Dynamic Host Configuration Protocol for IPv6 (DHCPv6) Option for Dual-Stack Lite
RFC 6334

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Internet Engineering Task Force (IETF)                        D. Hankins
Request for Comments: 6334                                        Google
Category: Standards Track                                   T. Mrugalski
ISSN: 2070-1721                          Gdansk University of Technology
                                                             August 2011

      Dynamic Host Configuration Protocol for IPv6 (DHCPv6) Option
                          for Dual-Stack Lite

Abstract

   This document specifies a DHCPv6 option that is meant to be used by a
   Dual-Stack Lite Basic Bridging BroadBand (B4) element to discover the
   IPv6 address of its corresponding Address Family Transition Router
   (AFTR).

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/rfc6334.

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.

Hankins & Mrugalski          Standards Track                    [Page 1]
RFC 6334                  DS-Lite DHCPv6 Option              August 2011

Table of Contents

   1. Introduction ....................................................2
   2. Requirements Language ...........................................2
   3. The AFTR-Name DHCPv6 Option .....................................2
   4. DHCPv6 Server Behavior ..........................................4
   5. DHCPv6 Client Behavior ..........................................4
   6. Security Considerations .........................................5
   7. IANA Considerations .............................................6
   8. Acknowledgements ................................................6
   9. Normative References ............................................6

1.  Introduction

   Dual-Stack Lite [RFC6333] is a solution to offer both IPv4 and IPv6
   connectivity to customers that are addressed only with an IPv6 prefix
   (no IPv4 address is assigned to the attachment device).  One of its
   key components is an IPv4-over-IPv6 tunnel, commonly referred to as a
   softwire.  A DS-Lite "Basic Bridging BroadBand" (B4) device will not
   know if the network it is attached to offers Dual-Stack Lite service,
   and if it did would not know the remote endpoint of the tunnel to
   establish a softwire.

   To inform the B4 of the Address Family Transition Router's (AFTR)
   location, a DNS [RFC1035] hostname may be used.  Once this
   information is conveyed, the presence of the configuration indicating
   the AFTR's location also informs a host to initiate Dual-Stack Lite
   (DS-Lite) service and become a softwire initiator.

   To provide the conveyance of the configuration information, a single
   DHCPv6 [RFC3315] option is used, expressing the AFTR's Fully
   Qualified Domain Name (FQDN) to the B4 element.

   The details of how the B4 establishes an IPv4-in-IPv6 softwire to the
   AFTR are out of scope for this document.

2.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

3.  The AFTR-Name DHCPv6 Option

   The AFTR-Name option consists of option-code and option-len fields
   (as all DHCPv6 options have), and a variable-length tunnel-endpoint-
   name field containing a fully qualified domain name that refers to
   the AFTR to which the client MAY connect.

Hankins & Mrugalski          Standards Track                    [Page 2]
RFC 6334                  DS-Lite DHCPv6 Option              August 2011

   The AFTR-Name option SHOULD NOT appear in any DHCPv6 messages other
   than the following: Solicit, Advertise, Request, Renew, Rebind,
   Information-Request, and Reply.

   The format of the AFTR-Name option is shown in the following figure:

      0                   1                   2                   3