SIPP Working Group S. Thomson (Bellcore) INTERNET-DRAFT March 1994 Simple Internet Protocol Plus (SIPP): DHCP Options and BOOTP Vendor Extensions 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." To learn the current status of any Internet-Draft, please check the 1id-abstracts.txt listing contained in the Internet-Drafts Shadow Directories on ds.internic.net, nic.nordu.net, ftp.isi.edu, or munnari.oz.au. Abstract This draft defines new options in the Bootstrap Protocol (BOOTP) and the Dynamic Host Configuration Protocol (DHCP) to enable SIPP hosts, that are also IPv4-capable, to configure themselves automatically. The options enable a SIPP host to derive an address sequence, determine the scope of IPv4 reachability and discover the address sequences of default SIPP routers. The options are intended to be useful to SIPP hosts that conform to the SIPP transition specification, and operate in sites with minimal SIPP deployment. Terminology defined in the SIPP Routing and Addressing Specification and the DHCP Specification applies here. SIPP WG, Expires September 25, 1994 [Page 1] INTERNET-DRAFT SIPP DHCP Options March 1994 1. Introduction This draft defines new options in the Bootstrap Protocol (BOOTP)[RFC951,RFC1532] and the Dynamic Host Configuration Protocol (DHCP)[RFC1531] to enable SIPP hosts to configure themselves automatically. The changes are intended to be useful to SIPP hosts that conform to the transition specification[SIPP-IPAE], and operate in sites with minimal SIPP deployment. To use this method of autoconfiguration, a SIPP host must be capable of sending and receiving IPv4 packets. The draft defines three new DHCP options (also called BOOTP vendor extensions): the 'SIPP prefix' option, the 'IPAE IPv4 reachability mask' option and the 'SIPP Router' option. The options are used by a BOOTP/DHCP server to communicate information to a client. The SIPP prefix is used by a host to derive a SIPP address sequence. The IPAE IPv4 reachability mask is used to determine whether a destination is reachable using IPv4 from a host interface. The list of SIPP routers indicates a host's default SIPP routers. This draft updates the list of DHCP options and BOOTP vendor extensions in RFC 1533. The options defined in this document consist of a tag octet and a length octet followed by the value of the option. The length octet contains the length in octets of the option value. The values of all options are in network byte order. 2. SIPP Prefix Option This option specifies the high-order 32 bits of a SIPP identifying address, and possibly higher-order addresses as well. The code for the SIPP prefix option is <62> pending assignment from IANA. The minimum length is 4 octets. The length may be longer in increments of 8 octets. Code Len SIPP Prefix +----+----+----+----+----+----+--- | 62 | n | a1 | a2 | a3 | a4 |... +----+----+----+----+----+----+--- SIPP WG, Expires September 25, 1994 [Page 2] INTERNET-DRAFT SIPP DHCP Options March 1994 3. IPAE IPv4 Reachability Mask Option This option specifies the IPAE IPv4 reachability mask. The code for the IPv4 Reachability Mask option is <63> pending assignment from IANA. The length is 8 octets. Code Len IPAE IPv4 Reachability Mask +----+----+----+----+----+----+----+----+----+----+ | 63 | n | m1 | m2 | m3 | m4 | m5 | m6 | m7 | m8 | +----+----+----+----+----+----+----+----+----+----+ 4. SIPP Router Option This option specifies a list of address sequences of SIPP routers. The address sequences of routers SHOULD be listed in order of preference. The list contains at least one address sequence. Each address sequence is specified by its length (in octets) and the value of the address sequence itself. The low-order address in an address sequence is encoded first, followed by the next higher-order address, etc. An address sequence consists of at least one address. Each address in an address sequence is 8 octets long. The code for the SIPP Router option is <64> pending assignment from IANA. The option length MUST equal the sum of the lengths of the address sequences plus the number of length octets themselves. Code Len len1 address sequence 1 +----+----+----+----+----+----+----+----+----+----+----+----+ | 64 | n | k | a1 | a2 | a3 | a4 | a5 | a6 | a7 / / ak | +----+----+----+----+----+----+----+----+----+----+----+----+ len2 address sequence 2 +----+----+----+----+----+----+----+----+----+----+--- | m | a1 | a2 | a3 | a4 | a5 | a6 | a7 / / am | ... +----+----+----+----+----+----+----+----+----+----+--- SIPP WG, Expires September 25, 1994 [Page 3] INTERNET-DRAFT SIPP DHCP Options March 1994 5. Using BOOTP to acquire SIPP configuration information On receiving a BOOTP request from a client, a BOOTP server MUST return the above options in the 'vendor extensions' field, if the option has been configured in the BOOTP database (e.g. by the system administrator). A BOOTP server SHOULD also return the IPv4 subnet mask ('subnet mask' option) and the IPv4 list of default routers ('router' option)[RFC1533], if present in the database. On receiving a BOOTP reply from a server, a client appends the 32-bit (IPv4) address returned in the 'yiaddr' field to the value of the 'SIPP prefix' option in the 'vend' (vendor extensions) field to form a SIPP address sequence. 6. Using DHCP to acquire SIPP configuration information To retrieve the above options or any other option of interest, a DHCP client MUST request the return of this information when a DHCPDISCOVER or DHCPREQUEST message is sent. These options are requested by including in a DHCPDISCOVER or DHCPREQUEST message the 'parameter request list' option containing the appropriate option codes. According to the DHCP specification, the server must return an option that is explicitly requested (assuming a value has been configured in the database). In particular, to acquire a SIPP address sequence, a DHCP client MUST request the return of the 'SIPP prefix' option in a DHCPDISCOVER and DHCPREQUEST message. On receiving a DHCPACK reply from a server, a client appends the 32-bit (IPv4) address returned in the 'yiaddr' field to the value of the 'SIPP prefix' option (contained in the 'option' field) to form a SIPP address sequence. 7. Acknowledgements I would like to thank Jim Bound (DEC), Paul Francis (NTT) and Ramesh Govindan (Bellcore) for reviewing versions of this document. SIPP WG, Expires September 25, 1994 [Page 4] INTERNET-DRAFT SIPP DHCP Options March 1994 8. 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, Bucknell University, October 1993. [RFC1532] W. Wimer, "Clarifications and Extensions for the Bootstrap Protocol", RFC 1532, Carnegie Mellon University, October 1993. [RFC1533] S. Alexander and R. Droms, "DHCP Options and BOOTP Vendor Extensions", Lachmann Technology and Bucknell University, October 1993. [SIPP-ROAD] S.Deering, P. Francis and R. Govindan, "Simple Internet Protocol Plus (SIPP): Routing and Addressing", Internet Draft, February 1994, . [SIPP-IPAE] Robert E. Gilligan, E. Nordmark, B. Hinden, "IPAE: The SIPP Interoperability and Transition Mechanism", Internet Draft, March 1994, Author's Address Susan Thomson Bellcore MRE 2P-343, 445 South Street, Morristown, NJ 07960 phone: (201) 829-4514 email: set@thumper.bellcore.com SIPP WG, Expires September 25, 1994 [Page 5] INTERNET-DRAFT SIPP DHCP Options March 1994 SIPP WG, Expires September 25, 1994 [Page 6]