draft-ietf-v6ops-6to4-to-historic-06.txt   draft-ietf-v6ops-6to4-to-historic-07.txt 
v6ops WG O. Troan v6ops WG O. Troan
Internet-Draft Cisco Internet-Draft Cisco
Obsoletes: 3056, 3068 (if approved) B. Carpenter, Ed. Obsoletes: 3068 (if approved) B. Carpenter, Ed.
Intended status: Best Current Practice Univ. of Auckland Intended status: Best Current Practice Univ. of Auckland
Expires: April 23, 2015 October 20, 2014 Expires: May 14, 2015 November 10, 2014
Deprecating Connection of IPv6 Domains via IPv4 Clouds (6to4) Deprecating Connection of IPv6 Domains via IPv4 Clouds (6to4)
draft-ietf-v6ops-6to4-to-historic-06.txt draft-ietf-v6ops-6to4-to-historic-07.txt
Abstract Abstract
Experience with the "Connection of IPv6 Domains via IPv4 Clouds Experience with the "Connection of IPv6 Domains via IPv4 Clouds
(6to4)" IPv6 transition mechanism has shown that the mechanism is (6to4)" IPv6 transition mechanism has shown that the mechanism is
unsuitable for widespread deployment and use in the Internet. This unsuitable for widespread deployment and use in the Internet,
document requests that RFC3056 and the companion document "An Anycast especially in its anycast mode. This document requests that RFC
Prefix for 6to4 Relay Routers" RFC3068 are made obsolete and moved to 3068, "An Anycast Prefix for 6to4 Relay Routers", be made obsolete
historic status. It also recommends that future products should not and moved to historic status. It also recommends that future
support 6to4 and that existing deployments should be reviewed. products should not support 6to4 anycast and that existing
deployments should be reviewed.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 23, 2015. This Internet-Draft will expire on May 14, 2015.
Copyright Notice Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
1. Introduction 1. Introduction
There would appear to be no evidence of any substantial deployment of There would appear to be no evidence of any substantial deployment of
the variant of 6to4 described in [RFC3056]. Its extension specified the variant of 6to4 described in [RFC3056]. Its extension specified
in "An Anycast Prefix for 6to4 Relay Routers" [RFC3068] has been in "An Anycast Prefix for 6to4 Relay Routers" [RFC3068] has been
shown to have severe practical problems when used in the Internet. shown to have severe practical problems when used in the Internet.
This document requests that RFC3056 and RFC3068 be moved to Historic This document requests that RFC 3068 be moved to Historic status as
status as defined in section 4.2.4 [RFC2026]. defined in section 4.2.4 of [RFC2026].
6to4 was designed to help transition the Internet from IPv4 to IPv6. 6to4 was designed to help transition the Internet from IPv4 to IPv6.
It has been a good mechanism for experimenting with IPv6, but because It has been a good mechanism for experimenting with IPv6, but because
of the high failure rates seen with 6to4 [HUSTON], end users may end of the high failure rates seen with anycast 6to4 [HUSTON], end users
up disabling IPv6 on hosts as a result, and some content providers may end up disabling IPv6 on hosts as a result, and some content
have been reluctant to make content available over IPv6. providers have been reluctant to make content available over IPv6.
[RFC6343] analyses the known operational issues in detail and [RFC6343] analyses the known operational issues in detail and
describes a set of suggestions to improve 6to4 reliability, given the describes a set of suggestions to improve 6to4 reliability, given the
widespread presence of hosts and customer premises equipment that widespread presence of hosts and customer premises equipment that
support it. However, experience shows that operational failures have support it. However, experience shows that operational failures have
continued despite this advice being available. Fortunately the continued despite this advice being available. Fortunately the
advice to disable 6to4 by default has been widely adopted in recent advice to disable 6to4 by default has been widely adopted in recent
operating systems, and the failure modes have been largely hidden operating systems, and the failure modes have been largely hidden
from users by many browsers adopting the "happy eyeballs" approach from users by many browsers adopting the "happy eyeballs" approach
[RFC6555]. Nevertheless, operational problems caused by 6to4 still [RFC6555]. Nevertheless, operational problems caused by 6to4 still
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mechanism has been shown to have a number of fundamental mechanism has been shown to have a number of fundamental
shortcomings. shortcomings.
6to4 depends on relays both in the forward and reverse direction to 6to4 depends on relays both in the forward and reverse direction to
enable connectivity with the native IPv6 Internet. A 6to4 node will enable connectivity with the native IPv6 Internet. A 6to4 node will
send IPv4 encapsulated IPv6 traffic to a 6to4 relay, that is send IPv4 encapsulated IPv6 traffic to a 6to4 relay, that is
connected both to the 6to4 cloud and to native IPv6. In the reverse 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 direction a 2002::/16 route is injected into the native IPv6 routing
domain to attract traffic from native IPv6 nodes to a 6to4 relay domain to attract traffic from native IPv6 nodes to a 6to4 relay
router. It is expected that traffic will use different relays in the router. It is expected that traffic will use different relays in the
forward and reverse direction. RFC3068 adds an extension that allows forward and reverse direction. RFC 3068 adds an extension that
the use of a well known IPv4 anycast address to reach the nearest allows the use of a well known IPv4 anycast address to reach the
6to4 relay in the forward direction. nearest 6to4 relay in the forward direction.
One model of 6to4 deployment as described in section 5.2, RFC3056, One model of 6to4 deployment, described in section 5.2 of RFC 3056,
suggests that a 6to4 router should have a set of managed connections suggests that a 6to4 router should have a set of managed connections
(via BGP connections) to a set of 6to4 relay routers. While this (via BGP connections) to a set of 6to4 relay routers. While this
makes the forward path more controlled, it does not guarantee a makes the forward path more controlled, it does not guarantee a
functional reverse path. In any case this model has the same functional reverse path. In any case this model has the same
operational burden as manually configured tunnels and has seen no operational burden as manually configured tunnels and has seen no
deployment in the public Internet. deployment in the public Internet.
List of some of the known issues with 6to4: List of some of the known issues with 6to4:
o Use of relays. 6to4 depends on an unknown third party to operate o Use of relays. 6to4 depends on an unknown third party to operate
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o A 6to4 relay for the reverse path and an anycast 6to4 relay used o A 6to4 relay for the reverse path and an anycast 6to4 relay used
for the forward path, are openly accessible, limited only by the for the forward path, are openly accessible, limited only by the
scope of routing. 6to4 relays can be used to anonymize traffic and scope of routing. 6to4 relays can be used to anonymize traffic and
inject attacks into IPv6 that are very difficult to trace. inject attacks into IPv6 that are very difficult to trace.
o 6to4 may silently discard traffic in the case where protocol (41) o 6to4 may silently discard traffic in the case where protocol (41)
is blocked in intermediate firewalls. Even if a firewall sent an is blocked in intermediate firewalls. Even if a firewall sent an
ICMP message unreachable back, an IPv4 ICMP message rarely ICMP message unreachable back, an IPv4 ICMP message rarely
contains enough of the original IPv6 packet so that it can be contains enough of the original IPv6 packet so that it can be
relayed back to the IPv6 sender. That makes this problem hard to relayed back to the IPv6 sender. That makes this problem hard to
detect and react upon by the sender of the packet. detect and react upon by the sender of the packet.
o As 6to4 tunnels across the Internet, the IPv4 addresses used must o As 6to4 tunnels across the Internet, the IPv4 addresses used must
be globally reachable. RFC3056 states that a private address be globally reachable. RFC 3056 states that a private address
[RFC1918] MUST NOT be used. 6to4 will not work in networks that [RFC1918] MUST NOT be used. 6to4 will not work in networks that
employ other addresses with limited topological span. In employ other addresses with limited topological span. In
particular it will predictably fail in the case of double network particular it will predictably fail in the case of double network
address translation (NAT444). address translation (NAT444).
For further analysis, see [RFC6343]. For further analysis, see [RFC6343].
Peer-to-peer usage of the 6to4 mechanism, not depending on the
anycast mechanism, might exist in the Internet, largely unknown to
operators. This is harmless to third parties and the current
document is not intended to prevent such traffic continuing.
4. Deprecation 4. Deprecation
This document formally deprecates the 6to4 transition mechanism and This document formally deprecates the anycast 6to4 transition
the IPv6 6to4 prefix defined in [RFC3056], i.e., 2002::/16. The mechanism defined in [RFC3068] and the associated anycast IPv4
prefix MUST NOT be reassigned for other use except by a future IETF address 192.88.99.1. It is NOT RECOMMENDED to include this mechanism
standards action. in new implementations. It is no longer considered to be a useful
service of last resort.
Disabling 6to4 in the IPv6 Internet will take some time. Firstly, it The prefix 192.88.99.0/24 MUST NOT be reassigned for other use except
is NOT RECOMMENDED to include this mechanism in new implementations. by a future IETF standards action.
If included, it MUST be disabled by default. It is no longer
considered to be a useful service of "last resort" as supported by The basic unicast 6to4 mechanism defined in [RFC3056] and the
[RFC6724]. associated 6to4 IPv6 prefix 2002::/16 are not deprecated. The
default address selection rules specified in [RFC6724] are not
modified. However, if included in implementations, unicast 6to4 MUST
be disabled by default.
Implementations capable of acting as 6to4 routers MUST NOT enable Implementations capable of acting as 6to4 routers MUST NOT enable
6to4 without explicit user configuration. In particular, enabling 6to4 without explicit user configuration. In particular, enabling
IPv6 forwarding on a device, MUST NOT automatically enable 6to4. IPv6 forwarding on a device MUST NOT automatically enable 6to4.
Current operators of an anycast 6to4 relay with the IPv4 address Current operators of an anycast 6to4 relay with the IPv4 address
192.88.99.1 SHOULD review the information in [RFC6343] and the 192.88.99.1 SHOULD review the information in [RFC6343] and the
present document, and then consider carefully when the anycast relay present document, and then consider carefully when the anycast relay
can be discontinued as traffic diminishes. can be discontinued as traffic diminishes. Internet service
providers SHOULD filter out routes to 192.88.99.1.
Operators of a 6to4 return relay announcing the IPv6 prefix 2002::/16 Operators of a 6to4 return relay announcing the IPv6 prefix 2002::/16
SHOULD review the information in [RFC6343] and the present document, SHOULD review the information in [RFC6343] and the present document,
and then consider carefully when the return relay can be discontinued and then consider carefully when the return relay can be discontinued
as traffic diminishes. As discussed in Section 4.5 of RFC 6343, as traffic diminishes. As discussed in Section 4.5 of RFC 6343,
content providers might choose to continue operating such a relay for content providers might choose to continue operating such a relay for
the benefit of any residual 6to4 clients. the benefit of their own residual 6to4 clients. Internet service
providers SHOULD announce the IPv6 prefix 2002::/16 if and only if it
Peer-to-peer usage of the 6to4 mechanism, not depending on the leads to a correctly operating return relay as described in RFC 6343.
anycast mechanism, might exist in the Internet, largely unknown to
operators. This is harmless to third parties and the current
document is not intended to prevent such traffic continuing.
The references to 6to4 should be removed as soon as practical from
the revision of the Special-Use IPv6 Addresses [RFC6890].
The references to the 6to4 relay anycast addresses (192.88.99.0/24) The references to the 6to4 relay anycast prefix (192.88.99.0/24)
should be removed as soon as practical from the revision of the should be removed as soon as practical from the revision of the
Special Use IPv4 addresses [RFC6890]. Special Use IPv4 addresses [RFC6890].
Incidental references to 6to4 should be removed from other IETF Incidental references to 6to4 should be reviewed and possibly removed
documents if and when they are updated. These documents include from other IETF documents if and when they are updated. These
RFC3162, RFC3178, RFC3790, RFC4191, RFC4213, RFC4389, RFC4779, documents include RFC3162, RFC3178, RFC3790, RFC4191, RFC4213,
RFC4852, RFC4891, RFC4903, RFC5157, RFC5245, RFC5375, RFC5971, and RFC4389, RFC4779, RFC4852, RFC4891, RFC4903, RFC5157, RFC5245,
RFC6071. RFC5375, RFC5971, and RFC6071.
5. IANA Considerations 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].
The delegation of the 2.0.0.2.ip6.arpa domain [RFC5158] should be
left in place. Redelegation of the domain for any usage requires
justification via an IETF Standards Action [RFC5226].
IANA is requested to mark the 192.88.99.0/24 prefix [RFC3068] as IANA is requested to mark the 192.88.99.0/24 prefix [RFC3068] as
"deprecated", pointing to this document. Redelegation of the domain "deprecated", pointing to this document. Redelegation of this prefix
for any usage requires justification via an IETF Standards Action for any usage requires justification via an IETF Standards Action
[RFC5226]. [RFC5226].
6. Security Considerations 6. Security Considerations
There are no new security considerations pertaining to this document. There are no new security considerations pertaining to this document.
General security issues with tunnels are listed in [RFC6169] and more General security issues with tunnels are listed in [RFC6169] and more
specifically to 6to4 in [RFC3964] and [RFC6324]. specifically to 6to4 in [RFC3964] and [RFC6324].
7. Acknowledgements 7. Acknowledgements
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[HUSTON] Huston, , "Flailing IPv6", December 2010, [HUSTON] Huston, , "Flailing IPv6", December 2010,
<http://www.potaroo.net/ispcol/2010-12/6to4fail.html>. <http://www.potaroo.net/ispcol/2010-12/6to4fail.html>.
[RFC1918] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and [RFC1918] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and
E. Lear, "Address Allocation for Private Internets", BCP E. Lear, "Address Allocation for Private Internets", BCP
5, RFC 1918, February 1996. 5, RFC 1918, February 1996.
[RFC3964] Savola, P. and C. Patel, "Security Considerations for [RFC3964] Savola, P. and C. Patel, "Security Considerations for
6to4", RFC 3964, December 2004. 6to4", RFC 3964, December 2004.
[RFC5158] Huston, G., "6to4 Reverse DNS Delegation Specification",
RFC 5158, March 2008.
[RFC5969] Townsley, W. and O. Troan, "IPv6 Rapid Deployment on IPv4 [RFC5969] Townsley, W. and O. Troan, "IPv6 Rapid Deployment on IPv4
Infrastructures (6rd) -- Protocol Specification", RFC Infrastructures (6rd) -- Protocol Specification", RFC
5969, August 2010. 5969, August 2010.
[RFC6169] Krishnan, S., Thaler, D., and J. Hoagland, "Security [RFC6169] Krishnan, S., Thaler, D., and J. Hoagland, "Security
Concerns with IP Tunneling", RFC 6169, April 2011. Concerns with IP Tunneling", RFC 6169, April 2011.
[RFC6324] Nakibly, G. and F. Templin, "Routing Loop Attack Using [RFC6324] Nakibly, G. and F. Templin, "Routing Loop Attack Using
IPv6 Automatic Tunnels: Problem Statement and Proposed IPv6 Automatic Tunnels: Problem Statement and Proposed
Mitigations", RFC 6324, August 2011. Mitigations", RFC 6324, August 2011.
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