Archive for March, 2010

XenServer - Windows Guest TCP/IP not working properly after XenTools Update2 Installed

Thursday, March 11th, 2010

intermittent communication failure between computers
that are running Windows XP or Windows Server 2003
http://support.microsoft.com/kb/904946/
To work around this problem, turn off checksum offloading on the network adapter. To do this, follow these steps:
1. Click Start, click Run, type regedit, and then click OK.
2. Locate and then click the following registry subkey:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
3. In the right pane, make sure that the DisableTaskOffload registry entry exists. If this entry does not exist, follow these steps to add the entry:
a. On the Edit menu, point to New, and then click DWORD Value.
b. Type DisableTaskOffload, and then press ENTER.
4. Click DisableTaskOffload.
5. On the Edit menu, click Modify.
6. Type 1 in the Value data box, and then press ENTER.
7. Exit Registry Editor.

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2. Use the registry editor and locate the “HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\xennet\nics” key.

3. Each key under nics will have an associated MAC address for each VIF.

4. Locate the “IPAddress” value and double click to edit.

5. The value contains two lines, one the IPv4 address of the interface and one an IPv6 address.

6. Delete the IPv6 address on the second line and leave the IPv4 address.

7. Under SubnetMask key, delete the corresponding subnet value for IPv6.

8. Reboot the VM.

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1. Install the XenTools and reboot the VM.

2. Use the registry editor and locate the “HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\Tcpip\Parameters\Interfaces” key.

3. Look at settings under each GUID to find the corresponding IPAddress and SubnetMask values.

4. Edit both the “IPAddress? and ?SubnetMask” value.

5. The value contains two lines, one the IPv4 address of the interface and one an IPv6 address.

6. Delete the IPv6 address on the second line and leave the IPv4 address.

7. Under SubnetMask key delete the corresponding subnet value for IPv6

8. Reboot the VM.

9. VM Networking, VIFs, and XenTools drivers should work as expected.

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