DHCP for Windows 2000

DHCP for IPv6

DHCP for IPv6, also known as DHCPv6, enables DHCP servers to deliver configuration parameters to IPv6 hosts. As stated earlier, IPv6 hosts by default use stateless autoconfiguration unless configured otherwise. DHCPv6 represents the stateful autoconfiguration option.

Much like DHCP in IPv4, DHCPv6 uses a client/server model. The DHCP server and the DHCP client converse with a series of messages to request, offer, and lease an IP address. Unlike DHCP in IPv4, DHCPv6 uses a combination of unicast and multicast messages for the bulk of the conversation instead of broadcast messages.

Table 12.2 shows the well-known multicast addresses that are used when DHCPv6 transmits multicast messages.

Table 12-2. Well-Known Multicast Addresses and Multicast Groups

Multicast Group Name	Multicast Address	Members
All-DHCP-Agents	FF02:0:0:0:0:0:1:2	All DHCP servers and relay agents
All-DHCP-Servers	FF05:0:0:0:0:0:1:3	All DHCP servers
All-DHCP-Relays	FF05:0:0:0:0:0:1:4	All DHCP relay agents

All DHCP messages being transmitted to a DHCP server are transmitted using UDP port 547. All DHCP messages being transmitted to a DHCP client are transmitted using UDP port 546.

The DHCPv6 Conversation

The following message types can be found in a DHCPv6 conversation. Notice the many similarities to the original DHCP message types.

01 DHCP Solicit

This message is an IP multicast message sent by a DHCP client to a DHCP server or relay agent.

02 DHCP Advertise

This message is an IP unicast message ...