SIPP Working Group S. Thomson (Bellcore) INTERNET-DRAFT February 1994 SIPP Extensions to BOOTP/DHCP Status of this Memo This document is an Internet Draft. Internet Drafts are working documents of the Internet Engineering Task Force (IETF), its Areas, and its Working Groups. Note that other groups may also distribute working documents as Internet Drafts). Internet Drafts are draft documents valid for a maximum of six months. Internet Drafts may be updated, replaced, or obsoleted by other documents at any time. It is not appropriate to use Internet Drafts as reference material or to cite them other than as a "working draft" or "work in progress." Please check the I-D abstract listing contained in each Internet Draft directory to learn the current status of this or any other Internet Draft. Abstract This draft discusses the short-term extensions that need to be made to BOOTP/DHCP to enable SIPP hosts to acquire an address automatically. This draft defines a new DHCP option (also called a BOOTP vendor extension) to return a SIPP address sequence prefix. The option enables a SIPP host that is also IPv4-capable to derive an address sequence that conforms to the SIPP transition specification. 1. Introduction This draft defines a new DHCP option (also called a BOOTP vendor extension) to return a SIPP address sequence prefix. The option enables a SIPP host that is also IPv4-capable to derive an address sequence that conforms to the IPAE transition specification[SIPP- IPAE]. A host derives a SIPP address sequence by concatenating the SIPP WG, Expires July 31, 1994 [Page 1] INTERNET-DRAFT SIPP Extensions to BOOTP/DHCP February 1994 SIPP prefix to the IPv4 address. This draft extends the list of DHCP options and BOOTP vendor exten- sions in RFC 1533. The option is a host IP layer parameter. The proposed extension to BOOTP/DHCP is motivated by the need to make available to a minimal SIPP host an autoconfiguration mechanism that requires minimal changes to existing software and provides at least the same functionality that IPv4 hosts have available. The extension allows existing relay agents and clients to operate unmodified, and requires trivial changes to servers and SIPP clients. The extension enables a host to acquire a SIPP address with an embedded IPv4 address in the low-order 32 bits. If DHCP is being used, the IPv4 part of the SIPP address may be automatically assigned by the server. The SIPP prefix is statically configured in the BOOTP/DHCP server database. Note that this mechanism does not work for SIPP hosts that are not IPv4-capable. 2. SIPP Prefix Option This option specifies the prefix of a SIPP address sequence in net- work byte order. The prefix is variable-length: it is at least 4 octets long but may be longer in increments of 8 octets. The code for the SIPP prefix option is <62> pending assignment from IANA. Code Len Address Prefix +----+----+----+----+----+----+ | 62 | n | prefix / +----+----+----+----+----+----+ 3. Using BOOTP to form a SIPP address BOOTP is defined in [RFC951] and extended and clarified in [RFC1532]. On receiving a BOOTP request from a client, a BOOTP server MUST return a SIPP prefix in the appropriate option in the 'vendor exten- sions' field, if one has been configured in the BOOTP database (e.g. by the system administrator). On receiving a BOOTP reply from a server, a client appends the returned IP address in the 'yiaddr' field to the value of the 'SIPP prefix' option in the 'vend' (vendor extensions) field to form a SIPP address. SIPP WG, Expires July 31, 1994 [Page 2] INTERNET-DRAFT SIPP Extensions to BOOTP/DHCP February 1994 4. Using DHCP to form a SIPP address To retrieve a SIPP address, a DHCP client MUST request the return of the 'SIPP prefix' option whenever a DHCPDISCOVER or DHCPREQUEST mes- sage is sent. The 'SIPP prefix' option is requested by including in a DHCPDISCOVER or DHCPREQUEST message the 'parameter request list' option containing the code for the 'SIPP prefix' option. According to the DHCP specification, the server must return an option that is explicitly requested (assuming a value has been configured in the database). On receiving a DHCPACK reply from a server, a client appends the returned IP address in the 'yiaddr' field to the value of the 'SIPP prefix' option (contained in the 'option' field) to form a SIPP address. 5. Acknowledgements I would like to thank Jim Bound (DEC), Paul Francis (NTT) and Ramesh Govindan (Bellcore) for reviewing this document. 6. References [RFC951] B. Croft and J.Gilmore, "Bootstrap Protocol (BOOTP)", RFC 951, Stanford University and Sun Microsystems, September 1985. [RFC1531] R. Droms, "Dynamic Host Configuration Protocol", RFC 1531, Buck- nell University, October 1993. [RFC1532] W. Wimer, "Clarifications and Extensions for the Bootstrap Pro- tocol", RFC 1532, Carnegie Mellon University, October 1993. [RFC1533] S. Alexander and R. Droms, "DHCP Options and BOOTP Vendor Exten- sions", Lachmann Technology and Bucknell University, October 1993. SIPP WG, Expires July 31, 1994 [Page 3] INTERNET-DRAFT SIPP Extensions to BOOTP/DHCP February 1994 [SIPP-IPAE] Robert E. Gilligan, E. Nordmark, B. Hinden, "IPAE: The SIPP Interoperability and Transition Mechanism", Internet Draft, November 1993, SIPP WG, Expires July 31, 1994 [Page 4]