You configure the Dynamic Host Configuration Protocol (DHCP) server service to set the default gateway address of a DHCP client computer to be the same as the IP address. After you do this, a Windows Vista-based client computer cannot connect to any off-link addresses.

Back to the top

This problem occurs because Windows Vista-based DHCP client computers configure the gateway address first. Then, the computers add the IP address to the computer. Therefore, the gateway address is configured on the Windows Vista-based computer as if it is the address of another computer.

When any network traffic must be sent to an off-link address, the Address Resolution Protocol (ARP) is used to connect to the gateway address. However, because the gateway address is the IP address of the Windows Vista-based computer, a response is not sent for the ARP request. Therefore, the network traffic is dropped.

Back to the top

Service pack information

To resolve this problem, obtain the latest service pack for Windows Vista. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

Back to the top

Update information

The following files are available for download from the Microsoft Download Center:

Update for Windows Vista

Download the 929824 package now. (http://www.microsoft.com/downloads/details.aspx?FamilyId=3D352266-CFA8-447A-B700-2B2100D4E04C)

Update for Windows Vista for x64-based systems

Download the 929824 package now. (http://www.microsoft.com/downloads/details.aspx?FamilyId=307C7ED8-DE20-47F0-B828-704C1B5F04C5)

For more information about how to download Microsoft support files, click the following article number to view the article in the Microsoft Knowledge Base: Microsoft scanned this file for viruses. Microsoft used the most current virus-detection software that was available on the date that the file was posted. The file is stored on security-enhanced servers that help prevent any unauthorized changes to the file.

Back to the top

To work around this problem, use one of the following methods:

•	Configure a gateway address on the network.
•	Manually delete the default gateway address, and then replace the gateway address on the computer.
•	Configure the DHCP server so that the server does not advertise a default gateway address. Instead, configure the DHCP server to advertise the IP address. Note Include the subnet mask value of 0 for the IP address in this configuration.

Back to the top

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section. This problem was first corrected in Windows Vista Service Pack 1.

Back to the top

If you configure the SwitchedNetworkFlag parameter by using Registry Editor, a DHCP client computer obtains a default gateway address that equals the IP address that the client computer receives. This behavior causes the client computer to use the ARP for all the IP addresses that are on the local subnet. This behavior is useful for switched networks that do not have a router. For more information about how to set the default gateway address of a DHCP client computer to its own IP address, click the following article number to view the article in the Microsoft Knowledge Base:

Back to the top