draft-ietf-dhc-options-1533update-02.txt   draft-ietf-dhc-options-1533update-03.txt 
Network Working Group S. Alexander Network Working Group S. Alexander
INTERNET DRAFT Lachman Technology, Inc. INTERNET DRAFT Silicon Graphics, Inc.
Obsoletes: draft-ietf-dhc-options-1533update-01.txt R. Droms Obsoletes: draft-ietf-dhc-options-1533update-02.txt R. Droms
Bucknell University Bucknell University
November 1995 April 1996
Expires May 1996 Expires October 1996
DHCP Options and BOOTP Vendor Extensions DHCP Options and BOOTP Vendor Extensions
<draft-ietf-dhc-options-1533update-02.txt> <draft-ietf-dhc-options-1533update-03.txt>
Status of this memo Status of this memo
This document is an Internet-Draft. Internet-Drafts are working This document is an Internet-Draft. Internet-Drafts are working
documents of the Internet Engineering Task Force (IETF), its areas, documents of the Internet Engineering Task Force (IETF), its areas,
and its working groups. Note that other groups may also distribute and its working groups. Note that other groups may also distribute
working documents as Internet-Drafts. working documents as Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
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Abstract Abstract
The Dynamic Host Configuration Protocol (DHCP) [1] provides a The Dynamic Host Configuration Protocol (DHCP) [1] provides a
framework for passing configuration information to hosts on a TCP/IP framework for passing configuration information to hosts on a TCP/IP
network. Configuration parameters and other control information are network. Configuration parameters and other control information are
carried in tagged data items that are stored in the 'options' field carried in tagged data items that are stored in the 'options' field
of the DHCP message. The data items themselves are also called of the DHCP message. The data items themselves are also called
"options." "options."
This document specifies the current set of DHCP options. This This document specifies the current set of DHCP options. Future
document will be periodically updated as new options are defined. options will be specified in separate RFCs. The current list of
Each superseding document will include the entire current list of valid options is also available in ftp://ftp.isi.edu/in-
valid options. The current list of valid options is also available notes/iana/assignments [22].
in ftp://ftp.isi.edu/in-notes/iana/assignments [22].
All of the vendor information extensions defined in RFC 1497 [2] may All of the vendor information extensions defined in RFC 1497 [2] may
be used as DHCP options. The definitions given in RFC 1497 are be used as DHCP options. The definitions given in RFC 1497 are
included in this document, which supersedes RFC 1497. All of the included in this document, which supersedes RFC 1497. All of the
DHCP options defined in this document, except for those specific to DHCP options defined in this document, except for those specific to
DHCP as defined in section 9, may be used as BOOTP vendor information
DRAFT DHCP Options and BOOTP Vendor Extensions November 1995 DRAFT DHCP Options and BOOTP Vendor Extensions April 1996
DHCP as defined in section 9, may be used as BOOTP vendor information
extensions. extensions.
Table of Contents Table of Contents
1. Introduction .............................................. 2 1. Introduction .............................................. 2
2. BOOTP Extension/DHCP Option Field Format .................. 2 2. BOOTP Extension/DHCP Option Field Format .................. 4
3. RFC 1497 Vendor Extensions ................................ 3 3. RFC 1497 Vendor Extensions ................................ 5
4. IP Layer Parameters per Host .............................. 10 4. IP Layer Parameters per Host .............................. 12
5. IP Layer Parameters per Interface ........................ 13 5. IP Layer Parameters per Interface ........................ 14
6. Link Layer Parameters per Interface ....................... 16 6. Link Layer Parameters per Interface ....................... 18
7. TCP Parameters ............................................ 17 7. TCP Parameters ............................................ 19
8. Application and Service Parameters ........................ 18 8. Application and Service Parameters ........................ 20
9. DHCP Extensions ........................................... 26 9. DHCP Extensions ........................................... 28
10. Extensions ................................................ 33 10. Defining new extensions ................................... 35
11. Acknowledgements .......................................... 33 11. Acknowledgements .......................................... 35
12. References ................................................ 33 12. References ................................................ 36
13. Security Considerations ................................... 35 13. Security Considerations ................................... 37
14. Authors' Addresses ........................................ 35 14. Authors' Addresses ........................................ 38
A. Changes to draft-ietf-dhc-options-1533update-00.txt........ 36 A. Changes to draft-ietf-dhc-options-1533update-00.txt........ 39
1. Introduction 1. Introduction
This document specifies options for use with both the Dynamic Host This document specifies options for use with both the Dynamic Host
Configuration Protocol and the Bootstrap Protocol. Configuration Protocol and the Bootstrap Protocol.
The full description of DHCP packet formats may be found in the DHCP The full description of DHCP packet formats may be found in the DHCP
specification document [1], and the full description of BOOTP packet specification document [1], and the full description of BOOTP packet
formats may be found in the BOOTP specification document [3]. This formats may be found in the BOOTP specification document [3]. This
document defines the format of information in the last field of DHCP document defines the format of information in the last field of DHCP
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previous documents for use with BOOTP (all may also be used with previous documents for use with BOOTP (all may also be used with
DHCP). Sections 4-8 define new options intended for use with both DHCP). Sections 4-8 define new options intended for use with both
DHCP and BOOTP. Section 9 defines options used only in DHCP. DHCP and BOOTP. Section 9 defines options used only in DHCP.
References further describing most of the options defined in sections References further describing most of the options defined in sections
2-6 can be found in section 12. The use of the options defined in 2-6 can be found in section 12. The use of the options defined in
section 9 is described in the DHCP specification [1]. section 9 is described in the DHCP specification [1].
Information on registering new options is contained in section 10. Information on registering new options is contained in section 10.
DRAFT DHCP Options and BOOTP Vendor Extensions November 1995 DRAFT DHCP Options and BOOTP Vendor Extensions April 1996
1.1 Requirements
Throughout this document, the words that are used to define the
significance of particular requirements are capitalized. These words
are:
o "MUST"
This word or the adjective "REQUIRED" means that the
item is an absolute requirement of this specification.
o "MUST NOT"
This phrase means that the item is an absolute prohibition
of this specification.
o "SHOULD"
This word or the adjective "RECOMMENDED" means that there
may exist valid reasons in particular circumstances to ignore
this item, but the full implications should be understood and
the case carefully weighed before choosing a different course.
o "SHOULD NOT"
This phrase means that there may exist valid reasons in
particular circumstances when the listed behavior is acceptable
or even useful, but the full implications should be understood
and the case carefully weighed before implementing any behavior
described with this label.
o "MAY"
This word or the adjective "OPTIONAL" means that this item is
truly optional. One vendor may choose to include the item
because a particular marketplace requires it or because it
enhances the product, for example; another vendor may omit the
same item.
1. Terminology
This document uses the following terms:
o "DHCP client"
A DHCP client or "client" is an Internet host using DHCP to obtain
configuration parameters such as a network address.
DRAFT DHCP Options and BOOTP Vendor Extensions April 1996
o "DHCP server"
A DHCP server of "server"is an Internet host that returns
configuration parameters to DHCP clients.
o "binding"
A binding is a collection of configuration parameters, including
at least an IP address, associated with or "bound to" a DHCP
client. Bindings are managed by DHCP servers.
2. BOOTP Extension/DHCP Option Field Format 2. BOOTP Extension/DHCP Option Field Format
DHCP options have the same format as the BOOTP 'vendor extensions' DHCP options have the same format as the BOOTP 'vendor extensions'
defined in RFC 1497 [2]. Options may be fixed length or variable defined in RFC 1497 [2]. Options may be fixed length or variable
length. All options begin with a tag octet, which uniquely length. All options begin with a tag octet, which uniquely
identifies the option. Fixed-length options without data consist of identifies the option. Fixed-length options without data consist of
only a tag octet. Only options 0 and 255 are fixed length. All only a tag octet. Only options 0 and 255 are fixed length. All
other options are variable-length with a length octet following the other options are variable-length with a length octet following the
tag octet. The value of the length octet does not include the two tag octet. The value of the length octet does not include the two
octets specifying the tag and length. The length octet is followed octets specifying the tag and length. The length octet is followed
by "length" octets of data. Options containing NVT ASCII data SHOULD by "length" octets of data.
NOT include a trailing NULL; however, the receiver of such options Options containing NVT ASCII data SHOULD NOT include a trailing NULL;
MUST be prepared to delete trailing nulls if they exist. The however, the receiver of such options MUST be prepared to delete
receiver MUST NOT require that a trailing null be included in the trailing nulls if they exist.
data. In the case of some variable-length options the length field The receiver MUST NOT
is a constant but must still be specified. require that a trailing null be included in the data. In the case
of some variable-length
options the length field is a constant but must still be specified.
Any options defined subsequent to this document MUST contain a length Any options defined subsequent to this document MUST contain a
octet even if the length is fixed or zero. length octet even if the length is fixed or zero.
All multi-octet quantities are in network byte-order. All multi-octet quantities are in network byte-order.
When used with BOOTP, the first four octets of the vendor information When used with BOOTP, the first four octets of the vendor information
field have been assigned to the "magic cookie" (as suggested in RFC field have been assigned to the "magic cookie" (as suggested in RFC
951). This field identifies the mode in which the succeeding data is 951). This field identifies the mode in which the succeeding data is
to be interpreted. The value of the magic cookie is the 4 octet to be interpreted. The value of the magic cookie is the 4 octet
dotted decimal 99.130.83.99 (or hexadecimal number 63.82.53.63) in dotted decimal 99.130.83.99 (or hexadecimal number 63.82.53.63) in
network byte order. network byte order.
All of the "vendor extensions" defined in RFC 1497 are also DHCP All of the "vendor extensions" defined in RFC 1497 are also DHCP
options. options.
Option codes 128 to 254 (decimal) are reserved for site-specific Option codes 128 to 254 (decimal) are reserved for site-specific
options. options.
DRAFT DHCP Options and BOOTP Vendor Extensions April 1996
Except for the options in section 9, all options may be used with Except for the options in section 9, all options may be used with
either DHCP or BOOTP. either DHCP or BOOTP.
Many of these options have their default values specified in other Many of these options have their default values specified in other
documents. In particular, RFC 1122 [4] specifies default values for documents. In particular, RFC 1122 [4] specifies default values for
most IP and TCP configuration parameters. most IP and TCP configuration parameters.
Many options supply one or more 32-bit IP address. Use of IP Many options supply one or more 32-bit IP address. Use of IP
addresses rather than fully-qualified Domain Names (FQDNs) may make addresses rather than fully-qualified Domain Names (FQDNs) may make
future renumbering of IP hosts more difficult. Use of these future renumbering of IP hosts more difficult. Use of these addresses
addresses is discouraged at sites that may require renumbering. is discouraged at sites that may require renumbering.
3. RFC 1497 Vendor Extensions 3. RFC 1497 Vendor Extensions
DRAFT DHCP Options and BOOTP Vendor Extensions November 1995 This section lists the vendor extensions as defined in RFC
1497. They are defined here for completeness.
This section lists the vendor extensions as defined in RFC 1497.
They are defined here for completeness.
3.1. Pad Option 3.1. Pad Option
The pad option can be used to cause subsequent fields to align on The pad option can be used to cause subsequent fields to align on
word boundaries. word boundaries.
The code for the pad option is 0, and its length is 1 octet. The code for the pad option is 0, and its length is 1 octet.
Code Code
+-----+ +-----+
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The end option marks the end of valid information in the vendor The end option marks the end of valid information in the vendor
field. Subsequent octets should be filled with pad options. field. Subsequent octets should be filled with pad options.
The code for the end option is 255, and its length is 1 octet. The code for the end option is 255, and its length is 1 octet.
Code Code
+-----+ +-----+
| 255 | | 255 |
+-----+ +-----+
DRAFT DHCP Options and BOOTP Vendor Extensions April 1996
3.3. Subnet Mask 3.3. Subnet Mask
The subnet mask option specifies the client's subnet mask as per RFC The subnet mask option specifies the client's subnet mask as per RFC
950 [5]. 950 [5].
If both the subnet mask and the router option are specified in a DHCP If both the subnet mask and the router option are specified in a DHCP
reply, the subnet mask option MUST be first. reply, the subnet mask option MUST be first.
The code for the subnet mask option is 1, and its length is 4 octets. The code for the subnet mask option is 1, and its length is 4 octets.
Code Len Subnet Mask Code Len Subnet Mask
+-----+-----+-----+-----+-----+-----+ +-----+-----+-----+-----+-----+-----+
| 1 | 4 | m1 | m2 | m3 | m4 | | 1 | 4 | m1 | m2 | m3 | m4 |
+-----+-----+-----+-----+-----+-----+ +-----+-----+-----+-----+-----+-----+
DRAFT DHCP Options and BOOTP Vendor Extensions November 1995
3.4. Time Offset 3.4. Time Offset
The time offset field specifies the offset of the client's subnet in The time offset field specifies the offset of the client's subnet in
seconds from Coordinated Universal Time (UTC). The offset is seconds from Coordinated Universal Time (UTC). The offset is
expressed as a two's complement 32-bit integer. The code for the time expressed as a two's complement 32-bit integer. The code for the time
offset option is 2, and its length is 4 octets. offset option is 2, and its length is 4 octets.
Code Len Time Offset Code Len Time Offset
+-----+-----+-----+-----+-----+-----+ +-----+-----+-----+-----+-----+-----+
| 2 | 4 | n1 | n2 | n3 | n4 | | 2 | 4 | n1 | n2 | n3 | n4 |
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The code for the router option is 3. The minimum length for the The code for the router option is 3. The minimum length for the
router option is 4 octets, and the length MUST always be a multiple router option is 4 octets, and the length MUST always be a multiple
of 4. of 4.
Code Len Address 1 Address 2 Code Len Address 1 Address 2
+-----+-----+-----+-----+-----+-----+-----+-----+-- +-----+-----+-----+-----+-----+-----+-----+-----+--
| 3 | n | a1 | a2 | a3 | a4 | a1 | a2 | ... | 3 | n | a1 | a2 | a3 | a4 | a1 | a2 | ...
+-----+-----+-----+-----+-----+-----+-----+-----+-- +-----+-----+-----+-----+-----+-----+-----+-----+--
DRAFT DHCP Options and BOOTP Vendor Extensions April 1996
3.6. Time Server Option 3.6. Time Server Option
The time server option specifies a list of RFC 868 [6] time servers The time server option specifies a list of RFC 868 [6] time servers
available to the client. Servers SHOULD be listed in order of available to the client. Servers SHOULD be listed in order of
preference. preference.
The code for the time server option is 4. The minimum length for The code for the time server option is 4. The minimum length for
this option is 4 octets, and the length MUST always be a multiple of this option is 4 octets, and the length MUST always be a multiple of
4. 4.
Code Len Address 1 Address 2 Code Len Address 1 Address 2
+-----+-----+-----+-----+-----+-----+-----+-----+-- +-----+-----+-----+-----+-----+-----+-----+-----+--
| 4 | n | a1 | a2 | a3 | a4 | a1 | a2 | ... | 4 | n | a1 | a2 | a3 | a4 | a1 | a2 | ...
+-----+-----+-----+-----+-----+-----+-----+-----+-- +-----+-----+-----+-----+-----+-----+-----+-----+--
DRAFT DHCP Options and BOOTP Vendor Extensions November 1995
3.7. Name Server Option 3.7. Name Server Option
The name server option specifies a list of IEN 116 [7] name servers The name server option specifies a list of IEN 116 [7] name servers
available to the client. Servers SHOULD be listed in order of available to the client. Servers SHOULD be listed in order of
preference. preference.
The code for the name server option is 5. The minimum length for The code for the name server option is 5. The minimum length for
this option is 4 octets, and the length MUST always be a multiple of this option is 4 octets, and the length MUST always be a multiple of
4. 4.
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The code for the domain name server option is 6. The minimum length The code for the domain name server option is 6. The minimum length
for this option is 4 octets, and the length MUST always be a multiple for this option is 4 octets, and the length MUST always be a multiple
of 4. of 4.
Code Len Address 1 Address 2 Code Len Address 1 Address 2
+-----+-----+-----+-----+-----+-----+-----+-----+-- +-----+-----+-----+-----+-----+-----+-----+-----+--
| 6 | n | a1 | a2 | a3 | a4 | a1 | a2 | ... | 6 | n | a1 | a2 | a3 | a4 | a1 | a2 | ...
+-----+-----+-----+-----+-----+-----+-----+-----+-- +-----+-----+-----+-----+-----+-----+-----+-----+--
DRAFT DHCP Options and BOOTP Vendor Extensions April 1996
3.9. Log Server Option 3.9. Log Server Option
The log server option specifies a list of MIT-LCS UDP log servers The log server option specifies a list of MIT-LCS UDP log servers
available to the client. Servers SHOULD be listed in order of available to the client. Servers SHOULD be listed in order of
preference. preference.
The code for the log server option is 7. The minimum length for this The code for the log server option is 7. The minimum length for this
option is 4 octets, and the length MUST always be a multiple of 4. option is 4 octets, and the length MUST always be a multiple of 4.
Code Len Address 1 Address 2 Code Len Address 1 Address 2
+-----+-----+-----+-----+-----+-----+-----+-----+-- +-----+-----+-----+-----+-----+-----+-----+-----+--
| 7 | n | a1 | a2 | a3 | a4 | a1 | a2 | ... | 7 | n | a1 | a2 | a3 | a4 | a1 | a2 | ...
+-----+-----+-----+-----+-----+-----+-----+-----+-- +-----+-----+-----+-----+-----+-----+-----+-----+--
DRAFT DHCP Options and BOOTP Vendor Extensions November 1995
3.10. Cookie Server Option 3.10. Cookie Server Option
The cookie server option specifies a list of RFC 865 [9] cookie The cookie server option specifies a list of RFC 865 [9] cookie
servers available to the client. Servers SHOULD be listed in order servers available to the client. Servers SHOULD be listed in order
of preference. of preference.
The code for the log server option is 8. The minimum length for this The code for the log server option is 8. The minimum length for this
option is 4 octets, and the length MUST always be a multiple of 4. option is 4 octets, and the length MUST always be a multiple of 4.
Code Len Address 1 Address 2 Code Len Address 1 Address 2
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of preference. of preference.
The code for the LPR server option is 9. The minimum length for this The code for the LPR server option is 9. The minimum length for this
option is 4 octets, and the length MUST always be a multiple of 4. option is 4 octets, and the length MUST always be a multiple of 4.
Code Len Address 1 Address 2 Code Len Address 1 Address 2
+-----+-----+-----+-----+-----+-----+-----+-----+-- +-----+-----+-----+-----+-----+-----+-----+-----+--
| 9 | n | a1 | a2 | a3 | a4 | a1 | a2 | ... | 9 | n | a1 | a2 | a3 | a4 | a1 | a2 | ...
+-----+-----+-----+-----+-----+-----+-----+-----+-- +-----+-----+-----+-----+-----+-----+-----+-----+--
DRAFT DHCP Options and BOOTP Vendor Extensions April 1996
3.12. Impress Server Option 3.12. Impress Server Option
The Impress server option specifies a list of Imagen Impress servers The Impress server option specifies a list of Imagen Impress servers
available to the client. Servers SHOULD be listed in order of available to the client. Servers SHOULD be listed in order of
preference. preference.
The code for the Impress server option is 10. The minimum length for The code for the Impress server option is 10. The minimum length for
this option is 4 octets, and the length MUST always be a multiple of this option is 4 octets, and the length MUST always be a multiple of
4. 4.
Code Len Address 1 Address 2 Code Len Address 1 Address 2
+-----+-----+-----+-----+-----+-----+-----+-----+-- +-----+-----+-----+-----+-----+-----+-----+-----+--
| 10 | n | a1 | a2 | a3 | a4 | a1 | a2 | ... | 10 | n | a1 | a2 | a3 | a4 | a1 | a2 | ...
+-----+-----+-----+-----+-----+-----+-----+-----+-- +-----+-----+-----+-----+-----+-----+-----+-----+--
DRAFT DHCP Options and BOOTP Vendor Extensions November 1995
3.13. Resource Location Server Option 3.13. Resource Location Server Option
This option specifies a list of RFC 887 [11] Resource Location This option specifies a list of RFC 887 [11] Resource Location
servers available to the client. Servers SHOULD be listed in order servers available to the client. Servers SHOULD be listed in order
of preference. of preference.
The code for this option is 11. The minimum length for this option The code for this option is 11. The minimum length for this option
is 4 octets, and the length MUST always be a multiple of 4. is 4 octets, and the length MUST always be a multiple of 4.
Code Len Address 1 Address 2 Code Len Address 1 Address 2
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preferred way to retrieve the domain name). See RFC 1035 for preferred way to retrieve the domain name). See RFC 1035 for
character set restrictions. character set restrictions.
The code for this option is 12, and its minimum length is 1. The code for this option is 12, and its minimum length is 1.
Code Len Host Name Code Len Host Name
+-----+-----+-----+-----+-----+-----+-----+-----+-- +-----+-----+-----+-----+-----+-----+-----+-----+--
| 12 | n | h1 | h2 | h3 | h4 | h5 | h6 | ... | 12 | n | h1 | h2 | h3 | h4 | h5 | h6 | ...
+-----+-----+-----+-----+-----+-----+-----+-----+-- +-----+-----+-----+-----+-----+-----+-----+-----+--
DRAFT DHCP Options and BOOTP Vendor Extensions April 1996
3.15. Boot File Size Option 3.15. Boot File Size Option
This option specifies the length in 512-octet blocks of the default This option specifies the length in 512-octet blocks of the default
boot image for the client. The file length is specified as an boot image for the client. The file length is specified as an
unsigned 16-bit integer. unsigned 16-bit integer.
The code for this option is 13, and its length is 2. The code for this option is 13, and its length is 2.
Code Len File Size Code Len File Size
+-----+-----+-----+-----+ +-----+-----+-----+-----+
| 13 | 2 | l1 | l2 | | 13 | 2 | l1 | l2 |
+-----+-----+-----+-----+ +-----+-----+-----+-----+
DRAFT DHCP Options and BOOTP Vendor Extensions November 1995
3.16. Merit Dump File 3.16. Merit Dump File
This option specifies the path-name of a file to which the client's This option specifies the path-name of a file to which the client's
core image should be dumped in the event the client crashes. The core image should be dumped in the event the client crashes. The
path is formatted as a character string consisting of characters from path is formatted as a character string consisting of characters from
the NVT ASCII character set. the NVT ASCII character set.
The code for this option is 14. Its minimum length is 1. The code for this option is 14. Its minimum length is 1.
Code Len Dump File Pathname Code Len Dump File Pathname
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This option specifies the domain name that client should use when This option specifies the domain name that client should use when
resolving hostnames via the Domain Name System. resolving hostnames via the Domain Name System.
The code for this option is 15. Its minimum length is 1. The code for this option is 15. Its minimum length is 1.
Code Len Domain Name Code Len Domain Name
+-----+-----+-----+-----+-----+-----+-- +-----+-----+-----+-----+-----+-----+--
| 15 | n | d1 | d2 | d3 | d4 | ... | 15 | n | d1 | d2 | d3 | d4 | ...
+-----+-----+-----+-----+-----+-----+-- +-----+-----+-----+-----+-----+-----+--
DRAFT DHCP Options and BOOTP Vendor Extensions April 1996
3.18. Swap Server 3.18. Swap Server
This specifies the IP address of the client's swap server. This specifies the IP address of the client's swap server.
The code for this option is 16 and its length is 4. The code for this option is 16 and its length is 4.
Code Len Swap Server Address Code Len Swap Server Address
+-----+-----+-----+-----+-----+-----+ +-----+-----+-----+-----+-----+-----+
| 16 | n | a1 | a2 | a3 | a4 | | 16 | n | a1 | a2 | a3 | a4 |
+-----+-----+-----+-----+-----+-----+ +-----+-----+-----+-----+-----+-----+
DRAFT DHCP Options and BOOTP Vendor Extensions November 1995
3.19. Root Path 3.19. Root Path
This option specifies the path-name that contains the client's root This option specifies the path-name that contains the client's root
disk. The path is formatted as a character string consisting of disk. The path is formatted as a character string consisting of
characters from the NVT ASCII character set. characters from the NVT ASCII character set.
The code for this option is 17. Its minimum length is 1. The code for this option is 17. Its minimum length is 1.
Code Len Root Disk Pathname Code Len Root Disk Pathname
+-----+-----+-----+-----+-----+-----+--- +-----+-----+-----+-----+-----+-----+---
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BOOTP Extensions Path field) within the file are BOOTP Extensions Path field) within the file are
ignored. ignored.
The code for this option is 18. Its minimum length is 1. The code for this option is 18. Its minimum length is 1.
Code Len Extensions Pathname Code Len Extensions Pathname
+-----+-----+-----+-----+-----+-----+--- +-----+-----+-----+-----+-----+-----+---
| 18 | n | n1 | n2 | n3 | n4 | ... | 18 | n | n1 | n2 | n3 | n4 | ...
+-----+-----+-----+-----+-----+-----+--- +-----+-----+-----+-----+-----+-----+---
DRAFT DHCP Options and BOOTP Vendor Extensions April 1996
4. IP Layer Parameters per Host 4. IP Layer Parameters per Host
This section details the options that affect the operation of the IP This section details the options that affect the operation of the IP
layer on a per-host basis. layer on a per-host basis.
4.1. IP Forwarding Enable/Disable Option 4.1. IP Forwarding Enable/Disable Option
This option specifies whether the client should configure its IP This option specifies whether the client should configure its IP
layer for packet forwarding. A value of 0 means disable IP layer for packet forwarding. A value of 0 means disable IP
forwarding, and a value of 1 means enable IP forwarding. forwarding, and a value of 1 means enable IP forwarding.
The code for this option is 19, and its length is 1. The code for this option is 19, and its length is 1.
Code Len Value Code Len Value
+-----+-----+-----+ +-----+-----+-----+
| 19 | 1 | 0/1 | | 19 | 1 | 0/1 |
DRAFT DHCP Options and BOOTP Vendor Extensions November 1995
+-----+-----+-----+ +-----+-----+-----+
4.2. Non-Local Source Routing Enable/Disable Option 4.2. Non-Local Source Routing Enable/Disable Option
This option specifies whether the client should configure its IP This option specifies whether the client should configure its IP
layer to allow forwarding of datagrams with non-local source routes layer to allow forwarding of datagrams with non-local source routes
(see Section 3.3.5 of [4] for a discussion of this topic). A value (see Section 3.3.5 of [4] for a discussion of this topic). A value
of 0 means disallow forwarding of such datagrams, and a value of 1 of 0 means disallow forwarding of such datagrams, and a value of 1
means allow forwarding. means allow forwarding.
The code for this option is 20, and its length is 1. The code for this option is 20, and its length is 1.
Code Len Value Code Len Value
+-----+-----+-----+ +-----+-----+-----+
| 20 | 1 | 0/1 | | 20 | 1 | 0/1 |
+-----+-----+-----+ +-----+-----+-----+
DRAFT DHCP Options and BOOTP Vendor Extensions April 1996
4.3. Policy Filter Option 4.3. Policy Filter Option
This option specifies policy filters for non-local source routing. This option specifies policy filters for non-local source routing.
The filters consist of a list of IP addresses and masks which specify The filters consist of a list of IP addresses and masks which specify
destination/mask pairs with which to filter incoming source routes. destination/mask pairs with which to filter incoming source routes.
Any source routed datagram whose next-hop address does not match one Any source routed datagram whose next-hop address does not match one
of the filters should be discarded by the client. of the filters should be discarded by the client.
See [4] for further information. See [4] for further information.
skipping to change at page 12, line 5 skipping to change at page 13, line 30
Code Len Address 1 Mask 1 Code Len Address 1 Mask 1
+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+ +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
| 21 | n | a1 | a2 | a3 | a4 | m1 | m2 | m3 | m4 | | 21 | n | a1 | a2 | a3 | a4 | m1 | m2 | m3 | m4 |
+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+ +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
Address 2 Mask 2 Address 2 Mask 2
+-----+-----+-----+-----+-----+-----+-----+-----+--- +-----+-----+-----+-----+-----+-----+-----+-----+---
| a1 | a2 | a3 | a4 | m1 | m2 | m3 | m4 | ... | a1 | a2 | a3 | a4 | m1 | m2 | m3 | m4 | ...
+-----+-----+-----+-----+-----+-----+-----+-----+--- +-----+-----+-----+-----+-----+-----+-----+-----+---
DRAFT DHCP Options and BOOTP Vendor Extensions November 1995
4.4. Maximum Datagram Reassembly Size 4.4. Maximum Datagram Reassembly Size
This option specifies the maximum size datagram that the client This option specifies the maximum size datagram that the client
should be prepared to reassemble. The size is specified as a 16-bit should be prepared to reassemble. The size is specified as a 16-bit
unsigned integer. The minimum value legal value is 576. unsigned integer. The minimum value legal value is 576.
The code for this option is 22, and its length is 2. The code for this option is 22, and its length is 2.
Code Len Size Code Len Size
+-----+-----+-----+-----+ +-----+-----+-----+-----+
| 22 | 2 | s1 | s2 | | 22 | 2 | s1 | s2 |
+-----+-----+-----+-----+ +-----+-----+-----+-----+
DRAFT DHCP Options and BOOTP Vendor Extensions April 1996
4.5. Default IP Time-to-live 4.5. Default IP Time-to-live
This option specifies the default time-to-live that the client should This option specifies the default time-to-live that the client should
use on outgoing datagrams. The TTL is specified as an octet with a use on outgoing datagrams. The TTL is specified as an octet with a
value between 1 and 255. value between 1 and 255.
The code for this option is 23, and its length is 1. The code for this option is 23, and its length is 1.
Code Len TTL Code Len TTL
+-----+-----+-----+ +-----+-----+-----+
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MTU values discovered by the mechanism defined in RFC 1191 [12]. The MTU values discovered by the mechanism defined in RFC 1191 [12]. The
timeout is specified as a 32-bit unsigned integer. timeout is specified as a 32-bit unsigned integer.
The code for this option is 24, and its length is 4. The code for this option is 24, and its length is 4.
Code Len Timeout Code Len Timeout
+-----+-----+-----+-----+-----+-----+ +-----+-----+-----+-----+-----+-----+
| 24 | 4 | t1 | t2 | t3 | t4 | | 24 | 4 | t1 | t2 | t3 | t4 |
+-----+-----+-----+-----+-----+-----+ +-----+-----+-----+-----+-----+-----+
DRAFT DHCP Options and BOOTP Vendor Extensions November 1995
4.7. Path MTU Plateau Table Option 4.7. Path MTU Plateau Table Option
This option specifies a table of MTU sizes to use when performing This option specifies a table of MTU sizes to use when performing
Path MTU Discovery as defined in RFC 1191. The table is formatted as Path MTU Discovery as defined in RFC 1191. The table is formatted as
a list of 16-bit unsigned integers, ordered from smallest to largest. a list of 16-bit unsigned integers, ordered from smallest to largest.
The minimum MTU value cannot be smaller than 68. The minimum MTU value cannot be smaller than 68.
The code for this option is 25. Its minimum length is 2, and the The code for this option is 25. Its minimum length is 2, and the
length MUST be a multiple of 2. length MUST be a multiple of 2.
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| 25 | n | s1 | s2 | s1 | s2 | ... | 25 | n | s1 | s2 | s1 | s2 | ...
+-----+-----+-----+-----+-----+-----+--- +-----+-----+-----+-----+-----+-----+---
5. IP Layer Parameters per Interface 5. IP Layer Parameters per Interface
This section details the options that affect the operation of the IP This section details the options that affect the operation of the IP
layer on a per-interface basis. It is expected that a client can layer on a per-interface basis. It is expected that a client can
issue multiple requests, one per interface, in order to configure issue multiple requests, one per interface, in order to configure
interfaces with their specific parameters. interfaces with their specific parameters.
DRAFT DHCP Options and BOOTP Vendor Extensions April 1996
5.1. Interface MTU Option 5.1. Interface MTU Option
This option specifies the MTU to use on this interface. The MTU is This option specifies the MTU to use on this interface. The MTU is
specified as a 16-bit unsigned integer. The minimum legal value for specified as a 16-bit unsigned integer. The minimum legal value for
the MTU is 68. the MTU is 68.
The code for this option is 26, and its length is 2. The code for this option is 26, and its length is 2.
Code Len MTU Code Len MTU
+-----+-----+-----+-----+ +-----+-----+-----+-----+
| 26 | 2 | m1 | m2 | | 26 | 2 | m1 | m2 |
+-----+-----+-----+-----+ +-----+-----+-----+-----+
DRAFT DHCP Options and BOOTP Vendor Extensions November 1995
5.2. All Subnets are Local Option 5.2. All Subnets are Local Option
This option specifies whether or not the client may assume that all This option specifies whether or not the client may assume that all
subnets of the IP network to which the client is connected use the subnets of the IP network to which the client is connected use the
same MTU as the subnet of that network to which the client is same MTU as the subnet of that network to which the client is
directly connected. A value of 1 indicates that all subnets share directly connected. A value of 1 indicates that all subnets share
the same MTU. A value of 0 means that the client should assume that the same MTU. A value of 0 means that the client should assume that
some subnets of the directly connected network may have smaller MTUs. some subnets of the directly connected network may have smaller MTUs.
The code for this option is 27, and its length is 1. The code for this option is 27, and its length is 1.
skipping to change at page 14, line 36 skipping to change at page 16, line 5
subnet. Legal values for broadcast addresses are specified in subnet. Legal values for broadcast addresses are specified in
section 3.2.1.3 of [4]. section 3.2.1.3 of [4].
The code for this option is 28, and its length is 4. The code for this option is 28, and its length is 4.
Code Len Broadcast Address Code Len Broadcast Address
+-----+-----+-----+-----+-----+-----+ +-----+-----+-----+-----+-----+-----+
| 28 | 4 | b1 | b2 | b3 | b4 | | 28 | 4 | b1 | b2 | b3 | b4 |
+-----+-----+-----+-----+-----+-----+ +-----+-----+-----+-----+-----+-----+
DRAFT DHCP Options and BOOTP Vendor Extensions April 1996
5.4. Perform Mask Discovery Option 5.4. Perform Mask Discovery Option
This option specifies whether or not the client should perform subnet This option specifies whether or not the client should perform subnet
mask discovery using ICMP. A value of 0 indicates that the client mask discovery using ICMP. A value of 0 indicates that the client
should not perform mask discovery. A value of 1 means that the should not perform mask discovery. A value of 1 means that the
client should perform mask discovery. client should perform mask discovery.
The code for this option is 29, and its length is 1. The code for this option is 29, and its length is 1.
Code Len Value Code Len Value
+-----+-----+-----+ +-----+-----+-----+
| 29 | 1 | 0/1 | | 29 | 1 | 0/1 |
+-----+-----+-----+ +-----+-----+-----+
DRAFT DHCP Options and BOOTP Vendor Extensions November 1995
5.5. Mask Supplier Option 5.5. Mask Supplier Option
This option specifies whether or not the client should respond to This option specifies whether or not the client should respond to
subnet mask requests using ICMP. A value of 0 indicates that the subnet mask requests using ICMP. A value of 0 indicates that the
client should not respond. A value of 1 means that the client should client should not respond. A value of 1 means that the client should
respond. respond.
The code for this option is 30, and its length is 1. The code for this option is 30, and its length is 1.
Code Len Value Code Len Value
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router discovery. A value of 1 means that the client should perform router discovery. A value of 1 means that the client should perform
router discovery. router discovery.
The code for this option is 31, and its length is 1. The code for this option is 31, and its length is 1.
Code Len Value Code Len Value
+-----+-----+-----+ +-----+-----+-----+
| 31 | 1 | 0/1 | | 31 | 1 | 0/1 |
+-----+-----+-----+ +-----+-----+-----+
DRAFT DHCP Options and BOOTP Vendor Extensions April 1996
5.7. Router Solicitation Address Option 5.7. Router Solicitation Address Option
This option specifies the address to which the client should transmit This option specifies the address to which the client should transmit
router solicitation requests. router solicitation requests.
The code for this option is 32, and its length is 4. The code for this option is 32, and its length is 4.
Code Len Address Code Len Address
+-----+-----+-----+-----+-----+-----+ +-----+-----+-----+-----+-----+-----+
| 32 | 4 | a1 | a2 | a3 | a4 | | 32 | 4 | a1 | a2 | a3 | a4 |
+-----+-----+-----+-----+-----+-----+ +-----+-----+-----+-----+-----+-----+
DRAFT DHCP Options and BOOTP Vendor Extensions November 1995
5.8. Static Route Option 5.8. Static Route Option
This option specifies a list of static routes that the client should This option specifies a list of static routes that the client should
install in its routing cache. If multiple routes to the same install in its routing cache. If multiple routes to the same
destination are specified, they are listed in descending order of destination are specified, they are listed in descending order of
priority. priority.
The routes consist of a list of IP address pairs. The first address The routes consist of a list of IP address pairs. The first address
is the destination address, and the second address is the router for is the destination address, and the second address is the router for
the destination. the destination.
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Code Len Destination 1 Router 1 Code Len Destination 1 Router 1
+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+ +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
| 33 | n | d1 | d2 | d3 | d4 | r1 | r2 | r3 | r4 | | 33 | n | d1 | d2 | d3 | d4 | r1 | r2 | r3 | r4 |
+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+ +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
Destination 2 Router 2 Destination 2 Router 2
+-----+-----+-----+-----+-----+-----+-----+-----+--- +-----+-----+-----+-----+-----+-----+-----+-----+---
| d1 | d2 | d3 | d4 | r1 | r2 | r3 | r4 | ... | d1 | d2 | d3 | d4 | r1 | r2 | r3 | r4 | ...
+-----+-----+-----+-----+-----+-----+-----+-----+--- +-----+-----+-----+-----+-----+-----+-----+-----+---
DRAFT DHCP Options and BOOTP Vendor Extensions April 1996
6. Link Layer Parameters per Interface 6. Link Layer Parameters per Interface
This section lists the options that affect the operation of the data This section lists the options that affect the operation of the data
link layer on a per-interface basis. link layer on a per-interface basis.
6.1. Trailer Encapsulation Option 6.1. Trailer Encapsulation Option
This option specifies whether or not the client should negotiate the This option specifies whether or not the client should negotiate the
use of trailers (RFC 893 [14]) when using the ARP protocol. A value use of trailers (RFC 893 [14]) when using the ARP protocol. A value
of 0 indicates that the client should not attempt to use trailers. A of 0 indicates that the client should not attempt to use trailers. A
value of 1 means that the client should attempt to use trailers. value of 1 means that the client should attempt to use trailers.
The code for this option is 34, and its length is 1. The code for this option is 34, and its length is 1.
Code Len Value Code Len Value
+-----+-----+-----+ +-----+-----+-----+
| 34 | 1 | 0/1 | | 34 | 1 | 0/1 |
+-----+-----+-----+ +-----+-----+-----+
DRAFT DHCP Options and BOOTP Vendor Extensions November 1995
6.2. ARP Cache Timeout Option 6.2. ARP Cache Timeout Option
This option specifies the timeout in seconds for ARP cache entries. This option specifies the timeout in seconds for ARP cache entries.
The time is specified as a 32-bit unsigned integer. The time is specified as a 32-bit unsigned integer.
The code for this option is 35, and its length is 4. The code for this option is 35, and its length is 4.
Code Len Time Code Len Time
+-----+-----+-----+-----+-----+-----+ +-----+-----+-----+-----+-----+-----+
| 35 | 4 | t1 | t2 | t3 | t4 | | 35 | 4 | t1 | t2 | t3 | t4 |
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client should use RFC 894 encapsulation. A value of 1 means that the client should use RFC 894 encapsulation. A value of 1 means that the
client should use RFC 1042 encapsulation. client should use RFC 1042 encapsulation.
The code for this option is 36, and its length is 1. The code for this option is 36, and its length is 1.
Code Len Value Code Len Value
+-----+-----+-----+ +-----+-----+-----+
| 36 | 1 | 0/1 | | 36 | 1 | 0/1 |
+-----+-----+-----+ +-----+-----+-----+
DRAFT DHCP Options and BOOTP Vendor Extensions April 1996
7. TCP Parameters 7. TCP Parameters
This section lists the options that affect the operation of the TCP This section lists the options that affect the operation of the TCP
layer on a per-interface basis. layer on a per-interface basis.
7.1. TCP Default TTL Option 7.1. TCP Default TTL Option
This option specifies the default TTL that the client should use when This option specifies the default TTL that the client should use when
sending TCP segments. The value is represented as an 8-bit unsigned sending TCP segments. The value is represented as an 8-bit unsigned
integer. The minimum value is 1. integer. The minimum value is 1.
The code for this option is 37, and its length is 1. The code for this option is 37, and its length is 1.
Code Len TTL Code Len TTL
+-----+-----+-----+ +-----+-----+-----+
| 37 | 1 | n | | 37 | 1 | n |
+-----+-----+-----+ +-----+-----+-----+
DRAFT DHCP Options and BOOTP Vendor Extensions November 1995
7.2. TCP Keepalive Interval Option 7.2. TCP Keepalive Interval Option
This option specifies the interval (in seconds) that the client TCP This option specifies the interval (in seconds) that the client TCP
should wait before sending a keepalive message on a TCP connection. should wait before sending a keepalive message on a TCP connection.
The time is specified as a 32-bit unsigned integer. A value of zero The time is specified as a 32-bit unsigned integer. A value of zero
indicates that the client should not generate keepalive messages on indicates that the client should not generate keepalive messages on
connections unless specifically requested by an application. connections unless specifically requested by an application.
The code for this option is 38, and its length is 4. The code for this option is 38, and its length is 4.
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should not be sent. A value of 1 indicates that a garbage octet should not be sent. A value of 1 indicates that a garbage octet
should be sent. should be sent.
The code for this option is 39, and its length is 1. The code for this option is 39, and its length is 1.
Code Len Value Code Len Value
+-----+-----+-----+ +-----+-----+-----+
| 39 | 1 | 0/1 | | 39 | 1 | 0/1 |
+-----+-----+-----+ +-----+-----+-----+
DRAFT DHCP Options and BOOTP Vendor Extensions April 1996
8. Application and Service Parameters 8. Application and Service Parameters
This section details some miscellaneous options used to configure This section details some miscellaneous options used to configure
miscellaneous applications and services. miscellaneous applications and services.
8.1. Network Information Service Domain Option 8.1. Network Information Service Domain Option
This option specifies the name of the client's NIS [17] domain. The This option specifies the name of the client's NIS [17] domain. The
domain is formatted as a character string consisting of characters domain is formatted as a character string consisting of characters
from the NVT ASCII character set. from the NVT ASCII character set.
The code for this option is 40. Its minimum length is 1. The code for this option is 40. Its minimum length is 1.
Code Len NIS Domain Name Code Len NIS Domain Name
+-----+-----+-----+-----+-----+-----+--- +-----+-----+-----+-----+-----+-----+---
| 40 | n | n1 | n2 | n3 | n4 | ... | 40 | n | n1 | n2 | n3 | n4 | ...
+-----+-----+-----+-----+-----+-----+--- +-----+-----+-----+-----+-----+-----+---
DRAFT DHCP Options and BOOTP Vendor Extensions November 1995
8.2. Network Information Servers Option 8.2. Network Information Servers Option
This option specifies a list of IP addresses indicating NIS servers This option specifies a list of IP addresses indicating NIS servers
available to the client. Servers SHOULD be listed in order of available to the client. Servers SHOULD be listed in order of
preference. preference.
The code for this option is 41. Its minimum length is 4, and the The code for this option is 41. Its minimum length is 4, and the
length MUST be a multiple of 4. length MUST be a multiple of 4.
Code Len Address 1 Address 2 Code Len Address 1 Address 2
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of preference. of preference.
The code for this option is 42. Its minimum length is 4, and the The code for this option is 42. Its minimum length is 4, and the
length MUST be a multiple of 4. length MUST be a multiple of 4.
Code Len Address 1 Address 2 Code Len Address 1 Address 2
+-----+-----+-----+-----+-----+-----+-----+-----+-- +-----+-----+-----+-----+-----+-----+-----+-----+--
| 42 | n | a1 | a2 | a3 | a4 | a1 | a2 | ... | 42 | n | a1 | a2 | a3 | a4 | a1 | a2 | ...
+-----+-----+-----+-----+-----+-----+-----+-----+-- +-----+-----+-----+-----+-----+-----+-----+-----+--
DRAFT DHCP Options and BOOTP Vendor Extensions April 1996
8.4. Vendor Specific Information 8.4. Vendor Specific Information
This option is used by clients and servers to exchange vendor- This option is used by clients and servers to exchange vendor-
specific information. The information is an opaque object of n specific information. The information is an opaque object of n
octets, presumably interpreted by vendor-specific code on the clients octets, presumably interpreted by vendor-specific code on the clients
and servers. The definition of this information is vendor specific. and servers. The definition of this information is vendor specific.
The vendor is indicated in the vendor class identifier option. The vendor is indicated in the vendor class identifier option.
Servers not equipped to interpret the vendor-specific information Servers not equipped to interpret the vendor-specific information
sent by a client MUST ignore it (although it may be reported). sent by a client MUST ignore it (although it may be reported).
Clients which do not receive desired vendor-specific information Clients which do not receive desired vendor-specific information
skipping to change at page 20, line 5 skipping to change at page 21, line 28
(and announce they are doing so) in a degraded mode. (and announce they are doing so) in a degraded mode.
If a vendor potentially encodes more than one item of information in If a vendor potentially encodes more than one item of information in
this option, then the vendor SHOULD encode the option using this option, then the vendor SHOULD encode the option using
"Encapsulated vendor-specific options" as described below: "Encapsulated vendor-specific options" as described below:
The Encapsulated vendor-specific options field SHOULD be encoded as a The Encapsulated vendor-specific options field SHOULD be encoded as a
sequence of code/length/value fields of identical syntax to the DHCP sequence of code/length/value fields of identical syntax to the DHCP
options field with the following exceptions: options field with the following exceptions:
DRAFT DHCP Options and BOOTP Vendor Extensions November 1995
1) There SHOULD NOT be a "magic cookie" field in the encapsulated 1) There SHOULD NOT be a "magic cookie" field in the encapsulated
vendor-specific extensions field. vendor-specific extensions field.
2) Codes other than 0 or 255 MAY be redefined by the vendor within 2) Codes other than 0 or 255 MAY be redefined by the vendor within
the encapsulated vendor-specific extensions field, but SHOULD the encapsulated vendor-specific extensions field, but SHOULD
conform to the tag-length-value syntax defined in section 2. conform to the tag-length-value syntax defined in section 2.
3) Code 255 (END), if present, signifies the end of the 3) Code 255 (END), if present, signifies the end of the
encapsulated vendor extensions, not the end of the vendor encapsulated vendor extensions, not the end of the vendor
extensions field. If no code 255 is present, then the end of extensions field. If no code 255 is present, then the end of
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+-----+-----+-----+-----+--- +-----+-----+-----+-----+---
When encapsulated vendor-specific extensions are used, the When encapsulated vendor-specific extensions are used, the
information bytes 1-n have the following format: information bytes 1-n have the following format:
Code Len Data item Code Len Data item Code Code Len Data item Code Len Data item Code
+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+ +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
| T1 | n | d1 | d2 | ... | T2 | n | D1 | D2 | ... | ... | | T1 | n | d1 | d2 | ... | T2 | n | D1 | D2 | ... | ... |
+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+ +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
DRAFT DHCP Options and BOOTP Vendor Extensions April 1996
8.5. NetBIOS over TCP/IP Name Server Option 8.5. NetBIOS over TCP/IP Name Server Option
The NetBIOS name server (NBNS) option specifies a list of RFC The NetBIOS name server (NBNS) option specifies a list of RFC
1001/1002 [19] [20] NBNS name servers listed in order of preference. 1001/1002 [19] [20] NBNS name servers listed in order of preference.
The code for this option is 44. The minimum length of the option is The code for this option is 44. The minimum length of the option is
4 octets, and the length must always be a multiple of 4. 4 octets, and the length must always be a multiple of 4.
Code Len Address 1 Address 2 Code Len Address 1 Address 2
+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+---- +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+----
| 44 | n | a1 | a2 | a3 | a4 | b1 | b2 | b3 | b4 | ... | 44 | n | a1 | a2 | a3 | a4 | b1 | b2 | b3 | b4 | ...
+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+---- +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+----
DRAFT DHCP Options and BOOTP Vendor Extensions November 1995
8.6. NetBIOS over TCP/IP Datagram Distribution Server Option 8.6. NetBIOS over TCP/IP Datagram Distribution Server Option
The NetBIOS datagram distribution server (NBDD) option specifies a The NetBIOS datagram distribution server (NBDD) option specifies a
list of RFC 1001/1002 NBDD servers listed in order of preference. The list of RFC 1001/1002 NBDD servers listed in order of preference. The
code for this option is 45. The minimum length of the option is 4 code for this option is 45. The minimum length of the option is 4
octets, and the length must always be a multiple of 4. octets, and the length must always be a multiple of 4.
Code Len Address 1 Address 2 Code Len Address 1 Address 2
+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+---- +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+----
| 45 | n | a1 | a2 | a3 | a4 | b1 | b2 | b3 | b4 | ... | 45 | n | a1 | a2 | a3 | a4 | b1 | b2 | b3 | b4 | ...
skipping to change at page 21, line 36 skipping to change at page 23, line 5
Value Node Type Value Node Type
----- --------- ----- ---------
0x1 B-node 0x1 B-node
0x2 P-node 0x2 P-node
0x4 M-node 0x4 M-node
0x8 H-node 0x8 H-node
In the above chart, the notation '0x' indicates a number in base-16 In the above chart, the notation '0x' indicates a number in base-16
(hexadecimal). (hexadecimal).
DRAFT DHCP Options and BOOTP Vendor Extensions April 1996
The code for this option is 46. The length of this option is always The code for this option is 46. The length of this option is always
1. 1.
Code Len Node Type Code Len Node Type
+-----+-----+-----------+ +-----+-----+-----------+
| 46 | 1 | see above | | 46 | 1 | see above |
+-----+-----+-----------+ +-----+-----+-----------+
DRAFT DHCP Options and BOOTP Vendor Extensions November 1995
8.8. NetBIOS over TCP/IP Scope Option 8.8. NetBIOS over TCP/IP Scope Option
The NetBIOS scope option specifies the NetBIOS over TCP/IP scope The NetBIOS scope option specifies the NetBIOS over TCP/IP scope
parameter for the client as specified in RFC 1001/1002. See [19], parameter for the client as specified in RFC 1001/1002. See [19],
[20], and [8] for character-set restrictions. [20], and [8] for character-set restrictions.
The code for this option is 47. The minimum length of this option is The code for this option is 47. The minimum length of this option is
1. 1.
Code Len NetBIOS Scope Code Len NetBIOS Scope
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preference. preference.
The code for this option is 48. The minimum length of this option is The code for this option is 48. The minimum length of this option is
4 octets, and the length MUST be a multiple of 4. 4 octets, and the length MUST be a multiple of 4.
Code Len Address 1 Address 2 Code Len Address 1 Address 2
+-----+-----+-----+-----+-----+-----+-----+-----+--- +-----+-----+-----+-----+-----+-----+-----+-----+---
| 48 | n | a1 | a2 | a3 | a4 | a1 | a2 | ... | 48 | n | a1 | a2 | a3 | a4 | a1 | a2 | ...
+-----+-----+-----+-----+-----+-----+-----+-----+--- +-----+-----+-----+-----+-----+-----+-----+-----+---
DRAFT DHCP Options and BOOTP Vendor Extensions April 1996
8.10. X Window System Display Manager Option 8.10. X Window System Display Manager Option
This option specifies a list of IP addresses of systems that are This option specifies a list of IP addresses of systems that are
running the X Window System Display Manager and are available to the running the X Window System Display Manager and are available to the
client. client.
Addresses SHOULD be listed in order of preference. Addresses SHOULD be listed in order of preference.
The code for the this option is 49. The minimum length of this option The code for the this option is 49. The minimum length of this option
is 4, and the length MUST be a multiple of 4. is 4, and the length MUST be a multiple of 4.
Code Len Address 1 Address 2 Code Len Address 1 Address 2
+-----+-----+-----+-----+-----+-----+-----+-----+--- +-----+-----+-----+-----+-----+-----+-----+-----+---
| 49 | n | a1 | a2 | a3 | a4 | a1 | a2 | ... | 49 | n | a1 | a2 | a3 | a4 | a1 | a2 | ...
+-----+-----+-----+-----+-----+-----+-----+-----+--- +-----+-----+-----+-----+-----+-----+-----+-----+---
DRAFT DHCP Options and BOOTP Vendor Extensions November 1995
8.11. Network Information Service+ Domain Option 8.11. Network Information Service+ Domain Option
This option specifies the name of the client's NIS+ [17] domain. The This option specifies the name of the client's NIS+ [17] domain. The
domain is formatted as a character string consisting of characters domain is formatted as a character string consisting of characters
from the NVT ASCII character set. from the NVT ASCII character set.
The code for this option is 64. Its minimum length is 1. The code for this option is 64. Its minimum length is 1.
Code Len NIS Client Domain Name Code Len NIS Client Domain Name
+-----+-----+-----+-----+-----+-----+--- +-----+-----+-----+-----+-----+-----+---
skipping to change at page 23, line 34 skipping to change at page 25, line 5
preference. preference.
The code for this option is 65. Its minimum length is 4, and the The code for this option is 65. Its minimum length is 4, and the
length MUST be a multiple of 4. length MUST be a multiple of 4.
Code Len Address 1 Address 2 Code Len Address 1 Address 2
+-----+-----+-----+-----+-----+-----+-----+-----+-- +-----+-----+-----+-----+-----+-----+-----+-----+--
| 65 | n | a1 | a2 | a3 | a4 | a1 | a2 | ... | 65 | n | a1 | a2 | a3 | a4 | a1 | a2 | ...
+-----+-----+-----+-----+-----+-----+-----+-----+-- +-----+-----+-----+-----+-----+-----+-----+-----+--
DRAFT DHCP Options and BOOTP Vendor Extensions April 1996
8.13. Mobile IP Home Agent option 8.13. Mobile IP Home Agent option
This option specifies a list of IP addresses indicating mobile IP This option specifies a list of IP addresses indicating mobile IP
home agents available to the client. Agents SHOULD be listed in home agents available to the client. Agents SHOULD be listed in
order of preference. order of preference.
The code for this option is 68. Its minimum length is 0 (indicating The code for this option is 68. Its minimum length is 0 (indicating
no home agents are available) and the length MUST be a multiple of 4. no home agents are available) and the length MUST be a multiple of 4.
It is expected that the usual length will be four octets, containing It is expected that the usual length will be four octets, containing
a single home agent's address. a single home agent's address.
Code Len Home Agent Addresses (zero or more) Code Len Home Agent Addresses (zero or more)
+-----+-----+-----+-----+-----+-----+-- +-----+-----+-----+-----+-----+-----+--
| 68 | n | a1 | a2 | a3 | a4 | ... | 68 | n | a1 | a2 | a3 | a4 | ...
+-----+-----+-----+-----+-----+-----+-- +-----+-----+-----+-----+-----+-----+--
DRAFT DHCP Options and BOOTP Vendor Extensions November 1995
8.14. Simple Mail Transport Protocol (SMTP) Server Option 8.14. Simple Mail Transport Protocol (SMTP) Server Option
The SMTP server option specifies a list of SMTP servers available to The SMTP server option specifies a list of SMTP servers available to
the client. Servers SHOULD be listed in order of preference. the client. Servers SHOULD be listed in order of preference.
The code for the SMTP server option is 69. The minimum length for The code for the SMTP server option is 69. The minimum length for
this option is 4 octets, and the length MUST always be a multiple of this option is 4 octets, and the length MUST always be a multiple of
4. 4.
Code Len Address 1 Address 2 Code Len Address 1 Address 2
skipping to change at page 24, line 35 skipping to change at page 26, line 5
The code for the POP3 server option is 70. The minimum length for The code for the POP3 server option is 70. The minimum length for
this option is 4 octets, and the length MUST always be a multiple of this option is 4 octets, and the length MUST always be a multiple of
4. 4.
Code Len Address 1 Address 2 Code Len Address 1 Address 2
+-----+-----+-----+-----+-----+-----+-----+-----+-- +-----+-----+-----+-----+-----+-----+-----+-----+--
| 70 | n | a1 | a2 | a3 | a4 | a1 | a2 | ... | 70 | n | a1 | a2 | a3 | a4 | a1 | a2 | ...
+-----+-----+-----+-----+-----+-----+-----+-----+-- +-----+-----+-----+-----+-----+-----+-----+-----+--
DRAFT DHCP Options and BOOTP Vendor Extensions April 1996
8.16. Network News Transport Protocol (NNTP) Server Option 8.16. Network News Transport Protocol (NNTP) Server Option
The NNTP server option specifies a list of NNTP available to the The NNTP server option specifies a list of NNTP available to the
client. Servers SHOULD be listed in order of preference. client. Servers SHOULD be listed in order of preference.
The code for the NNTP server option is 71. The minimum length for The code for the NNTP server option is 71. The minimum length for
this option is 4 octets, and the length MUST always be a multiple of this option is 4 octets, and the length MUST always be a multiple of
4. 4.
Code Len Address 1 Address 2 Code Len Address 1 Address 2
+-----+-----+-----+-----+-----+-----+-----+-----+-- +-----+-----+-----+-----+-----+-----+-----+-----+--
| 71 | n | a1 | a2 | a3 | a4 | a1 | a2 | ... | 71 | n | a1 | a2 | a3 | a4 | a1 | a2 | ...
+-----+-----+-----+-----+-----+-----+-----+-----+-- +-----+-----+-----+-----+-----+-----+-----+-----+--
DRAFT DHCP Options and BOOTP Vendor Extensions November 1995
8.17. Default World Wide Web (WWW) Server Option 8.17. Default World Wide Web (WWW) Server Option
The WWW server option specifies a list of WWW available to the The WWW server option specifies a list of WWW available to the
client. Servers SHOULD be listed in order of preference. client. Servers SHOULD be listed in order of preference.
The code for the WWW server option is 72. The minimum length for The code for the WWW server option is 72. The minimum length for
this option is 4 octets, and the length MUST always be a multiple of this option is 4 octets, and the length MUST always be a multiple of
4. 4.
Code Len Address 1 Address 2 Code Len Address 1 Address 2
skipping to change at page 25, line 35 skipping to change at page 27, line 5
The code for the Finger server option is 73. The minimum length for The code for the Finger server option is 73. The minimum length for
this option is 4 octets, and the length MUST always be a multiple of this option is 4 octets, and the length MUST always be a multiple of
4. 4.
Code Len Address 1 Address 2 Code Len Address 1 Address 2
+-----+-----+-----+-----+-----+-----+-----+-----+-- +-----+-----+-----+-----+-----+-----+-----+-----+--
| 73 | n | a1 | a2 | a3 | a4 | a1 | a2 | ... | 73 | n | a1 | a2 | a3 | a4 | a1 | a2 | ...
+-----+-----+-----+-----+-----+-----+-----+-----+-- +-----+-----+-----+-----+-----+-----+-----+-----+--
DRAFT DHCP Options and BOOTP Vendor Extensions April 1996
8.19. Default Internet Relay Chat (IRC) Server Option 8.19. Default Internet Relay Chat (IRC) Server Option
The IRC server option specifies a list of IRC available to the The IRC server option specifies a list of IRC available to the
client. Servers SHOULD be listed in order of preference. client. Servers SHOULD be listed in order of preference.
The code for the IRC server option is 74. The minimum length for The code for the IRC server option is 74. The minimum length for
this option is 4 octets, and the length MUST always be a multiple of this option is 4 octets, and the length MUST always be a multiple of
4. 4.
Code Len Address 1 Address 2 Code Len Address 1 Address 2
+-----+-----+-----+-----+-----+-----+-----+-----+-- +-----+-----+-----+-----+-----+-----+-----+-----+--
| 74 | n | a1 | a2 | a3 | a4 | a1 | a2 | ... | 74 | n | a1 | a2 | a3 | a4 | a1 | a2 | ...
+-----+-----+-----+-----+-----+-----+-----+-----+-- +-----+-----+-----+-----+-----+-----+-----+-----+--
DRAFT DHCP Options and BOOTP Vendor Extensions November 1995
8.20. StreetTalk Server Option 8.20. StreetTalk Server Option
The StreetTalk server option specifies a list of StreetTalk servers The StreetTalk server option specifies a list of StreetTalk servers
available to the client. Servers SHOULD be listed in order of available to the client. Servers SHOULD be listed in order of
preference. preference.
The code for the StreetTalk server option is 75. The minimum length The code for the StreetTalk server option is 75. The minimum length
for this option is 4 octets, and the length MUST always be a multiple for this option is 4 octets, and the length MUST always be a multiple
of 4. of 4.
skipping to change at page 26, line 37 skipping to change at page 28, line 5
The code for the StreetTalk Directory Assistance server option is 76. The code for the StreetTalk Directory Assistance server option is 76.
The minimum length for this option is 4 octets, and the length MUST The minimum length for this option is 4 octets, and the length MUST
always be a multiple of 4. always be a multiple of 4.
Code Len Address 1 Address 2 Code Len Address 1 Address 2
+-----+-----+-----+-----+-----+-----+-----+-----+-- +-----+-----+-----+-----+-----+-----+-----+-----+--
| 76 | n | a1 | a2 | a3 | a4 | a1 | a2 | ... | 76 | n | a1 | a2 | a3 | a4 | a1 | a2 | ...
+-----+-----+-----+-----+-----+-----+-----+-----+-- +-----+-----+-----+-----+-----+-----+-----+-----+--
DRAFT DHCP Options and BOOTP Vendor Extensions April 1996
9. DHCP Extensions 9. DHCP Extensions
This section details the options that are specific to DHCP. This section details the options that are specific to DHCP.
9.1. Requested IP Address 9.1. Requested IP Address
This option is used in a client request (DHCPDISCOVER) to allow the This option is used in a client request (DHCPDISCOVER) to allow the
client to request that a particular IP address be assigned. client to request that a particular IP address be assigned.
The code for this option is 50, and its length is 4. The code for this option is 50, and its length is 4.
Code Len Address Code Len Address
+-----+-----+-----+-----+-----+-----+ +-----+-----+-----+-----+-----+-----+
| 50 | 4 | a1 | a2 | a3 | a4 | | 50 | 4 | a1 | a2 | a3 | a4 |
+-----+-----+-----+-----+-----+-----+ +-----+-----+-----+-----+-----+-----+
DRAFT DHCP Options and BOOTP Vendor Extensions November 1995
9.2. IP Address Lease Time 9.2. IP Address Lease Time
This option is used in a client request (DHCPDISCOVER or DHCPREQUEST) This option is used in a client request (DHCPDISCOVER or DHCPREQUEST)
to allow the client to request a lease time for the IP address. In a to allow the client to request a lease time for the IP address. In a
server reply (DHCPOFFER), a DHCP server uses this option to specify server reply (DHCPOFFER), a DHCP server uses this option to specify
the lease time it is willing to offer. the lease time it is willing to offer.
The time is in units of seconds, and is specified as a 32-bit The time is in units of seconds, and is specified as a 32-bit
unsigned integer. unsigned integer.
skipping to change at page 27, line 35 skipping to change at page 29, line 5
This option is used to indicate that the DHCP 'sname' or 'file' This option is used to indicate that the DHCP 'sname' or 'file'
fields are being overloaded by using them to carry DHCP options. A fields are being overloaded by using them to carry DHCP options. A
DHCP server inserts this option if the returned parameters will DHCP server inserts this option if the returned parameters will
exceed the usual space allotted for options. exceed the usual space allotted for options.
If this option is present, the client interprets the specified If this option is present, the client interprets the specified
additional fields after it concludes interpretation of the standard additional fields after it concludes interpretation of the standard
option fields. option fields.
DRAFT DHCP Options and BOOTP Vendor Extensions April 1996
The code for this option is 52, and its length is 1. Legal values The code for this option is 52, and its length is 1. Legal values
for this option are: for this option are:
Value Meaning Value Meaning
----- -------- ----- --------
1 the 'file' field is used to hold options 1 the 'file' field is used to hold options
2 the 'sname' field is used to hold options 2 the 'sname' field is used to hold options
3 both fields are used to hold options 3 both fields are used to hold options
Code Len Value Code Len Value
skipping to change at page 28, line 5 skipping to change at page 29, line 28
| 52 | 1 |1/2/3| | 52 | 1 |1/2/3|
+-----+-----+-----+ +-----+-----+-----+
9.4 TFTP server name 9.4 TFTP server name
This option is used to identify a TFTP server when the 'sname' This option is used to identify a TFTP server when the 'sname'
field in the DHCP header has been used for DHCP options. field in the DHCP header has been used for DHCP options.
The code for this option is 66, and its minimum length is 1. The code for this option is 66, and its minimum length is 1.
DRAFT DHCP Options and BOOTP Vendor Extensions November 1995
Code Len TFTP server Code Len TFTP server
+-----+-----+-----+-----+-----+--- +-----+-----+-----+-----+-----+---
| 66 | n | c1 | c2 | c3 | ... | 66 | n | c1 | c2 | c3 | ...
+-----+-----+-----+-----+-----+--- +-----+-----+-----+-----+-----+---
9.5 Bootfile name 9.5 Bootfile name
This option is used to identify a bootfile when the 'file' field in the This option is used to identify a bootfile when the 'file' field in
DHCP header has been used for DHCP options. the DHCP header has been used for DHCP options.
The code for this option is 67, and its minimum length is 1. The code for this option is 67, and its minimum length is 1.
Code Len Bootfile name Code Len Bootfile name
+-----+-----+-----+-----+-----+--- +-----+-----+-----+-----+-----+---
| 67 | n | c1 | c2 | c3 | ... | 67 | n | c1 | c2 | c3 | ...
+-----+-----+-----+-----+-----+--- +-----+-----+-----+-----+-----+---
DRAFT DHCP Options and BOOTP Vendor Extensions April 1996
9.6. DHCP Message Type 9.6. DHCP Message Type
This option is used to convey the type of the DHCP message. The code This option is used to convey the type of the DHCP message. The code
for this option is 53, and its length is 1. Legal values for this for this option is 53, and its length is 1. Legal values for this
option are: option are:
Value Message Type Value Message Type
----- ------------ ----- ------------
1 DHCPDISCOVER 1 DHCPDISCOVER
2 DHCPOFFER 2 DHCPOFFER
skipping to change at page 29, line 5 skipping to change at page 30, line 29
5 DHCPACK 5 DHCPACK
6 DHCPNAK 6 DHCPNAK
7 DHCPRELEASE 7 DHCPRELEASE
8 DHCPINFORM 8 DHCPINFORM
Code Len Type Code Len Type
+-----+-----+-----+ +-----+-----+-----+
| 53 | 1 | 1-9 | | 53 | 1 | 1-9 |
+-----+-----+-----+ +-----+-----+-----+
DRAFT DHCP Options and BOOTP Vendor Extensions November 1995
9.7. Server Identifier 9.7. Server Identifier
This option is used in DHCPOFFER and DHCPREQUEST messages, and may This option is used in DHCPOFFER and DHCPREQUEST messages, and may
optionally be included in the DHCPACK and DHCPNAK messages. DHCP optionally be included in the DHCPACK and DHCPNAK messages. DHCP
servers include this option in the DHCPOFFER in order to allow the servers include this option in the DHCPOFFER in order to allow the
client to distinguish between lease offers. DHCP clients indicate client to distinguish between lease offers. DHCP clients indicate
which of several lease offers is being accepted by including this which of several lease offers is being accepted by including this
option in a DHCPREQUEST message. option in a DHCPREQUEST message.
The identifier is the IP address of the selected server. The identifier is the IP address of the selected server.
The code for this option is 54, and its length is 4. The code for this option is 54, and its length is 4.
Code Len Address Code Len Address
+-----+-----+-----+-----+-----+-----+ +-----+-----+-----+-----+-----+-----+
| 54 | 4 | a1 | a2 | a3 | a4 | | 54 | 4 | a1 | a2 | a3 | a4 |
+-----+-----+-----+-----+-----+-----+ +-----+-----+-----+-----+-----+-----+
DRAFT DHCP Options and BOOTP Vendor Extensions April 1996
9.8. Parameter Request List 9.8. Parameter Request List
This option is used by a DHCP client to request values for specified This option is used by a DHCP client to request values for specified
configuration parameters. The list of requested parameters is configuration parameters. The list of requested parameters is
specified as n octets, where each octet is a valid DHCP option code specified as n octets, where each octet is a valid DHCP option code
as defined in this document. as defined in this document.
The client MAY list the options in order of preference. The DHCP The client MAY list the options in order of preference. The DHCP
server is not required to return the options in the requested order, server is not required to return the options in the requested order,
but MUST try to insert the requested options in the order requested but MUST try to insert the requested options in the order requested
by the client. by the client.
The code for this option is 55. Its minimum length is 1. The code for this option is 55. Its minimum length is 1.
Code Len Option Codes Code Len Option Codes
+-----+-----+-----+-----+--- +-----+-----+-----+-----+---
| 55 | n | c1 | c2 | ... | 55 | n | c1 | c2 | ...
+-----+-----+-----+-----+--- +-----+-----+-----+-----+---
DRAFT DHCP Options and BOOTP Vendor Extensions November 1995
9.9. Message 9.9. Message
This option is used by a DHCP server to provide an error message to a This option is used by a DHCP server to provide an error message to a
DHCP client in a DHCPNAK message in the event of a failure. A client DHCP client in a DHCPNAK message in the event of a failure. A client
may use this option in a DHCPDECLINE message to indicate the why the may use this option in a DHCPDECLINE message to indicate the why the
client declined the offered parameters. The message consists of n client declined the offered parameters. The message consists of n
octets of NVT ASCII text, which the client may display on an octets of NVT ASCII text, which the client may display on an
available output device. available output device.
The code for this option is 56 and its minimum length is 1. The code for this option is 56 and its minimum length is 1.
Code Len Text Code Len Text
+-----+-----+-----+-----+--- +-----+-----+-----+-----+---
| 56 | n | c1 | c2 | ... | 56 | n | c1 | c2 | ...
+-----+-----+-----+-----+--- +-----+-----+-----+-----+---
DRAFT DHCP Options and BOOTP Vendor Extensions April 1996
9.10. Maximum DHCP Message Size 9.10. Maximum DHCP Message Size
This option specifies the maximum length DHCP message that it is This option specifies the maximum length DHCP message that it is
willing to accept. The length is specified as an unsigned 16-bit willing to accept. The length is specified as an unsigned 16-bit
integer. A client may use the maximum DHCP message size option in integer. A client may use the maximum DHCP message size option in
DHCPDISCOVER or DHCPREQUEST messages, but should not use the option DHCPDISCOVER or DHCPREQUEST messages, but should not use the option
in DHCPDECLINE messages. in DHCPDECLINE messages.
The code for this option is 57, and its length is 2. The minimum The code for this option is 57, and its length is 2. The minimum
legal value is 576 octets. legal value is 576 octets.
skipping to change at page 31, line 5 skipping to change at page 32, line 38
The value is in units of seconds, and is specified as a 32-bit The value is in units of seconds, and is specified as a 32-bit
unsigned integer. unsigned integer.
The code for this option is 58, and its length is 4. The code for this option is 58, and its length is 4.
Code Len T1 Interval Code Len T1 Interval
+-----+-----+-----+-----+-----+-----+ +-----+-----+-----+-----+-----+-----+
| 58 | 4 | t1 | t2 | t3 | t4 | | 58 | 4 | t1 | t2 | t3 | t4 |
+-----+-----+-----+-----+-----+-----+ +-----+-----+-----+-----+-----+-----+
DRAFT DHCP Options and BOOTP Vendor Extensions November 1995
9.12. Rebinding (T2) Time Value 9.12. Rebinding (T2) Time Value
This option specifies the time interval from address assignment until This option specifies the time interval from address assignment until
the client transitions to the REBINDING state. the client transitions to the REBINDING state.
The value is in units of seconds, and is specified as a 32-bit The value is in units of seconds, and is specified as a 32-bit
unsigned integer. unsigned integer.
The code for this option is 59, and its length is 4. The code for this option is 59, and its length is 4.
Code Len T2 Interval Code Len T2 Interval
+-----+-----+-----+-----+-----+-----+ +-----+-----+-----+-----+-----+-----+
| 59 | 4 | t1 | t2 | t3 | t4 | | 59 | 4 | t1 | t2 | t3 | t4 |
+-----+-----+-----+-----+-----+-----+ +-----+-----+-----+-----+-----+-----+
DRAFT DHCP Options and BOOTP Vendor Extensions April 1996
9.13. Vendor class identifier 9.13. Vendor class identifier
This option is used by DHCP clients to optionally identify the vendor This option is used by DHCP clients to optionally identify the vendor
type and configuration of a DHCP client. The information is a string type and configuration of a DHCP client. The information is a string
of n octets, interpreted by servers. Vendors may choose to define of n octets, interpreted by servers. Vendors may choose to define
specific vendor class identifiers to convey particular configuration specific vendor class identifiers to convey particular configuration
or other identification information about a client. For example, the or other identification information about a client. For example, the
identifier may encode the client's hardware configuration. Servers identifier may encode the client's hardware configuration. Servers
not equipped to interpret the class-specific information sent by a not equipped to interpret the class-specific information sent by a
client MUST ignore it (although it may be reported). Servers that client MUST ignore it (although it may be reported). Servers that
respond SHOULD only use option 43 to return the vendor-specific respond SHOULD only use option 43 to return the vendor-specific
information to the client. information to the client.
The code for this option is 60, and its minimum length is 1. The code for this option is 60, and its minimum length is 1.
Code Len Vendor class Identifier Code Len Vendor class Identifier
+-----+-----+-----+-----+--- +-----+-----+-----+-----+---
| 60 | n | i1 | i2 | ... | 60 | n | i1 | i2 | ...
+-----+-----+-----+-----+--- +-----+-----+-----+-----+---
DRAFT DHCP Options and BOOTP Vendor Extensions November 1995
9.14. Client-identifier 9.14. Client-identifier
This option is used by DHCP clients to specify their unique This option is used by DHCP clients to specify their unique
identifier. DHCP servers use this value to index their database of identifier. DHCP servers use this value to index their database of
address bindings. This value is expected to be unique for all address bindings. This value is expected to be unique for all
clients in an administrative domain. clients in an administrative domain.
Identifiers SHOULD be treated as opaque objects by DHCP servers. Identifiers SHOULD be treated as opaque objects by DHCP servers.
The client identifier MAY consist of type-value pairs similar to the The client identifier MAY consist of type-value pairs similar to the
'htype'/'chaddr' fields defined in [3]. For instance, it MAY consist 'htype'/'chaddr' fields defined in [3]. For instance, it MAY consist
of a hardware type and hardware address. In this case the type field of a hardware type and hardware address. In this case the type field
SHOULD be one of the ARP hardware types defined in STD2 [22]. A SHOULD be one of the ARP hardware types defined in STD2 [22]. A
hardware type of 0 (zero) should be used when the value field hardware type of 0 (zero) should be used when the value field
contains an identifier other than a hardware address (e.g. a fully contains an identifier other than a hardware address (e.g. a fully
qualified domain name). qualified domain name).
For correct identification of clients, each client's client-
identifier MUST be unique among the client-identifiers used on the
subnet to which the client is attached. Vendors and system
administrators are responsible for choosing client-identifiers that
meet this requirement for uniqueness.
DRAFT DHCP Options and BOOTP Vendor Extensions April 1996
The code for this option is 61, and its minimum length is 2. The code for this option is 61, and its minimum length is 2.
Code Len Type Client-Identifier Code Len Type Client-Identifier
+-----+-----+-----+-----+-----+--- +-----+-----+-----+-----+-----+---
| 61 | n | t1 | i1 | i2 | ... | 61 | n | t1 | i1 | i2 | ...
+-----+-----+-----+-----+-----+--- +-----+-----+-----+-----+-----+---
9.15. User Class Information 9.15. User Class Information
This option is used by a DHCP client to optionally identify the type This option is used by a DHCP client to optionally identify the type
skipping to change at page 33, line 5 skipping to change at page 34, line 38
Servers not equipped to interpret any of user classes specified by a Servers not equipped to interpret any of user classes specified by a
client MUST ignore it (although it may be reported). Otherwise, client MUST ignore it (although it may be reported). Otherwise,
servers SHOULD respond with the set of options corresponding to the servers SHOULD respond with the set of options corresponding to the
user class specified by the client. Further, if the server responds, user class specified by the client. Further, if the server responds,
it MUST return this option to the client. it MUST return this option to the client.
Clients which do not receive information for the user class requested Clients which do not receive information for the user class requested
SHOULD make an attempt to operate without it, although they may do so SHOULD make an attempt to operate without it, although they may do so
(and may announce they are doing so) in a degraded mode. (and may announce they are doing so) in a degraded mode.
DRAFT DHCP Options and BOOTP Vendor Extensions November 1995
The code for this option is 77. The minimum length for this option The code for this option is 77. The minimum length for this option
is two. is two.
Code Len text1 Code Len text1
+-----+-----+-----+-----+----- +-----+-----+-----+-----+-----
| 77 | N | c1 | c2 | ... | 77 | N | c1 | c2 | ...
+-----+-----+-----+-----+----- +-----+-----+-----+-----+-----
10. Extensions DRAFT DHCP Options and BOOTP Vendor Extensions April 1996
Additional generic data fields may be registered by contacting: 10. Defining new extensions
The author of a new DHCP option will follow these steps to obtain
acceptance of the option as a part of the DHCP Internet Standard:
1. The author devises the new option.
2. The author requests a number for the new option from IANA by
contacting:
Internet Assigned Numbers Authority (IANA) Internet Assigned Numbers Authority (IANA)
USC/Information Sciences Institute USC/Information Sciences Institute
4676 Admiralty Way 4676 Admiralty Way
Marina del Rey, California 90292-6695 Marina del Rey, California 90292-6695
or by email as: iana@isi.edu or by email as: iana@isi.edu
Implementation specific use of undefined generic types (those in the 3. The author documents the new option, using the newly obtained
range 61-127) may conflict with other implementations, and option number, as an Internet Draft.
registration is required. 4. The author submits the Internet Draft for review through the IETF
standards process as defined in "Internet Official Protocol
Standards" (STD 1). The new option will be submitted for eventual
acceptance as an Internet Standard.
5. The new option progresses through the IETF standards process; the
new option will be reviewed by the Dynamic Host Configuration
Working Group (if that group still exists), or as an Internet
Draft not submitted by an IETF working group.
6. If the new option fails to gain acceptance as an Internet
Standard, the assigned option number will be returned to IANA for
reassignment.
This procedure for defining new extensions will ensure that:
* allocation of new option numbers is coordinated from a single
authority,
* new options are reviewed for technical correctness and
appropriateness, and
* documentation for new options is complete and published.
11. Acknowledgements 11. Acknowledgements
The authors would like to thank Philip Almquist for his feedback on The authors would like to thank Philip Almquist for his feedback
this document. The comments of the DHCP Working Group are also on this document. The comments of the DHCP Working Group are
gratefully acknowledged. In particular, Mike Carney and Jon Dreyer also gratefully acknowledged. In particular, Mike Carney and
from SunSelect suggested the current format of the Vendor-specific Jon Dreyer from SunSelect suggested the current format of the
Information option. Vendor-specific Information option.
RFC 1497 is based on earlier work by Philip Prindeville, with help RFC 1497 is based on earlier work by Philip Prindeville, with
from Drew Perkins, Bill Croft, and Steve Deering. help from Drew Perkins, Bill Croft, and Steve Deering.
DRAFT DHCP Options and BOOTP Vendor Extensions April 1996
12. References 12. References
[1] Droms, R., "Dynamic Host Configuration Protocol", RFC 1531, [1] Droms, R., "Dynamic Host Configuration Protocol", RFC 1531,
Bucknell University, October 1993. Bucknell University, October 1993.
[2] Reynolds, J., "BOOTP Vendor Information Extensions", RFC 1497, [2] Reynolds, J., "BOOTP Vendor Information Extensions", RFC 1497,
USC/Information Sciences Institute, August 1993. USC/Information Sciences Institute, August 1993.
[3] Croft, W., and J. Gilmore, "Bootstrap Protocol", RFC 951, [3] Croft, W., and J. Gilmore, "Bootstrap Protocol", RFC 951,
Stanford University and Sun Microsystems, September 1985. Stanford University and Sun Microsystems, September 1985.
[4] Braden, R., Editor, "Requirements for Internet Hosts - [4] Braden, R., Editor, "Requirements for Internet Hosts -
Communication Layers", STD 3, RFC 1122, USC/Information Sciences Communication Layers", STD 3, RFC 1122, USC/Information Sciences
DRAFT DHCP Options and BOOTP Vendor Extensions November 1995
Institute, October 1989. Institute, October 1989.
[5] Mogul, J., and J. Postel, "Internet Standard Subnetting [5] Mogul, J., and J. Postel, "Internet Standard Subnetting
Procedure", STD 5, RFC 950, USC/Information Sciences Institute, Procedure", STD 5, RFC 950, USC/Information Sciences Institute,
August 1985. August 1985.
[6] Postel, J., and K. Harrenstien, "Time Protocol", STD 26, RFC [6] Postel, J., and K. Harrenstien, "Time Protocol", STD 26, RFC
868, USC/Information Sciences Institute, SRI, May 1983. 868, USC/Information Sciences Institute, SRI, May 1983.
[7] Postel, J., "Name Server", IEN 116, USC/Information Sciences [7] Postel, J., "Name Server", IEN 116, USC/Information Sciences
skipping to change at page 34, line 42 skipping to change at page 37, line 4
[12] Mogul, J. and S. Deering, "Path MTU Discovery", RFC 1191, [12] Mogul, J. and S. Deering, "Path MTU Discovery", RFC 1191,
DECWRL, Stanford University, November 1990. DECWRL, Stanford University, November 1990.
[13] Deering, S., "ICMP Router Discovery Messages", RFC 1256, [13] Deering, S., "ICMP Router Discovery Messages", RFC 1256,
Xerox PARC, September 1991. Xerox PARC, September 1991.
[14] Leffler, S. and M. Karels, "Trailer Encapsulations", RFC 893, [14] Leffler, S. and M. Karels, "Trailer Encapsulations", RFC 893,
U. C. Berkeley, April 1984. U. C. Berkeley, April 1984.
[15] Hornig, C., "Standard for the Transmission of IP Datagrams over [15] Hornig, C., "Standard for the Transmission of IP Datagrams over
DRAFT DHCP Options and BOOTP Vendor Extensions April 1996
Ethernet Networks", RFC 894, Symbolics, April 1984. Ethernet Networks", RFC 894, Symbolics, April 1984.
[16] Postel, J. and J. Reynolds, "Standard for the Transmission of [16] Postel, J. and J. Reynolds, "Standard for the Transmission of
IP Datagrams Over IEEE 802 Networks", RFC 1042, USC/Information IP Datagrams Over IEEE 802 Networks", RFC 1042, USC/Information
Sciences Institute, February 1988. Sciences Institute, February 1988.
[17] Sun Microsystems, "System and Network Administration", March [17] Sun Microsystems, "System and Network Administration", March
1990. 1990.
[18] Mills, D., "Internet Time Synchronization: The Network Time [18] Mills, D., "Internet Time Synchronization: The Network Time
Protocol", RFC 1305, UDEL, March 1992. Protocol", RFC 1305, UDEL, March 1992.
[19] NetBIOS Working Group, "Protocol Standard for a NetBIOS Service [19] NetBIOS Working Group, "Protocol Standard for a NetBIOS Service
DRAFT DHCP Options and BOOTP Vendor Extensions November 1995
on a TCP/UDP transport: Concepts and Methods", STD 19, RFC 1001, on a TCP/UDP transport: Concepts and Methods", STD 19, RFC 1001,
March 1987. March 1987.
[20] NetBIOS Working Group, "Protocol Standard for a NetBIOS Service [20] NetBIOS Working Group, "Protocol Standard for a NetBIOS Service
on a TCP/UDP transport: Detailed Specifications", STD 19, RFC on a TCP/UDP transport: Detailed Specifications", STD 19, RFC
1002, March 1987. 1002, March 1987.
[21] Scheifler, R., "FYI On the X Window System", FYI 6, RFC 1198, [21] Scheifler, R., "FYI On the X Window System", FYI 6, RFC 1198,
MIT Laboratory for Computer Science, January 1991. MIT Laboratory for Computer Science, January 1991.
[22] Reynolds, J., and J. Postel, "Assigned Numbers", STD 2, RFC 1700, [22] Reynolds, J., and J. Postel, "Assigned Numbers", STD 2, RFC 1700,
USC/Information Sciences Institute, July 1992. USC/Information Sciences Institute, July 1992.
13. Security Considerations 13. Security Considerations
Security issues are not discussed in this memo. Security issues are not discussed in this memo.
DRAFT DHCP Options and BOOTP Vendor Extensions April 1996
14. Authors' Addresses 14. Authors' Addresses
Steve Alexander Steve Alexander
Lachman Technology, Inc. Silicon Graphics, Inc.
1901 North Naper Boulevard 2011 N. Shoreline Boulevard
Naperville, IL 60563-8895 Mailstop 510
Mountain View, CA 94043-1389
Phone: (708) 505-9555 x256 Phone: (415) 933-6172
EMail: stevea@lachman.com EMail: sca@engr.sgi.com
Ralph Droms Ralph Droms
Computer Science Department Computer Science Department
323 Dana Engineering 323 Dana Engineering
Bucknell University Bucknell University
Lewisburg, PA 17837 Lewisburg, PA 17837
Phone: (717) 524-1145 Phone: (717) 524-1145
EMail: droms@bucknell.edu EMail: droms@bucknell.edu
DRAFT DHCP Options and BOOTP Vendor Extensions November 1995 DRAFT DHCP Options and BOOTP Vendor Extensions April 1996
A. Changes to draft-ietf-dhc-options-1533update-0[01].txt: A. Changes to draft-ietf-dhc-options-1533update-0[0-3].txt:
* Section 8.4 - changed to indicate vendor-specific information is * Section 8.4 - changed to indicate vendor-specific information is
interpreted based on vendor class identifier. interpreted based on vendor class identifier.
* Section 9.13 - changed "Class-identifier" to "Vendor class * Section 9.13 - changed "Class-identifier" to "Vendor class
identifier" identifier"
* Added section 9.15 describing "User class identifier" * Added section 9.15 describing "User class identifier"
* Added "Many options supply one or more 32-bit IP address. Use of IP * Added "Many options supply one or more 32-bit IP address. Use of IP
addresses rather than fully-qualified Domain Names (FQDNs) may make addresses rather than fully-qualified Domain Names (FQDNs) may make
future renumbering of IP hosts more difficult. Use of these addresses future renumbering of IP hosts more difficult. Use of these addresses
is discouraged at sites that may require renumbering." to section 2. is discouraged at sites that may require renumbering." to section 2.
* In section 3.4 (Time Offset), replaced "signed" with "two's * In section 3.4 (Time Offset), replaced "signed" with "two's
complement". complement".
* In section 2, replaced "should" with "MUST" in "Any options defined * In section 2, replaced "should" with "MUST" in "Any options defined
subsequent to this document MUST contain a length octet even if the subsequent to this document MUST contain a length octet even if the
length is fixed or zero. length is fixed or zero.
* Added sections 1.1 and 1.2 defining requirements language and DHCP
terminology used throughout the document.
* Added text to section 9.14 to emphasize the need for uniqueness
among client-identifiers:
"For correct identification of clients, each client's client-identifier
MUST be unique among the client-identifiers used on the subnet to
which the client is attached. Vendors and system administrators are
responsible for choosing client-identifiers that meet this requirement
for uniqueness."
* Modified section 10 to specify a new procedure for defining new DHCP
options.
 End of changes. 

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