Network performance issues that are caused by Global address list (GAL) file downloads or by GAL delta file downloads in Office Communicator 2007 R2

Symptoms

In Microsoft Office Communicator 2007 R2, you experience network performance issues in one or more of the following situations:

1. The Global address list (GAL) file download is triggered in client computers in different scenarios. This occurs when the GAL delta file exists on the Communications Server 2007 R2 server.

2. The download of files uses a large network bandwidth.
   

3. No GAL delta file is created on the server even though the changes are not substancial in Active Directory.

4. All Communicator 2007 R2 clients logon at the same time and connect to the server to download GAL files or GAL delta files.

Cause

The following causes match the symptoms described in this article:

1. The download of the GAL files can be caused by any local failure in the parsing of the GAL delta files or while you are updating the local database.

2. Because the GAL file is downloaded randomly and GAL delta files should be downloaded daily, these downloads use a large amount of bandwidth on the network.

3. The server looks for any change in the Communicator 2007 R2 contacts. If the number of changed contacts is more than one eighth of the size of the GAL file, the server does not create a GAL delta file. This causes clients to download the GAL file instead of incremental GAL delta files.
   

4. GAL delta files are generated every day. Therefore, users have to download the GAL delta files when they start Communicator for the first time every day. In some organizations, many users connect at the same time. This could cause network congestions because of the concurrent download of the GAL delta files.

Resolution

To resolve this issue, apply both the following updates:

• For more information, click the following article number to view the article in the Microsoft Knowledge Base:

  969695 Description of the update for the Communicator 2007 R2: July 2009
  
  

• For more information, click the following article number to view the article in the Microsoft Knowledge Base:

  969821 Description of the update package for Office Communications Server 2007 R2: July, 2009
  
  

For situation 4, set the GalDownloadInitialDelay registry entry for immediate download of the GAL file. 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_CURRENT_USER\Software\Policies\Microsoft\Communicator
   

3. On the Edit menu, point to
   New, and then click DWORD Value.

4. In the New Value #1 dialog box, type
   GalDownloadInitialDelay, and then press the ENTER key.
   

5. Right-click the GalDownloadInitialDelayregistry entry, and then click Modify.

6. In the Value data box, type
   0, and then click OK.
   

   • If you set the value as 0, the address book download will take effect immediately after sign-in.

   • If you do not set this registry value, the default value is random value between 0 and 60 minutes. Therefore, the delay is random a random value between 0 and 60 minutes.

7. Exit Registry Editor.

If an administrator updates the ABServer.exe.config file before the update is installed, this file will not be updated as part of the update deployment. This is to make sure that changes that are made by the administrator before the latest update are not lost as part of the update. Follow these steps to update theABServer.exe.config file to incorporate the latest updates:

1. Open the ABServer.exe.config file in Notepad.
   
   Note The file is located at %ProgramFiles%\Microsoft Office Communications Server 2007 R2\Server\Core

2. In the ABServer.exe.config file, add the following lines under the configuration\appsettings section:
   

   • <add key="CompactDeltaOnly" value="false" />               <!-- Turn to true to stop generating legacy GAL delta files if all clients migrate to this update -->

   • <add key="CompactDelta_ExcludedIfSipURI" value="title,physicalDeliveryOfficeName"/>

   • <add key="CompactDelta_AlwaysExclude" value="otherHomePhone,otherMobile,manager"/> 

Note If you do not make this change, an unnecessary surge in bandwidth may occur when the contact information in Communicator 2007 R2 changes. For example, a surge in bandwidth will occur if a company moves to a different location. This causes a change in the address information for all the employees in the company. In this example, every computer Communicator 2007 R2 user will download the GAL file again.

Note The setting for the redirect key in the appsetting section in the Web.config file for the address book file handler must be changed from false to true. This causes the handler to redirect traffic to a virtual directory that points to the underlying file share. IIS understands the Background Intelligent Transfer Service (BITS) protocol. Therefore, IIS sends the files. To do this, follow these steps:

1. Open the Web.config file in Notepad from the following locations:
   

   • %ProgramFiles%\Microsoft Office Communications Server 2007 R2\Web Components\Address Book Files\Int\Handler\

   • %ProgramFiles%\Microsoft Office Communications Server 2007 R2\Web Components\Address Book Files\Ext\Handler\

2. In the Web.config file, locate the following line in the appsetting section:

   <add key="redirect" value="false"/>

3. Replace the line in the step 3 with the following:

   <add key="redirect" value="true"/>
   

4. Save and close the Web.config file.

Set the EnableBitsForGalDownload registry entry on the client where the OC is installed. 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_CURRENT_USER\Software\Policies\Microsoft\Communicator
   

3. On the Edit menu, point to
   New, and then click DWORD Value.

4. In the New Value #1 dialog box, type
   EnableBitsForGalDownload, and then press the ENTER key.
   

5. Right-click the EnableBitsForGalDownloadregistry entry, and then click Modify.

6. In the Value data box, type
   1, and then click OK.

7. Exit Registry Editor.

More Information

If you are planning to implement the resolution for situation 4 that is listed in the Symptoms section of this KB article then be sure to read the following Technet information in regard to BITS group policy configurations. For more information about the how to configure BITS 2.0 and 3.0, visit the following Web site:
http://technet.microsoft.com/en-us/library/cc720428(WS.10).aspx