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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.
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.
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
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
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
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
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
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
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
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
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.
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.
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)
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)
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
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
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.
[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.
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[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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RFC 3679 Unused DHCP Option Codes January 2004
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