Lightweight DHCPv6 Relay Agent
RFC 6221

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Internet Engineering Task Force (IETF)                     D. Miles, Ed.
Request for Comments: 6221                                      S. Ooghe
Updates: 3315                                             Alcatel-Lucent
Category: Standards Track                                         W. Dec
ISSN: 2070-1721                                            Cisco Systems
                                                             S. Krishnan
                                                             A. Kavanagh
                                                                Ericsson
                                                                May 2011

                     Lightweight DHCPv6 Relay Agent

Abstract

   This document proposes a Lightweight DHCPv6 Relay Agent (LDRA) that
   is used to insert relay agent options in DHCPv6 message exchanges
   identifying client-facing interfaces.  The LDRA can be implemented in
   existing access nodes (such as Digital Subscriber Link Access
   Multiplexers (DSLAMs) and Ethernet switches) that do not support IPv6
   control or routing functions.

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/rfc6221.

Miles, et al.                Standards Track                    [Page 1]
RFC 6221                          LDRA                          May 2011

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.

Table of Contents

   1. Introduction ....................................................3
      1.1. Requirements Language ......................................3
   2. Background ......................................................3
   3. Terminology .....................................................3
   4. Server Considerations ...........................................5
   5. Message Format ..................................................5
      5.1. Relay-Forward Message ......................................5
      5.2. Relay-Reply Message ........................................6
      5.3. Mandatory DHCP Options .....................................6
           5.3.1. Relay-Message Option ................................6
           5.3.2. Interface-ID Option .................................6
   6. Agent Behaviour .................................................7
      6.1. Relaying a Client Message ..................................7
           6.1.1. Client Message Validation ...........................8
           6.1.2. Trusted and Untrusted Interfaces ....................8
      6.2. Relaying a Relay-Reply Message from the Network ............8
   7. Network Topology ................................................9
      7.1. Client and Server on Same Link .............................9
      7.2. Client and Server behind Relay Agent ......................11
      7.3. Relay Agent in Front of LDRA ..............................12
   8. Contributors ...................................................15
   9. Security Considerations ........................................15
   10. References ....................................................15
      10.1. Normative References .....................................15
      10.2. Informative References ...................................16

Miles, et al.                Standards Track                    [Page 2]
RFC 6221                          LDRA                          May 2011

1.  Introduction

   DHCPv6 Relay Agents [RFC3315] are deployed to forward DHCPv6 messages
   between clients and servers when they are not on the same IPv6 link
   and are often implemented alongside a routing function in a common
   node.  A Lightweight DHCPv6 Relay Agent (LDRA) allows Relay Agent
   Information to be inserted by an access node that performs a link-
   layer bridging (i.e., non-routing) function.  An LDRA resides on the