ECRIT H. Schulzrinne Internet-Draft Columbia University Intended status: Standards Track J. Polk Expires:
January 9,November 30, 2008 Cisco H. Tschofenig Nokia Siemens Networks July 8, 2007May 29, 2008 A Dynamic Host Configuration Protocol (DHCP) based Location-to-Service Translation Protocol (LoST) Discovery Procedure draft-ietf-ecrit-dhc-lost-discovery-02.txtdraft-ietf-ecrit-dhc-lost-discovery-03.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 January 9,November 30, 2008. Copyright Notice Copyright (C) The 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 . . . . . . . . . . . . . . . . . . . 45 6. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 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 . . . . . . . . . . . . . . . . . . . . . . . . . . 7 10.1. Normative References . . . . . . . . . . . . . . . . . . . 7 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 finallyeventually needs to know itsdiscover the server's 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 serverserver, 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 [RFC4848]). This document specifies a DHCPv4 and a DHCPv6 option that allows LoST clients to discover local LoST servers. Section 2 provides terminology. Section 3 shows the encoding of the domain name. 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][RFC5012] 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. TheSince every 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. 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 |TBD1| n | s1 | s2 | s3 | s4 | s5 | ... +-----+-----+-----+-----+-----+-----+-----+---- Figure 1: LoST FQDN DHCPv4 Option The values s1, s2, s3, etc. represent the domain name labels in the domain name encoding. Note that the length field in the DHCPv4 option represents the length of the entire domain name encoding, whereas the length fields in the domain name encoding (see Section 3) is the length of a single domain name label. Code: OPTION_V4_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. A DHCPv4 client MAY request a LoST server domain name in an Parameter Request List option, as described in [RFC2131]. The encoding of the domain name is described in Section 3. OnlyThis option contains a single domain namedoamin name, and as such MUST be present in the DHCPv4 option.contain precisely one root label. 5. LoST Server DHCPv6 Option This documentsection defines a DHCPv6 optionsoption to carry a domain name. The DHCPv6 option has the format shown in Figure 3.2. 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_V6_LOST | option-length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LoST Server Domain Name | | ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 3:2: DHCPv6 Option for LoST Server Domain Name List option-code: OPTION_V6_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]. A DHCPv4 client MAY request a LoST server domain name in an Parameter Request List option, as described in [RFC2131].The encoding of the domain name is described in Section 3. OnlyThis option contains a single domain namedoamin name, and as such MUST be present in the DHCPv6 option.contain precisely one root label. 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+----+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ |TBD1|13 | 7 |'e'|'x'|'a'|'m'|'p'|'l'|'e'| 3 |'c'|'o'|'m'| 0 | +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---++----+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ Figure 5:3: 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_V4_LOST TBDTBD1 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_V6_LOST TBDTBD2 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].[RFC5069]. The security considerations in [RFC2131], [RFC2132] and [RFC3315] are applicable to this document. With respect to the LoST security mechanisms please refer to [I-D.ietf-ecrit-lost]. 9. Acknowledgements The authors would like to thank Andrew Newton and Leslie Daigle for their draft review. We would like to particularly thank Andrew Newtonreview and Andy for the simplifications he proposed.proposed simplifications. Mark Stapp and David W. Hankins did the document review of this documentfor the DHC working group as part of the joint working group last call. We would like to thank Vijay K. Gurbani for the Gen-ART review. Furthermore, we would like to thank Russ Housley, Tim Polk, Jari Arkko, and Christian Vogt. 10. References 10.1. Normative References [RFC1034] Mockapetris, P., "Domain names - concepts and facilities", STD 13, RFC 1034, November 1987. [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. [RFC3396] Lemon, T. and S. Cheshire, "Encoding Long Options in the Dynamic Host Configuration Protocol (DHCPv4)", RFC 3396, November 2002. 10.2. Informative References [I-D.ietf-ecrit-lost] Hardie, T., Newton, A., Schulzrinne, H., and H. Tschofenig, "LoST: A Location-to-Service Translation Protocol", draft-ietf-ecrit-lost-05draft-ietf-ecrit-lost-10 (work in progress), MarchMay 2008. [RFC4848] Daigle, L., "Domain-Based Application Service Location Using URIs and the Dynamic Delegation Discovery Service (DDDS)", RFC 4848, April 2007. [I-D.ietf-ecrit-requirements][RFC5012] Schulzrinne, H. and R. Marshall, "Requirements for Emergency Context Resolution with Internet Technologies", draft-ietf-ecrit-requirements-13 (work in progress), March 2007. [I-D.ietf-ecrit-security-threats]RFC 5012, January 2008. [RFC5069] Taylor, T., Tschofenig, H., Schulzrinne, H., and M. Shanmugam, "Security Threats and Requirements for Emergency Call Marking and Mapping", draft-ietf-ecrit-security-threats-04 (work in progress), April 2007. [RFC4848] Daigle, L., "Domain-Based Application Service Location Using URIs and the Dynamic Delegation Discovery Service (DDDS)",RFC 4848, April 2007.5069, January 2008. 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: firstname.lastname@example.org URI: http://www.cs.columbia.edu James Polk Cisco 2200 East President George Bush Turnpike Richardson, Texas 75082 US Email: email@example.com Hannes Tschofenig Nokia Siemens Networks Otto-Hahn-RingLinnoitustie 6 Munich, Bavaria 81739 GermanyEspoo 02600 Finland Phone: +49 89 636 40390+358 (50) 4871445 Email: Hannes.Tschofenig@nsn.com URI: http://www.tschofenig.comhttp://www.tschofenig.priv.at Full Copyright Statement Copyright (C) The IETF Trust (2007).(2008). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. 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