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IETF RFC 2855

DHCP for IEEE 1394

Last modified on Thursday, June 8th, 2000

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Network Working Group                                        K. Fujisawa
Request for Comments: 2855                              Sony Corporation
Category: Standards Track                                    June 2000


                           DHCP for IEEE 1394

 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.

 Copyright Notice

   Copyright © The Internet Society (2000).  All Rights Reserved.

 Abstract

   IEEE Std 1394-1995 is a standard for a High Performance Serial Bus.
   Since 1394 uses a different link-layer addressing method than
   conventional IEEE802/Ethernet, the usage of some fields must be
   clarified to achieve interoperability.  This memo describes the 1394
   specific usage of some fields of DHCP messages.

1. Introduction

   IEEE Std 1394-1995 is a standard for a High Performance Serial Bus.
   IETF IP1394 Working Group specified the method to carry IPv4
   datagrams and 1394 ARP packets over an IEEE1394 network [RFC 2734].

   The Dynamic Host Configuration Protocol (DHCP) [RFC 2131] provides a
   framework for passing configuration information to hosts on a TCP/IP
   network.

   Since 1394 uses a different link-layer addressing method than
   conventional IEEE802/Ethernet, the usage of some fields must be
   clarified to achieve interoperability.  This memo describes the 1394
   specific usage of some fields of DHCP.  See [RFC 2131] for the
   mechanism of DHCP and the explanations of each field.

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED",  "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC 2119].





Fujisawa                    Standards Track                  PAGE 1 top


RFC 2855 DHCP for IEEE 1394 June 2000 2. Issues related to 1394 link address With conventional link-layer protocols, such as an Ethernet, the 'chaddr' (client hardware address) field may be used to return a reply message from a DHCP server (or relay-agent) to a client. Since a 1394 link address (node_ID) is transient and will not be consistent across the 1394 bridge, we have chosen not to put it in the 'chaddr' field. A DHCP client should request that the server sends a broadcast reply by setting the BROADCAST flag when 1394 ARP is not possible yet. Note: In general, the use of a broadcast reply is discouraged, but we consider the impact in a 1394 network as a non issue. 3. 1394 specific usage of DHCP message fields Following rules should be used when a DHCP client is connected to an IEEE1394 network. 'htype' (hardware address type) MUST be 24 [ARPPARAM]. 'hlen' (hardware address length) MUST be 0. The 'chaddr' (client hardware address) field is reserved. The sender MUST set this field to zero, and the recipient and the relay agent MUST ignore its value on receipt. A DHCP client on 1394 SHOULD set a BROADCAST flag in DHCPDISCOVER and DHCPREQUEST messages (and set 'ciaddr' to zero) to ensure that the server (or the relay agent) broadcasts its reply to the client. Note: As described in [RFC 2131], 'ciaddr' MUST be filled in with client's IP address during BOUND, RENEWING or REBINDING state, therefore, the BROADCAST flag MUST NOT be set. In these cases, the DHCP server unicasts DHCPACK message to the address in 'ciaddr'. The link address will be resolved by 1394 ARP. 'client identifier' option MUST be used in DHCP messages from the client to the server due to the lack of the 'chaddr'. 'client identifier' option may consist of any data. Because every IP over 1394 node has an EUI-64 (node unique ID), the EUI-64 makes an obvious 'client identifier'. 1394 clients SHOULD include an EUI-64 identifier in the 'client identifier' option. The type value for the EUI-64 is 27 [ARPPARAM], and the format is illustrated as follows. Fujisawa Standards Track PAGE 2 top

RFC 2855 DHCP for IEEE 1394 June 2000 Code Len Type Client-Identifier +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+ | 61 | 9 | 27 | EUI-64 (node unique ID) | +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+ Note that the use of other 'client identifier' type, such as a fully qualified domain name (FQDN), is not precluded by this memo. For more details, see "9.14. Client-identifier" in [RFC 2132]. 4. Security Considerations DHCP currently provides no authentication or security mechanisms. Potential exposures to attack are discussed in section 7 of the DHCP protocol specification [RFC 2131]. A malicious client can falsify its EUI-64 identifier, thus masquerading as another client. Acknowledgments The author appreciates the members of the Dynamic Host Configuration Working Group for their review and valuable comments. References [RFC 2734] Johansson, P., "IPv4 over IEEE 1394", RFC 2734, December 1999. [RFC 2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", RFC 2119, March 1997. [RFC 2131] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131, March 1997. [RFC 2132] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor Extensions", RFC 2132, March 1997. [ARPPARAM] http://www.iana.org/numbers.html Fujisawa Standards Track PAGE 3 top

RFC 2855 DHCP for IEEE 1394 June 2000 Author's Address Kenji Fujisawa Sony Corporation 6-7-35, Kitashinagawa, Shinagawa-ku, Tokyo, 141-0001 Japan Phone: +81-3-5448-8507 EMail: fujisawa@sm.sony.co.jp Fujisawa Standards Track PAGE 4 top

RFC 2855 DHCP for IEEE 1394 June 2000 Full Copyright Statement Copyright © The Internet Society (2000). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Acknowledgement Funding for the RFC Editor function is currently provided by the Internet Society. Fujisawa Standards Track PAGE 5 top

DHCP for IEEE 1394 RFC TOTAL SIZE: 8070 bytes PUBLICATION DATE: Thursday, June 8th, 2000 LEGAL RIGHTS: The IETF Trust (see BCP 78)


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