isatap adapterDo you sometimes notice an error message that says something about an ISATAP adapter in your system? This is a piece of software designed for helping companies transition from a 32-bit older Internet Protocol infrastructure address to the newer IP system of 128-bits and is called an ISATAP adapter.

This adapter will most likely never be something that users encounter. Some users with Windows Server 2008-based computers or with Windows Visa might experience errors where it looks like the adapter is a device that is not functioning in the Device Manager of Windows.

In most cases, this device can be safely disabled. Unlike a similar older protocol using multicast IPv4 called 6over4, ISATAP uses a virtual non-broadcast multiple-access network NBMA data link layer which is virtual, so it doesn’t require the underlying network infrastructure of IPv4 for multicast support.

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The Intra-Site Automatic Tunnel Addressing Protocol (ISATAP) acts as a mechanism of transition between IPv6 and IPv4. On an existing IPv4 network, it is able to transmit both packet types. In the Microsoft Vista and XP, ISATAP adapters were implemented. It was also implemented in the FreeBSD/KAME, 6WINDGate, Cisco IOS and the Linux kernel 2.6.25.

Internet Protocol Infrastructure

The IP which stands for Internet Protocol provides a standard set of rules for sending or receiving information online. The older protocol IPv4 is a system of 32-bits and is the version most widely used, but can serve only about four-point-three billion addresses. The new protocol IPv6 is an IP system with 128-bits and can provide a lot more addresses with the condition that users need to do move from the old to the new.

Neighbor Discovery

Since IPv6 is used by ISATAP as a non-broadcast/multicast capable link layer unlike Ethernet, Neighbor Discovery ICMPV6 cannot be accomplished like usual. This is what makes ISATAP somewhat complex.

It is in the IPv6 address lower order of 32-bits that the given IPv6 address is contained, making Neighbor Discovery not really necessary. However, the use of automatic Router Discovery is prevented with the lack of multicast support. Thus, hosts of ISATAP need to be configured with a PRL or a potential routers list.

Each router is probed infrequently by a Router Discovery ICMPv6 message to find out which are functional and to perform auto-configuration that is unicast-only. In actual practices, PRL is built by implementations through a DNS query, which is for example if the local domain is, they would then be looking up Typically, it is through DHCP over IPv4 that the local domain is obtained.

Address Generation of Local Links

Any host can set up a virtual IPv6 network interface is they wish to participate in ISATAP over a given network of IPv4. Determine the link-local address by prepending or attaching fe80::0000:5efe:… for private addresses or fe80::0200:5efe for unique global addresses in front of the host’s IPv4 32 bits address. For example, the link-local IPv5 address fe80::0200:5efe: would be used by the IPv4 global address

Errors in Windows

According to Microsoft, some Windows versions will suffer from problems with the device driver related to the ISATAP adapter of Microsoft. It appears that the adapter shows up in the device list of Device Manager with an exclamation mark beside its name.

The dialog properties for the device indicates error messages such as code 31: ‘Windows cannot load driver.’ This is a problem that Windows has confirmed but you are advised to ignore it by Microsoft. Speaking of Microsoft,  here is an article you might be interested in entitled Microsoft Windows 8 Network Settings.

What to Do

Many users don’t really need the functionality of the adapter. If you see a related error to the ISATAP, you should be able to simply leave it alone or disable the device safely in Device Manager. If needed, you can also get the entire IPv6 disabled in your folder of Network Connections. This will result in a more efficient system but will not let you join other networks and workgroups that rely on the system of IPv6.

Installing an ISATAP Adapter

When default or plug and play services such as the adapter ISATAP are not seen in the window that says ‘Device Manager,’ of Legacy devices, what you should do is follow the manual procedure for installation. In Windows 7, ISATAP drivers are used for tunnel-establishment through the version 4 of Internet Protocol that transports version 6 traffic when applications want to be run on a IPv6 in a network that is IPv4.

In Windows 7, you can use the utility Device Manager to begin the wizard for adding Legacy Hardware and getting your ISATAP adapter installed. By the way you might want to check out this course entitled Windows 7 Productivity Essentials that will help you learn a host of essential tips for operating Windows 7 in such a way that you will increase your productivity.

To do this, log into the Windows 7 computer using the Administrator’s password and username On the Windows 7 taskbar, click the button that says ‘Start’ and click the box ‘Search.’ Type: ‘devmgmt.msc’ in the search box without the quotation marks and hit enter. You will then see the window for Device Manager. Click the menu for ‘Action’ and click ‘Add Legacy Hardware’ in the menu that appears, before clicking the button ‘Next.’

Click the box that says ‘Install the hardware’ before clicking ‘Next.’ Begin scrolling downwards and in the leftmost pane, click the word ‘Microsoft.’ In the rightmost pane, click ‘Microsoft ISATAP Adapter’ before clicking next. Click ‘Finish’ to complete the installation.

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