Forward-looking organizations are beginning to evaluate the benefits of moving to the next version of TCP/IP—IPv6, which, among other benefits, eliminates the need for the patchwork of fixes, such as Network Address Translation, that has invaded many a networked environment over the past few years.

It is necessary to rework many TCP/IP stacks and applications to take advantage of the new architecture and features. You’re in luck if you’re running Windows XP because it’s in the beginning stages of making use of IPv6. I’ll show you how to enable IPv6 under XP and give you some tips on what to look out for. I’ve also created an IPv6 command list that is available as a download.

Not quite ready for prime time
IPv6 is not recommended for production use yet. While IPv6 functionality is present in Windows XP, it’s definitely not as well supported as IPv4, the current version of TCP/IP. This lack of functionality is evident because even the earliest stages of enabling IPv6 support in the new OS are difficult to configure. For instance, everything related to IPv6 is performed at the command line. Also, none of the current GUI utilities present in XP will show you any IPv6 information, even when it is enabled and you’re actively using it.

Installing and verifying the stack
As a separate service to Windows XP, you must install IPv6 before you can use it. This installation can only be performed while you’re logged on as an administrative user. In my examples, I’ll always be logged in as Administrator.

To install IPv6, start a command prompt session and type the following:
Ipv6 install

You’ll be greeted with a very simple message: “Installing…,” followed by “Succeeded.”

Once IPv6 is installed, make sure that the stack is actually up and operational with the command below, which will give you a list of the IPv6 interfaces present on your system:
Ipv6 if

Windows’ response to this command is quite lengthy, as shown in Table A.
Table A

C:\Documents and Settings\Administrator>ipv6 if
Interface 4: Ethernet: Local Area Connection
    uses Neighbor Discovery
    uses Router Discovery
    link-layer address: 00-50-56-40-4c-ee
        preferred link-local fe80::250:56ff:fe40:4cee, life infinite
        multicast interface-local ff01::1, 1 refs, not reportable
        multicast link-local ff02::1, 1 refs, not reportable
        multicast link-local ff02::1:ff40:4cee, 1 refs, last reporter
    link MTU 1500 (true link MTU 1500)
    current hop limit 128
    reachable time 21000ms (base 30000ms)
    retransmission interval 1000ms
    DAD transmits 1
Interface 3: 6to4 Tunneling Pseudo-Interface
    does not use Neighbor Discovery
    does not use Router Discovery
    link MTU 1280 (true link MTU 65515)
    current hop limit 128
    reachable time 16500ms (base 30000ms)
    retransmission interval 1000ms
    DAD transmits 0
Interface 2: Automatic Tunneling Pseudo-Interface
    does not use Neighbor Discovery
    does not use Router Discovery
    router link-layer address:
    EUI-64 embedded IPv4 address:
        preferred link-local fe80::5efe:, life infinite
    link MTU 1280 (true link MTU 65515)
    current hop limit 128
    reachable time 27500ms (base 30000ms)
    retransmission interval 1000ms
    DAD transmits 0
Interface 1: Loopback Pseudo-Interface
    does not use Neighbor Discovery
    does not use Router Discovery
    link-layer address:
        preferred link-local ::1, life infinite
        preferred link-local fe80::1, life infinite
    link MTU 1500 (true link MTU 4294967295)
    current hop limit 128
    reachable time 35500ms (base 30000ms)
    retransmission interval 1000ms
    DAD transmits 0

The IPv6 interface list

As you can see, this is a very different list of interfaces from those you get when you work with IPv4. For this example, I have a total of four IPv6 interfaces present in my Windows XP test system (Table B). The first three interfaces should be the same in most of the systems that you use. Interfaces four and up vary from system to system, depending on the hardware in use.
Table B

Interface number


1 Loopback Pseudo-Interface If you have used the IPv4 address to test network connectivity, you already know what this interface is used for. This interface provides an IPv6 loopback interface with the address ::1 or fe80::1
2 Automatic Tunneling Pseudo-Interface As its name implies, this is an interface used for automatic tunneling.
3 6to4 Tunneling Pseudo-Interface This interface provides an IPv6 to IPv4 tunnel.
4 Network adapters Interfaces four and up are created on the fly and are dependent on the hardware that exists in the workstation.

Windows XP IPv6 interface explanation

As a second step in making sure that your Windows XP machine’s IPv6 stack is operational, you can use the ping command, aptly named ping6 for IPv6. To ping the loopback interface in IPv4, you used the command ping because that was the address of the loopback interface on your machine. For IPv6, you can use either of the following commands; the results are shown in Table C.
ping6 ::1
ping6 fe80::1

Table C

C:\Documents and Settings\Administrator>ping6 ::1

Pinging ::1
from ::1 with 32 bytes of data:

Reply from ::1: bytes=32 time=4ms
Reply from ::1: bytes=32 time<1ms
Reply from ::1: bytes=32 time<1ms
Reply from ::1: bytes=32 time<1ms

Ping statistics for ::1:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 0ms, Maximum = 4ms, Average = 1ms

Statistics using IPv6 to ping the loopback interface

Using the IPv6 commands
As described in the accompanying download, the Windows XP IPv6 command provides significant functionality for installing and using IPv6 in XP. In addition to this command, XP provides ping6 and tracert6, which perform the same functions as their IPv4 counterparts. Also, XP’s telnet and FTP clients work with IPv6 addresses.

When to expect the full version
Current IPv6 functionality is still in the dark ages with its command-line-only interface. Microsoft is slated to release Windows XP Service Pack 1 on August 14, 2002. One of the significant changes will be in the area of IPv6. With XP SP1, Microsoft will release a fully supported, fully GUI-integrated version of IPv6. With this much backing from Microsoft, you can be sure IPv6 will slowly begin to supplant IPv4 as organizations acquire hardware and software that can support it.