Network Working Group                                           R. Droms
Request for Comments: 1534                           Bucknell University
Category: Standards Track                                   October 1993


                Interoperation Between DHCP and BOOTP

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

  DHCP provides a superset of the functions provided by BOOTP. This
  document describes the interactions between DHCP and BOOTP network
  participants.

1. Introduction

  The Dynamic Host Configuration Protocol (DHCP) provides a mechanism
  for transmitting configuration parameters to hosts using the TCP/IP
  protocol suite.  The format of DHCP messages is based on the format
  of BOOTP messages, so that, in certain circumstances, DHCP and BOOTP
  participants may exchange messages.  This document specifies the ways
  in which DHCP and BOOTP participants may interoperate.

  DHCP introduces a small change in terminology intended to clarify the
  meaning of one of the fields.  What was the "vendor extensions" field
  in BOOTP has been re-named the "options" field in DHCP.  Similarly,
  the tagged data items that were used inside the BOOTP "vendor
  extensions" field, which were formerly referred to as "vendor
  extensions", are now termed simply "options".  This document will
  refer to BOOTP vendor extensions and DHCP options uniformly as
  "options".

  Throughout this document, DHCP messages that include a 'DHCP message
  type' option will be referred to by the type of the message; e.g., a
  DHCP message with 'DHCP message type' option type 1 will be referred
  to as a "DHCPDISCOVER" message.








Droms                                                           [Page 1]

RFC 1534         Interoperation Between DHCP and BOOTP      October 1993


2. BOOTP clients and DHCP servers

  The format of DHCP messages is defined to be compatible with the
  format of BOOTP messages, so that existing BOOTP clients can
  interoperate with DHCP servers.  Any message received by a DHCP
  server that includes a 'DHCP message type' (51) option is assumed to
  have been sent by a DHCP client.  Messages without the DHCP Message
  Type option are assumed to have been sent by a BOOTP client.  Support
  of BOOTP clients by a DHCP server is optional at the discretion of
  the local system administrator.  If a DHCP server that is not
  configured to support BOOTP clients receives a BOOTREQUEST message
  from a BOOTP client, that server silently discards the BOOTREQUEST
  message.

  If a DHCP server is configured to support BOOTP clients, it may be
  configured to supply static addresses, automatic addresses or both.
  Static addresses are those that have been previously assigned by a
  system administrator and are stored in a database available to the
  DHCP server.  Automatic addresses are those selected by the DHCP
  server from its pool of unassigned addresses.

  Since BOOTP clients may not be prepared to receive automatic
  addresses, the decision to allow a DHCP server to return automatic
  addresses must be under the control of the system administrator.  If
  a DHCP server supports supplying automatic addresses to BOOTP
  clients, this feature must be configurable, and the feature must
  default off.  Enabling of the feature must be the result of an active
  decision by the system administrator.

  If a DHCP server returns a automatic address, the BOOTP client will
  not be aware of the DHCP lease mechanism for network address
  assignment.  Thus the DHCP server must assign an infinite lease
  duration to for automatic addresses assigned to BOOTP clients.  Such
  network addresses cannot be automatically reassigned by the server.
  The local system administrator may choose to manually release network
  addresses assigned to BOOTP clients.

  A DHCP server that supports BOOTP clients MUST interact with BOOTP
  clients according to the BOOTP protocol.  The server MUST formulate a
  BOOTP BOOTREPLY message rather than a DHCP DHCPOFFER message (i.e.,
  the server MUST NOT include the 'DHCP message type' option and MUST
  NOT exceed the size limit for BOOTREPLY messages).  The server marks
  a binding for a BOOTP client as BOUND after sending the BOOTP
  BOOTREPLY, as a non-DHCP client will not send a DHCPREQUEST message
  nor will that client expect a DHCPACK message.

  DHCP servers MAY send any DHCP Options to a BOOTP client as allowed
  by the "DHCP Options and BOOTP Vendor Extensions" RFC [2].



Droms                                                           [Page 2]

RFC 1534         Interoperation Between DHCP and BOOTP      October 1993


  In summary, a DHCP server:

     o MAY support BOOTP clients,

     o May return automatic addresses to BOOTP clients,

     o MUST provide a configuration switch if returning automatic
       addresses to BOOTP clients,

     o MUST default this optional configuration to OFF,

     o MUST abide by the BOOTP specification when interacting with
       BOOTP clients, and

     o MAY send DHCP options (those options defined in the DHCP options
       document but not in the BOOTP vendor extensions documents) to
       a BOOTP client.

3. DHCP clients and BOOTP servers

  A DHCP client MAY use a reply from a BOOTP server if the
  configuration returned from the BOOTP server is acceptable to the
  DHCP client.  A DHCP client MUST assume that an IP address returned
  in a message from a BOOTP server has an infinite lease.  A DHCP
  client SHOULD choose to use a reply from a DHCP server in preference
  to a reply from a BOOTP server.

4. References

  [1] Wimer, W., "Clarifications and Extensions for the Bootstrap
      Protocol", RFC 1532, Carnegie Mellon University, October 1993.

  [2] Alexander, S., and R. Droms, "DHCP Options and BOOTP Vendor
      Extensions", RFC 1533, Lachman Technology, Inc., Bucknell
      University, October 1993.

  [3] Droms, R., "Dynamic Host Configuration Protocol", RFC 1531,
      Bucknell University, October 1993.


5. Security Considerations

  Security issues are not discussed in this memo.








Droms                                                           [Page 3]

RFC 1534         Interoperation Between DHCP and BOOTP      October 1993


6. Author's Address

  Ralph Droms
  Computer Science Department
  323 Dana Engineering
  Bucknell University
  Lewisburg, PA 17837

  Phone:(717) 524-1145
  EMail: [email protected]









































Droms                                                           [Page 4]


You are viewing proxied material from gopher.fnord.one. The copyright of proxied material belongs to its original authors. Any comments or complaints in relation to proxied material should be directed to the original authors of the content concerned. Please see the disclaimer for more details.