Network Working GroupECRIT H. Schulzrinne Internet-Draft Columbia U. Intended status: Standards Track J. Polk Expires: June 13,September 21, 2007 Cisco H. Tschofenig Siemens Networks GmbH & Co KG December 10, 2006March 20, 2007 A Dynamic Host Configuration Protocol (DHCP) based Location-to-Service Translation Protocol (LoST) Discovery Procedure draft-ietf-ecrit-dhc-lost-discovery-00.txtdraft-ietf-ecrit-dhc-lost-discovery-01.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. 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 June 13,September 21, 2007. Copyright Notice Copyright (C) The Internet Society (2006).IETF Trust (2007). Abstract The Location-to-Service Translation Protocol (LoST) describes an XML- based protocol for mapping service identifiers and geospatial or civic location information to service contact Uniform Resource Locators (URLs). LoST servers can be located anywhere but a placement closer to the end host, e.g., in the access network, is desireable. Such a LoST server placement provides benefits in disaster situations with intermittent network connectivity regarding the resiliency of emergency service communication. This document describes how a LoST client can discover a LoST server using the Dynamic Host Configuration Protocol (DHCP). Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Domain Name Encoding . . . . . . . . . . . . . . . . . . . . . 3 4. LoST Server DHCPv4 Option . . . . . . . . . . . . . . . . . . . 4 5. LoST Server DHCPv6 Option . . . . . . . . . . . . . . . . . . . 4 6. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 7.1. IANA Consideration for DHCPv4 Option . . . . . . . . . . . 6 7.2. IANA Consideration for DHCPv6 Option . . . . . . . . . . . 6 8. Security Considerations . . . . . . . . . . . . . . . . . . . . 6 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 10.1. Normative References . . . . . . . . . . . . . . . . . . . 6 10.2. Informative References . . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8 Intellectual Property and Copyright Statements . . . . . . . . . . 9 1. Introduction The Location-to-Service Translation Protocol (LoST) [I-D.ietf-ecrit-lost] describes an XML-based protocol for mapping service identifiers and geospatial or civic location information to service contact Uniform Resource Locators (URLs). In order to interact with a LoST server, the LoST client finally needs to know its IP address. Several mechanisms can be used to learn this address, including manual configuration. In environments where the access network itself either deploys a LoST server or knows a third party that operates a LoST server DHCP can provide the end host with a domain name. This domain name is then used as input to the DNS-based resolution mechanism described in LoST [I-D.ietf-ecrit-lost] that reuses the URI-enabled NAPTR specification (see [I-D.daigle-unaptr]). This document specifies a DHCPv4 and a DHCPv6 option that allows LoST clients to discover local LoST servers. Section 2 provides terminology. Section 4 describes the DHCPv4 option while Section 5 describes the DHCPv6 option, with the same functionality. IANA and Security Considerations complete the document in Section 7 and Section 8. 2. Terminology In this document, the key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" are to be interpreted as described in RFC 2119 [RFC2119]. Within this document, we use terminology from [I-D.ietf-ecrit-requirements] and [I-D.ietf-ecrit-lost]. 3. Domain Name Encoding This section describes the encoding of the domain name used in the DHCPv4 option shown in Section 4 and also used in the DHCPv6 option shown in Section 5. The domain name is encoded according to Section 3.1 of RFC 1035 [RFC1035] whereby each label is represented as a one octet length field followed by that number of octets. The domain name ends with the null label of the root, a domain name is terminated by a length byte of zero. The high order two bits of every length octet must be zero, and the remaining six bits of the length field limit the label to 63 octets or less. To simplify implementations, the total length of a domain name (i.e., label octets and label length octets) is restricted to 255 octets or less. RFC 1035 [RFC1035] encoding was chosen to accommodate future internationalized domain name mechanisms.For DHCPv4 only: If the length of the domain name exceeds the maximum permissible within a single option (i.e., 254 octets), then the domain name MUST be represented in the DHCP message as specified in [RFC3396]. 4. LoST Server DHCPv4 Option The LoST server DHCPv4 option carries a DNS (RFC 1035 [RFC1035]) fully-qualified domain name to be used by the LoST client to locate a LoST server. The DHCP option for this encoding has the following format: Code Len LoST Server Domain Name +-----+-----+-----+-----+-----+-----+-----+---- | TBD | n | s1 | s2 | s3 | s4 | s5 | ... +-----+-----+-----+-----+-----+-----+-----+---- Figure 1: LoST FQDN DHCPv4 Option Code: OPTION_LOST (TBD1) Len: Length of the 'LoST Server Domain Name' field in octets; variable. LoST server Domain Name: The domain name of the LoST server for the client to use. The encoding of the domain name is described in Section 3. Only a single domain name MUST be present in the DHCPv4 option. 5. LoST Server DHCPv6 Option This document defines a DHCPv6 options to carry a domain name. The DHCPv6 option has the format shown in Figure 3. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OPTION_LOST | option-length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LoST Server Domain Name | | ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 3: DHCPv6 Option for LoST Server Domain Name List option-code: OPTION_LOST (TBD2) option-length: Length of the 'LoST Server Domain Name' field in octets; variable. LoST server Domain Name: The domain name of the LoST server for the client to use. A DHCPv6 client may request a LoST server domain name in an Options Request Option (ORO) as described in [RFC3315]. The encoding of the domain name is described in Section 3. Only a single domain name MUST be present in the DHCPv6 option. 6. Example This section shows an example of a DHCPv4 option where the DHCP server wants to offer the "example.com" domain name to the client as input to the U-NAPTR LoST discovery procedure. This domain name would be encoded as follows: +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ |TBD|13 | 7 |'e'|'x'|'a'|'m'|'p'|'l'|'e'| 3 |'c'|'o'|'m'| 0 | +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ Figure 5: Example for a LoST FQDN DHCPv4 Option 7. IANA Considerations 7.1. IANA Consideration for DHCPv4 Option The following DHCPv4 option code for the Location-to-Service Translation Protocol (LoST) server option must be assigned by IANA: Option Name Value Described in ----------------------------------------------- OPTION_LOST TBD Section 4 7.2. IANA Consideration for DHCPv6 Option IANA is requested to assign the following DHCPv6 option codes for the Location-to-Service Translation Protocol (LoST) options: Option Name Value Described in ------------------------------------------------ OPTION_LOST TBD Section 5 8. Security Considerations If an adversary manages to modify the response from a DHCP server or insert its own response, a LoST client could be led to contact a rogue LoST server under the control of the adversary or be given an invalid address. These threats are documented in [I-D.ietf-ecrit-security-threats]. The security considerations in [RFC2131], [RFC2132] and [RFC3315] are applicable to this document. 9. Acknowledgements The authors would like to thank Andrew Newton and Leslie Daigle for their draft review. We would like to particularly thank Andrew Newton for the simplifications he proposed. 10. References 10.1. Normative References [I-D.ietf-ecrit-lost] Hardie, T., "LoST: A Location-to-Service Translation Protocol", draft-ietf-ecrit-lost-02draft-ietf-ecrit-lost-05 (work in progress), October 2006.March 2007. [RFC1035] Mockapetris, P., "Domain names - implementation and specification", STD 13, RFC 1035, November 1987. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", RFC 2119, BCP 14, March 1997. [RFC2131] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131, March 1997. [RFC2132] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor Extensions", RFC 2132, March 1997. [RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and M. Carney, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", RFC 3315, July 2003. 10.2. Informative References [I-D.daigle-unaptr] Daigle, L., "Domain-based Application Service Location Using URIs and the Dynamic Delegation Discovery Service (DDDS)", draft-daigle-unaptr-01draft-daigle-unaptr-02 (work in progress), October 2006.February 2007. [I-D.ietf-ecrit-requirements] Schulzrinne, H. and R. Marshall, "Requirements for Emergency Context Resolution with Internet Technologies", draft-ietf-ecrit-requirements-12draft-ietf-ecrit-requirements-13 (work in progress), August 2006.March 2007. [I-D.ietf-ecrit-security-threats] Taylor, T., "Security Threats and Requirements for Emergency Call Marking and Mapping", draft-ietf-ecrit-security-threats-03 (work in progress), July 2006. [RFC3319] Schulzrinne, H. and B. Volz, "Dynamic Host Configuration Protocol (DHCPv6) Options for Session Initiation Protocol (SIP) Servers", RFC 3319, July 2003. [RFC3361] Schulzrinne, H., "Dynamic Host Configuration Protocol (DHCP-for-IPv4) Option for Session Initiation Protocol (SIP) Servers", RFC 3361, August 2002. [RFC3396] Lemon, T. and S. Cheshire, "Encoding Long Options in the Dynamic Host Configuration Protocol (DHCPv4)", RFC 3396, November 2002. Authors' Addresses Henning Schulzrinne Columbia University Department of Computer Science 450 Computer Science Building New York, NY 10027 US Phone: +1 212 939 7004 Email: email@example.com URI: http://www.cs.columbia.edu James Polk Cisco 2200 East President George Bush Turnpike Richardson, Texas 75082 US Email: firstname.lastname@example.org Hannes Tschofenig Siemens Networks GmbH & Co KG Otto-Hahn-Ring 6 Munich, Bavaria 81739 Germany Phone: +49 89 636 40390 Email: Hannes.Tschofenig@siemens.com URI: http://www.tschofenig.com Full Copyright Statement Copyright (C) The Internet Society (2006).IETF Trust (2007). 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