RFC 2939 (rfc2939) - Page 2 of 7

Procedures and IANA Guidelines for Definition of New DHCP Options and Message Types

RFC 2939            Procedures for New DHCP Options       September 2000


   DHCP protocol messages are identified by the 'DHCP Message Type'
   option (option code 51).  Each message type is defined by the data
   value carried in the 'DHCP Message Type' option.

   This document describes the procedure for defining new DHCP options
   and message types.  The procedure will guarantee that:

   * allocation of new option numbers and message type numbers is
     coordinated from a single authority,
   * new options and message types are reviewed for technical
     correctness and appropriateness, and
   * documentation for new options and message types is complete and
     published.

   As indicated in, "Guidelines for Writing an IANA Considerations
   Section in RFCs", (see references), IANA acts as a central authority
   for assignment of numbers such as DHCP option and message type codes.
   The new procedure outlined in this document will provide guidance to
   IANA in the assignment of new option and message type codes.

   This document updates and replaces RFC 2489.

2. Overview and background

   This document specifies procedures for defining new option codes and
   message types.

2.1 New DHCP option codes

   The procedure described in this document modifies and clarifies the
   procedure for defining new options in RFC 2131 [2].  The primary
   modification is to the time at which a new DHCP option is assigned an
   option number.  In the procedure described in this document, the
   option number is not assigned until specification for the option is
   about to be published as an RFC.

   Since the publication of RFC 2132, the option number space for
   publicly defined DHCP options (1-127) has almost been exhausted.
   Many of the defined option numbers have not been followed up with
   Internet Drafts submitted to the DHC WG.  There has been a lack of
   specific guidance to IANA from the DHC WG as to the assignment of
   DHCP option numbers.

   The procedure as specified in RFC 2132 does not clearly state that
   new options are to be reviewed individually for technical
   correctness, appropriateness and complete documentation.  RFC 2132
   also does not require that new options are to be submitted to the
   IESG for review, and that the author of the option specification is



Droms                    Best Current Practice