DHC Working Group J. Littlefield Internet-Draft Cisco Systems, Inc. Expires: August 5, 2004 February 5, 2004 Vendor-Identifying Vendor Options for DHCPv4 draft-ietf-dhc-vendor-01.txt Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. 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 and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http:// www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on August 5, 2004. Copyright Notice Copyright (C) The Internet Society (2004). All Rights Reserved. Abstract The DHCP options for Vendor Class and Vendor-Specific Information can be ambiguous when a DHCP client represents multiple vendors. This document defines two new options, modeled on the IPv6 options for vendor class and vendor-specific information, which contain Enterprise Numbers to remove ambiguity. Conventions used in this document 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]. Littlefield Expires August 5, 2004 [Page 1] Internet-Draft Vendor-Identifying Vendor Options February 2004 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Multiple Instances of Options . . . . . . . . . . . . . . . . . 3 3. Vendor-Identifying Vendor Class Option . . . . . . . . . . . . . 3 4. Vendor-Identifying Vendor-Specific Information Option . . . . . 5 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 6 References . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 7 Intellectual Property and Copyright Statements . . . . . . . . . 8 Littlefield Expires August 5, 2004 [Page 2] Internet-Draft Vendor-Identifying Vendor Options February 2004 1. Introduction The DHCP protocol for IPv4 defines options to allow a client to indicate its vendor type (option 60), and to allow the DHCP client and server to exchange vendor-specific information (option 43) [3]. While there is no prohibition against passing multiple copies of these options in a single packet, doing so would introduce ambiguity of interpretation, particularly if conveying vendor-specific information for multiple vendors. The vendor identified by option 60 defines the interpretation of option 43, which itself carries no vendor identifier. There are circumstances where an implementation may need to support multiple, independently defined forms of vendor-specific information. For example, implementations that must conform to an industry- standard use of DHCPv4, to allow interoperability in a particular technology space, may be required to support the vendor-specific options of that industry group. But the same implementation may also require support for vendor-specific options defined by the manufacturer. In particular, this is an issue for vendors of devices supporting CableLabs standards, such as DOCSIS, CableHome, and PacketCable, since those standards define an industry-specific use for options 60 and 43. This document defines two new options, modeled on the IPv6 options for vendor class and vendor-specific information defined in RFC 3315 [4], which contain Enterprise Numbers to remove ambiguity. If desired, these new options can be used in addition to the current vendor class and vendor information options, whose definition is unaffected by this document. 2. Multiple Instances of Options The options defined in this document are intended to occur multiple times in a DHCP packet, as may be required. To provide support for long option values, RFC 3396 [2] requires that all multiply instanced options be contatenated into one long instance. Because of this, the format of these new vendor options includes extra length fields to allow concatenation of multiple instances, while preserving the integrity of each. Support for RFC 3396 is not widespread at the time of this writing, so implementations SHOULD attempt to format instances of these new vendor options such that they can be interpreted without concatenation, if support for RFC 3396 is in doubt. 3. Vendor-Identifying Vendor Class Option A DHCP client may use this option to unambiguously identify the Littlefield Expires August 5, 2004 [Page 3] Internet-Draft Vendor-Identifying Vendor Options February 2004 vendor that manufactured the hardware on which the client is running, or an industry consortium to which the vendor belongs. The information contained in the data area of this option is contained in one or more opaque fields that may identify details of the hardware configuration. The format of the V-I Vendor Class option is: 1 1 1 1 1 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | option-code | option-len | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | enterprise-number | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | data-len | | +-+-+-+-+-+-+-+-+ | / vendor-class-data / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ option-code OPTION_V-I VENDOR_CLASS (to be assigned by IANA) option-len 5 + length of vendor class data field enterprise-number The vendor's 32-bit Enterprise Number as registered with IANA [5]. data-len Length of vendor-class-data field vendor-class-data Details of the hardware configuration of the host on which the client is running, or of industry consortium compliance Each instance of this option contains information corresponding to one or more Enterprise Numbers. Multiple instances of this option may be present, and may be concatenated in accordance with RFC 3396. An Enterprise Number SHOULD only occur once among all instances of this option. Behavior is undefined if an Enterprise Number occurs multiple times. The information for each Enterprise Number is treated independently, regardless or whether it occurs in an option with other Enterprise Numbers, or in a separate option. The vendor-class-data is composed of a series of separate items, each of which describes some characteristic of the client's hardware configuration or capabilities. Examples of vendor-class-data instances might include the version of the operating system the client is running or the amount of memory installed on the client. Littlefield Expires August 5, 2004 [Page 4] Internet-Draft Vendor-Identifying Vendor Options February 2004 Each instance of the vendor-class-data is formatted as follows: 1 1 1 1 1 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | data-len | | +-+-+-+-+-+-+-+-+ opaque-data | / / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The data-len is one octet long and specifies the length of the opaque vendor class data in network byte order. 4. Vendor-Identifying Vendor-Specific Information Option DHCP clients and servers may use this option to exchange vendor- specific information. The format of the V-I Vendor-specific Information option is: 1 1 1 1 1 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | option-code | option-len | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | enterprise-number | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | data-len | | +-+-+-+-+-+-+-+-+ option-data | / / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ option-code OPTION_V-I VENDOR_OPTS (to be assigned by IANA) option-len 5 + length of option-data field enterprise-number The vendor's registered 32-bit Enterprise Number as registered with IANA [5]. data-len Length of option-data field option-data Vendor-specific options, described below. The definition of the information carried in this option is vendor specific. The vendor is indicated in the enterprise-number field. Each instance of this option contains information corresponding to one or more Enterprise Numbers. Multiple instances of this option Littlefield Expires August 5, 2004 [Page 5] Internet-Draft Vendor-Identifying Vendor Options February 2004 may be present, and may be concatenated in accordance with RFC 3396. An Enterprise Numbers SHOULD only occur once among all instances of this option. Behavior is undefined if an Enterprise Number occurs multiple times. The information for each Enterprise Number is treated independently, regardless or whether it occurs in an option with other Enterprise Numbers, or in a separate option. Use of vendor-specific information allows enhanced operation, utilizing additional features in a vendor's DHCP implementation. Servers not equipped to interpret the vendor-specific information sent by a client MUST ignore it. Clients that do not receive desired vendor-specific information SHOULD make an attempt to operate without it. The encapsulated vendor-specific options field MUST be encoded as a sequence of code/length/value fields of identical format to the DHCP options field. The option codes are defined by the vendor identified in the enterprise-number field and are not managed by IANA. Option codes 0 and 255 have no pre-defined interpretation or format. Each of the encapsulated options is formatted as follows: 1 1 1 1 1 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | subopt-code | subopt-len | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / sub-option-data / / / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ subopt-code The code for the encapsulated option subopt-len An unsigned integer giving the length of the option-data field in this encapsulated option in octets. sub-option-data Data area for the encapsulated option 5. IANA Considerations The values for the V-I VENDOR CLASS and V-I VENDOR OPTS option codes must be assigned from the numbering space defined for public DHCP Options in RFC 2939 [6]. 6. Security Considerations This document in and by itself provides no security, nor does it Littlefield Expires August 5, 2004 [Page 6] Internet-Draft Vendor-Identifying Vendor Options February 2004 impact existing security. DHCP provides an authentication and message integrity mechanism, as described in RFC 3118 [7], which may be used if authenticity is required for data carried by the options defined in this document. References [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [2] Lemon, T. and S. Chesire, "Encoding Long Options in the Dynamic Host Configuration Protocol (DHCPv4)", RFC 3396, November 2002. [3] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor Extensions", RFC 2132, March 1997. [4] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C. and M. Carney, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", RFC 3315, July 2003. [5] IANA, "Private Enterprise Numbers", . [6] Droms, R., "Procedures and IANA Guidelines for Definition of New DHCP Options and Message Types", BCP 43, RFC 2939, September 2000. [7] Droms, R. and W. Arbaugh, "Authentication for DHCP Message", RFC 3118, June 2001. Author's Address Josh Littlefield Cisco Systems, Inc. 1414 Massachusetts Avenue Boxborough, MA 01719 USA Phone: +1 978-936-1379 EMail: joshl@cisco.com Littlefield Expires August 5, 2004 [Page 7] Internet-Draft Vendor-Identifying Vendor Options February 2004 Intellectual Property Statement The IETF takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. 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