Network Working Group B. Volz
Request for Comments: 4649 Cisco Systems, Inc.
Category: Standards Track August 2006
Dynamic Host Configuration Protocol for IPv6 (DHCPv6)
Relay Agent Remote-ID Option
Status 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
in RFC 3046.
Table of Contents
1. Introduction ....................................................2
2. Requirements Terminology ........................................2
3. The Relay Agent Remote-ID Option ................................2
4. DHCPv6 Relay Agent Behavior .....................................3
5. DHCPv6 Server Behavior ..........................................3
6. Security Considerations .........................................3
7. IANA Considerations .............................................4
8. Acknowledgements ................................................4
9. References ......................................................4
9.1. Normative References .......................................4
9.2. Informative References .....................................4
Volz Standards Track [Page 1]
RFC 4649 Relay Agent Remote-ID August 2006 1. 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, and section 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. 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. [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 2006 Author's Address Bernard Volz Cisco Systems, Inc. 1414 Massachusetts Ave. Boxborough, MA 01719 USA Phone: +1 978 936 0382 EMail: volz@cisco.com Volz Standards Track [Page 5]
RFC 4649 Relay Agent Remote-ID August 2006 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. 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 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. Acknowledgement Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA). Volz Standards Track [Page 6]
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