Link-Layer Address Assignment Mechanism for DHCPv6
RFC 8947

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Internet Engineering Task Force (IETF)                           B. Volz
Request for Comments: 8947                                         Cisco
Category: Standards Track                                   T. Mrugalski
ISSN: 2070-1721                                                      ISC
                                                           CJ. Bernardos
                                                                    UC3M
                                                           December 2020

           Link-Layer Address Assignment Mechanism for DHCPv6

Abstract

   In certain environments, e.g., large-scale virtualization
   deployments, new devices are created in an automated manner.  Such
   devices may have their link-layer addresses assigned in an automated
   fashion.  With sufficient scale, the likelihood of a collision using
   random assignment without duplication detection is not acceptable.
   Therefore, an allocation mechanism is required.  This document
   proposes an extension to DHCPv6 that allows a scalable approach to
   link-layer address assignments where preassigned link-layer address
   assignments (such as by a manufacturer) are not possible or are
   unnecessary.

Status of This Memo

   This is an Internet Standards Track document.

   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
   Internet Standards is available in Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc8947.

Copyright Notice

   Copyright (c) 2020 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
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   (https://trustee.ietf.org/license-info) in effect on the date of
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   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.

Table of Contents

   1.  Introduction
   2.  Requirements Language
   3.  Terminology
   4.  Deployment Scenarios
     4.1.  Scenario: Proxy Client Mode
     4.2.  Scenario: Direct Client Mode
   5.  Mechanism Overview
   6.  Design Assumptions
   7.  Information Encoding
   8.  Requesting Addresses
   9.  Renewing Addresses
   10. Releasing Addresses
   11. Option Definitions
     11.1.  Identity Association for Link-Layer Addresses Option
     11.2.  Link-Layer Addresses Option
   12. Selecting Link-Layer Addresses for Assignment to an IA_LL
   13. IANA Considerations
   14. Security Considerations
   15. Privacy Considerations
   16. References
     16.1.  Normative References
     16.2.  Informative References
   Appendix A.  IEEE 802c Summary
   Acknowledgments
   Authors' Addresses

1.  Introduction

   There are several deployment types that deal with a large number of
   devices that need to be initialized.  One of them is a scenario where
   virtual machines (VMs) are created on a massive scale.  Typically,
   the new VM instances are assigned a link-layer address, but random
   assignment does not scale well due to the risk of a collision (see
   Appendix A.1 of [RFC4429]).  Another use case is Internet of Things
   (IoT) devices (see [RFC7228]).  The huge number of such devices could
   strain the IEEE's available Organizationally Unique Identifier (OUI)
   global address space.  While there is typically no need to provide
   global link-layer address uniqueness for such devices, a link-layer
   assignment mechanism allows for conflicts to be avoided inside an
   administrative domain.  For those reasons, it is desired to have some
   form of mechanism that would be able to assign locally unique Media
   Access Control (MAC) addresses.

   This document proposes a new mechanism that extends DHCPv6 operation
   to handle link-layer address assignments.

   Since DHCPv6 [RFC8415] is a protocol that can allocate various types
   of resources (non-temporary addresses, temporary addresses, prefixes,
   as well as many options) and has the necessary infrastructure to
   maintain such allocations (numerous server and client
   implementations, large deployed relay infrastructure, and supportive
   solutions such as leasequery and failover), it is a good candidate to
   address the desired functionality.

   While this document presents a design that should be usable for any
   link-layer address type, some of the details are specific to IEEE 802