draft-ietf-dhc-reclassify-options-00.txt   draft-ietf-dhc-reclassify-options-01.txt 
Network Working Group B. Volz Network Working Group B. Volz
Internet-Draft (Unaffiliated) Internet-Draft Cisco Systems, Inc.
Expires: July 5, 2004 January 5, 2004 Expires: October 25, 2004 April 26, 2004
Reclassifying DHCPv4 Options Reclassifying DHCPv4 Options
draft-ietf-dhc-reclassify-options-00 draft-ietf-dhc-reclassify-options-01
Status of this Memo Status of this Memo
This document is an Internet-Draft and is in full conformance with By submitting this Internet-Draft, I certify that any applicable
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and any of which I become aware will be disclosed, in accordance with
RFC 3668.
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Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2004). All Rights Reserved. Copyright (C) The Internet Society (2004). All Rights Reserved.
Abstract Abstract
This document revises RFC 2132 to reclassify DHCPv4 option codes 128 This document revises RFC 2132 to reclassify DHCPv4 option codes 128
to 223 (decimal) as publicly defined options to be managed by IANA in to 223 (decimal) as publicly defined options to be managed by IANA in
accordance with RFC 2939. This document directs IANA to make these accordance with RFC 2939. This document directs IANA to make these
option codes available for assignment as publicly defined DHCP option codes available for assignment as publicly defined DHCP
options for future options. options for future options.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements notation . . . . . . . . . . . . . . . . . . . . 3 2. Requirements notation . . . . . . . . . . . . . . . . . . . . 3
3. Background . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Background . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3.1 Publicly Defined Options Range . . . . . . . . . . . . . . . . 3 3.1 Publicly Defined Options Range . . . . . . . . . . . . . . 3
3.2 Site-Specific Options Range . . . . . . . . . . . . . . . . . 4 3.2 Site-Specific Options Range . . . . . . . . . . . . . . . 4
4. Reclassifying Options . . . . . . . . . . . . . . . . . . . . 4 4. Reclassifying Options . . . . . . . . . . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . 5 5. Security Considerations . . . . . . . . . . . . . . . . . . . 5
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6
References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6
8.1 Normative References . . . . . . . . . . . . . . . . . . . . 6
8.2 Informative References . . . . . . . . . . . . . . . . . . . 6
Author's Address . . . . . . . . . . . . . . . . . . . . . . . 7 Author's Address . . . . . . . . . . . . . . . . . . . . . . . 7
Intellectual Property and Copyright Statements . . . . . . . . 8 Intellectual Property and Copyright Statements . . . . . . . . 8
1. Introduction 1. Introduction
The DHCPv4 [RFC2131] publicly defined options range, options 1-127, The DHCPv4 [RFC2131] publicly defined options range, options 1-127,
is nearly used up. Efforts such as [unused-optioncodes] help extend is nearly used up. Efforts such as [RFC3679] help extend the life of
the life of this space, but ultimately the space is expected to be this space, but ultimately the space is expected to be exhausted.
exhausted.
This document reclassifies much of the site-specific option range, This document reclassifies much of the site-specific option range,
which has not been widely used for its original intended purpose, to which has not been widely used for its original intended purpose, to
extend the publicly defined options space. extend the publicly defined options space.
2. Requirements notation 2. Requirements notation
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
3. Background 3. Background
The DHCP option space (0-255) was divided into two principal ranges: The DHCP option space (0-255) is divided into two ranges [RFC2132]:
1. 1-127 are publicly defined options, now allocated in accordance 1. 1-127 are publicly defined options, now allocated in accordance
with [RFC2939]. with [RFC2939].
2. 128-254 are site-specific options. 2. 128-254 are site-specific options.
Options 0 (pad) and 255 (end) are special and defined in [RFC2131]. Options 0 (pad) and 255 (end) are special and defined in [RFC2131].
3.1 Publicly Defined Options Range 3.1 Publicly Defined Options Range
The publicly defined options space (1-127) is nearly exhausted. The publicly defined options space (1-127) is nearly exhausted.
Recent work ([unused-optioncodes]) will buy more time as several Recent work ([RFC3679]) will buy more time as several allocated but
allocated but never used option codes are reclaimed. And, a review never used option codes are reclaimed. And, a review could be done
could be done from time to time to determine if there are other from time to time to determine if there are other option codes that
option codes that can be reclaimed. can be reclaimed.
A longer term solution to the eventual exhaustion of the publicly A longer term solution to the eventual exhaustion of the publicly
defined options space is desired. The DHC WG evaluated several defined options space is desired. The DHC WG evaluated several
solutions: solutions:
1. Using options 126 and 127 to carry 16-bit options as originally 1. Using options 126 and 127 to carry 16-bit options as originally
proposed by Ralph Droms in late 1996. However, this significantly proposed by Ralph Droms in late 1996. However, this significantly
penalizes the first option assigned to this new space, as it penalizes the first option assigned to this new space, as it
requires implementing the 16-bit option support. Because of this, requires implementing the 16-bit option support. Because of this,
options 126 and 127 have been reclaimed [unused-optioncodes]. options 126 and 127 have been reclaimed [RFC3679].
2. Using a new magic cookie and 16-bit option code format. However, 2. Using a new magic cookie and 16-bit option code format. However,
this proposal: this proposal:
* penalizes the first option assigned to this new space, as it * penalizes the first option assigned to this new space, as it
requires significant changes to clients, servers, and relay requires significant changes to clients, servers, and relay
agents, agents,
* could adversely impact existing clients, servers, and relay * could adversely impact existing clients, servers, and relay
agents that fail to properly check the magic cookie value, agents that fail to properly check the magic cookie value,
* requires support of both message formats for the foreseeable * requires support of both message formats for the foreseeable
skipping to change at page 5, line 44 skipping to change at page 5, line 44
If no Internet-Draft is published within the 18 months or should If no Internet-Draft is published within the 18 months or should
one of these Internet-Drafts expire after the 18 months, IANA one of these Internet-Drafts expire after the 18 months, IANA
will move the option to the "Unassigned" state and the option may will move the option to the "Unassigned" state and the option may
then be assigned to any new publicly defined options in then be assigned to any new publicly defined options in
accordance with [RFC2939]. accordance with [RFC2939].
Sites that are presently using site-specific option codes within the Sites that are presently using site-specific option codes within the
reclassified range SHOULD take steps to renumber these options to reclassified range SHOULD take steps to renumber these options to
values within the remaining range. If a site needs more than 31 values within the remaining range. If a site needs more than 31
site-specific options, the site must switch to using suboptions as site-specific options, the site must switch to using suboptions as
has been done for other options, such as the Relay Agent Option has been done for other options, such as the Relay Agent Information
[RFC3046]. Option [RFC3046].
5. Security Considerations 5. Security Considerations
This document in and by itself provides no security, nor does it This document in and by itself provides no security, nor does it
impact existing DCHP security as described in [RFC2131]. impact existing DCHP security as described in [RFC2131].
6. IANA Considerations 6. IANA Considerations
IANA is requested to: IANA is requested to:
skipping to change at page 6, line 31 skipping to change at page 6, line 31
thereafter as long as there is an option listed as thereafter as long as there is an option listed as
"Tentatively-Assigned", change the listing of any options listed "Tentatively-Assigned", change the listing of any options listed
as "Tentatively-Assigned" to "Unavailable" if no un-expired as "Tentatively-Assigned" to "Unavailable" if no un-expired
Internet-Draft exists documenting the usage. Internet-Draft exists documenting the usage.
7. Acknowledgements 7. Acknowledgements
Many thanks to Ralph Droms and Ted Lemon for their valuable input and Many thanks to Ralph Droms and Ted Lemon for their valuable input and
earlier work on the various alternatives. earlier work on the various alternatives.
References 8. References
8.1 Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2131] Droms, R., "Dynamic Host Configuration Protocol", RFC [RFC2131] Droms, R., "Dynamic Host Configuration Protocol", RFC
2131, March 1997. 2131, March 1997.
[RFC2132] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor [RFC2132] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor
Extensions", RFC 2132, March 1997. Extensions", RFC 2132, March 1997.
[RFC2939] Droms, R., "Procedures and IANA Guidelines for Definition [RFC2939] Droms, R., "Procedures and IANA Guidelines for Definition
of New DHCP Options and Message Types", BCP 43, RFC 2939, of New DHCP Options and Message Types", BCP 43, RFC 2939,
September 2000. September 2000.
8.2 Informative References
[RFC3046] Patrick, M., "DHCP Relay Agent Information Option", RFC [RFC3046] Patrick, M., "DHCP Relay Agent Information Option", RFC
3046, January 2001. 3046, January 2001.
[unused-optioncodes] [RFC3679] Droms, R., "Unused Dynamic Host Configuration Protocol
Droms, R., "Unused DHCP Option Codes", (DHCP) Option Codes", RFC 3679, January 2004.
draft-ietf-dhc-unused-optionscodes-07.txt (work in
progress), October 2003.
Author's Address Author's Address
Bernard Volz Bernard Volz
(Unaffiliated) Cisco Systems, Inc.
116 Hawkins Pond Road 1414 Massachusetts Ave.
Center Harbor, NH 03226 Boxborough, MA 01719
US USA
Phone: +1 603 968 3062 Phone: +1 978 936 0382
EMail: volz@metrocast.net EMail: volz@cisco.com
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