Internet Engineering Task Force (IETF) S. Jiang
Request for Comments: 6264 D. Guo
Category: Informational Huawei
ISSN: 2070-1721 B. Carpenter
University of Auckland
June 2011
An Incremental Carrier-Grade NAT (CGN) for IPv6 Transition
Abstract
Global IPv6 deployment was slower than originally expected. As IPv4
address exhaustion approaches, IPv4 to IPv6 transition issues become
more critical and less tractable. Host-based transition mechanisms
used in dual-stack environments cannot meet all transition
requirements. Most end users are not sufficiently expert to
configure or maintain host-based transition mechanisms. Carrier-
Grade NAT (CGN) devices with integrated transition mechanisms can
reduce the operational changes required during the IPv4 to IPv6
migration or coexistence period.
This document proposes an incremental CGN approach for IPv6
transition. It can provide IPv6 access services for IPv6 hosts and
IPv4 access services for IPv4 hosts while leaving much of a legacy
ISP network unchanged during the initial stage of IPv4 to IPv6
migration. Unlike CGN alone, incremental CGN also supports and
encourages smooth transition towards dual-stack or IPv6-only ISP
networks. An integrated configurable CGN device and an adaptive home
gateway (HG) device are described. Both are reusable during
different transition phases, avoiding multiple upgrades. This
enables IPv6 migration to be incrementally achieved according to real
user requirements.
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.
Jiang, et al. Informational [Page 1]RFC 6264 Incremental CGN for IPv6 Transition June 2011
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/rfc6264.
Copyright Notice
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Table of Contents
1. Introduction ....................................................2
2. An Incremental CGN Approach .....................................4
2.1. Incremental CGN Approach Overview ..........................4
2.2. Choice of Tunneling Technology .............................5
2.3. Behavior of Dual-Stack Home Gateway ........................6
2.4. Behavior of Dual-Stack CGN .................................6
2.5. Impact for Existing Hosts and Unchanged Networks ...........7
2.6. IPv4/IPv6 Intercommunication ...............................7
2.7. Discussion .................................................8
3. Smooth Transition towards IPv6 Infrastructure ...................8
4. Security Considerations ........................................10
5. Acknowledgements ...............................................10
6. References .....................................................10
6.1. Normative References ......................................10
6.2. Informative References ....................................11
1. Introduction
Global IPv6 deployment did not happen as was forecast 10 years ago.
Network providers were hesitant to make the first move while IPv4 was
and is still working well. However, IPv4 address exhaustion is
imminent. The dynamically updated IPv4 Address Report [IPUSAGE] has
analyzed this issue. IANA unallocated address pool exhaustion
occurred in February 2011, and at the time of publication, the site
datatracker.ietf.org