v6ops WG O. Troan Internet-Draft G. Van de Velde Obsoletes: 3056 (if approved) Cisco Intended status: Standards Track March 10, 2011 Expires: September 11, 2011 Request to move Connection of IPv6 Domains via IPv4 Clouds (6to4) to Historic status draft-troan-v6ops-6to4-to-historic-01.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 September 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 (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 include Simplified BSD License text as described in Section 4.e of Troan & Van de Velde Expires September 11, 2011 [Page 1] Internet-Draft 6to4 to Historic status March 2011 the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. 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 as defined in section 4.2.4 [RFC2026]. See also the document Non-Managed IPv6 Tunnels considered Harmful [I-D.vandevelde-v6ops-harmful-tunnels] for details. [I-D.kuarsingh-v6ops-6to4-provider-managed-tunnel] are proposing a mechanism using IPv6 NAT to solve the 6to4 reverse path problem. [I-D.carpenter-v6ops-6to4-teredo-advisory] are proposing a set of suggestions to improve 6to4 reliability. 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 Troan & Van de Velde Expires September 11, 2011 [Page 2] Internet-Draft 6to4 to Historic status March 2011 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 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 (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 and has seen no deployment in the public Internet. 6to4 issues: o 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. With the use of mechanism specified in [RFC3068] in both directions, without it only in the reverse direction (from native to 6to4) [RFC3056]. 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 addresses with limited topological span. 4. Recommendations for 6to4 Relay Operators See [I-D.carpenter-v6ops-6to4-teredo-advisory]. Troan & Van de Velde Expires September 11, 2011 [Page 3] Internet-Draft 6to4 to Historic status March 2011 5. Recommendations for implementors If the implementation continues to support 6to4, then the 6to4 functionality MUST NOT be enabled by default. If the implementation continues to support 6to4, then the Source Address Selection algorithm [RFC3484] MUST use a 6to4 address as a last resort. I.e. only use it the node has no other means of IPv6 connectivity and the destination is IPv6 only. 6. IANA Considerations This specification does not require any IANA actions. 7. 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 [I-D.ietf-v6ops-tunnel-loops] and [I-D.vandevelde-v6ops-harmful-tunnels]. 8. Acknowledgements The authors would like to acknowledge Fred Baker, Jack Bates, Cameron Byrne, Brian Carpenter, Gert Doering, Joel Jaeggli, Jason Livingood, Keith Moore, Daniel Roesen and Mark Townsley, for their contributions and discussions on this topic. 9. References 9.1. Normative References [RFC1918] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and E. Lear, "Address Allocation for Private Internets", BCP 5, RFC 1918, February 1996. [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 Troan & Van de Velde Expires September 11, 2011 [Page 4] Internet-Draft 6to4 to Historic status March 2011 via IPv4 Clouds", RFC 3056, February 2001. [RFC3068] Huitema, C., "An Anycast Prefix for 6to4 Relay Routers", RFC 3068, June 2001. [RFC3484] Draves, R., "Default Address Selection for Internet Protocol version 6 (IPv6)", RFC 3484, February 2003. 9.2. Informative References [I-D.carpenter-v6ops-6to4-teredo-advisory] Carpenter, B., "Advisory Guidelines for 6to4 Deployment", draft-carpenter-v6ops-6to4-teredo-advisory-02 (work in progress), February 2011. [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-04 (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. [I-D.kuarsingh-v6ops-6to4-provider-managed-tunnel] Kuarsingh, V., Lee, Y., and O. Vautrin, "6to4 Provider Managed Tunnels", draft-kuarsingh-v6ops-6to4-provider-managed-tunnel-01 (work in progress), February 2011. [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. Troan & Van de Velde Expires September 11, 2011 [Page 5] Internet-Draft 6to4 to Historic status March 2011 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 Troan & Van de Velde Expires September 11, 2011 [Page 6]