Advisory Guidelines for 6to4 Deployment
RFC 6343
Internet Engineering Task Force (IETF) B. Carpenter
Request for Comments: 6343 Univ. of Auckland
Category: Informational August 2011
ISSN: 2070-1721
Advisory Guidelines for 6to4 Deployment
Abstract
This document provides advice to network operators about deployment
of the 6to4 technique for automatic tunneling of IPv6 over IPv4. It
is principally addressed to Internet Service Providers (ISPs),
including those that do not yet support IPv6, and to Content
Providers. Some advice to implementers is also included. The
intention of the advice is to minimize both user dissatisfaction and
help-desk calls.
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for informational purposes.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are a candidate for any level of Internet
Standard; see Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc6343.
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
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Carpenter Informational [Page 1]
RFC 6343 6to4 Advisory August 2011
Table of Contents
1. Introduction ....................................................2
2. Principles of Operation .........................................3
2.1. Router 6to4 ................................................3
2.2. Anycast 6to4 ...............................................4
3. Problems Observed ...............................................5
4. Advisory Guidelines ............................................10
4.1. Vendor Issues .............................................10
4.2. Consumer ISPs, and Enterprise Networks, That Do
Not Support IPv6 in Any Way ...............................11
4.2.1. Anycast Address Availability .......................11
4.2.2. Protocol 41 ........................................11
4.2.3. IPv4 Prefix Issues .................................12
4.2.4. DNS Issues .........................................12
4.2.5. Rogue Router Advertisements ........................12
4.2.6. Planning for IPv6 Deployment .......................13
4.3. Consumer ISPs, and Enterprise Networks, That Do
Support IPv6 ..............................................13
4.4. Transit ISPs and Internet Exchange Points .................14
4.5. Content Providers and Their ISPs ..........................15
5. Tunnels Managed by ISPs ........................................17
6. Security Considerations ........................................17
7. Acknowledgements ...............................................18
8. References .....................................................18
8.1. Normative References ......................................18
8.2. Informative References ....................................18
1. Introduction
A technique for automatic tunneling of IPv6 over IPv4, intended for
situations where a user may wish to access IPv6-based services via a
network that does not support IPv6, was defined a number of years
ago. It is known as 6to4 [RFC3056] [RFC3068] and is quite widely
deployed in end systems, especially desktop and laptop computers.
Also, 6to4 is supported in a number of popular models of CPE routers,
some of which have it enabled by default, leading to quite widespread
unintentional deployment by end users.
Unfortunately, experience shows that the method has some problems in
current deployments that can lead to connectivity failures. These
failures cause either long retry delays or complete failures for
users trying to connect to services. In many cases, the user may be
quite unaware that 6to4 is in use; when the user contacts a help
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