Microsoft KB Archive/168599

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Article ID: 168599

Article Last Modified on 10/27/2006


  • Microsoft Systems Management Server 1.2 Standard Edition

This article was previously published under Q168599


This article provides a brief overview of 32-bit Program Group Control (PGC) for Windows 95 clients in Systems Management Server 1.2.


In previous versions of Systems Management Server, PGC monitored and reconfigured Windows registry settings each time an application was launched using the Appstart functionality of PGC. This was done so that PGC would be able to provide dynamic server selection at launch time. For this to work, a special application (called Smssetup.exe) was required to perform these changes. This implementation proved to be difficult to support, and a better solution now exists for Windows 95.

Under Windows 95, Program Group Control performs server name substitution at the file system level instead of reconfiguring the application at launch time. The application gets installed normally, and then when it tries to use any of its components, PGC recognizes that the application was installed from a Systems Management Server package, connects to the Systems Management Server share point at the file system level, and then the application can access the necessary files. This functionality is only available to applications that are capable of running from a UNC path (for example, \\servername\sharepoint).

The Systems Management Server Router technology (Program Group Control's file system redirection capability) is implemented as a VxD file system driver called Smsroutr.vxd. Applications that use the Systems Management Server Router technology only deliver the application's setup icon to the user's desktop. After the user installs the application from the icon delivered by Systems Management Server, the application should be run from the icons created by the setup program. Choosing the Systems Management Server-delivered icon will only reinstall the application.

The implementation of Program Group Control for Windows NT clients has always been 32-bit, but its functionality is identical to that of the 16-bit PGC that runs on Windows 3.x clients. The new functionality of PGC under Windows 95 is not available to Windows NT clients using Systems Management Server. Windows NT clients run the shared application successfully, but only from the server that the application was installed from. Therefore, load balancing and fault tolerance will not be available for Windows NT clients.


Network Naming Provider (NNP) is a system application (running at Ring 3) that provides the non-real time component of the Systems Management Server Router. NNP loads at boot time, reads the system registry for Systems Management Server information, formats that information, and passes it to the Logical Network Redirector (LNR). In addition, NNP verifies server and share status as needed, and updates the information for LNR.


Logical Network Redirector (LNR) is a Windows 95 system VxD (running at Ring 0) that contains the real-time portion of Systems Management Server Router. LNR loads at startup, hooks the installable file system (IFS) manager, and is transparent to user applications. LNR is used to monitor appropriate file operations for accesses to Systems Management Server controlled resources and when necessary to redirect operations that fail to an alternate path. In addition, LNR does load leveling on the initial use of a share.

Additional query words: prodsms win95 SMSRouter

Keywords: kbinfo kbnetwork kbpgc kbsetup kbsmsappman KB168599