Implement IPv6 on your Network 

IPv6 needs no introduction. It's the next upgrade to IPv4, the protocol that runs the Internet today. Eventually as all IPv4 addresses get consumed, IPv6 will come to the rescue, offering more IP addresses, better QoS, greater security and even support for more media types. IPv6 supports a 128-bit addressing scheme, and many large enterprises have already started integrating it with their existing IPv4 networks. If IPv6 will eventually take over, it's important for organizations to at least test how well it integrates with their existing network. This way they'll be ready when it comes. So in this
article, we'll create an IPv6 router on a Windows 2003 server to allow an IPv6-based network to communicate with the
IPv4-based Internet. 

The prerequisites

The setup for an IPv6 network can be seen in the diagram below. To set this up, you need the following.

• A machine running Windows 2003 Server with SP1 and having two network cards. This will be your IPv6 router.
• A DNS server running on your network, preferably on the Windows 2000/2003 Server. 
• Clients running Win XP Professional with SP2.

In our setup, we created two subnets--10.0.1.x, which will be IPv6 and 10.0.2.x, which will be IPv4. 

Install IPv6

Go to each client that's connected to the IPv6 network and install the IPv6 protocol. To do this, click on Start>Run and type in 'cmd'. Next type in the following command.

C:\> netsh interface IPv6 install

This will install the IPv6 protocol on the machine. To check this machine's IPv6 address, issue the following command:

C:\>netsh interface IPv6 show address 

This will show the IPv6 address as well as its pseudo interface. After this, you need to configure your DNS server and router.

If you think IPv4 addresses are difficult to remember, then wait till you see the IPv6 addresses. That's why setting up a DNS is even more critical for IPv6 networks. The DNS Server will map the 128-bit IPv4 addresses with a naming convention and route the request to an IPv6 machine. Set up your Windows 2003 DNS server like you usually would. Create your Primary, Forward and Reverse Look up zones. 

Configure it to 'Allow non-secure and secure dynamic updates'.

Configure router 

Go to your IPv6 router machine and run regedit.exe. From the regedit console, go to
HKEY_LOCAL_MACHINE\SYSTEM \CurrentControlSet\Services\Tcpip\Parameters and set IPEnableRouter property to 1. This will enable IPv4 routing between the two subnets. Restart the machine. Now you have to set up what's called ISATAP routing for IPv6 connectivity. ISATAP is an address assignment and automatic tunneling technology that is used to provide unicast IPv6 connectivity between IPv6-enabled hosts on an IPv4 intranet. It forwards IPv6 packets between ISATAP hosts on the IPv4 intranet. To configure ISATAP, run 'cmd' on the router. At the command prompt, issue the following commands.

Left part of the network is completely on IPv6 and the right portion is on IPv4. ISATAP router is used to establish connectivity between both

C:\>netsh interface IPv6 isatap set router 10.0.2.1

C:\>netsh interface IPv6 set interface "Automatic Tunneling Pseudo-Interface" forwarding=enabled advertise=enabled

(Here 10.0.2.1 is a segment connected to IPv4)

Now you need to add a route for the subnet IDs of the logical subnet of the IPv4 intranet to the Automatic Tunneling Pseudo-Interface (IPv6 interface) and configure it to be published. For this, issue this command.

C:\>netsh interface IPv6 add route fec0:0:0:10::/64 "Automatic Tunneling Pseudo-Interface" publish=yes

Here fec0:0:0:10::/64 is a logical subnet of IPv4. With this your ISATAP router is ready.

Configure ISATAP address on DNS server

To configure ISATAP address on a DNS Server, open DNS from Start>control panel>Administrative Tools. On the console tree select the zone name that you have created above (dns.pcql.net) and right click on it. Now from the context menu select 'New Host A'. In the New Host A text box, type ISATAP and in the IP address give the IP of the router interface, which is connected to the IPv4 portion of your network. In our case it was 10.0.2.1. Click on the 'Add Host' button to add the new host record to the zone. 

Configure clients on IPv4 segment

Lastly you need to configure the DNS settings on the clients sitting on the IPv4 portion. To do this, go to the clients and open their Network Properties and select 'TCPIP settings' and modify the configuration on the clients. Add the DNS Server address, 10.0.1.2 and the DNS suffix to dns.pcql.net and save the settings. Now renew the client configuration to recognize the ISATAP router's IPv4 address and obtain an ISATAP address with the site-local prefix of FEC0:0:0:10::/64. On the client machine, issue this command from the command prompt:

C:\>netsh interface IPv6 renew

If everything goes well, you will be able to ping the clients sitting on the IPv6 segment from the IPv4 portion of your
network. Remember to ping the IPv6 segment by their naming conventions only.

Sanjay Majumder