DHCPv6 Stateful Message Exchange

A DHCPv6 stateful message exchange to obtain both IPv6 addresses and configuration settings—when both M and O flags in a received router advertisement are set to 1—typically consists of the following messages:

1.A Solicit message sent by the client to locate the servers.

2.An Advertise message sent by a server to indicate that it can provide addresses and configuration settings.

3.A Request message sent by the client to request addresses and configuration settings from a specific server.

4.A Reply message sent by the requested server that contains addresses and configuration settings.

For an example of a DHCPv6 stateful message exchange, see Network Monitor capture 08_02 in the \NetworkMonitorCaptures folder on the companion CD-ROM.

If there is a relay agent between the client and the server, the relay agent sends the server Relay-Forward messages containing the encapsulated Solicit and Request messages from the client. The server sends the relay agent Relay-Reply messages containing the encapsulated Advertise and Reply messages for the client.

DHCPv6 Stateless Message Exchange

A DHCPv6 stateless message exchange to obtain only configuration settings—when the M flag is set to 0 and the O flag is set to 1 in a received router advertisement—typically consists of the following messages:

1.An Information-Request message sent by the client to request configuration settings from a server.

2.A Reply message sent by a server that contains the requested configuration settings.

For an IPv6 network that has routers configured to assign stateless address prefixes to IPv6 hosts, the two-message DHCPv6 exchange can be used to assign DNS servers, DNS domain names, and other configuration settings that are not included in the router advertisement message.

For an example of a DHCPv6 stateless message exchange, see Network Monitor capture 08_03 in the \NetworkMonitorCaptures folder on the companion CD-ROM.

DHCPv6 Support in Windows

DHCPv6 support in Windows Server 2008 and Windows Vista includes the following:

■ DHCPv6 client

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■DHCPv6 relay agent

■DHCPv6 stateless and stateful server

DHCPv6 Client

Windows Server 2008 and Windows Vista include a DHCPv6 client. The DHCPv6 client attempts DHCPv6-based configuration based on the values of the M and O flags in received Router Advertisement messages. Therefore, to use DHCPv6, you must configure DHCPv6 servers and relay agents to service each IPv6 subnet and then configure your advertising IPv6 routers to set these two flags to their appropriate values. If there are multiple advertising routers for a given subnet, they should be configured to advertise the same stateless address prefixes and values of the M and O flags. IPv6 hosts running Windows XP or Windows Server 2003 do not include a DHCPv6 client and ignore the values of the M and O flags in received router advertisements.

DHCPv6 Relay Agent

Windows Server 2008 supports a DCHPv6 relay agent as a component of Routing and Remote Access. To install and configure the DHCPv6 relay agent component, do the following:

1.Use the Server Manager administrative tool to add the Routing and Remote Access Services role service of the Network Policy and Access Services role.

2.Click Start, point to Administrative Tools, and then click Routing and Remote Access.

3.If needed, run the Routing And Remote Access Server Setup Wizard to perform the initial setup of Routing And Remote Access. In the console tree of the Routing and Remote Access snap-in, right-click the server name, and then click Configure And Enable Routing And Remote Access.

4.On the Welcome To The Routing And Remote Access Server Setup Wizard page, click Next. On the Configuration page, click Custom Configuration, and then click Next. On the Custom Configuration page, click LAN Routing, and then click Next. On the Completing The Routing And Remote Access Server Setup Wizard page, click Finish.

5.In the console tree of the Routing And Remote Access snap-in, expand the IPv6 node.

6.Right-click General, and then click New Routing Protocol. In the New Routing Protocol dialog box, click DHCPv6 Relay Agent and then click OK.

7.In the console tree of the Routing And Remote Access snap-in, right-click DHCPv6 Relay Agent, and then click Interface. In the New Interface For DHCPv6 Relay Agent dialog box, click the interface on which the Routing and Remote Access server will be listening for DHCPv6 messages sent by DHCPv6 clients, and then click OK. Modify settings on the DHCPv6 Relay Properties dialog box as needed, and then click OK. Repeat this step for all the appropriate interfaces of the Routing and Remote Access server.

8.In the console tree of the Routing And Remote Access snap-in, right-click DHCPv6 Relay Agent, and then click Properties. In the DHCPv6 Relay Agent Properties dialog box, click the Servers tab. Figure 8-7 shows an example.

Figure 8-7 The DHCPv6 Relay Agent Properties dialog box

9.Type the non-link-local address of a DHCPv6 server on your network, and then click Add. Repeat this step as needed for additional DHCPv6 servers.

10.Click OK.

DHCPv6 Stateless and Stateful Server

The DHCP Server service in Windows Server 2008 supports DHCPv6 stateful and stateless configuration as a DHCPv6 server.

To configure DHCPv6 options for DHCPv6 stateless operation with the DHCP Server service, do the following:

1.Use the Server Manager administrative tool to add the DHCP Server role.

2.Click Start, point to Administrative Tools, and then click DHCP.

3.In the console tree of the DHCP snap-in, right-click DHCP, and then click Add Server. In the Add Server dialog box, click This Authorized DHCP Server, click the name of the server, and then click OK.

4.In the console tree of the DHCP snap-in, expand the IPv6 node.

5.Right-click Server Options, and then click Configure Options.

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6.On the General tab, enable the appropriate DHCPv6 options and configure their settings as needed. Typical options for DHCPv6 stateless include option 23 (DNS Recursive Name Server IPv6 Address List) and option 24 (Domain Search List), as defined in RFC 3646.

7.Click OK.

To configure DHCPv6 scopes and options for DHCPv6 stateful operation with the DHCP Server service, do the following:

1.In the console tree of the DHCP snap-in, expand the IPv6 node.

2.To configure IPv6 configuration settings that apply to all IPv6 scopes, right-click Server Options, and then click Configure Options.

3.On the General tab, enable the appropriate DHCPv6 options and configure their settings as needed.

4.To create an IPv6 scope, right-click IPv6, and then click New Scope.

5.On the Welcome To The New Scope Wizard page of the New Scope Wizard, click Next.

6.On the Scope Name page, type the name and description of the scope and then click Next.

7.On the Scope Prefix page, type the subnet prefix for the scope. For example, type 2001:db8:23aa:1414:: for the 2001:db8:23aa:1414::/64 subnet prefix. Specify a preference value if needed. Figure 8-8 shows an example.

Figure 8-8 The Scope Prefix page

8.Click Next. On the Add Exclusions page, type the list of starting and ending interface IDs to exclude from the range as needed. Click Next.