Possible Causes of Elevated CPU Utilization with TAPI 2.0 and RAS

• Microsoft Windows NT Workstation version 4.0
• Microsoft Windows NT Server version 4.0
• Microsoft Windows NT Server, Enterprise Edition version 4.0

SYMPTOMS

Tapisrv.exe may begin to use an excessive amount of processor time (from 50% to 100%) with Remote Access Services (RAS) installed.

CAUSE

This problem may occur if you use TAPI 2.0 and any of the following are true:

• RAS is configured with modems that are no longer connected to the system or that are powered off.



• Your serial device or modem uses an outdated driver.



• You are using a multi-port device that does not appear on the Microsoft Windows NT 4.0 Hardware Compatibility List. For more information on the Windows NT Hardware Compatibility List, please see the following article in the Microsoft Knowledge Base:
  
  ARTICLE-ID: Q131303
  TITLE : Latest Windows 2000/Windows NT Hardware Compatibility List (HCL)

RESOLUTION

To resolve this problem, perform one of the following:

• Remove any modems listed in the RAS Server configuration that are no longer on the system.



• Connect the modems listed in the RAS Server configuration.



• Turn on all modems connected to the system.



• Update outdated serial device or modem drivers.



• Make sure your serial device or modem is on the Hardware Compatibility List.



• Update the firmware for your serial device or modem.

MORE INFORMATION

This information does not apply to TAPI 2.1.

To determine the version of TAPI on your computer, check date and file size of the Tapisrv.exe file in the %SystemRoot%\System32 folder.

File	Date	Size	Version
Tapisrv.exe	May 01, 1997	120,592 bytes	TAPI 2.0 (from Windows NT 4.0 Service Pack 3)

Additional query words: ntsee serial rras

Keywords : kbenv ntras
Version : winnt:4.0
Platform : winnt
Issue type :