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 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 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 Troan & Carpenter Expires August 1, 2015 [Page 1]

Internet-Draft Deprecating 6to4 Anycast January 2015 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 the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. 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 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]. Troan & Carpenter Expires August 1, 2015 [Page 2]

Internet-Draft Deprecating 6to4 Anycast January 2015 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 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 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 Troan & Carpenter Expires August 1, 2015 [Page 3]

Internet-Draft Deprecating 6to4 Anycast January 2015 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 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, Troan & Carpenter Expires August 1, 2015 [Page 4]

Internet-Draft Deprecating 6to4 Anycast January 2015 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 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 RFC6169] and more specifically to 6to4 in [RFC3964] and [RFC6324]. 9 . Acknowledgements Troan & Carpenter Expires August 1, 2015 [Page 6]

Internet-Draft Deprecating 6to4 Anycast January 2015 Brian Carpenter (editor) Department of Computer Science University of Auckland PB 92019 Auckland 1142 New Zealand Email: brian.e.carpenter@gmail.com Troan & Carpenter Expires August 1, 2015 [Page 9]