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Versions: 00                                                            
Network Working Group                     Vijayabhaskar A Kalusivalingam
Internet-Draft                                 Senthil K Balasubramanian
Expires: August 2004                                     Hewlett-Packard
                                                                Feb 2004

                    DHCPv6 Support for Remote Boot

Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
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   This Internet-Draft will expire on August 2004.

Copyright Notice

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


   This document provides new DHCPv6 (Dynamic Host Configuration
   protocol version 6) options for clients, to obtain information about
   FTP (Trivial File Transfer Protocol) servers and bootfiles needed
   for booting.

1. Introduction

   Network booting is widely used mechanism for booting up of the
   clients.  The clients contact the TFTP server to download the
   bootfiles for bootup.  The advantages of using network booting are;
   softwares will be in central server and requires maintenance at only
   one location rather than maintaining individual systems separately.
   Also, switching between different operating systems becomes easy when
   network booting is being used.  In some cases, the nodes may need
   multiple bootfiles also.  The additional boot files may be used as
   supporting software for the boot image.  Different Operating System

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   vendors use different way of handling this.  Single TFTP server for
   huge number of diskless clients is prone to single point of failure.
   So, Multiple TFTP servers are needed for high availability.

   DHCPv6 (Dynamic Host Configuration Protocol Version 6) provides a
   framework for passing configuration information for hosts on an IPv6
   network.  However, DHCPv6 does not provide a way to send information
   about TFTP server address and bootfile names.  This document defines
   two options, Remote boot option and Remote Boot parameter option to
   provide information about TFTP servers and bootfile names to the
   clients.  These options are required for the clients, which are
   booting over a network.

2. Requirements

   SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL, when they appear in this
   document, are to be interpreted as described in RFC 2119 [2]

3. Terminology

   This document uses terminology specific to IPv6 and DHCPv6 as defined
   in "Terminology" section of the DHCPv6 specification [1].

4. Remote Boot Option

   The Remote Boot Option is used to carry the parameters needed for
   remote boot of the DHCPv6 clients.  Using the information provided by
   this option, the DHCPv6 clients will bootp up.  This will be mainly
   used by the clients, which are booting using remote boot server.

   The format of the Remote Boot Option is as shown below:

       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_REMOTE_BOOT     |         option-len            |
      |                                                               |
      .                   Remote-Boot-options                         .
      .                                                               .

   option-code:   OPTION_REMOTE_BOOT (tbd)

   option-len: Length of the 'Remote-Boot-options' fields in octets;

   Remote_Boot-options: Options associated with the Remote Boot Option.

   The Remote Boot option encapsulates those options that are specific
   to remote boot. This document defines one such option called
   Remote Boot Parameters Option. Multiple Remote Boot Parameters
   Options can appear in this option. This option is defined in the
   Section 5.

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5. Remote Boot Parameters Option

   The Remote Boot Parameters Option is used by the server to convey
   the client about the TFTP Server IPv6 address and list of boot files
   needed for booting of the clients.  The clients are supposed to
   contact the TFTP Server, obtain the boot files one by one and boot up
   using these files.

       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_REMOTE_BOOT_PARAMS    |         option-len            |
      |                                                               |
      |                  TFTP Server (IPv6 address)                   |
      |                                                               |
      |                                                               |
      |                                                               |
      .                      Boot Files                               .
      .                                                               .

   option-code:   OPTION_REMOTE_BOOT_PARAMS (tbd)

   option-len: Length of the 'TFTP Server' (16 bytes) +  'Boot Files'
           in Octets;

   Boot Files: One or more Boot File names in the NVT-ASCII string
           format. Each file name should be NULL terminated. They
           should be represented as fully qualified directory-path name.

   If multiple boot files are provided by the server, then, they should
   appear in the order of their execution in the client. The first
   appearing boot file name should be downloaded and executed first for
   boot up, then the next and so on.

   This option MUST appear only in the Remote Boot Option.  If multiple
   Remote Boot Parameters Options are present in the Remote Boot Option,
   then the clients MUST treat them as an ordered list.  The server MAY
   list them in the order of preference.

6.  Appearance of these options

   The Remote Boot Option MUST NOT appear in other than the following
   messages: Solicit, Advertise, Request, Renew, Rebind,
   Information-Request and Reply.

   The option number of Remote Boot option MAY appear in the Option
   Request Option [1] in the following messages: Solicit, Request,
   Renew, Rebind, Information-Request and Reconfigure.

   The Remote Boot Parameters Option MUST appear only in the Remote
   Boot Option.

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7. Security Considerations

   The Remote Boot Option may be used by an intruder DHCPv6 server to
   cause DHCPv6 clients to contact rogue TFTP server (or) to send
   invalid file names.  This will make booting up of DHCPv6 clients to
   fail.  This will have a greater impact, if the clients are running
   some time critical applications.  It has a direct impact on the
   security of the networks, if the clients are running any security

   To avoid attacks through this option, the DHCP client SHOULD use
   authenticated DHCP (see section "Authentication of DHCP messages" in
   the DHCPv6 specification [1]).

8. IANA Considerations

   IANA is requested to assign an option code to the following options
   from the option-code space defined in "DHCPv6 Options" section of the
   DHCPv6 specification [1].

         Option Name            Value    Described in
      OPTION_REMOTE_BOOT         tbd       Section 4
   OPTION_REMOTE_BOOT_PARAMS     tbd       Section 5

9. Normative References

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

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

10. Informative References

   [3]  K. Sollins, The TFTP Protocol (Revision 2), RFC 1350, July 1992.

Authors' Addresses

   Vijayabhaskar A Kalusivalingam
   Hewlett-Packard STSD-I
   29, Cunningham Road
   Bangalore - 560052

   Phone: +91-80-22053085
   E-Mail: vijayak@india.hp.com

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   Senthil K Balasubramanian
   Hewlett-Packard STSD-I
   29, Cunningham Road
   Bangalore - 560052

   Phone: +91-80-22053103
   E-Mail: ksenthil@india.hp.com

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