Internet Engineering Task Force (IETF) Y. Cui
Request for Comments: 7040 J. Wu
Category: Informational P. Wu
ISSN: 2070-1721 Tsinghua University
O. Vautrin
Juniper Networks
Y. Lee
Comcast
November 2013
Public IPv4-over-IPv6 Access Network
Abstract
This document describes a mechanism called Public 4over6, which is
designed to provide IPv4 Internet connectivity over an IPv6 access
network using global IPv4 addresses. Public 4over6 was developed in
the IETF and is in use in some existing deployments but is not
recommended for new deployments. Future deployments of similar
scenarios should use Lightweight 4over6. Public 4over6 follows the
Hub and Spoke softwire model and uses an IPv4-in-IPv6 tunnel to
forward IPv4 packets over an IPv6 access network. The
bidirectionality of the IPv4 communication is achieved by explicitly
allocating global non-shared IPv4 addresses to end users and by
maintaining IPv4-IPv6 address binding on the border relay. Public
4over6 aims to provide uninterrupted IPv4 services to users, like
Internet Content Providers (ICPs), etc., while an operator makes the
access network transition to an IPv6-only access network.
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/rfc7040.
Cui, et al. Informational [Page 1]RFC 7040 Public 4over6 November 2013Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the
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described in the Simplified BSD License.
Table of Contents
1. Introduction ....................................................2
2. Terminology .....................................................4
3. Scenario and Use Cases ..........................................4
4. Public 4over6 Address Provisioning ..............................6
4.1. Basic Provisioning Steps ...................................6
4.2. Public IPv4 Address Allocation .............................7
5. 4over6 CE Behavior ..............................................7
6. 4over6 BR Behavior ..............................................8
7. Fragmentation and Reassembly ....................................9
8. DNS .............................................................9
9. Security Considerations ........................................10
10. Contributors ..................................................11
11. References ....................................................12
11.1. Normative References .....................................12
11.2. Informative References ...................................12
1. Introduction
When operators make the access network transition to an IPv6-only
access network, they must continue to provide IPv4 services to their
users to access IPv4 contents. IPv4 connectivity is required when
communicating with the IPv4-only Internet. This document describes a
mechanism called Public 4over6 for providing IPv4 connectivity over a
native IPv6-only access network. This memo focuses on interactions
between Public 4over6 elements as well as the deployment
datatracker.ietf.org