Article ID: 171386 - View products that this article applies to.
This article was previously published under Q171386
You may experience a delay when you attempt to connect to network resources from a system with multiple redirectors installed. This delay only happens the first time that you attempt the connection.
When a non-WNET API initial UNC connection attempt is made to a network resource from a system with multiple redirectors, the Windows NT system sends the request to the multiple UNC provider (MUP) to identify which redirector should handle the request.
Windows NT 4.0To resolve this problem, obtain the latest service pack for Windows NT 4.0 or Windows NT Server 4.0, Terminal Server Edition. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
(http://support.microsoft.com/kb/152734/ )How to obtain the latest Windows NT 4.0 service pack
Windows 2000 and Windows XPA modification to the MUP has been made such that, if the redirector with the highest priority is attempted first with a successful response, those redirectors with lower priorities are then bypassed and the connection is made through the redirector with the highest priority.
Enabling this capability requires an updated Mup.sys. The speed improvement can be increased by modifying the registry entry DisableDFS.
Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:
(http://support.microsoft.com/kb/322756/ )How to back up and restore the registry in Windows
Warning Using Registry Editor incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk.
For information about how to edit the registry, view the "Changing Keys And Values" online Help topic in Registry Editor (Regedit.exe) or the "Add and Delete Information in the Registry" and "Edit Registry Data" online Help topics in Regedt32.exe. Note that you should back up the registry before you edit it.
The MUP first establishes whether Distributed File System (Dfs) is in use and passes the request to Dfs.
The MUP then checks its internal cache to see whether the connection had been made previously (entries in the MUP cache are held for 15 minutes). The MUP then sends the request to each redirector that handles each request synchronously and attempts to identify a resource on the network that matches the request. After all redirectors return, the MUP chooses (based on response and priority) which redirector the application will use.
The delays come from two locations: first, the attempt to access the resource through Dfs and, second, the MUP must wait and accept all responses from all redirectors before completing the request. Therefore, even if a resource is readily available and accessible over one redirector, the request must still be made over the other installed redirectors before the request completes.
Depending on the number of redirectors, protocols, and timer configurations for connectivity, these delays can exceed 13 seconds for each initial connection.
The NetWare Redirector will be used as an example.
The following illustrates an initial UNC connection attempt:
The priority for the redirectors can be configured using the following steps:
Microsoft has confirmed that this is a problem in Windows NT 4.0 and Windows NT Server 4.0, Terminal Server Edition. This problem was first corrected in Windows NT 4.0 Service Pack 4.0 and Windows NT Server 4.0, Terminal Server Edition Service Pack 4.
Article ID: 171386 - Last Review: April 14, 2009 - Revision: 5.1