DHCP Options and BOOTP Vendor Extensions
RFC 1533

Document Type RFC - Proposed Standard (October 1993; Errata)
Obsoleted by RFC 2132
Last updated 2014-07-09
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Network Working Group                                       S. Alexander
Request for Comments: 1533                      Lachman Technology, Inc.
Obsoletes: 1497, 1395, 1084, 1048                               R. Droms
Category: Standards Track                            Bucknell University
                                                            October 1993

               DHCP Options and BOOTP Vendor Extensions

Status of this Memo

   This RFC specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" for the standardization state and status
   of this protocol.  Distribution of this memo is unlimited.

Abstract

   The Dynamic Host Configuration Protocol (DHCP) [1] provides a
   framework for passing configuration information to hosts on a TCP/IP
   network.  Configuration parameters and other control information are
   carried in tagged data items that are stored in the "options" field
   of the DHCP message.  The data items themselves are also called
   "options."

   This document specifies the current set of DHCP options.  This
   document will be periodically updated as new options are defined.
    Each superseding document will include the entire current list of
   valid options.

   All of the vendor information extensions defined in RFC 1497 [2] may
   be used as DHCP options.  The definitions given in RFC 1497 are
   included in this document, which supersedes RFC 1497.  All of the
   DHCP options defined in this document, except for those specific to
   DHCP as defined in section 9, may be used as BOOTP vendor information
   extensions.

Table of Contents

    1.  Introduction ..............................................  2
    2.  BOOTP Extension/DHCP Option Field Format ..................  2
    3.  RFC 1497 Vendor Extensions ................................  3
    4.  IP Layer Parameters per Host .............................. 10
    5.  IP Layer Parameters per Interface ........................  13
    6.  Link Layer Parameters per Interface ....................... 16
    7.  TCP Parameters ............................................ 17
    8.  Application and Service Parameters ........................ 18

Alexander & Droms                                               [Page 1]
RFC 1533        DHCP Options and BOOTP Vendor Extensions    October 1993

    9.  DHCP Extensions ........................................... 23
   10.  Extensions ................................................ 27
   11.  Acknowledgements .......................................... 28
   12.  References ................................................ 28
   13.  Security Considerations ................................... 19
   14.  Authors' Addresses ........................................ 30

1. Introduction

   This document specifies options for use with both the Dynamic Host
   Configuration Protocol and the Bootstrap Protocol.

   The full description of DHCP packet formats may be found in the DHCP
   specification document [1], and the full description of BOOTP packet
   formats may be found in the BOOTP specification document [3].  This
   document defines the format of information in the last field of DHCP
   packets ('options') and of BOOTP packets ('vend').  The remainder of
   this section defines a generalized use of this area for giving
   information useful to a wide class of machines, operating systems and
   configurations. Sites with a single DHCP or BOOTP server that is
   shared among heterogeneous clients may choose to define other, site-
   specific formats for the use of the 'options' field.

   Section 2 of this memo describes the formats of DHCP options and
   BOOTP vendor extensions.  Section 3 describes options defined in
   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 and BOOTP. Section 9 defines options used only in DHCP.

   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
   section 9 is described in the DHCP specification [1].

   Information on registering new options is contained in section 10.

2. BOOTP Extension/DHCP Option Field Format

   DHCP options have the same format as the BOOTP "vendor extensions"
   defined in RFC 1497 [2].  Options may be fixed length or variable
   length.  All options begin with a tag octet, which uniquely
   identifies the option.  Fixed-length options without data consist of
   only a tag octet.  Only options 0 and 255 are fixed length.  All
   other options are variable-length with a length octet following the
   tag octet.  The value of the length octet does not include the two
   octets specifying the tag and length.  The length octet is followed
   by "length" octets of data.  In the case of some variable-length
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