v6ops WG O. Troan
Internet-Draft G. Van de Velde
Obsoletes: 3056 (if approved) Cisco
Intended status: Standards Track February 7, 2011
Expires: August 11, 2011
Request to move Connection of IPv6 Domains via IPv4 Clouds (6to4) to
Historic status
draft-troan-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 [RFC3056] is moved to historic status.
Status of this Memo
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This Internet-Draft will expire on August 11, 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
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the Trust Legal Provisions and are provided without warranty as
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described in the Simplified BSD License.
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1. Introduction
The IPv6 transitioning mechanism "Connection of IPv6 Domains via IPv4
Clouds (6to4) described in [RFC3056] and the extension in "An Anycast
Prefix for 6to4 Relay Routers" RFC3068 [RFC3068] have been shown to
have severe practical problems being used in the Internet. This
document requests that RFC3056 and RFC3068 be moved to Historic
status.
See also the document Non-Managed IPv6 Tunnels considered Harmful
[I-D.vandevelde-v6ops-harmful-tunnels] for details.
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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].
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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
domain to attrach 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
(read BGP peers) to a set of 6to4 relay routers. While this makes
the forward path more controlled, it does not help the reverse path.
In any case this model has the same operational burden has manually
configured tunnels.
Use of relays. 6to4 depends on the charity of an unknown third-
party to operate the relays between the 6to4 cloud and the native
IPv6 Internet. There is no financial incentive for a relay
provider to offer good service.
The placement of the relay can lead to increased latency, and in
the case the relay is overloaded packet loss.
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.
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.
6to4 has now provision to handle the case where the protocol (41)
is blocked in intermediate firewalls. It can not be expected that
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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.
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. There are 6to4 implementations that
enable 6ot4 by default. In the brave new world, where the use of
address sharing will be common 6to4 will not work.
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4. IANA Considerations
This specification does not require any IANA actions.
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5. Security Considerations
This document does not introduce any new security vulnerabilities.
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6. Acknowledgements
The authors would like to acknowledge N.N for their contributions and
discussions on this topic.
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7. Normative References
[I-D.vandevelde-v6ops-harmful-tunnels]
Velde, G., Troan, O., and T. Chown, "Non-Managed IPv6
Tunnels considered Harmful",
draft-vandevelde-v6ops-harmful-tunnels-01 (work in
progress), August 2010.
[RFC1918] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and
E. Lear, "Address Allocation for Private Internets",
BCP 5, RFC 1918, February 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.
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Authors' Addresses
Ole Troan
Cisco
Oslo,
Norway
Email: ot@cisco.com
Gunter Van de Velde
Cisco
De Kleetlaan 6a
Diegem 1831
Belgium
Phone: +32 2704 5473
Email: gvandeve@cisco.com
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