Dynamic Host Configuration Protocol (DHCP) Options for the Intel Preboot eXecution Environment (PXE)
RFC 4578
Document | Type | RFC - Informational (November 2006; Errata) | |
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Authors | Michael Johnston , Stig Venaas | ||
Last updated | 2020-01-21 | ||
Stream | Internet Engineering Task Force (IETF) | ||
Formats | plain text html pdf htmlized (tools) htmlized with errata bibtex | ||
Stream | WG state | (None) | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 4578 (Informational) | |
Action Holders |
(None)
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Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | Margaret Cullen | ||
Send notices to | rdroms@cisco.com |
Network Working Group M. Johnston Request for Comments: 4578 Intel Corporation Category: Informational S. Venaas, Ed. UNINETT November 2006 Dynamic Host Configuration Protocol (DHCP) Options for the Intel Preboot eXecution Environment (PXE) Status of This Memo This memo provides information for the Internet community. It does not specify an Internet standard of any kind. Distribution of this memo is unlimited. Copyright Notice Copyright (C) The IETF Trust (2006). Abstract We define Dynamic Host Configuration Protocol (DHCP) options being used by Preboot eXecution Environment (PXE) and Extensible Firmware Interface (EFI) clients to uniquely identify booting client machines and their pre-OS runtime environment so that the DHCP and/or PXE boot server can return the correct OS bootstrap image (or pre-boot application) name and server to the client. Table of Contents 1. Introduction ....................................................2 1.1. Requirements Language ......................................2 2. Option Definitions ..............................................2 2.1. Client System Architecture Type Option Definition ..........2 2.2. Client Network Interface Identifier Option Definition ......3 2.3. Client Machine Identifier Option Definition ................4 2.4. Options Requested by PXE Clients ...........................4 3. Acknowledgements ................................................5 4. IANA Considerations .............................................5 5. Security Considerations .........................................5 6. Normative References ............................................5 Johnston & Venaas Informational [Page 1] RFC 4578 DHCP PXE Options November 2006 1. Introduction These DHCP [2] options are being widely used by PXE-compliant clients to uniquely identify booting client machines themselves and their pre-OS runtime environment so that the DHCP and/or PXE boot server can return the correct OS bootstrap image (or pre-boot application) name and server to the client. In the past, this work was done by examining the network Media Access Code (MAC) address in the "chaddr" field in the BOOTP/ DHCP header and keeping a database of MAC addresses on the BOOTP/DHCP server. This was deemed insufficient for large and complex networks for two main reasons. 1) Multiple laptops could end up with the same MAC address if the network interface was in a shared docking station. 2) Multiple network devices and MAC addresses could be used by one machine for redundancy or because of repairs. Another issue that came up was the machine that could change its pre-OS runtime environment. This issue caused the creation of another new option to identify the runtime environment so that the correct binary image could be matched up with the booting machine. These options are defined by Intel in the PXE [3] and EFI [4] specifications and are being documented in this draft for completeness within the IETF. 1.1. Requirements Language 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 [1]. 2. Option Definitions There are three DHCP options [5] defined for use by PXE clients. 2.1. Client System Architecture Type Option Definition The format of the option is: Code Len 16-bit Type +----+-----+-----+-----+ | 93 | n | n1 | n2 | +----+-----+-----+-----+ Johnston & Venaas Informational [Page 2] RFC 4578 DHCP PXE Options November 2006 Octet "n" gives the number of octets containing "architecture types" (not including the code and len fields). It MUST be an even number greater than zero. Clients that support more than one architecture type MAY include a list of these types in their initial DHCP and PXE boot server packets. The list of supported architecture types MAY be reduced in any packet exchange between the client and server(s). Octets "n1" and "n2" encode a 16-bit architecture type identifier that describes the pre-boot runtime environment(s) of the client machine. As of the writing of this document, the following pre-boot architecture types have been requested. Type Architecture Name ---- ----------------- 0 Intel x86PC 1 NEC/PC98 2 EFI ItaniumShow full document text