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Network Working Group                                        K. FujisawaRequest for Comments: 2855                              Sony CorporationCategory: Standards Track                                      June 2000DHCP for IEEE 1394Status 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 (C) 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 [RFC2734].   The Dynamic Host Configuration Protocol (DHCP) [RFC2131] 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 [RFC2131] 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 inRFC 2119 [RFC2119].Fujisawa                    Standards Track                     [Page 1]

RFC 2855                   DHCP for IEEE 1394                  June 20002. 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 [RFC2131], '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]

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 [RFC2132].4. Security Considerations   DHCP currently provides no authentication or security mechanisms.   Potential exposures to attack are discussed insection 7 of the DHCP   protocol specification [RFC2131].   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   [RFC2734]  Johansson, P., "IPv4 over IEEE 1394",RFC 2734, December              1999.   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate              Requirement Levels",RFC 2119, March 1997.   [RFC2131]  Droms, R., "Dynamic Host Configuration Protocol",RFC2131, March 1997.   [RFC2132]  Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor              Extensions",RFC 2132, March 1997.   [ARPPARAM]http://www.iana.org/numbers.htmlFujisawa                    Standards Track                     [Page 3]

RFC 2855                   DHCP for IEEE 1394                  June 2000Author'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.jpFujisawa                    Standards Track                     [Page 4]

RFC 2855                   DHCP for IEEE 1394                  June 2000Full Copyright Statement   Copyright (C) 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]