100-Megabit Ethernet May Hang or Exhibit Poor Performance

• Microsoft Windows NT Workstation versions 3.5 and 3.51
• Microsoft Windows NT Server versions 3.5 and 3.51

SYMPTOMS

The client system may stop responding when transferring files between two Microsoft Windows NT version 3.51 computers using 100-megabit Ethernet cards over a 100-megabit segment. The receiving system or client stops responding and the CPU usage stays at 100 percent until the file transfer is completed. You may also see lower than expected transfer rates.

WORKAROUND

To work around this problem, change the Server Optimization to Balance on both the Windows NT Server and Windows NT Workstation. To change the Server Optimization for a Windows NT Server, configure the Server service using the Control Panel Network tool, and set Server Optimization to Balance. To change the Server Optimization for a Windows NT Workstation you need to modify the Registry.

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.

1. Start Registry Editor (Regedt32.exe) select the following subkey:

   HKEY_LOCAL_MACHINE\System\CurrentControlSet \Services\LanmanServer\Parameters

2. Add or change the following value:

   Size REG_DWORD: 0 x 2

STATUS

Microsoft has confirmed this to be a problem in Microsoft Windows NT versions 3.50 and 3.51. We are researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.