Renumbering Requirements for Stateless Dynamic Host Configuration Protocol for IPv6 (DHCPv6)
RFC 4076

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Network Working Group                                           T. Chown
Request for Comments: 4076                     University of Southampton
Category: Informational                                        S. Venaas
                                                                 UNINETT
                                                        A. Vijayabhaskar
                                   Cisco Systems (India) Private Limited
                                                                May 2005

                Renumbering Requirements for Stateless
         Dynamic Host Configuration Protocol for IPv6 (DHCPv6)

Status of This Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2005).

Abstract

   IPv6 hosts using Stateless Address Autoconfiguration are able to
   configure their IPv6 address and default router settings
   automatically.  However, further settings are not available.  If
   these hosts wish to configure their DNS, NTP, or other specific
   settings automatically, the stateless variant of the Dynamic Host
   Configuration Protocol for IPv6 (DHCPv6) could be used.  This
   combination of Stateless Address Autoconfiguration and stateless
   DHCPv6 could be used quite commonly in IPv6 networks.  However, hosts
   using this combination currently have no means by which to be
   informed of changes in stateless DHCPv6 option settings; e.g., the
   addition of a new NTP server address, a change in DNS search paths,
   or full site renumbering.  This document is presented as a problem
   statement from which a solution should be proposed in a subsequent
   document.

Chown, et al.                Informational                      [Page 1]
RFC 4076            Renumbering for Stateless DHCPv6            May 2005

Table of Contents

   1.  Introduction ...................................................2
   2.  Problem Statement ..............................................3
   3.  Renumbering Scenarios ..........................................3
       3.1.  Site Renumbering .........................................4
       3.2.  Changes to a DHCPv6-assigned Setting .....................4
   4.  Renumbering Requirements .......................................4
   5.  Considerations in Choosing a Solution ..........................4
   6.  Solution Space .................................................5
   7.  Summary ........................................................5
   8.  Security Considerations ........................................6
   9.  Acknowledgements ...............................................6
   10. References .....................................................6
       10.1. Normative References .....................................6
       10.2. Informative References ...................................6

1.  Introduction

   IPv6 hosts using Stateless Address Autoconfiguration [2] are able to
   configure their IPv6 address and default router settings
   automatically.  Although Stateless Address Autoconfiguration for IPv6
   allows automatic configuration of these settings, it does not provide
   a mechanism for additional non IP-address settings to be configured
   automatically.

   The full version of the Dynamic Host Configuration Protocol for IPv6
   (DHCPv6) [3] is designed to provide both stateful address assignment
   to IPv6 hosts, as well as additional (non IP-address) configuration
   including DNS, NTP, and other specific settings.  A full stateful
   DHCPv6 server allocates the addresses and maintains the clients'
   bindings to keep track of client leases.

   If hosts using Stateless Address Autoconfiguration for IPv6 wish to
   configure their DNS, NTP, or other specific settings automatically,
   the stateless variant [4] of DHCPv6 could be used.  This variant is
   more lightweight.  It does not do address assignment; instead, it
   only provides additional configuration parameters, such as DNS
   resolver addresses.  It does not maintain dynamic state about the
   information assigned to clients, and therefore there is no need to
   maintain dynamic per-client state on the server.

   This combination of Stateless Address Autoconfiguration and stateless
   DHCPv6 could be used quite commonly in IPv6 networks.

Chown, et al.                Informational                      [Page 2]
RFC 4076            Renumbering for Stateless DHCPv6            May 2005

2.  Problem Statement

   A problem, however, lies in the ability, or lack of ability, of
   clients using this combination to be informed of (or to deduce)
   changes in DHCPv6-assigned settings.

   While a DHCPv6 server unicasts Reconfigure messages to individual
   clients to trigger them to initiate Information-request/reply
   configuration exchanges to update their configuration settings, the