1. Introduction and Overview

The Dynamic Host Configuration Protocol for IPv6 (DHCP) enables DHCP servers to pass configuration parameters such as IPv6 network addresses to IPv6 nodes. It provides the capability for automatic allocation of reusable network addresses and additional configuration flexibility. This protocol is a stateful counterpart to "IPv6 Stateless Address Autoconfiguration" (RFC 2462), and can be used separately or together with the latter to obtain configuration parameters.

1.1. Protocols and Addressing

IPv6 nodes can use stateless address autoconfiguration to configure their IPv6 addresses. Stateless address autoconfiguration does not provide any additional configuration information to nodes, such as a list of DNS servers or a domain name. DHCPv6 provides a mechanism through which servers can provide such additional configuration information to IPv6 nodes.

DHCPv6 can be used for IPv6 configuration in several ways:

To obtain IPv6 addresses and other configuration parameters
To obtain only configuration parameters (stateless DHCPv6)
In combination with stateless address autoconfiguration

1.2. Client-server Exchanges Involving Two Messages

A client can request a server to assign one or more IPv6 addresses. The client sends a Solicit message to locate a server. Servers that can satisfy the client's request respond with an Advertise message. The client then selects one of the servers and sends a Request message to that server. The server responds with a Reply message containing the confirmed addresses and configuration parameters.

1.3. Client-server Exchanges Involving Four Messages

For efficiency and load balancing, a client can use a two-message exchange to obtain addresses and configuration parameters. The client sends a Solicit message with a Rapid Commit option. Servers that support rapid commit respond directly with a Reply message containing addresses and configuration parameters. This reduces the overhead of the four-message exchange and allows faster network configuration.