You cannot view some Web sites when you use a dial-up connection in Virtual PC for Mac Version 7 (918904)


The information in this article applies to:

  • Microsoft Virtual PC for Mac Version 7

Notice

Important This article contains information about how to modify the registry. Make sure to back up the registry before you modify it. Make sure that you know how to restore the registry if a problem occurs. For more information about how to back up, restore, and modify the registry, click the following article number to view the article in the Microsoft Knowledge Base:

256986 Description of the Microsoft Windows registry

SYMPTOMS

In Microsoft Virtual PC for Mac Version 7, you cannot view some Web sites in a browser window.

CAUSE

This issue occurs because of an incompatible Maximum Transfer Unit (MTU) network setting. The default Microsoft Windows maximum transmission unit size is 1500. A dial-up connection uses a maximum transmission unit size of 576.

This issue occurs even though you can view these Web sites in a browser in Mac OS X.

This issue may occur if the Macintosh computer is configured to use a dial-up connection to the Internet.

RESOLUTION

Warning Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall your operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.

To resolve this issue, modify the MTU size in the virtual machine. To do this, follow these steps:
  1. Back up the Virtual PC for Mac Version 7 virtual machine. For information about how to back up a virtual machine in Virtual PC for Mac Version 7, follow these steps:
    1. Start Virtual PC for Mac Version 7.
    2. On the Help menu, click Virtual PC Help.
    3. In the Search box, type backup, and then press ENTER.
  2. In the Virtual PC List window, click the virtual machine that you want, and then click Start Up.
  3. In the virtual machine, click Start, click Run, type cmd, and then click OK.
  4. At the command prompt, type ipconfig, and then press ENTER. Note the IP Address that appears.
  5. At the command prompt, type exit, and then press ENTER.
  6. Back up the Windows registry in the virtual machine.

    For more information about how to back up the Windows registry, click the following article numbers to view the articles in the Microsoft Knowledge Base:

    322756 How to back up, edit, and restore the registry in Windows XP and Windows Server 2003

    322755 How to back up, edit, and restore the registry in Windows 2000

  7. Click Start, click Run, type regedit, and then click OK.
  8. Locate and then click the follow registry key:

    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces

  9. Expand Interface.
  10. Under Interface, click each subkey, and then note the DhcpIPAddress value in the right-pane.
  11. When you locate a subkey that has the same DhcpIPAddress value as the IP Address that you noted in step 4, click the subkey in the left pane.
  12. On the Edit menu, point to New, and then click DWORD Value.
  13. Type MTU, and then press ENTER.
  14. Click MTU, click Edit, and then click Modify.
  15. In the Value Data box, type 576, click Decimal, and then click OK.
  16. Restart the virtual machine.

REFERENCES

For more information about how to change the Default Maximum Transmission Unit (MTU) Size Settings for PPP Connections or for VPN Connections, click the following article number to view the article in the Microsoft Knowledge Base:

826159 How to change the default Maximum Transmission Unit (MTU) size settings for PPP connections or for VPN connections

For more information about the default MTU size in network topologies, click the following article number to view the article in the Microsoft Knowledge Base:

314496 Default MTU size for different network topology

Modification Type:MajorLast Reviewed:5/12/2006
Keywords:kbnetwork kbtshoot kbprb KB918904 kbAudEndUser kbAudGeneralUser
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