DHCPv6 Relay Agent Echo Request Option
RFC 4994
Document | Type | RFC - Proposed Standard (September 2007; No errata) | |
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Authors | Shengyou Zeng , Bernie Volz , Kim Kinnear , John Brzozowski | ||
Last updated | 2015-10-14 | ||
Replaces | draft-szeng-dhc-dhcpv6-ero | ||
Stream | IETF | ||
Formats | plain text html pdf htmlized bibtex | ||
Reviews | |||
Stream | WG state | (None) | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 4994 (Proposed Standard) | |
Action Holders |
(None)
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Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | Jari Arkko | ||
Send notices to | (None) |
Network Working Group S. Zeng Request for Comments: 4994 B. Volz Category: Standards Track K. Kinnear Cisco Systems, Inc. J. Brzozowski Comcast Cable September 2007 DHCPv6 Relay Agent Echo Request 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. 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 ....................................................2 2. Requirements Terminology ........................................2 3. The Relay Agent Echo Request Option .............................2 4. DHCPv6 Relay Agent Behavior .....................................3 5. DHCPv6 Server Behavior ..........................................3 6. Security Considerations .........................................4 7. IANA Considerations .............................................4 8. Acknowledgements ................................................4 9. References ......................................................4 9.1. Normative References .......................................4 9.2. Informative References .....................................4 Zeng, et al. Standards Track [Page 1] RFC 4994 Relay Agent ERO September 2007 1. Introduction DHCPv6 [2] 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 [3]. However, DHCPv6 [2] does not require the server to do so. 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 [1]. 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 of the list of relay agent options that the server must echo back. Zeng, et al. Standards Track [Page 2] RFC 4994 Relay Agent ERO September 2007 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+Show full document text