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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Article ID: 937841 - View products that this article applies to.
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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 = true
    
    Sub 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 If
    
    End Sub
    
    Sub CheckError()
    
        If Err.Number <> 0 Then
            WScript.Echo "An error occurred: 0x" & Hex(Err.Number) & " " & Err.Description
            Err.Clear
        End If
    
    End Sub
    
    SetValue
    
    
  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: August 14, 2007 - Revision: 1.0
APPLIES TO
  • Microsoft Internet Security and Acceleration Server 2006 Standard Edition
  • Microsoft Internet Security and Acceleration Server 2006 Enterprise Edition
Keywords: 
kbtshoot kbexpertiseinter kbprb KB937841

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