A Windows Vista-based DHCP client does not accept a new IP address until two DHCPOFFER packets are exchanged

In a Worldwide Interoperability for Microwave Access (WiMAX) network, you have a Windows Vista-based Dynamic Host Configuration Protocol (DHCP) client computer. After this client computer receives a DHCPNACK packet, the computer incorrectly rejects the DHCPOFFER packet from the DHCP server. This DHCPOFFER packet contains a new IP address. The client computer does not accept the new IP address until two DHCPOFFER packets are exchanged between the server and the client. This behavior slightly delays the client computer when it obtains a new valid IP address.

This problem occurs because the Windows Vista-based DHCP client computer does not comply with RFC2131 when the client computer tries to renew an IP address that was previously used. When a DHCPNACK packet is received from the DHCP server, the client must invalidate its previous configuration for the interface. Then, the client must return to the initial state to start the renew process.

Hotfix information

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site: Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.

Important Windows Vista and Windows Server 2008 hotfixes are included in the same packages. However, only one of these products may be listed on the �Hotfix Request� page. To request the hotfix package that applies to both Windows Vista and Windows Server 2008, just select the product that is listed on the page.

Prerequisites

To apply this hotfix, the computer must be running one of the following operating systems:

• Windows Vista
• Windows Vista Service Pack 1
• Windows Server 2008

Restart requirement

You have to restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace any other previously released hotfixes.

Registry information

To use this hotfix, you do not have to make any changes to the registry.

File information

The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time item in Control Panel.

Windows Vista and Windows Server 2008 file information notes

• The files that apply to a specific product, milestone (RTM, SPn) can be identified by examining the file version numbers as shown in the following table.

  Version	Product	Milestone	Service branch
  6.0.6000.20xxx	Windows	RTM	LDR
  6.0.6001.22xxx	Windows Vista SP1 and Windows Server 2008 SP1	SP1	LDR

• Service Pack 1 is integrated into Windows Server 2008. Therefore, RTM milestone files apply only to Windows Vista. RTM milestone files have a 6.0.0000.xxxxxx version number.
• The .manifest files and the .mum files that are installed in each environment are listed separately in the "Additional file information for Windows Server 2008 and for Windows Vista" section. These files and their associated .cat (security catalog) files are critical to maintaining the state of the updated component. The .cat files are signed with a Microsoft digital signature. The attributes of these security files are not listed.

For all supported 32-bit versions of Windows Server 2008 and of Windows Vista

For all supported 64-bit versions of Windows Server 2008 and of Windows Vista

For all supported Itanium-based versions of Windows Server 2008

Additional file information for Windows Server 2008 and for Windows Vista

Additional files for all supported 32-bit versions of Windows Server 2008 and of Windows Vista

Additional files for all supported 64-bit versions of Windows Server 2008 and of Windows Vista

Additional files for all supported Itanium-based versions of Windows Server 2008

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

For more information about DHCP, click the following article number to view the article in the Microsoft Knowledge Base: For more information, click the following article number to view the article in the Microsoft Knowledge Base: