IPv6 Group R. Droms Internet-Draft Cisco Systems, Inc. Expires: August 24, 2006 D. Evans ARRIS International, Inc. February 20, 2006 Time Protocol Servers and Time Offset Options for IPv6 DHCP draft-ietf-dhc-dhcpv6-rfc868-servers-00.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 August 24, 2006. Copyright Notice Copyright (C) The Internet Society (2006). Abstract The Time Protocol Servers option for IPv6 DHCP (RFC 3315) carries the IPv6 addresses of servers that a host should use for the Time Protocol (RFC 868). The Time Offset option carries the offset in seconds from Coordinated Universal Time (UTC) that a client may use to determine its local time. Droms & Evans Expires August 24, 2006 [Page 1] Internet-Draft DHCPv6 Time Protocol and Offset Options February 2006 1. Introduction The Time Protocol [1] can be used to obtain the current time from a server. The Time Protocol Servers option defined in this document provides an option to provide the IPv6 addresses of Time Protocol servers to a host through DHCP [2]. The Time Offset option defined in this document provides an option to provide an offset in seconds from UTC that a client can use to determine its local time. This option is only meaningful if the server has knowledge of the physical location of the client. The options defined in this document are based on the IPv4 DHCP [3] Time Server and Time Offset options [4]. This document has no effect on IPv4 DHCP, which will continue to use the Time Server option to provide the IPv4 addresses of RFC 868 Time Protocol servers and the Time Offset option to provide the offset between UTC and local time to clients. 2. Terminology 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 RFC2119 [5]. Throughout this document, unless indicated otherwise for clarity, the acronym "DHCP" refers to "Dynamic Host Configuration Protocol for IPv6" [2]. 3. Format of the Time Protocol Servers option The Time Protocol Servers option defines a list of Time Protocol servers available to the DHCP client. The IPv6 address of each server is included in the option. The addresses SHOULD be listed in order of preference. The addresses MUST be unicast or anycast addresses. The Time Protocol Servers option has the following format: Droms & Evans Expires August 24, 2006 [Page 2] Internet-Draft DHCPv6 Time Protocol and Offset Options February 2006 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_RFC868_SERVER | option-len | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | server-address1 | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | server-address2 | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ . . . . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | server-addressN | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ option-code OPTION_RFC868_SERVERS (TBD). option-len 16 * N. server-address1-N The IPv6 addresses of the Time Protocol servers. 4. Time Offset option The Time Offset option specifies the offset in seconds from Coordinated Universal Time (UTC) that the client should use to determine its local time. The offset is expressed as a two's complement 32-bit integer. A positive offset indicates a location east of the zero meridian and a negative offset indicates a location west of the zero meridian. It is recommended that this option be used only when the concept of local time based on a 24-hour day is known to be meaningful. The Time Offset option has the following format: Droms & Evans Expires August 24, 2006 [Page 3] Internet-Draft DHCPv6 Time Protocol and Offset Options February 2006 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_TIME_OFFSET | option-len | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | time_offset | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ option-code OPTION_TIME_OFFSET (TBD). option-len 4. server-address1-N Offset in seconds from UTC. 5. Security Considerations A server could use this option to return invalid or incorrect addresses or valid addresses of malicious Time Protocol servers to the client. A server could use this option to return incorrect or inappropriate time offset values to the client. Authentication of DHCP messages [2] can be used to ensure that the contents of this option are not altered in transit between the DHCP server and client. 6. IANA Considerations IANA is requested to assign an option code from the IPv6 DHCP options registry to OPTION_RFC868_SERVER and OPTION_TIME_OFFSET. 7. Normative References [1] Postel, J. and K. Harrenstien, "Time Protocol", STD 26, RFC 868, May 1983. [2] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and M. Carney, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", RFC 3315, July 2003. [3] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131, March 1997. [4] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor Extensions", RFC 2132, March 1997. [5] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. Droms & Evans Expires August 24, 2006 [Page 4] Internet-Draft DHCPv6 Time Protocol and Offset Options February 2006 Authors' Addresses Ralph Droms Cisco Systems, Inc. 1414 Massachusetts Avenue Boxborough, MA 01719 USA Phone: +1 978.936.1674 Email: rdroms@cisco.com D. R. Evans ARRIS International, Inc. 7912 Fairview Road Boulder, CO 80303 USA Phone: +1 303.494.0394 Email: N7DR@arrisi.com Full Copyright Statement Copyright (C) The Internet Society (2006). 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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Information on the procedures with respect to rights in RFC documents can be Droms & Evans Expires August 24, 2006 [Page 5] Internet-Draft DHCPv6 Time Protocol and Offset Options February 2006 found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Droms & Evans Expires August 24, 2006 [Page 6]