Abstract

    1: DHCPv6 offers the capability of automatic allocation of reusable network addresses and additional configuration flexibility.

    2: DHCPv6 is a stateful counterpart to "IPv6 SLAAC(Stateless Address Autoconfiguration)", and can be used seprately or concurrently with the latter

        to obtain configuration  parameters.

    3: 

一： Introduction and Overview

     (1) DHCPv6 can provide other configuration information, which  are carried in options.

     (2) DHCPv6 can be extended through the definition of new options to carry configuration information  not specified in this document.

    1.1. Protocols and Addressing

        (1) using UDP;

        (2) DHCP servers receive messages from clients using a reserved, link-scoped multicast address.

             A DHCP client transmits most messages to this reserved multicast address, so that this client need not to be configured with the address or

             addreses of DHCP servers.

        (3) A DHCP relay agent allows a DHCP client to send a message to a DHCP server that is not on the same link.

        (4) Once  the client  has determined the address  of a server, it may under some circumstances send messages directly to the server using unicast.

    1.2. Client-server Exchanges Involving Two Messages 

         (1) When a DHCP client does not need to have a DHCP server assign  it IP addresses, the client can obtain configuration information such as

               a list of DNS servers or NTP servers through a single message and reply exchanged with a DHCP server.

               The client first sends an Information-Request message to the ALL_DHCP_Relay_Agents_and_Servers multicast address. Server responds.

        (2)   The above message assumes that the client requires only configuration information not including IPv6 address.
    1.3. Client-server Exchanges Involving Four Messages