Stateless Dynamic Host Configuration Protocol (DHCP) Service for IPv6
RFC 3736

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Network Working Group                                           R. Droms
Request for Comments: 3736                                 Cisco Systems
Category: Standards Track                                     April 2004

 Stateless Dynamic Host Configuration Protocol (DHCP) Service for IPv6

Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2004).  All Rights Reserved.

Abstract

   Stateless Dynamic Host Configuration Protocol service for IPv6
   (DHCPv6) is used by nodes to obtain configuration information, such
   as the addresses of DNS recursive name servers, that does not require
   the maintenance of any dynamic state for individual clients.  A node
   that uses stateless DHCP must have obtained its IPv6 addresses
   through some other mechanism, typically stateless address
   autoconfiguration.  This document explains which parts of RFC 3315
   must be implemented in each of the different kinds of DHCP agents so
   that agent can support stateless DHCP.

1.  Introduction

   Nodes that have obtained IPv6 addresses through some other mechanism,
   such as stateless address autoconfiguration [6] or manual
   configuration, can use stateless DHCP to obtain other configuration
   information such as a list of DNS recursive name servers or SIP
   servers.  A stateless DHCP server provides only configuration
   information to nodes and does not perform any address assignment.
   Such a server is called "stateless" because it need not maintain any
   dynamic state for individual clients.

   While the DHCP specification [1] defines more than 10 protocol
   messages and 20 options, only a subset of those messages and options
   are required for stateless DHCP service.  This document explains
   which messages and options defined in RFC 3315 are required for
   stateless DHCP service.  The intended use of the document is to guide

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RFC 3736            Stateless DHCP Service for IPv6           April 2004

   the interoperable implementation of clients and servers that use
   stateless DHCP service.

   The operation of relay agents is the same for stateless and stateful
   DHCP service.  The operation of relay agents is described in the DHCP
   specification.

   Section 4 of this document lists the sections of the DHCP document
   that an implementor should read for an overview of the DHCP
   specification and the basic requirements of a DHCP service.  Section
   5 lists the specific messages and options that are specifically
   required for stateless DHCP service.  Section 6 describes how
   stateless and stateful DHCP servers interact to provide service to
   clients that require address assignment and clients that require only
   stateless service.

2.  Terminology

   Throughout this document, "DHCP" refers to DHCP for IPv6.

   This document uses the terminology defined in RFC 2460 [2], the DHCP
   specification [1], and the DHCP DNS configuration options
   specification [3].

   "Stateless DHCP" refers to the use of DHCP to provide configuration
   information to clients that does not require the server to maintain
   dynamic state about the DHCP clients.

3.  Overview

   This document assumes that a node using stateless DHCP configuration
   is not using DHCP for address assignment, and that a node has
   determined at least a link-local address as described in section 5.3
   of RFC 2461 [4].

   To obtain configuration parameters through stateless DHCP, a node
   uses the DHCP Information-request message.  DHCP servers respond to
   the node's message with a Reply message that carries configuration
   parameters for the node.  The Reply message from the server can carry
   configuration information, such as a list of DNS recursive name
   servers [3] and SIP servers [5].

   This document does not apply to the function of DHCP relay agents as
   described in RFC 3315.  A network element can provide both DHCP
   server and DHCP relay service.  For example, a network element can
   provide stateless DHCP service to hosts requesting stateless DHCP
   service, while relaying messages from hosts requesting address
   assignment through DHCP to another DHCP server.

Droms                       Standards Track                     [Page 2]
RFC 3736            Stateless DHCP Service for IPv6           April 2004

4.  Basic Requirements for Implementation of DHCP

   Several sections of the DHCP specification provide background
   information or define parts of the specification that are common to
   all implementations:

   1-4:   give an introduction to DHCP and an overview of DHCP message