Software Compression Compatibility in Windows NT 3.5 RAS

The information in this article applies to:

• Microsoft Windows NT Workstation version 3.5
• Microsoft Windows NT Server version 3.5

SUMMARY

Several fixes were made to Windows NT Remote Access Service (RAS) that are included in the latest U.S. Service Pack for Windows NT version 3.5. This article provides background information on client compatibility with RAS.

MORE INFORMATION

NOTE: If you don't already have RAS installed, install it from your original Windows NT installation media before applying the Service Pack.

RAS Software Compression Compatibility with Windows for Workgroups 3.11 and Windows NT 3.1

In addition to other fixes, the Service Pack installs files that make Windows NT 3.5 software compression compatible with Windows for Workgroups 3.11 and Windows NT 3.1. Throughput should improve significantly 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:

1. In Remote Access, make sure the Disable Software Compression option in the Options menu is not selected.

2. 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).

Windows NT Servers and Clients and RAS Software Compression

If you install the Service Pack on a Windows NT 3.5 RAS server, unmodified Windows NT 3.5 RAS clients do not lose software compression compatibility when calling the RAS server. Windows for Workgroups 3.11 and Windows NT 3.1 RAS clients can use RAS software compression without any need for new files, except as noted below.

All copies of Windows NT 3.5 have RAS software compression built-in. Only Windows NT 3.5 computers that are acting as RAS servers need the Service Pack for compression compatibility with Windows NT 3.1 and Windows for Workgroups 3.11 RAS clients. However, because of several code improvements, Microsoft recommends that you also apply this patch to Windows NT 3.5 RAS clients. The patch is required for RAS software compression compatibility when you call a Windows NT 3.1 or Windows for Workgroups 3.11 RAS server from a Windows NT 3.5 RAS client.

Software Compression in Windows for Workgroups 3.11 and Windows NT 3.1 RAS Clients

Software compression is available, by default, in the following RAS clients unless you select Disable Software Compression 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:

   Filename     Bytes   Compression
   --------------------------------
   RASMAC.386   49209   Yes
   RASMAC.386   27193   No

   Filename       Bytes    Compression
   -----------------------------------
   ASYNCMAC.SYS   53188    Yes
   ASYNCMAC.SYS   53716    Yes
   ASYNCMAC.SYS   33732    No

STATUS

These fixes are included in the latest Windows NT 3.5 U.S. Service Pack. For information on obtaining the Service Pack, query on the following word in the Microsoft Knowledge Base (without the spaces):

   S E R V P A C K