You may experience a long delay when you try to use Internet Explorer to access a redirected Web page and Internet Explorer uses ISA Server 2004 as a Web proxy server (905179)


The information in this article applies to:

  • Microsoft Internet Security and Acceleration Server 2004, Enterprise Edition
  • Microsoft Internet Security and Acceleration Server 2004, Standard Edition
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

You configure Microsoft Internet Explorer to use Microsoft Internet Security and Acceleration (ISA) Server 2004 as a Web proxy server. When you try to use Internet Explorer to access a redirected Web page, you may experience a long delay.

CAUSE

This problem occurs when the ISA Server-based computer sends an HTTP GET request that spans two packets to a Web server that is running BEA WebLogic Server. In this situation, the Web server may respond to the HTTP GET request by sending an HTTP 302 Redirect message before the Web server receives the second packet. The Web server may not acknowledge the second packet for a long time. Therefore, the packet eventually times out.

By default, the EnablePMTUDiscovery registry entry is disabled after you install ISA Server 2004 on a computer that is running Microsoft Windows Server 2003. Therefore, the data is sent with a packet size of 576 bytes. In this situation, the HTTP GET request may span more than one packet.

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 problem, enable the EnablePMTUDiscovery registry entry on the computer that is running ISA Server 2004. To do this, follow these steps:
  1. Click Start, click Run, type regedit, and then click OK.
  2. In Registry Editor, locate and then click the following registry subkey: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
  3. Right-click the EnablePMTUDiscovery entry.
  4. On the Edit menu, click Modify, and then type 1 in the Value date box.
  5. Quit Registry Editor.

STATUS

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

MORE INFORMATION

The third-party products that this article discusses are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, regarding the performance or reliability of these products.
Modification Type:MajorLast Reviewed:10/21/2005
Keywords:kbtshoot kbprb KB905179 kbAudITPRO
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