Microsoft KB Archive/889510

= Logging on to a domain with Shared Networking (NAT) may take a long time in Virtual PC 2004 Service Pack 1 =

Article ID: 889510

Article Last Modified on 11/23/2004

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APPLIES TO


 * Microsoft Virtual PC 2004 Service Pack 1

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SYMPTOMS
When you try to log on to a domain from a virtual computer that is running in Microsoft Virtual PC 2004 Service Pack 1 (SP1), the logon process may take a long time to finish.



CAUSE
This problem occurs when the virtual computer uses Microsoft Windows XP or Microsoft Windows 2000 as the guest operating system, and uses Shared Networking to connect to the network domain. Shared Networking does not easily handle fragmented UDP packets that are created by Kerberos authentication. Typically, the Windows XP and the Windows 2000 implementations of Kerberos create messages that are too large to fit in a single UDP packet.

Note The Networking setting in Virtual PC uses the term &quot;Shared Networking (NAT),&quot; where &quot;NAT&quot; indicates Network Address Translation.



WORKAROUND
To work around this problem, you must force Kerberos in the guest operating system to use TCP instead of UDP for authentication. For additional information about how to force Kerberos to use TCP instead of UDP, click the following article number to view the article in the Microsoft Knowledge Base:

244474 How to force Kerberos to use TCP instead of UDP



STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the &quot;Applies to&quot; section.

Additional query words: vpc vpc2004 vpc2k4 login

Keywords: kbtshoot kblogin kbkerberos kbprb KB889510

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