DHC S. Zeng Internet-Draft B. Volz Intended status: Standards Track K. Kinnear Expires:
April 5,September 16, 2007 Cisco Systems, Inc. J. Brzozowski Comcast Cable October 02, 2006March 15, 2007 DHCPv6 Relay Agent Echo Request Option draft-ietf-dhc-dhcpv6-ero-00.txtdraft-ietf-dhc-dhcpv6-ero-01 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 April 5,September 16, 2007. Copyright Notice Copyright (C) The Internet Society (2006).IETF Trust (2007). 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. 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 . . . . . . . . . . . . . . . . . . . . . . . . 6 Intellectual Property and Copyright Statements . . . . . . . . . . 87 1. Introduction DHCPv6  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 . However, DHCPv6  does not require the server to do so. As a matter of fact, for certain relay agent options, the server is required to echo back the options only if it recognizes them (e.g., , )., ). 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. 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. 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  to request the server to return options (e.g., )) other than relay agent options in the Relay Forward message. 5. DHCPv6 Server Behavior When a server creates a Relay-Reply, it SHOULD perform ERO processing after processing the ORO and other options processing. For each option in the ERO: a. If the option is already in the 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 remaining options in the ERO. c. Otherwise, the server MUST copy the option, verbatim, from the received Relay-Forward to the 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,  section 21.1, provides details on securing DHCPv6 messages sent between servers and relay agents. And,  section 23, provides general DHCPv6 security considerations. 7. IANA Considerations IANA is requested to assign a DHCPv6 option code for the OPTION_ERO (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  Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.  Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and M. Carney, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", RFC 3315, July 2003.  Patrick, M., "DHCP Relay Agent Information Option", RFC 3046, January 2001. 9.2. Informative References  Troan, O. and R. Droms, "IPv6 Prefix Options for DynamicVolz, B., "Dynamic Host Configuration Protocol (DHCP) version 6", RFC 3633, December 2003.  Volz, B., "DHCPv6for IPv6 (DHCPv6) Relay Agent Subscriber-ID Option", draft-ietf-dhc-dhcpv6-subid-01 (work in progress), MarchRFC 4580, June 2006.  Volz, B., "DHCPv6"Dynamic Host Configuration Protocol for IPv6 (DHCPv6) Relay Agent Remote IDRemote-ID Option", draft-ietf-dhc-dhcpv6-remoteid-01 (work in progress), MarchRFC 4649, August 2006.  Droms, R., "DHCPv6 Relay Agent Assignment Notification (RAAN) Option", draft-ietf-dhc-dhcpv6-agentopt-delegate-01draft-ietf-dhc-dhcpv6-agentopt-delegate-02 (work in progress), AugustNovember 2006. Authors' Addresses Shengyou Zeng Cisco Systems, Inc. 1414 Massachusetts Ave. Boxborough, MA 01719 USA Phone: +1 978 936 0000 Email: firstname.lastname@example.org Bernard Volz Cisco Systems, Inc. 1414 Massachusetts Ave. Boxborough, MA 01719 USA Phone: +1 978 936 0000 Email: email@example.com Kim Kinnear Cisco Systems, Inc. 1414 Massachusetts Ave. Boxborough, MA 01719 USA Phone: +1 978 936 0000 Email: firstname.lastname@example.org John Jason Brzozowski Comcast Cable 1800 Bishops Gate Boulevard Mt. Laurel, NJ 08054 USA Phone: +1 856 324 2671 Email: email@example.com Full Copyright Statement Copyright (C) The Internet Society (2006).IETF Trust (2007). 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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