1. Introduction

This section preserves the RFC text for DHCPv6, including message exchanges, relay behavior, DUIDs, IA_NA, IA_TA, IA_PD, DHCP options, RKAP authentication, IANA registries, normative requirements, and appendix option-appearance matrices.

Original RFC Text

1.  Introduction

   This document specifies DHCP for IPv6 (DHCPv6), a client/server
   protocol that provides managed configuration of devices.  The basic
   operation of DHCPv6 provides configuration for clients connected to
   the same link as the server.  Relay agent functionality is also
   defined for enabling communication between clients and servers that
   are not on the same link.

   DHCPv6 can provide a device with addresses assigned by a DHCPv6
   server and other configuration information; this data is carried in
   options.  DHCPv6 can be extended through the definition of new
   options to carry configuration information not specified in this
   document.

   DHCPv6 also supports a mechanism for automated delegation of IPv6
   prefixes.  Through this mechanism, a server can delegate prefixes to
   clients.  Use of this mechanism is specified as part of [RFC7084] and
   by [TR-187].  Note that those documents use "requesting router" and
   "delegating router" where this document uses "client" and "server",
   respectively.

   DHCP can also be used just to provide other configuration options
   (i.e., no addresses or prefixes).  That implies that the server does
   not have to track any state; thus, this mode is called "stateless
   DHCPv6".  Mechanisms necessary to support stateless DHCPv6 are much
   simpler than mechanisms needed to support stateful DHCPv6.

1.1.  Relationship to Previous DHCPv6 Standards

   [RFC8415] provided a unified, corrected, and cleaned-up definition of
   DHCPv6 that also covered all applicable errata filed against older
   RFCs at the time of its writing.  It also obsoleted a small number of
   mechanisms: delayed authentication, lifetime, and timer hints sent by
   a client.

   This document obsoletes [RFC8415].  It applies verified errata
   reports and obsoletes two features that have not been widely
   implemented - the assignment of temporary addresses using the IA_TA
   option and allowing clients to unicast some messages directly to the
   server if the server sent the Server Unicast option to a client in an
   early exchange.  It also clarifies the UDP ports used by clients,
   servers, and relay agents (Section 7.2).  See Appendix A for a list
   of differences from [RFC8415].

1.2.  Topics Out of Scope

   This document specifies DHCPv6 behavior.  The server policy, such as
   what options to assign to which clients, which subnets or pools of
   resources to use, which clients' requests should be denied, etc. are
   out of scope for this document.

   Server configuration, operation, and management are also out of
   scope.  An approach to manage DHCPv6 relays and servers is specified
   in [RFC9243].

   Merging DHCPv4 [RFC2131] and DHCPv6 configuration is out of scope for
   this document.  [RFC4477] discusses some issues and possible
   strategies for running DHCPv4 and DHCPv6 services together.  While
   [RFC4477] is a bit dated, it provides a good overview of the issues
   at hand.  The consensus of the IETF at the time of writing is that
   DHCPv4 should be used rather than DHCPv6 when conveying IPv4
   configuration information to nodes.  For IPv6-only networks,
   [RFC7341] describes a transport mechanism to carry DHCPv4 messages
   using DHCPv6 for the dynamic provisioning of IPv4 address and
   configuration information.