Microsoft KB Archive/119004

= WinNT 3.5 RAS Compression Lost If Linked to Older RAS Version =

Article ID: 119004

Article Last Modified on 10/16/2003

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APPLIES TO


 * Microsoft Windows NT Workstation 3.5
 * Microsoft Windows NT Server 3.5

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This article was previously published under Q119004



SYMPTOMS
While you have a Remote Access Service (RAS) link established, you notice two symptoms:


 * In the Port Status dialog boxes of the RAS server and client, the Incoming and Outgoing Compression fields indicate loss of software compression, because they display 0 percent instead of a number greater than zero.
 * The effective throughput is much less than usual (presumably because of zero software compression).

These symptoms occur after you upgrade your RAS server or client from Windows NT version 3.1 to Windows NT version 3.5 (without Service Pack 2 installed), and the RAS client or server on the other side of the RAS link is running a downlevel RAS version, such as Windows NT 3.1 RAS or Windows for Workgroups version 3.11 RAS.

NOTE: These symptoms do not occur if the RAS client and server are both running Windows NT 3.5.



CAUSE
The software compression method used in Windows NT version 3.1 RAS and Windows for Workgroups version 3.11 RAS is not compatible with the software compression used in Windows NT version 3.5.



RESOLUTION

 * To work around the throughput problem, use modem hardware compression. This, however, cannot give you as much throughput as RAS software compression. Modem hardware compression is not monitored by RAS; therefore, the Incoming and Outgoing Compression fields always display zero.
 * To resolve the display and throughput problems, upgrade Windows NT 3.5 to version 3.51.

NOTE: Service Pack 2 for Windows NT 3.5 also fixes the throughput problem, but not the display problem.

RAS software compression can significantly improve throughput in comparison to modem hardware compression, unless previously compressed files are copied.

For best performance, Microsoft suggests you configure the RAS client software on Windows for Workgroups 3.11, Windows NT 3.1, and Windows NT 3.51 (or Windows NT 3.5 with Service Pack 2 installed) as follows:

 In Remote Access, make sure the Disable Software Compression option in the Options menu is not checked. Choose the Edit button, then choose the Modem button, and select the following:

 Enable Hardware Flow Control Enable Modem Error Control

Clear the Enable Modem Compression check box so software compression and modem compression are not used at the same time (as this reduces throughput).

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MORE INFORMATION
If you still don't get compression after installing Windows NT 3.51, verify that your downlevel RAS software has the drivers for software compression installed.

Software

Compression in Windows for Workgroups 3.11 and Windows NT 3.1 RAS Clients
Software compression is available by default in these RAS clients unless you set the Disable Software Compression option from the Options menu or you purchased your copy of Windows for Workgroups 3.11 or Windows NT 3.1 after February 1994. You can tell whether or not you have RAS software compression by using the following information:

Windows for Workgroups 3.11: <pre class="fixed_text">  Filename     Bytes   Compression RASMAC.386  49209   YES RASMAC.386  27193   NO Windows NT 3.1: <pre class="fixed_text">  Filename       Bytes    Compression ---  ASYNCMAC.SYS   53188    YES ASYNCMAC.SYS  53716    YES ASYNCMAC.SYS  33732    NO NOTE: The Windows NT 3.1 and Windows for Workgroups 3.11 RAS compression files can be obtained from the SUPPORT\RAS directory on the Windows NT 3.5 U.S. Service Pack 2 CD.

Additional query words: wfw wfwg prodnt 3.11 3.51 SP2

Keywords: KB119004

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