Microsoft KB Archive/309640

= Creating a Bridge with Two Internal Adapters on a Windows XP Internet Connection Sharing Host Does Not Work =

Article ID: 309640

Article Last Modified on 8/4/2002

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APPLIES TO


 * Microsoft Windows XP Professional
 * Microsoft Windows XP Home Edition

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This article was previously published under Q309640



SYMPTOMS
When you attempt to create a bridge by using two adapters on a Windows XP-based Internet Connection Sharing (ICS) host, the following error message may be displayed:

An unexpected error occurred while configuring the Network Bridge

This behavior occurs if all of the following conditions exist:
 * The computer has at least three network connections.
 * One of the adapters that you use in trying to create the bridge is the internal (also called private) ICS connection. This adapter has an IP address of 192.168.0.1.
 * The second adapter that you use in trying to create the bridge is not the public ICS connection.



CAUSE
To create a network bridge by using the private ICS connection and another network connection (other than the public ICS connection), you must create the bridge before enabling ICS. If you do not, the network bridge cannot properly bind to the private ICS connection, and the bridge is not created.



RESOLUTION
There are two methods for correctly configuring the bridge. You can use the Network Setup Wizard to create the network bridge and to enable ICS, or you can manually configure these options. The remainder of this article describes how to manually configure the network bridge and enable ICS.

NOTE: Use the following procedure at any time that you want to configure a bridge, or any time you intend to add or remove an interface on a Windows XP-based computer that hosts ICS.

To Manually Create the Network Bridge and Enable ICS
 Disable ICS and Internet Connection Firewall (ICF) on the public interface. After you do this, ICS and ICF should not be enabled on any network connection on the computer. To disable ICS and ICF:  Click Start, click Control Panel, click Network and Internet Connections, and then click Network Connections. Right-click the Internet connection, and then click Properties. Click the Advanced tab. Clear the Protect my computer and network by limiting or preventing access to this computer from the Internet check box if it is selected. Clear the Allow other network users to connect check box if it is selected.</li> Click OK in each dialog box until you return to the Network Connections folder.</li></ol> </li> In the Network Connections folder, select the two adapters that you want to use to create the bridge. Make sure that neither of the adapters is the connection to the Internet. To select two network adapters, first click one network connection. Then, hold down the CTRL key while you click the second network connection.</li> Right-click either connection, and then click Bridge Connection. Windows XP creates a network bridge by using the two network connections you specified. After this process is finished, continue with the next step.</li> In the Network Connections folder, right-click the Internet connection, and then click Properties. Remember that the Internet connection cannot be one of the connections that you used to create the bridge if your intent is to run ICS or ICF on the Internet connection.</li> On the Advanced tab, select the Allow other network users to connect check box to enable ICS. Remember that because you have bridged two network connections together, both network adapters that are used in the bridge are on the internal side of ICS, and clients from either network can access the Internet.

NOTE: If you have more than two potential internal networks, ICS requires that you specify which network should be the private network that is used by ICS. For example, you may have one network connection to the Internet, two additional network connections that are part of a bridge, and a fourth network connection (for example, a wireless connection). In this example, either the wireless connection or the bridged connection could be configured as the private ICS network. If your intent is to have both the current bridged connections and the wireless connection be configured as the private ICS network, you must add the wireless connection to the bridge. If you do not, you must choose which network is the private ICS network, and which network is allowed to access the Internet through the Windows XP-based ICS host.

To add an additional adapter to the network bridge: <ol style="list-style-type: lower-alpha;"> Right-click the network bridge in the Network Connections folder, and then click Properties.</li> On the General tab, make sure that each adapter that should be configured as part of the bridge has a check mark next to it in the Adapters list.</li> Click OK to have the bridge bind any new adapters.</li></ol>

It is a good idea to completely configure the bridge before you enable ICS or ICF on the Internet connection.

</li> Select the Protect my computer and network by limiting or preventing access to this computer from the Internet check box if your intent is to protect this computer and other computers on the private network from the Internet.</li> Click OK in each dialog box until you return to the Network Connections folder. Close the Network Connections folder.</li> Enable ICS again if it has been disabled. Note that you cannot create a bridge by using the shared (public) ICS connection and the private ICS connection because of the design of ICS and network address translation (NAT) in general. Attempting to do so results in the following error message:

To create a Network Bridge, you must select at least two network connections that are not being used by Internet Connection Sharing or the Internet Connection Firewall

</li></ol>

Keywords: kbnetwork kbprb KB309640

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