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Network Working Group                                            B. VolzRequest for Comments: 4649                           Cisco Systems, Inc.Category: Standards Track                                    August 2006Dynamic Host Configuration Protocol for IPv6 (DHCPv6)Relay Agent Remote-ID OptionStatus of This Memo   This document specifies an Internet standards track protocol for the   Internet community, and requests discussion and suggestions for   improvements.  Please refer to the current edition of the "Internet   Official Protocol Standards" (STD 1) for the standardization state   and status of this protocol.  Distribution of this memo is unlimited.Copyright Notice   Copyright (C) The Internet Society (2006).Abstract   This memo defines a new Relay Agent Remote-ID option for the Dynamic   Host Configuration Protocol for IPv6 (DHCPv6).  This option is the   DHCPv6 equivalent for the Dynamic Host Configuration Protocol for   IPv4 (DHCPv4) Relay Agent Option's Remote-ID suboption as specified   inRFC 3046.Table of Contents1. Introduction ....................................................22. Requirements Terminology ........................................23. The Relay Agent Remote-ID Option ................................24. DHCPv6 Relay Agent Behavior .....................................35. DHCPv6 Server Behavior ..........................................36. Security Considerations .........................................37. IANA Considerations .............................................48. Acknowledgements ................................................49. References ......................................................49.1. Normative References .......................................49.2. Informative References .....................................4Volz                        Standards Track                     [Page 1]

RFC 4649                 Relay Agent Remote-ID               August 20061.  Introduction   DHCPv6 [1] provides IP addresses and configuration information for   IPv6 clients.  It includes a relay agent capability, in which   processes within the network infrastructure receive multicast   messages from clients and relay them to DHCPv6 servers.  In some   network environments, it will be useful for the relay agent to add   information to the DHCPv6 message before relaying it.   The information that relay agents supply can also be used in the   server's decision making about the addresses, delegated prefixes [4],   and configuration parameters that the client is to receive.   The memo specifies the DHCPv6 equivalent of the DHCPv4 Relay Agent   option's Remote-ID suboption as specified in [2].  The motivation and   usage scenarios are provided in [2].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 Remote-ID Option   This option may be added by DHCPv6 relay agents that terminate   switched or permanent circuits and have mechanisms to identify the   remote host end of the circuit.   The format of the DHCPv6 Relay Agent Remote-ID 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_REMOTE_ID        |         option-len            |       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+       |                       enterprise-number                       |       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+       .                                                               .       .                           remote-id                           .       .                                                               .       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+       option-code        OPTION_REMOTE_ID (37)       option-len         4 + the length, in octets, of the remote-id                          field.  The minimum option-len is 5 octets.Volz                        Standards Track                     [Page 2]

RFC 4649                 Relay Agent Remote-ID               August 2006       enterprise-number  The vendor's registered Enterprise Number as                          registered with IANA [5].       remote-id          The opaque value for the remote-id.   The definition of the remote-id carried in this option is vendor   specific.  The vendor is indicated in the enterprise-number field.   The remote-id field may be used to encode, for instance:   o  a "caller ID" telephone number for dial-up connection   o  a "user name" prompted for by a Remote Access Server   o  a remote caller ATM address   o  a "modem ID" of a cable data modem   o  the remote IP address of a point-to-point link   o  a remote X.25 address for X.25 connections   o  an interface or port identifier   Each vendor must ensure that the remote-id is unique for its   enterprise-number, as the octet sequence of enterprise-number   followed by remote-id must be globally unique.  One way to achieve   uniqueness might be to include the relay agent's DHCP Unique   Identifier (DUID) [1] in the remote-id.4.  DHCPv6 Relay Agent Behavior   DHCPv6 relay agents may be configured to include a Remote-ID option   in relayed (RELAY-FORW) DHCPv6 messages.5.  DHCPv6 Server Behavior   This option provides additional information to the DHCPv6 server.   The DHCPv6 server, if it is configured to support this option, may   use this information to select parameters specific to particular   users, hosts, or subscriber modems.  The combined enterprise-number   and remote-id SHOULD be considered an opaque value, with policies   based on exact string match only; that is, the remote-id field SHOULD   NOT be internally parsed by the server.   There is no requirement that a server return this option and its data   in a RELAY-REPLY message.6.  Security Considerations   See [1]section 21.1, on securing DHCPv6 messages sent between   servers and relay agents, andsection 23, on general DHCPv6 security   considerations.  [2] discusses how this information can be used to   enhance trust in some environments.Volz                        Standards Track                     [Page 3]

RFC 4649                 Relay Agent Remote-ID               August 2006   Note that even if the DHCP server trusts the relay agent not to   modify information provided in this option, the confidence in that   information is no higher than the confidence that the relay agent has   in the information it puts in the option.  For example, in some   protocols it may be possible for a DHCP client to spoof or otherwise   choose port identifiers, caller ID information, or other information   carried in this option.  Sites should consider such possible spoofing   and how likely it is in their environment when deciding what uses of   this option are appropriate.7.  IANA Considerations   IANA has assigned the DHCPv6 option code 37 for the Relay Agent   Remote-ID Option.8.  Acknowledgements   Thanks to Michael Patrick for [2], from which I've liberally borrowed   text.9.  References9.1.  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.   [3]  Bradner, S., "Key words for use in RFCs to Indicate Requirement        Levels",BCP 14,RFC 2119, March 1997.9.2.  Informative References   [4]  Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic Host        Configuration Protocol (DHCP) version 6",RFC 3633, December        2003.   [5]  IANA, "Private Enterprise Numbers",        <http://www.iana.org/assignments/enterprise-numbers>.Volz                        Standards Track                     [Page 4]

RFC 4649                 Relay Agent Remote-ID               August 2006Author's Address   Bernard Volz   Cisco Systems, Inc.   1414 Massachusetts Ave.   Boxborough, MA  01719   USA   Phone: +1 978 936 0382   EMail: volz@cisco.comVolz                        Standards Track                     [Page 5]

RFC 4649                 Relay Agent Remote-ID               August 2006Full Copyright Statement   Copyright (C) The Internet Society (2006).   This document is subject to the rights, licenses and restrictions   contained inBCP 78, and except as set forth therein, the authors   retain all their rights.   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.Intellectual Property   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 inBCP 78 andBCP 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 athttp://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.Acknowledgement   Funding for the RFC Editor function is provided by the IETF   Administrative Support Activity (IASA).Volz                        Standards Track                     [Page 6]