DHC Working Group M-K. Shin INTERNET-DRAFT ETRI/NIST Expires: December 2004 H-C. Lee ETRI June 2004 IPv4 Prefix Options for DHCPv6 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 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 obsolete by other documents at anytime. 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. Abstract This document describes new options for Dynamic Host Configuration Protocol (DHCP) version 6 that provide a mechanism for the delegation of IPv4 prefixes. Through these options, a delegating router can delegate IPv4 prefixes to authorized requesting devices. 1. Introduction and Applicability This document describes new options for DHCPv6 [1] that provide a mechanism for the delegation of IPv4 prefixes. The deployment of IPv6 will require a tightly coupled use of IPv4 addresses to support both IPv6 and IPv4 connectivities within IPv6 dominant network. At that time, these options would be used by an IPv4/IPv6 dual service provider to assign an IPv4 prefix to a Customer Premise Equipment (CPE) device acting as an IPv4 router and/or dynamic address allocation server (e.g., DHCPv4) as well as an IPv6 router between the subscriber's internal network and the service provider's core network. Shin et al. Expires December 2004 [Page 1] INTERNET-DRAFT IPv4 Prefix Option for DHCPv6 June 2004 Through these options, a delegating router can delegate IPv4 prefixes to authorized requesting devices. This mechanism is intended to automate the process of informing the customer's networking equipment of the IPv4 prefixes to be used at the customer's site. In addition, DSTM (Dual Stack Transition Mechanism) server [6] or TSP (Tunnel Setup Protocol) broker/server [7] might be one of good examples requesting an IPv4 prefix to its service provider within IPv6 network. This mechanism is intended as one of dual stack requirements for DHCPv6 during the period of co-existence of IPv4 and IPv6 [5]. It is not intended as a permanent solution. 2. Terminology This document uses the terminology defined in RFC 3315 [1], RFC 2460 [2], and RFC 3633 [3]. 3. Requirements The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD, SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL, when they appear in this document, are to be interpreted as described in BCP 14, RFC 2119 [4]. 4. Identity Association for IPv4 Prefix Delegation Option The IA_PD4 option is used to carry an IPv4 prefix delegation identity association, the parameters associated with the IA_PD4 and the prefixes associated with it. The format of the IA_PD4 option is: 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_IA_PD4 | option-length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IAID (4 octets) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | T1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | T2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ . . . IA_PD4-options . . . Shin et al. Expires December 2004 [Page 2] INTERNET-DRAFT IPv4 Prefix Option for DHCPv6 June 2004 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ option-code: OPTION_IA_PD4 (TBD) option-length: 12 + length of IA_PD4-options field. IAID: The unique identifier for this IA_PD4; the IAID must be unique among the identifiers for all of this requesting router's IA_PD4s. T1: The time at which the requesting router should contact the delegating router from which the IPv4 prefixes in the IA_PD4 were obtained to extend the lifetimes of the prefixes delegated to the IA_PD4; T1 is a time duration relative to the current time expressed in units of seconds. T2: The time at which the requesting router should contact any available delegating router to extend the lifetimes of the IPv4 prefixes assigned to the IA_PD4; T2 is a time duration relative to the current time expressed in units of seconds. IA_PD4-options: Options associated with this IA_PD4. 5. IA_PD4 Prefix Option The IA_PD4 Prefix option is used to specify IPv4 address prefixes associated with an IA_PD4. The IA_PD4 Prefix option must be encapsulated in the IA_PD4-options field of an IA_PD4 option. The format of the IA_PD4 Prefix option is: 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_IAPREFIX4 | option-length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | preferred-lifetime | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | valid-lifetime | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | prefix-length | IPv4 prefix (4 octets) | |-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | (cont.) | . +-+-+-+-+-+-+-+-+ IAprefix4-options . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ option-code: OPTION_IAPREFIX4 (TBD) Shin et al. Expires December 2004 [Page 3] INTERNET-DRAFT IPv4 Prefix Option for DHCPv6 June 2004 option-length: 13 + length of IAprefix4-options field preferred-lifetime: The preferred-lifetime for the IPv4 prefix in the option, expressed in units of seconds. valid-lifetime: The valid lifetime for the IPv4 prefix in the option, expressed in units of seconds. prefix-length: Length for this IPv4 prefix in bits IPv4-prefix: An IPv4 prefix IAprefix4-options: Options associated with this IPv4 prefix 6. Appearance of This Option The apprearance of options above is exactly the same with that of IPv6 prefix delegation options for DHCPv6 [1]. An IA_PD4 option may only appear in the options area of a DHCPv6 message. A DHCPv6 message may contain multiple IA_PD4 options. The status of any operations involving this IA_PDv4 is indicated in a Status Code option in the IA_PD4-options field. The IA_PD4-options field encapsulates those options that are specific to this IA_PD4. 7. Security Considerations The options may be used by an intruder DHCP server to assign an invalid prefixes to a requesting router in a denial of service attack. To avoid this security hazard, a requesting router MUST use authenticated DHCP to confirm that it is exchanging the options with an authorized DHCP server. 8. IANA Considerations IANA is requested to assign an option code to the following options from the option-code space defined in "DHCPv6 Options" section of the DHCPv6 specification [2]. Option Name Value Described in OPTION_IA_PD4 TBD Section 4 OPTION_IAPREFIX4 TBD Section 5 Shin et al. Expires December 2004 [Page 4] INTERNET-DRAFT IPv4 Prefix Option for DHCPv6 June 2004 9. References Normative References [1] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C. and M. Carney, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)," RFC 3315, July 2003. [2] Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6) Specification," RFC 2460, December 1998. [3] Troan, O., Droms, R.,"IPv6 Prefix Options for Dynamic Host Configuration Protocol (DHCP) version 6," RFC 3633, December 2003. [4] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. Informative References [5] Chown, T., Venaas, S., Strauf, C., "IPv4 and IPv6 Dual-Stack Issues for DHCPv6," draft-ietf-dhc-dual-stack-00.txt, Work-in- Progress, March 2004. [6] Bound, J. et al., "Dual Stack Transition Mechanism," draft- bound-dstm-exp-01.txt, Work-in-Progress, April 2004. [7] Blanchet, M., "IPv6 Tunnel Broker with the Tunnel Setup Protocol (TSP)," draft-blanchet-v6ops-tunnelbroker-tsp-00.txt, Work-in-Progress, February 2004. Authors' Addresses Myung-Ki Shin ETRI/NIST 820 West Diamond Avenue Gaithersburg, MD 20899 USA Tel : +1 301 975-3613 E-mail : mshin@nist.gov Hee-Cheol Lee ETRI PEC 161 Gajong-Dong, Yusong-Gu, Daejon 305-350, Korea Phone: +82 42 860 1833 Email: hclee_shep@etri.re.kr Shin et al. Expires December 2004 [Page 5] INTERNET-DRAFT IPv4 Prefix Option for DHCPv6 June 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. Information on the IETF's procedures with respect to rights in standards-track and standards-related documentation can be found in BCP-11. Copies of claims of rights made available for publication 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 implementors or users of this specification can be obtained from the IETF Secretariat. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights which may cover technology that may be required to practice this standard. Please address the information to the IETF Executive Director. Full Copyright Statement Copyright (C) The Internet Society (2003). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assignees. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Shin et al. Expires December 2004 [Page 6] INTERNET-DRAFT IPv4 Prefix Option for DHCPv6 June 2004 Acknowledgement Funding for the RFC Editor function is currently provided by the Internet Society. Shin et al. Expires December 2004 [Page 7]