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Versions: (draft-troan-v6ops-6to4-to-historic)
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RFC 7526
v6ops WG O. Troan
Internet-Draft Cisco
Obsoletes: 3056, 3068 April 5, 2011
(if approved)
Intended status: Standards Track
Expires: October 7, 2011
Request to move Connection of IPv6 Domains via IPv4 Clouds (6to4) to
Historic status
draft-ietf-v6ops-6to4-to-historic-00.txt
Abstract
Experience with the "Connection of IPv6 Domains via IPv4 Clouds
(6to4)" IPv6 transitioning mechanism has shown that the mechanism is
unsuitable for widespread deployment and use in the Internet. This
document requests that RFC3056 and the companion document "An Anycast
Prefix for 6to4 Relay Routers" RFC3068 are moved to historic status.
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
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on October 7, 2011.
Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
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include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
1. Introduction
The managed IPv6 transition mechanism "Connection of IPv6 Domains via
IPv4 Clouds (6to4)" described in [RFC3056] has rarely if ever been
deployed. Its extension in "An Anycast Prefix for 6to4 Relay
Routers" [RFC3068] has been shown to have severe practical problems
when used in the Internet. This document requests that RFC3056 and
RFC3068 be moved to Historic status as defined in section 4.2.4
[RFC2026].
[I-D.ietf-v6ops-6to4-advisory] analyses the known operational issues
and describes a set of suggestions to improve 6to4 reliability, given
the widespread presence of hosts and customer premises equipment that
support it.
Declaring the mechanism historic is not expected to have immediate
product implications. The IETF sees no evolutionary future for the
mechanism and it is not recommended to include this mechanism in new
implementations.
2. Conventions
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 RFC 2119 [RFC2119].
3. 6to4 operational problems
6to4 is a mechanism designed to allow isolated IPv6 islands to reach
each other using IPv6 over IPv4 automatic tunneling. To reach the
native IPv6 Internet the mechanism uses relay routers both in the
forward and reverse direction. The mechanism is supported in many
IPv6 implementations. With the increased deployment of IPv6, the
mechanism has been shown to have a number of fundamental
shortcomings.
6to4 depends on relays both in the forward and reverse direction to
enable connectivity with the native IPv6 Internet. A 6to4 node will
send IPv4 encapsulated IPv6 traffic to a 6to4 relay, that is
connected both to the 6to4 cloud and to native IPv6. In the reverse
direction a 2002::/16 route is injected into the native IPv6 routing
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domain to attract traffic from native IPv6 nodes to a 6to4 relay
router. It is expected that traffic will use different relays in the
forward and reverse direction. RFC3068 adds an extension that allows
the use of a well known IPv4 anycast address to reach the nearest
6to4 relay in the forward direction.
One model of 6to4 deployment as described in section 5.2, RFC3056,
suggests that a 6to4 router should have a set of managed connections
(via BGP connections) to a set of 6to4 relay routers. While this
makes the forward path more controlled, it does not guarantee a
functional reverse path. In any case this model has the same
operational burden has manually configured tunnels and has seen no
deployment in the public Internet.
6to4 issues:
o Use of relays. 6to4 depends on an unknown third- party to operate
the relays between the 6to4 cloud and the native IPv6 Internet.
o The placement of the relay can lead to increased latency, and in
the case the relay is overloaded packet loss.
o There is generally no customer relationship or even a way for the
end-user to know who the relay operator is, so no support is
possible.
o In case of the reverse path 6to4 relay and the anycast forward
6to4 relay, these have to be open for any address. Only limited
by the scope of the routing advertisement. 6to4 relays can be used
to anonymize traffic and inject attacks into IPv6 that are very
difficult to trace.
o 6to4 has no specified mechanism to handle the case where the
protocol (41) is blocked in intermediate firewalls. It can not be
expected that path MTU discovery across the Internet works
reliably; ICMP messages may be blocked and in any case an IPv4
ICMP message rarely has enough of the original packet in it to be
useful to proxy back to the IPv6 sender.
o As 6to4 tunnels across the Internet, the IPv4 addresses used must
be globally reachable. RFC3056 states that a private address
[RFC1918] MUST NOT be used. 6to4 will not work in networks that
employ other addresses with limited topological span.
4. Deprecation
This document formally deprecates the 6to4 transition mechanism and
the IPv6 6to4 prefix defined in [RFC3056], i.e., 2002::/16. The
prefix MUST NOT be reassigned for other use except by a future IETF
standards action.
It is expected that disabling 6to4 in the IPv6 Internet will take
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some time. The initial approach is to make the 6to4 a service of
"last resort" in host implementations, ensure that the 6to4 service
is disabled by default in 6to4 routers, and deploy native IPv6
service. In order to limit the impact of end-users, it is
recommended that operators retain their existing 6to4 relay routers
and follow the recommendations found in
[I-D.ietf-v6ops-6to4-advisory]. When traffic levels diminish, these
routers can be decommissioned.
1. IPv6 nodes SHOULD treat 6to4 as a service of "last resort" as
recommended in [I-D.ietf-6man-rfc3484-revise]
2. Implementations capable of acting as 6to4 routers SHOULD NOT
enable 6to4 without explicit user configuration. In particular,
enabling IPv6 forwarding on a device, SHOULD NOT automatically
enable 6to4.
3. If implemented in future products 6to4 SHOULD be disabled by
default.
Existing implementations and deployments MAY continue to use 6to4.
The references to 6to4 should be removed as soon as practical from
the revision of the Special-Use IPv6 Addresses [RFC5156].
Incidental references to 6to4 should be removed from other IETF
documents if and when they are updated. These documents include
RFC3162, RFC3178, RFC3790, RFC4191, RFC4213, RFC4389, RFC4779,
RFC4852, RFC4891, RFC4903, RFC5157, RFC5245, RFC5375, RFC5971, and
RFC6071.
5. IANA Considerations
IANA is requested to mark the 2002::/16 prefix as "deprecated",
pointing to this document. Reassignment of the prefix for any usage
requires justification via an IETF Standards Action [RFC5226].
IANA is requested to mark the 2.0.0.2.ip6.arpa domain [RFC5158] as
"deprecated", pointing to this document. Redelegation of the domain
for any usage requires justification via an IETF Standards Action
[RFC5226].RFC5158
6. Security Considerations
There are no new security considerations pertaining to this document.
General security issues with tunnels are listed in
[I-D.ietf-v6ops-tunnel-security-concerns] and more specifically to
6to4 in [RFC3964] and [I-D.ietf-v6ops-tunnel-loops].
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7. Acknowledgements
The authors would like to acknowledge Jack Bates, Cameron Byrne, Gert
Doering, Joel Jaeggli, Kurt Erik Lindqvist, Jason Livingood, Keith
Moore, Daniel Roesen and Mark Townsley, for their contributions and
discussions on this topic.
Special thanks go to Fred Baker, Geoff Huston, Brian Carpenter, and
Wes George for their significant contributions.
8. References
8.1. Normative References
[I-D.ietf-6man-rfc3484-revise]
Matsumoto, A., Kato, J., and T. Fujisaki, "Update to RFC
3484 Default Address Selection for IPv6",
draft-ietf-6man-rfc3484-revise-02 (work in progress),
March 2011.
[I-D.ietf-v6ops-6to4-advisory]
Carpenter, B., "Advisory Guidelines for 6to4 Deployment",
draft-ietf-v6ops-6to4-advisory-00 (work in progress),
March 2011.
[RFC2026] Bradner, S., "The Internet Standards Process -- Revision
3", BCP 9, RFC 2026, October 1996.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3056] Carpenter, B. and K. Moore, "Connection of IPv6 Domains
via IPv4 Clouds", RFC 3056, February 2001.
[RFC3068] Huitema, C., "An Anycast Prefix for 6to4 Relay Routers",
RFC 3068, June 2001.
[RFC5156] Blanchet, M., "Special-Use IPv6 Addresses", RFC 5156,
April 2008.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
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8.2. Informative References
[I-D.ietf-v6ops-tunnel-loops]
Nakibly, G. and F. Templin, "Routing Loop Attack using
IPv6 Automatic Tunnels: Problem Statement and Proposed
Mitigations", draft-ietf-v6ops-tunnel-loops-06 (work in
progress), March 2011.
[I-D.ietf-v6ops-tunnel-security-concerns]
Krishnan, S., Thaler, D., and J. Hoagland, "Security
Concerns With IP Tunneling",
draft-ietf-v6ops-tunnel-security-concerns-04 (work in
progress), October 2010.
[RFC1918] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and
E. Lear, "Address Allocation for Private Internets",
BCP 5, RFC 1918, February 1996.
[RFC3964] Savola, P. and C. Patel, "Security Considerations for
6to4", RFC 3964, December 2004.
[RFC5158] Huston, G., "6to4 Reverse DNS Delegation Specification",
RFC 5158, March 2008.
Author's Address
Ole Troan
Cisco
Oslo,
Norway
Email: ot@cisco.com
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