Internet DRAFT - draft-ietf-v6ops-6to4-to-historic
draft-ietf-v6ops-6to4-to-historic
v6ops WG O. Troan
Internet-Draft Cisco
Obsoletes: 3068, 6732 (if approved) B. Carpenter, Ed.
Intended status: Best Current Practice Univ. of Auckland
Expires: August 1, 2015 January 28, 2015
Deprecating Anycast Prefix for 6to4 Relay Routers
draft-ietf-v6ops-6to4-to-historic-11.txt
Abstract
Experience with the "Connection of IPv6 Domains via IPv4 Clouds
(6to4)" IPv6 transition mechanism defined in RFC 3056 has shown that
when used in its anycast mode, the mechanism is unsuitable for
widespread deployment and use in the Internet. This document
therefore requests that RFC 3068, "An Anycast Prefix for 6to4 Relay
Routers", be made obsolete and moved to historic status. It also
obsoletes RFC 6732 "6to4 Provider Managed Tunnels". It recommends
that future products should not support 6to4 anycast and that
existing deployments should be reviewed. This complements the
guidelines in RFC 6343.
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
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This Internet-Draft will expire on August 1, 2015.
Copyright Notice
Copyright (c) 2015 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
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publication of this document. Please review these documents
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Related Work . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. 6to4 operational problems . . . . . . . . . . . . . . . . . . 3
4. Deprecation . . . . . . . . . . . . . . . . . . . . . . . . . 4
5. Implementation Recommendations . . . . . . . . . . . . . . . 5
6. Operational Recommendations . . . . . . . . . . . . . . . . . 5
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
8. Security Considerations . . . . . . . . . . . . . . . . . . . 6
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
10.1. Normative References . . . . . . . . . . . . . . . . . . 7
10.2. Informative References . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
The original form of the 6to4 transition mechanism [RFC3056] relies
on unicast addressing. However, its extension specified 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 RFC 3068 and RFC 6732 be moved to Historic
status as defined in section 4.2.4 of [RFC2026]. It complements the
deployment guidelines in [RFC6343].
6to4 was designed to help transition the Internet from IPv4 to IPv6.
It has been a good mechanism for experimenting with IPv6, but because
of the high failure rates seen with anycast 6to4 [HUSTON], end users
may end up disabling IPv6 on hosts as a result, and in the past some
content providers were reluctant to make content available over IPv6
for this reason.
[RFC6343] analyses the known operational issues in detail and
describes a set of suggestions to improve 6to4 reliability, given the
widespread presence of hosts and customer premises equipment that
support it. The advice to disable 6to4 by default has been widely
adopted in recent operating systems, and the failure modes have been
widely hidden from users by many browsers adopting the "Happy
Eyeballs" approach [RFC6555].
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Nevertheless, a measurable amount of 6to4 traffic is still observed
by IPv6 content providers. The remaining successful users of anycast
6to4 are likely to be on hosts using the obsolete policy table
[RFC3484], which prefers 6to4 above IPv4, and running without Happy
Eyeballs. Furthermore, they must have a route to an operational
anycast relay and they must be accessing an IPv6 host that has a
route to an operational return relay.
However, experience shows that operational failures caused by anycast
6to4 have continued, despite the advice in RFC 6343 being available.
1.1. Related Work
IPv6 Rapid Deployment on IPv4 Infrastructures (6rd) [RFC5969]
explicitly builds on the 6to4 mechanism, using a service provider
prefix instead of 2002::/16. However, the deployment model is based
on service provider support, such that 6rd avoids the problems
observed with anycast 6to4.
The framework for 6to4 Provider Managed Tunnels [RFC6732] is intended
to help a service provider manage 6to4 anycast tunnels. This
framework only exists because of the problems observed with anycast
6to4.
2. Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in RFC
2119 [RFC2119].
The word "deprecate" and its derivatives are used only in their
generic sense of "criticize or express disapproval" and do not have
any specific normative meaning. A deprecated function might exist in
the Internet for many years to allow backwards compatibility.
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 shortcomings.
In the forward direction 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
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injected into the native IPv6 routing 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.
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
(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 as manually configured tunnels and has seen no
deployment in the public Internet.
RFC 3068 adds an extension that allows the use of a well known IPv4
anycast address to reach the nearest 6to4 relay in the forward
direction. However, this anycast mechanism has a number of
operational issues and problems, which are described in detail in
Section 3 of [RFC6343]. This document is intended to deprecate the
anycast mechanism.
Peer-to-peer usage of the 6to4 mechanism exists in the Internet,
likely unknown to many operators. This usage is harmless to third
parties and is not dependent on the anycast 6to4 mechanism that this
document deprecates.
4. Deprecation
This document formally deprecates the anycast 6to4 transition
mechanism defined in [RFC3068] and the associated anycast IPv4
address 192.88.99.1. It is no longer considered to be a useful
service of last resort.
The prefix 192.88.99.0/24 MUST NOT be reassigned for other use except
by a future IETF standards action.
The basic unicast 6to4 mechanism defined in [RFC3056] and the
associated 6to4 IPv6 prefix 2002::/16 are not deprecated. The
default address selection rules specified in [RFC6724] are not
modified.
In the absence of 6to4 anycast, 6to4 Provider Managed Tunnels
[RFC6732] will no longer be necessary, so they are also deprecated by
this document.
Incidental references to 6to4 should be reviewed and possibly removed
from other IETF documents if and when they are updated. These
documents include RFC3162, RFC3178, RFC3790, RFC4191, RFC4213,
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RFC4389, RFC4779, RFC4852, RFC4891, RFC4903, RFC5157, RFC5245,
RFC5375, RFC5971, RFC6071 and RFC6890.
5. Implementation Recommendations
It is NOT RECOMMENDED to include the anycast 6to4 transition
mechanism in new implementations. If included in any
implementations, the anycast 6to4 mechanism MUST be disabled by
default.
In host implementations, unicast 6to4 MUST also be disabled by
default. All hosts using 6to4 MUST support the IPv6 address
selection policy described in [RFC6724].
In router implementations, 6to4 MUST be disabled by default. In
particular, enabling IPv6 forwarding on a device MUST NOT
automatically enable 6to4.
6. Operational Recommendations
This document does not imply a recommendation for the generalized
filtering of traffic or routes for 6to4 or even anycast 6to4. It
simply recommends against further deployment of the anycast 6to4
mechanism, calls for current 6to4 deployments to evaluate the
efficacy of continued use of the anycast 6to4 mechanism, and makes
recommendations intended to prevent any use of 6to4 from hampering
broader deployment and use of native IPv6 on the Internet as a whole.
Networks SHOULD NOT filter out packets whose source address is
192.88.99.1, because this is normal 6to4 traffic from a 6to4 return
relay somewhere in the Internet. This includes ensuring that traffic
from a local 6to4 return relay with a source address of 192.88.99.1
is allowed through anti-spoofing filters such as those described in
[RFC2827] and [RFC3704] or through Unicast Reverse-Path-Forwarding
(uRPF) checks [RFC5635].
The guidelines in Section 4 of [RFC6343] remain valid for those who
choose to continue operating Anycast 6to4 despite its deprecation.
Current operators of an anycast 6to4 relay with the IPv4 address
192.88.99.1 SHOULD review the information in [RFC6343] and the
present document, and then consider carefully whether the anycast
relay can be discontinued as traffic diminishes. Internet service
providers that do not operate an anycast relay but do provide their
customers with a route to 192.88.99.1 SHOULD verify that it does in
fact lead to an operational anycast relay, as discussed in
Section 4.2.1 of [RFC6343]. Furthermore, Internet service providers
and other network providers MUST NOT originate a route to
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192.88.99.1, unless they actively operate and monitor an anycast 6to4
relay service as detailed in Section 4.2.1 of [RFC6343].
Operators of a 6to4 return relay responding to the IPv6 prefix
2002::/16 SHOULD review the information in [RFC6343] and the present
document, and then consider carefully whether the return relay can be
discontinued as traffic diminishes. To avoid confusion, note that
nothing in the design of 6to4 assumes or requires that return packets
are handled by the same relay as outbound packets. As discussed in
Section 4.5 of RFC 6343, content providers might choose to continue
operating a return relay for the benefit of their own residual 6to4
clients. Internet service providers SHOULD announce the IPv6 prefix
2002::/16 to their own customers if and only if it leads to a
correctly operating return relay as described in RFC 6343. IPv6-only
service providers, including those operating a NAT64 service
[RFC6146], are advised that their own customers need a route to such
a relay in case a residual 6to4 user served by a different service
provider attempts to communicate with them.
Operators of 6to4 Provider Managed Tunnels [RFC6732] SHOULD carefully
consider when this service can be discontinued as traffic diminishes.
7. IANA Considerations
The document creating the IANA IPv4 Special-Purpose Address Registry
[RFC6890] included the 6to4 relay anycast prefix (192.88.99.0/24) as
Table 10. Instead, IANA is requested to mark the 192.88.99.0/24
prefix originally defined by [RFC3068] as "Deprecated (6to4 Relay
Anycast)", pointing to the present document. Redelegation of this
prefix for any usage requires justification via an IETF Standards
Action [RFC5226].
8. Security Considerations
There are no new security considerations pertaining to this document.
General security issues with tunnels are listed in [RFC6169] and more
specifically to 6to4 in [RFC3964] and [RFC6324].
9. Acknowledgements
The authors would like to acknowledge Tore Anderson, Mark Andrews,
Dmitry Anipko, Jack Bates, Cameron Byrne, Ben Campbell, Lorenzo
Colitti, Gert Doering, Nick Hilliard, Philip Homburg, Ray Hunter,
Joel Jaeggli, Victor Kuarsingh, Kurt Erik Lindqvist, Jason Livingood,
Jeroen Massar, Keith Moore, Tom Petch, Daniel Roesen, Mark Townsley
and James Woodyatt for their contributions and discussions on this
topic.
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Special thanks go to Fred Baker, David Farmer, Wes George, and Geoff
Huston for their significant contributions.
Many thanks to Gunter Van de Velde for documenting the harm caused by
non-managed tunnels and stimulating the creation of this document.
10. References
10.1. Normative References
[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.
[RFC2827] Ferguson, P. and D. Senie, "Network Ingress Filtering:
Defeating Denial of Service Attacks which employ IP Source
Address Spoofing", BCP 38, RFC 2827, May 2000.
[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.
[RFC3704] Baker, F. and P. Savola, "Ingress Filtering for Multihomed
Networks", BCP 84, RFC 3704, March 2004.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
[RFC6146] Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful
NAT64: Network Address and Protocol Translation from IPv6
Clients to IPv4 Servers", RFC 6146, April 2011.
[RFC6724] Thaler, D., Draves, R., Matsumoto, A., and T. Chown,
"Default Address Selection for Internet Protocol Version 6
(IPv6)", RFC 6724, September 2012.
[RFC6890] Cotton, M., Vegoda, L., Bonica, R., and B. Haberman,
"Special-Purpose IP Address Registries", BCP 153, RFC
6890, April 2013.
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10.2. Informative References
[HUSTON] Huston, , "Flailing IPv6", December 2010,
<http://www.potaroo.net/ispcol/2010-12/6to4fail.html>.
[RFC3484] Draves, R., "Default Address Selection for Internet
Protocol version 6 (IPv6)", RFC 3484, February 2003.
[RFC3964] Savola, P. and C. Patel, "Security Considerations for
6to4", RFC 3964, December 2004.
[RFC5635] Kumari, W. and D. McPherson, "Remote Triggered Black Hole
Filtering with Unicast Reverse Path Forwarding (uRPF)",
RFC 5635, August 2009.
[RFC5969] Townsley, W. and O. Troan, "IPv6 Rapid Deployment on IPv4
Infrastructures (6rd) -- Protocol Specification", RFC
5969, August 2010.
[RFC6169] Krishnan, S., Thaler, D., and J. Hoagland, "Security
Concerns with IP Tunneling", RFC 6169, April 2011.
[RFC6324] Nakibly, G. and F. Templin, "Routing Loop Attack Using
IPv6 Automatic Tunnels: Problem Statement and Proposed
Mitigations", RFC 6324, August 2011.
[RFC6343] Carpenter, B., "Advisory Guidelines for 6to4 Deployment",
RFC 6343, August 2011.
[RFC6555] Wing, D. and A. Yourtchenko, "Happy Eyeballs: Success with
Dual-Stack Hosts", RFC 6555, April 2012.
[RFC6732] Kuarsingh, V., Lee, Y., and O. Vautrin, "6to4 Provider
Managed Tunnels", RFC 6732, September 2012.
Authors' Addresses
Ole Troan
Cisco
Oslo
Norway
Email: ot@cisco.com
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Brian Carpenter (editor)
Department of Computer Science
University of Auckland
PB 92019
Auckland 1142
New Zealand
Email: brian.e.carpenter@gmail.com
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