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Even though I only scratched the surface of IPv6 theory in my little IPv6 tutorial, it is now time for a little IPv6 praxis. One of the first things you probably will want to do when you deploy IPv6 in your test network is to install a DHCP server to assign IPv6 addresses to client computers. Since DHCP for IPv6 works a bit differently than DHCP for IPv4, there is a new name for the protocol: DHCPv6. If you are interested in how DHCPv6 works in detail, I recommend this article. In today's post, I will just explain the minimum configuration tasks for getting a DHCP server running for IPv6 on Windows Server 2008 R2.
Configure an IPv6 address for the interface on the DHCPv6 server
By default, IPv6 is enabled on Windows Server 2008 R2. This means that the server already has a link-local IPv6 address. Link-local addresses are supposed to allow communication on the link, and DHCP is such a local service. However, if you don't manually assign a global, site-local, or unique local IPv6 address to the network interface of a Windows DHCPv6 server, it can't assign IPv6 addresses to clients.
To assign an IPv6 address, open the Network and Sharing Center on the server, click "change adapter settings," right-click the network adapter, and launch the properties page. For the purpose of this test, you can use this IPv6 address: 2001:DB8::1
Install the DHCP server role
To install a DHCP server on Windows Server 2008 R2, you have to add the DHCP server role in Server Manager by right-clicking the Roles node. After you select the DHCP server role, a wizard will guide you through the installation process. If you only want to play with DHCPv6, you don't need to configure any of the settings in the wizard. This also applies for DHCPv6-related settings about the stateful and stateless mode. Most tutorials on the web will tell you to disable stateless mode, but according to my tests this is unnecessary; I will explain this in detail in my next post.
If you already have a DHCP server running on Windows Server 2008 R2, you can skip this step. Whenever you add the DHCP server role to a Windows Server 2008 R2 machine, you automatically also install a DHCPv6 server.
Add an IPv6 scope to the DHCPv6 server
Right-click the IPv6 node in the DHCP management console and then click "New Scope." After specifying a name for the scope, you can use 2001:DB8:: as a prefix for testing purposes. You can change the Preference of the scope to 255 to make IP address assignments a bit quicker. If you have multiple DHCPv6 servers, the Preference setting tells DHCPv6 clients which server to use. Whenever a client receives an Advertise message of 255, it will immediately proceed with the DHCPv6 message exchange process.
Windows client configuration
I added this section because many tutorials on the web will tell you to disable Router Discovery and enable Managed Address Configuration or Other Stateful Configuration on Windows clients. The source of this information is probably this Microsoft KB article, which explains how to configure a Windows Vista client to obtain an IPv6 DHCP address. According to my tests, these configurations are not required on Vista SP2 and Windows 7. The only thing you have to ensure is that "Obtain IPv6 address automatically" is selected in the IPv6 properties of the client network adapter.
Obtain an IPv6 address with ipconfig
To assign an IPv6 address through DHCPv6, launch an elevated command prompt and run ipconfig /renew6. Notice that ipconfig /renew won't do the trick because the renew parameter is only for IPv4. This also applies for the release parameter. If you want to release an IPv6 address, you have to type ipconfig /release6. If you want to renew the IPv6 address only for a particular network interface, you have to specify the the name of the interface: ipconfig /renew6 "Local Area Connection".
Add scope or server options
As with DHCP for IPv4, you can assign additional parameters to Windows clients, such as DNS servers or a domain search list. These parameters can either be added for all scopes on the DHCP server or only for a particular scope.
These server options will play a crucial role in my next post, where I will explain the difference between stateless and stateful mode of a Windows Server 2008 R2 DHCPv6 server.