DHCP Options and BOOTP Vendor Extensions
RFC 2132

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Network Working Group                                       S. Alexander
Request for Comments: 2132                        Silicon Graphics, Inc.
Obsoletes: 1533                                                 R. Droms
Category: Standards Track                            Bucknell University
                                                              March 1997

                DHCP Options and BOOTP Vendor Extensions

Status of this memo

   This document 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" (STD 1) 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.  Future
   options will be specified in separate RFCs.  The current list of
   valid options is also available in ftp://ftp.isi.edu/in-
   notes/iana/assignments [22].

   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 ..................  4
    3.  RFC 1497 Vendor Extensions ................................  5
    4.  IP Layer Parameters per Host .............................. 11
    5.  IP Layer Parameters per Interface ........................  13
    6.  Link Layer Parameters per Interface ....................... 16
    7.  TCP Parameters ............................................ 17
    8.  Application and Service Parameters ........................ 18
    9.  DHCP Extensions ........................................... 25

Alexander & Droms           Standards Track                     [Page 1]
RFC 2132        DHCP Options and BOOTP Vendor Extensions      March 1997

   10.  Defining new extensions ................................... 31
   11.  Acknowledgements .......................................... 31
   12.  References ................................................ 32
   13.  Security Considerations ................................... 33
   14.  Authors' Addresses ........................................ 34

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.

   This document updates the definition of DHCP/BOOTP options that
   appears in RFC1533.  The classing mechanism has been extended to
   include vendor classes as described in section 8.4 and 9.13.  The new
   procedure for defining new DHCP/BOOTP options in described in section
   10.  Several new options, including NIS+ domain and servers, Mobile
   IP home agent, SMTP server, TFTP server and Bootfile server, have
   been added.  Text giving definitions used throughout the document has
   been added in section 1.1.  Text emphasizing the need for uniqueness
   of client-identifiers has been added to section 9.14.