Internet Engineering Task Force                                S. Venaas
Internet Draft                                                   UNINETT
Expiration Date: May 2004
                                                           November 2003


                       Lifetime Option for DHCPv6

                    draft-venaas-dhc-lifetime-00.txt

Status of this Memo

   This document is an Internet-Draft and is subject to all provisions
   of Section 10 of RFC2026.

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Abstract

   This document describes an option for specifying lifetime of other
   configuration options.  It's mainly intended for the stateless DHCP,
   but also useful when there are no addresses or other entities with
   lifetimes that can tell the client when to contact the DHCP server
   and update its configuration.













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Table of Contents

   1.  Introduction  ...............................................   2
   2.  Terminology  ................................................   2
   3.  Lifetime option definition  .................................   3
   4.  IANA Considerations  ........................................   3
   5.  Acknowledgments  ............................................   3
   6.  Security Considerations  ....................................   3
   7.  References  .................................................   4
     7.1.  Normative References  ...................................   4
   Author's Address  ...............................................   4




1. Introduction

   For IPv6, many hosts will use stateless autoconfiguration as
   specified in [RFC 2462] for address assignment, and use DHCP [RFC
   3315] for other configuration data.  This other configuration data
   will typically have no associated lifetime, hence there may be no
   information telling a host when to update its DHCP configuration
   data.

   The option specified here tells the host the lifetime of the
   configuration data.  When the lifetime expires, the host should make
   a new DHCP request, updating the current configuration.  This request
   will usually be an Information-request Message.  If the host fails to
   update the information, it should keep the current configuration, and
   retry at regular intervals.


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].













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3. Lifetime option definition

   A client supporting this option SHOULD include it in the Option
   Request option when sending an Information-request message to the
   DHCP server.

   A server supporting this option SHOULD include the option when
   requested by the client, but MAY also add it if not.

   The format of the Lifetime option is:

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       OPTION_LIFETIME         |           option-len          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                           lifetime                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      option-code: OPTION_LIFETIME (to be decided)

      option-len:  4

      lifetime:    lifetime in seconds


4. IANA Considerations

   IANA is requested to assign an option-code for the lifetime option
   from the option-code space defined in [RFC 3315].


5. Acknowledgments

   The author thanks Tim Chown and A.K. Vijayabhaskar for valuable
   discussions.


6. Security Considerations

   This option is believed not to have any impact on security.










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7. References

7.1. Normative References

   [RFC 2119]  Bradner, S., "Key words for use in RFCs to Indicate
               Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC 2462]  S. Thomson, T. Narten., "IPv6 Stateless Address
               Autoconfiguration", RFC 2462, December 1998.

   [RFC 3315]  R. Droms, Ed., J. Bound, B. Volz, T. Lemon, C. Perkins,
               M. Carney, "Dynamic Host Configuration Protocol for IPv6
               (DHCPv6)", RFC 3315, July 2003.

Author's Address

   Stig Venaas
   UNINETT
   NO-7465 Trondheim, Norway
   Email: venaas@uninett.no































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