Singh, H. and W. Beebee, "IPv6 CPE Router
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Recommendations", draft-ietf-v6ops-ipv6-cpe-router-01
(work in progress), August 2009.
[I-D.ymbk-aplusp]
Bush, R., "The A+P Approach to the IPv4 Address Shortage",
draft-ymbk-aplusp-04 (work in progress), July 2009.
[RFC2629] Rose, M., "Writing I-Ds and RFCs using XML", RFC 2629,
June 1999.
[RFC4029] Lind, M., Ksinant, V., Park, S., Baudot, A., and P.
Savola, "Scenarios and Analysis for Introducing IPv6 into
ISP Networks", RFC 4029, March 2005.
[RFC4294] Loughney, J., "IPv6 Node Requirements", RFC 4294,
April 2006.
[RFC4779] Asadullah, S., Ahmed, A., Popoviciu, C., Savola, P., and
J. Palet, "ISP IPv6 Deployment Scenarios in Broadband
Access Networks", RFC 4779, January 2007.
[RFC4798] De Clercq, J., Ooms, D., Prevost, S., and F. Le Faucheur,
"Connecting IPv6 Islands over IPv4 MPLS Using IPv6
Provider Edge Routers (6PE)", RFC 4798, February 2007.
[RFC4864] Van de Velde, G., Hain, T., Droms, R., Carpenter, B., and
E. Klein, "Local Network Protection for IPv6", RFC 4864,
May 2007.
[RFC4942] Davies, E., Krishnan, S., and P. Savola, "IPv6 Transition/
Co-existence Security Considerations", RFC 4942,
September 2007.
[RFC5121] Patil, B., Xia, F., Sarikaya, B., Choi, JH., and S.
Madanapalli, "Transmission of IPv6 via the IPv6
Convergence Sublayer over IEEE 802.16 Networks", RFC 5121,
February 2008.
[RFC5181] Shin, M-K., Han, Y-H., Kim, S-E., and D. Premec, "IPv6
Deployment Scenarios in 802.16 Networks", RFC 5181,
May 2008.
[RFC5211] Curran, J., "An Internet Transition Plan", RFC 5211,
July 2008.
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Appendix A. Questionnaire
This appendix reproduces a questionnaire that was made available for
ISPs to express their requirements, plans and experience.
TBD
Authors' Addresses
Brian Carpenter
Department of Computer Science
University of Auckland
PB 92019
Auckland, 1142
New Zealand
Email: brian.e.carpenter@gmail.com
Sheng Jiang
Huawei Technologies Co., Ltd
KuiKe Building, No.9 Xinxi Rd.,
Shang-Di Information Industry Base, Hai-Dian District, Beijing
P.R. China
Email: shengjiang@huawei.com
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