Network Working Group                                           R. Droms
Request for Comments: 3679                                 Cisco Systems
Category: Informational                                     January 2004


     Unused Dynamic Host Configuration Protocol (DHCP) Option Codes

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 (2004).  All Rights Reserved.

Abstract

   Prior to the publication of RFC 2489 (which was updated by RFC 2939),
   several option codes were assigned to proposed Dynamic Host
   Configuration Protocol (DHCP) options that were subsequently never
   used.  This document lists those unused option codes and directs IANA
   to make these option codes available for assignment to other DHCP
   options in the future.

   The document also lists several option codes that are not currently
   documented in an RFC but should not be made available for
   reassignment to future DHCP options.

1. Introduction

   Section 2 of this document lists the unused DHCP option codes from
   the IANA list of BOOTP and DHCP option codes [1].  Each option code
   includes any known documentation and contact information from the
   IANA list.  IANA will make these option codes available for
   assignment to other DHCP options in the future.

   Section 3 lists several DHCP option codes that are not currently
   documented in an RFC but should not be made available for
   reassignment to future DHCP options.

2. Unused DHCP Option Codes to be Reassigned to Future DHCP Options

   The option codes listed in this section are to be returned to IANA
   for reassignment to new options.  Responses from associated contact
   persons are noted where they have been received.

2.1. Service Location Protocol Naming Authority

   Code:              80
   Name:              Service Location Protocol Naming Authority
   Defined in:        (expired Internet-Draft)
   Contact:           Charlie Perkins
   Reason to recover: Never published as standard and not in general use

2.2. Relay Agent Options

   Codes:             83, 84
   Name:              Relay Agent Options
   Defined in:        Early draft of RFC 3046 [2]
   Contact:           (none)
   Reason to recover: Not defined in RFC 3046 as published

2.3. IEEE 1003.1 POSIX Timezone

   Code:              88
   Name:              IEEE 1003.1 POSIX Timezone
   Defined in:        (expired Internet-Draft)
   Contact:           Mike Carney
   Reason to recover: Never published as standard and not in general use

2.4. FQDNs in DHCP Options

   Code:              89
   Name:              FQDNs in DHCP Options
   Defined in:        (expired Internet-Draft)
   Contact:           Ralph Droms; agrees that option code should be
                      reassigned
   Reason to recover: Never published as standard and not in general use

2.5. VINES TCP/IP Server

   Code:              91
   Name:              VINES TCP/IP Server
   Defined in:        (none)
   Contact:           (none)
   Reason to recover: Never published as Internet-Draft

2.6. Server Selection

   Code:              92
   Name:              Server Selection
   Defined in:        (none)
   Contact:           (none)
   Reason to recover: Never published as Internet-Draft

2.7 IPv6 Transition

   Code:              96
   Name:              IPv6 Transition
   Defined in:        (expired Internet-Draft)
   Contact:           Dan Harrington; agrees that option code should be
                      reassigned
   Reason to recover: Never published as standard and not in general use

2.8. Printer Name

   Code:              100
   Name:              Printer Name
   Defined in:        (none)
   Contact:           (none)
   Reason to recover: Never published as Internet-Draft

2.9. Multicast Assignment through DHCP

   Code:              101
   Name:              Multicast Assignment through DHCP
   Defined in:        (expired Internet-Draft)
   Contact:           Baiju Patel, Munil Shah
   Reason to recover: Never published as standard and not in general use

2.10. Swap Path

   Code:              108
   Name:              Swap Path
   Defined in:        (none)
   Contact:           (none)
   Reason to recover: Never published as Internet-Draft

2.11. IPX Compatibility

   Code:              110
   Name:              IPX Compatibility
   Defined in:        (none)
   Contact:           Juan Luciani; agrees that option code should be
                      reassigned
   Reason to recover: Never published as Internet-Draft

2.12. Failover

   Code:              115
   Name:              Failover
   Defined in:        Early revisions of "DHCP Failover Protocol" [3]
   Contact:           Kim Kinnear
   Reason to recover: Current version of "DHCP Failover Protocol" does
                      not use a DHCP option

3. Option codes to be reserved by IANA

   The option codes listed in this section are the subject of ongoing
   work in the DHC Working Group (WG).  These option codes should remain
   on the IANA list of assigned option codes [1] until the DHC WG has
   made a final decision about their disposition.

3.1. Option codes used in PXE Specification

   The following option codes are used in the "Preboot Execution
   Environment (PXE) Specification, Version 2.1" [4].  However, although
   these options are in widespread use by devices that use PXE, none of
   these option codes have been described in a published RFC.

   The DHC WG will endeavor to have specifications for these options
   published.

3.1.1. Client System

   Code:              93
   Name:              Client System
   Defined in:        "Preboot Execution Environment (PXE)
                      Specification, Version 2.1" [4]
   Contact:           Michael Johnston
                      (frenchy@quiet-like-a-panther.org)

3.1.2. Client NDI

   Code:              94
   Name:              Client NDI
   Defined in:        "Preboot Execution Environment (PXE)
                      Specification, Version 2.1" [4]
   Contact:           Michael Johnston
                      (frenchy@quiet-like-a-panther.org)

3.1.3. UUID/GUID Client Identifier

   Code:              97
   Name:              UUID/GUID Client Identifier
   Defined in:        "Preboot Execution Environment (PXE)
                      Specification, Version 2.1" [4] (and an expired
                      Internet-Draft)
   Contact:           Dan Harrington, Michael Johnston
                      (frenchy@quiet-like-a-panther.org)

3.2. In Use by Apple

   The following option codes are used by devices from Apple Computer.
   However, none of these option codes have been described in a
   published RFC.

   The DHC WG will endeavor to have specifications for these options
   published.

3.2.1. LDAP Servers

   Code:              95
   Name:              LDAP Servers
   Defined in:        (none)
   Contact:           Dieter Siegmund, dieter@apple.com
   Reason to recover: Never published in an RFC

3.2.2. Netinfo Parameters

   Codes:             112, 113
   Name:              Netinfo Address, Netinfo Tag
   Defined in:        (none)
   Contact:           Dieter Siegmund, dieter@apple.com
   Reason to recover: Never published in an RFC

3.2.3. URL

   Code:              114
   Name:              URL
   Defined in:        (none)
   Contact:           Dieter Siegmund, dieter@apple.com
   Reason to recover: Never published in an RFC

3.3. Option Code Extensions

   Note that these option codes are identified in "Extending DHCP
   Options Codes" [5] as part of a mechanism for extending the set of
   option codes available to DHCP.  If these option codes are not used
   for DHCP option code extension, they will be returned to IANA for
   reassignment to other DHCP options.

   Codes:             126, 127
   Name:              Option Code Extensions
   Defined in:        (expired Internet-Draft)
   Contact:           Ralph Droms

4. Already Returned for Reassignment

   The option codes 99, 102-107, 109 and 111 have already been returned
   for reassignment to future DHCP options.

5. Security Considerations

   This document has no known security implications, as none of the
   reclaimed options are known to be in use.

6. IANA Considerations

   IANA has returned the DHCP option codes listed in Section 2 to the
   list of available option codes.  These option codes may be reassigned
   to new DHCP options, according to the procedures in RFC 2939 [6].
   IANA is requested to reassign these option codes after the list of
   option codes that have never been assigned or have previously been
   returned has been exhausted.

Informative References

   [1]  Assigned Numbers Editor, IANA., "BOOTP and DHCP Parameters",
        http://www.iana.org/assignments/bootp-dhcp-parameters, February
        2003.

   [2]  Patrick, M., "DHCP Relay Agent Information Option", RFC 3046,
        January 2001.

   [3]  Droms, R., Kinnear, K., Stapp, M., Volz, B., Gonczi, S., Rabil,
        G., Dooley, M. and A. Kapur, "DHCP Failover Protocol", Work in
        Progress.

   [4]  Intel Corporation, "Preboot Execution Environment (PXE)
        Specification Version 2.1", http://www.pix.net/software/pxeboot/
        archive/pxespec.pdf, September 1999.

   [5]  Volz, B., Droms, R. and T. Lemon, "Extending DHCP Options
        Codes", Work in Progress.

   [6]  Droms, R., "Procedures and IANA Guidelines for Definition of New
        DHCP Options and Message Types", BCP 43, RFC 2939, September
        2000.

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Author's Address

   Ralph Droms
   Cisco Systems
   1414 Massachusetts Avenue
   Boxborough, MA  01719
   USA

   Phone: +1 978 936 1674
   EMail: rdroms@cisco.com

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