Internet Engineering Task Force (IETF) D. Hankins Request for Comments: 7227 Google BCP: 187 T. Mrugalski Updates: 3315 M. Siodelski Category: Best Current Practice ISC ISSN: 2070-1721 S. Jiang Huawei Technologies Co., Ltd. S. Krishnan Ericsson May 2014Guidelines for Creating New DHCPv6 Options
Abstract This document provides guidance to prospective DHCPv6 option developers to help them create option formats that are easily adoptable by existing DHCPv6 software. It also provides guidelines for expert reviewers to evaluate new registrations. This document updates RFC 3315. Status of This Memo This memo documents an Internet Best Current Practice. This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on BCPs is available in Section 2 of RFC 5741. Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc7227. Hankins, et al. Best Current Practice [Page 1]
RFC 7227 DHCPv6 Option Guidelines May 2014 Copyright Notice Copyright (c) 2014 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Hankins, et al. Best Current Practice [Page 2]
RFC 7227 DHCPv6 Option Guidelines May 2014 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Requirements Language . . . . . . . . . . . . . . . . . . . . 5 3. When to Use DHCPv6 . . . . . . . . . . . . . . . . . . . . . 5 4. General Principles . . . . . . . . . . . . . . . . . . . . . 5 5. Reusing Other Option Formats . . . . . . . . . . . . . . . . 6 5.1. Option with IPv6 Addresses . . . . . . . . . . . . . . . 7 5.2. Option with Single Flag (Boolean) . . . . . . . . . . . . 8 5.3. Option with IPv6 Prefix . . . . . . . . . . . . . . . . . 9 5.4. Option with 32-bit Integer Value . . . . . . . . . . . . 10 5.5. Option with 16-bit Integer Value . . . . . . . . . . . . 10 5.6. Option with 8-bit Integer Value . . . . . . . . . . . . . 11 5.7. Option with URI . . . . . . . . . . . . . . . . . . . . . 11 5.8. Option with Text String . . . . . . . . . . . . . . . . . 12 5.9. Option with Variable-Length Data . . . . . . . . . . . . 13 5.10. Option with DNS Wire Format Domain Name List . . . . . . 14 6. Avoid Conditional Formatting . . . . . . . . . . . . . . . . 15 7. Avoid Aliasing . . . . . . . . . . . . . . . . . . . . . . . 15 8. Choosing between an FQDN and an Address . . . . . . . . . . . 16 9. Encapsulated Options in DHCPv6 . . . . . . . . . . . . . . . 19 10. Additional States Considered Harmful . . . . . . . . . . . . 20 11. Configuration Changes Occur at Fixed Times . . . . . . . . . 21 12. Multiple Provisioning Domains . . . . . . . . . . . . . . . . 21 13. Chartering Requirements and Advice for Responsible Area Directors . . . . . . . . . . . . . . . . . . . . . . . . . . 22 14. Considerations for Creating New Formats . . . . . . . . . . . 23 15. Option Size . . . . . . . . . . . . . . . . . . . . . . . . . 23 16. Singleton Options . . . . . . . . . . . . . . . . . . . . . . 24 17. Option Order . . . . . . . . . . . . . . . . . . . . . . . . 25 18. Relay Options . . . . . . . . . . . . . . . . . . . . . . . . 25 19. Clients Request Their Options . . . . . . . . . . . . . . . . 26 20. Transition Technologies . . . . . . . . . . . . . . . . . . . 26 21. Recommended Sections in the New Document . . . . . . . . . . 27 21.1. DHCPv6 Client Behavior Text . . . . . . . . . . . . . . 28 21.2. DHCPv6 Server Behavior Text . . . . . . . . . . . . . . 28 21.3. DHCPv6 Relay Agent Behavior Text . . . . . . . . . . . . 29 22. Should the New Document Update Existing RFCs? . . . . . . . . 29 23. Security Considerations . . . . . . . . . . . . . . . . . . . 29 24. Privacy Considerations . . . . . . . . . . . . . . . . . . . 31 25. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 31 26. References . . . . . . . . . . . . . . . . . . . . . . . . . 31 26.1. Normative References . . . . . . . . . . . . . . . . . . 31 26.2. Informative References . . . . . . . . . . . . . . . . . 32 Hankins, et al. Best Current Practice [Page 3]