Information Refresh Time Option for Dynamic Host Configuration Protocol for IPv6 (DHCPv6)
draft-ietf-dhc-lifetime-03

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Internet Engineering Task Force                                S. Venaas
Internet Draft                                 University of Southampton
Expiration Date: July 2005
                                                                T. Chown
                                               University of Southampton

                                                                 B. Volz
                                                     Cisco Systems, Inc.

                                                            January 2005

               Information Refresh Time Option for DHCPv6

                     draft-ietf-dhc-lifetime-03.txt

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Copyright Notice

   Copyright (C) The Internet Society (2005). All Rights Reserved.

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Internet Draft       draft-ietf-dhc-lifetime-03.txt         January 2005

Abstract

   This document describes a DHCPv6 option for specifying an upper bound
   for how long a client should wait before refreshing information
   retrieved from DHCPv6.  It is used with stateless DHCPv6 as there are
   no addresses or other entities with lifetimes that can tell the
   client when to contact the DHCPv6 server to refresh its
   configuration.

Table of Contents

   1.  Introduction  ...............................................   2
   2.  Terminology  ................................................   3
   3.  Information refresh time option definition  .................   3
     3.1.  Constants  ..............................................   4
     3.2.  Client behaviour  .......................................   4
     3.3.  Server behaviour  .......................................   5
     3.4.  Option format  ..........................................   5
   4.  IANA Considerations  ........................................   6
   5.  Acknowledgements  ...........................................   6
   6.  Security Considerations  ....................................   6
   7.  References  .................................................   6
     7.1.  Normative References  ...................................   6
     7.2.  Informative References  .................................   7
   Authors' Addresses  .............................................   7
   Intellectual Property and Copyright Statements  .................   7

1. Introduction

   DHCPv6 [RFC 3315] specifies stateful autoconfiguration for IPv6
   hosts.  However, many hosts will use stateless autoconfiguration as
   specified in [RFC 2462] for address assignment, and use DHCPv6 only
   for other configuration data, see [RFC 3736].  This other
   configuration data will typically have no associated lifetime, hence
   there may be no information telling a host when to refresh its DHCPv6
   configuration data.  Therefore, an option that can be used from
   server to client to inform the client when it should refresh the
   other configuration data is needed.

   This option is useful in many situations:

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       - Unstable environments where unexpected changes are likely to
         occur.

       - For planned changes, including renumbering.  An administrator
         can gradually decrease the time as the event nears.

       - Limit the amount of time before new services or servers are
         available to the client, such as the addition of a new NTP
         server or a change of address of a DNS server.  See
         [RENUMREQS].

2. Terminology

   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 BCP 14, RFC 2119 [RFC
   2119].

3. Information refresh time option definition

   The information refresh time option specifies an upper bound for how
   long a client should wait before refreshing information retrieved