Duplicate Address Detection Proxy
RFC 6957

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Internet Engineering Task Force (IETF)                          F. Costa
Request for Comments: 6957                              J-M. Combes, Ed.
Category: Standards Track                                    X. Pougnard
ISSN: 2070-1721                                    France Telecom Orange
                                                                   H. Li
                                                     Huawei Technologies
                                                               June 2013

                   Duplicate Address Detection Proxy

Abstract

   The document describes a proxy-based mechanism allowing the use of
   Duplicate Address Detection (DAD) by IPv6 nodes in a point-to-
   multipoint architecture with a "split-horizon" forwarding scheme,
   primarily deployed for Digital Subscriber Line (DSL) and Fiber access
   architectures.  Based on the DAD signaling, the first-hop router
   stores in a Binding Table all known IPv6 addresses used on a point-
   to-multipoint domain (e.g., VLAN).  When a node performs DAD for an
   address already used by another node, the first-hop router defends
   the address rather than the device using the address.

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/rfc6957.

Costa, et al.                Standards Track                    [Page 1]
RFC 6957                        DAD-Proxy                      June 2013

Copyright Notice

   Copyright (c) 2013 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.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  Background  . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Why Existing IETF Solutions Are Not Sufficient  . . . . . . .   4
     3.1.  Duplicate Address Detection . . . . . . . . . . . . . . .   4
     3.2.  Neighbor Discovery Proxy  . . . . . . . . . . . . . . . .   5
     3.3.  6LoWPAN Neighbor Discovery  . . . . . . . . . . . . . . .   5
     3.4.  IPv6 Mobility Manager . . . . . . . . . . . . . . . . . .   6
   4.  Duplicate Address Detection Proxy (DAD-Proxy) Specifications    6
     4.1.  DAD-Proxy Data Structure  . . . . . . . . . . . . . . . .   6
     4.2.  DAD-Proxy Mechanism . . . . . . . . . . . . . . . . . . .   7
       4.2.1.  No Entry Exists for the Tentative Address . . . . . .   7
       4.2.2.  An Entry Already Exists for the Tentative Address . .   7
       4.2.3.  Confirmation of Reachability to Check the Validity of
               the Conflict  . . . . . . . . . . . . . . . . . . . .   9
   5.  Manageability Considerations  . . . . . . . . . . . . . . . .  11
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  11
     6.1.  Interoperability with SEND  . . . . . . . . . . . . . . .  11
     6.2.  Protection against IP Source Address Spoofing . . . . . .  11
   7.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  11
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  12
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  12
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  12
   Appendix A.  DAD-Proxy State Machine  . . . . . . . . . . . . . .  14

Costa, et al.                Standards Track                    [Page 2]
RFC 6957                        DAD-Proxy                      June 2013

1.  Introduction

   This document specifies a function called Duplicate Address Detection
   (DAD) proxy allowing the use of DAD by the nodes on the same point-
   to-multipoint domain with a "split-horizon" forwarding scheme,
   primarily deployed for Digital Subscriber Line (DSL) and Fiber access
   architectures [TR-101].  It only impacts the first-hop router and it
   doesn't need modifications on the other IPv6 nodes.  This mechanism