DHC S. Zeng Internet-Draft B. Volz Expires: October 26, 2006 K. Kinnear Cisco Systems, Inc. J. Brzozowski Comcast Cable April 24, 2006 DHCPv6 Relay Agent Echo Request Option draft-szeng-dhc-dhcpv6-ero-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 October 26, 2006. Copyright Notice Copyright (C) The Internet Society (2006). Abstract This memo defines a Relay Agent Echo Request option for the Dynamic Host Configuration Protocol for IPv6 (DHCPv6). The option allows a DHCPv6 relay agent to request a list of relay agent options that the server echoes back to the relay agent. Zeng, et al. Expires October 26, 2006 [Page 1] Internet-Draft Relay Agent ERO April 2006 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Requirements Terminology . . . . . . . . . . . . . . . . . . . 3 3. The Relay Agent Echo Request Option . . . . . . . . . . . . . . 3 4. DHCPv6 Relay Agent Behavior . . . . . . . . . . . . . . . . . . 4 5. DHCPv6 Server Behavior . . . . . . . . . . . . . . . . . . . . 4 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5 9.1. Normative References . . . . . . . . . . . . . . . . . . . 5 9.2. Informative References . . . . . . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7 Intellectual Property and Copyright Statements . . . . . . . . . . 8 Zeng, et al. Expires October 26, 2006 [Page 2] Internet-Draft Relay Agent ERO April 2006 1. Introduction DHCPv6 [1] provides a framework for configuring IPv6 clients with addresses and other network parameters. It includes a relay agent capability. A relay agent is an intermediary node that delivers DHCP messages between clients and servers. The relay agent and the server exchange information using options in relay agent messages. The relay agent may add relay agent options to the client DHCP message before forwarding it. The information that relay agents supply can be used in the server's decision making about the addresses, delegated prefixes, and configuration parameters that the client is to receive. Likewise, the relay may need some of the information to efficiently return replies to clients. In DHCPv4, the server generally echoes the relay agent option back verbatim to the relay agent in server-to-client replies [2]. However, DHCPv6 [1] does not require the server to do so. As matter of fact, for certain relay agent options, the server is required to echo back the options only if it recognizes them (e.g., [4], [5]). This could be problematic, as the relay agent may need to use some relay options even if the server does not recognize them. This memo defines a relay agent echo request option that the relay agent uses to explicitly request a list of options that the server echoes back to the relay agent. 2. Requirements 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 [3]. 3. The Relay Agent Echo Request Option The relay agent adds options in the Relay Forward message that the server uses to guide its decision making with regard to address assignment, prefix delegation, and configuration parameters. The relay agent also knows which of these options that it will need to efficiently return replies to the client. It uses the relay agent Echo Request option to inform the server the list of relay agent options that the server must echo back. Zeng, et al. Expires October 26, 2006 [Page 3] Internet-Draft Relay Agent ERO April 2006 The format of the DHCPv6 Relay Agent Echo Request option is shown below: 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_ERO | option-len | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | requested-option-code-1 | requested-option-code-2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ option-code OPTION_ERO (TBD). option-len 2 * number of requested options. requested-option-code-n The option code for an option requested by the relay agent. 4. DHCPv6 Relay Agent Behavior A relay agent MAY include an Echo Request option in a Relay Forward message to inform the server about options the relay agent wants the server to echo back to the relay agent. If the relay agent takes different actions based on whether an option is echoed back or not, then the relay agent SHOULD NOT include such an option in the Echo Request option. Note that the relay uses the OPTION_ORO [1] to request the server to return options (e.g., [6]) other than relay agent options in the Relay Forward message. 5. DHCPv6 Server Behavior A server SHOULD perform ERO processing after processing the ORO and other options processing with respect to the Relay-Reply. For each option in the ERO: a. If the option is already in the received Relay-Reply, the server MUST ignore that option and continue to process any remaining options in the ERO. b. If the option was not in the received Relay-Forward, the server MUST ignore that option and continue to process any remaing options in the ERO. Zeng, et al. Expires October 26, 2006 [Page 4] Internet-Draft Relay Agent ERO April 2006 c. Otherwise, the server MUST copy the option, verbatim, from the received Relay-Forward to the corresponding Relay-Reply, even if the server does not otherwise recognize that option. 6. Security Considerations As the Echo Request option is only exchanged between relay agents and DHCPv6 servers, [1] section 21.1, provides details on securing DHCPv6 messages sent between servers and relay agents. And, [1] section 23, provides general DHCPv6 security considerations. 7. IANA Considerations IANA is requested to assign a DHCPv6 option code for the Relay Agent Echo Request Option. 8. Acknowledgements Thanks to Ralph Droms, Josh Littlefield, Richard Johnson, and Hemant Singh for their consistent input, ideas and review during the production of this document. 9. References 9.1. 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] Patrick, M., "DHCP Relay Agent Information Option", RFC 3046, January 2001. 9.2. Informative References [3] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [4] Volz, B., "DHCPv6 Relay Agent Subscriber-ID Option", draft-ietf-dhc-dhcpv6-subid-01 (work in progress), March 2006. [5] Volz, B., "DHCPv6 Relay Agent Remote ID Option", draft-ietf-dhc-dhcpv6-remoteid-01 (work in progress), March 2006. Zeng, et al. Expires October 26, 2006 [Page 5] Internet-Draft Relay Agent ERO April 2006 [6] Droms, R., "DHCP Relay Agent Assignment Notification Option", draft-ietf-dhc-dhcpv6-agentopt-delegate-00 (work in progress), January 2006. Zeng, et al. Expires October 26, 2006 [Page 6] Internet-Draft Relay Agent ERO April 2006 Authors' Addresses Shengyou Zeng Cisco Systems, Inc. 1414 Massachusetts Ave. Boxborough, MA 01719 USA Phone: +1 978 936 1609 Email: szeng@cisco.com Bernard Volz Cisco Systems, Inc. 1414 Massachusetts Ave. Boxborough, MA 01719 USA Phone: +1 978 936 0382 Email: volz@cisco.com Kim Kinnear Cisco Systems, Inc. 1414 Massachusetts Ave. Boxborough, MA 01719 USA Phone: +1 978 936 1597 Email: kkinnear@cisco.com John Brzozowski Comcast Cable 1700 Market St. Philadelphia, PA 19103 USA Phone: +1 856 324 2671 Email: john_brzozowski@cable.comcast.com Zeng, et al. Expires October 26, 2006 [Page 7] Internet-Draft Relay Agent ERO April 2006 Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights 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; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be 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. Disclaimer of Validity This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM 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. 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. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Zeng, et al. Expires October 26, 2006 [Page 8]