ISA Server 2006 forwards requests to an incorrect Web server when a client computer accesses Web sites that have different URLs in the same session

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SYMPTOMS
Consider the following scenario:
  • In Microsoft Internet Security and Acceleration (ISA) Server 2006, you create a Web farm that contains multiple Web servers.
  • You create multiple Web publishing rules to publish multiple Web sites by using this Web farm.
  • In the Web publishing rules, the load balance mechanism is set to Cookie based.
In this scenario, ISA Server forwards requests to an incorrect Web server. When a client computer accesses Web sites that have different URLs in the same session, ISA Server does not forward the requests to the same Web server.

For example, this problem occurs when the client computer accesses the following Web sites in the same session:
  • http://host_name/Site1
  • http://host_name/Site2
CAUSE
This problem occurs because ISA Server implements load balancing based on specific policy rules. If all requests from a client session are enabled by the same policy rule, they reach the same Web server. However, if requests are enabled by different policy rules, requests from the same session may reach different Web servers.
RESOLUTION
  1. Apply hotfix 940250. For more information about this hotfix, click the following article number to view the article in the Microsoft Knowledge Base:
    940250 Description of the ISA Server 2006 hotfix package: July 16, 2007
  2. Start Notepad, and then paste the following script into a new document.
    Const SE_VPS_GUID = "{143F5698-103B-12D4-FF34-1F34767DEabc}"Const SE_VPS_NAME = "EnableHotfix937841"Const SE_VPS_VALUE = trueSub SetValue()    ' Create the root obect.    Dim root  ' The FPCLib.FPC root object    Set root = CreateObject("FPC.Root")    'Declare the other objects needed.    Dim array       ' An FPCArray object    Dim VendorSets  ' An FPCVendorParametersSets collection    Dim VendorSet   ' An FPCVendorParametersSet object    ' Get references to the array object    ' and the network rules collection.    Set array = root.GetContainingArray    Set VendorSets = array.VendorParametersSets    On Error Resume Next    Set VendorSet = VendorSets.Item( SE_VPS_GUID )    If Err.Number <> 0 Then        Err.Clear        ' Add the item        Set VendorSet = VendorSets.Add( SE_VPS_GUID )        CheckError        WScript.Echo "New VendorSet added... " & VendorSet.Name    Else        WScript.Echo "Existing VendorSet found... value- " &  VendorSet.Value(SE_VPS_NAME)    End If    if VendorSet.Value(SE_VPS_NAME) <> SE_VPS_VALUE Then        Err.Clear        VendorSet.Value(SE_VPS_NAME) = SE_VPS_VALUE        If Err.Number <> 0 Then            CheckError        Else            VendorSets.Save false, true            CheckError            If Err.Number = 0 Then                WScript.Echo "Done with " & SE_VPS_NAME & ", saved!"            End If        End If    Else        WScript.Echo "Done with " & SE_VPS_NAME & ", no change!"    End IfEnd SubSub CheckError()    If Err.Number <> 0 Then        WScript.Echo "An error occurred: 0x" & Hex(Err.Number) & " " & Err.Description        Err.Clear    End IfEnd SubSetValue
  3. Save the file by using the .vbs file name extension. For example, use the following name to save the file:
    EnableKB937841.vbs
    Note Microsoft Visual Basic script files use the .vbs file name extension.
  4. At a command prompt, move to the location where you saved the .vbs file, type the following command, and then press ENTER:
    cscript EnableKB937841.vbs
STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
MORE INFORMATION
For more information about a similar problem, click the following article number to view the article in the Microsoft Knowledge Base:
940242 ISA Server 2006 forwards requests to an incorrect Web server when a client computer accesses Web sites that have different host names in the same session
Properties

Article ID: 937841 - Last Review: 01/15/2015 15:31:22 - Revision: 1.0

  • Microsoft Internet Security and Acceleration Server 2006 Standard Edition
  • Microsoft Internet Security and Acceleration Server 2006 Enterprise Edition
  • kbnosurvey kbarchive kbtshoot kbexpertiseinter kbprb KB937841
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