Internet Engineering Task Force (IETF) A. Durand
Request for Comments: 6333 Juniper Networks
Category: Standards Track R. Droms
ISSN: 2070-1721 Cisco
J. Woodyatt
Apple
Y. Lee
Comcast
August 2011
Dual-Stack Lite Broadband Deployments Following IPv4 Exhaustion
Abstract
This document revisits the dual-stack model and introduces the Dual-
Stack Lite technology aimed at better aligning the costs and benefits
of deploying IPv6 in service provider networks. Dual-Stack Lite
enables a broadband service provider to share IPv4 addresses among
customers by combining two well-known technologies: IP in IP (IPv4-
in-IPv6) and Network Address Translation (NAT).
Status of This Memo
This is an Internet Standards Track document.
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). Further information on
Internet Standards is available in 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/rfc6333.
Durand, et al. Standards Track [Page 1]RFC 6333 Dual-Stack Lite August 2011Copyright 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
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described in the Simplified BSD License.
Table of Contents
1. Introduction ....................................................3
2. Requirements Language ...........................................4
3. Terminology .....................................................4
4. Deployment Scenarios ............................................4
4.1. Access Model ...............................................4
4.2. CPE ........................................................5
4.3. Directly Connected Device ..................................6
5. B4 Element ......................................................7
5.1. Definition .................................................7
5.2. Encapsulation ..............................................7
5.3. Fragmentation and Reassembly ...............................7
5.4. AFTR Discovery .............................................7
5.5. DNS ........................................................8
5.6. Interface Initialization ...................................8
5.7. Well-Known IPv4 Address ....................................8
6. AFTR Element ....................................................9
6.1. Definition .................................................9
6.2. Encapsulation ..............................................9
6.3. Fragmentation and Reassembly ...............................9
6.4. DNS .......................................................10
6.5. Well-Known IPv4 Address ...................................10
6.6. Extended Binding Table ....................................10
7. Network Considerations .........................................10
7.1. Tunneling .................................................10
7.2. Multicast Considerations ..................................10
8. NAT Considerations .............................................11
8.1. NAT Pool ..................................................11
8.2. NAT Conformance ...........................................11
8.3. Application Level Gateways (ALGs) .........................11
8.4. Sharing Global IPv4 Addresses .............................11
8.5. Port Forwarding / Keep Alive ..............................11
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