Client Link-Layer Address Option in DHCPv6
RFC 6939

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Internet Engineering Task Force (IETF)                       G. Halwasia
Request for Comments: 6939                                   S. Bhandari
Category: Standards Track                                         W. Dec
ISSN: 2070-1721                                            Cisco Systems
                                                                May 2013

               Client Link-Layer Address Option in DHCPv6

Abstract

   This document specifies the format and mechanism that is to be used
   for encoding the client link-layer address in DHCPv6 Relay-Forward
   messages by defining a new DHCPv6 Client Link-Layer Address option.

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/rfc6939.

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.

Halwasia, et al.             Standards Track                    [Page 1]
RFC 6939         DHCPv6 Client Link-Layer Address Option        May 2013

Table of Contents

   1. Introduction ....................................................2
   2. Requirements Language ...........................................2
   3. Problem Background and Scenario .................................2
   4. DHCPv6 Client Link-Layer Address Option .........................4
   5. DHCPv6 Relay Agent Behavior .....................................4
   6. DHCPv6 Server Behavior ..........................................4
   7. DHCPv6 Client Behavior ..........................................5
   8. IANA Considerations .............................................5
   9. Security Considerations .........................................5
   10. Acknowledgements ...............................................6
   11. References .....................................................6
      11.1. Normative References ......................................6
      11.2. Informative References ....................................6

1.  Introduction

   This specification defines an optional mechanism and the related
   DHCPv6 option to allow first-hop DHCPv6 relay agents (relay agents
   that are connected to the same link as the client) to provide the
   client's link-layer address in the DHCPv6 messages being sent towards
   the server.

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.  Problem Background and Scenario

   The DHCPv4 specification [RFC2131] provides a way to specify the
   client link-layer address in the DHCPv4 message header.  A DHCPv4
   message header has 'htype' and 'chaddr' fields to specify the client
   link-layer address type and the link-layer address, respectively.
   The client link-layer address thus learned can be used by the DHCPv4
   server and the relay agent in different ways.  In some of the
   deployments, DHCPv4 servers use 'chaddr' as a customer identifier and
   a key for lookup in the client lease database.

   With the incremental deployment of IPv6 to existing IPv4 networks,
   which results in a dual-stack network environment, there will be
   devices that act as both DHCPv4 and DHCPv6 clients.  In service
   provider deployments, a typical DHCPv4 implementation will use the
   client link-layer address as one of the keys to build the DHCP client
   lease database.  In dual-stack scenarios, operators need to be able

Halwasia, et al.             Standards Track                    [Page 2]
RFC 6939         DHCPv6 Client Link-Layer Address Option        May 2013

   to associate DHCPv4 and DHCPv6 messages with the same client
   interface, based on an identifier that is common to the interface.
   The client link-layer address is such an identifier.

   Currently, the DHCPv6 specification [RFC3315] does not define a way