Using Traffic Control Monitor (TCMon) to simulate slow-link or dial-up connections

Traffic Control Monitor (TCMon) is a tool used to interact with the windows Quality of Service (QOS) Provider in the Windows Networking component.  By adjusting the settings in QOS, TCMon is able to do some really amazing simulations such as:

  • Control network bandwidth on Ethernet connections to simulate 56k dial-up, ISDN, etc.
  • Increase/Reduce packet delay
  • Add/Remove packet loss  


TCMon is included in the Resource Kit Tools for Windows 2000, Windows XP, and Windows Server 2003. The Server 2003 kit can be downloaded at

After downloading the kit, run the installation package and install the tools.  After installation, goto the install folder (usually C:\Program Files\Windows Resource Kits\Tools) and run tcmon.bat.  This installs the TCMon kernel driver and configures the components required to control the network connection.

TCMon requires that QOS Service be enabled to control connection speed.  Goto Control Panel > Network Connections and right click on the network connection to ensure QOS is enabled. 

Running TCMon

Assuming installation goes smoothly, we can configure TCMon to control our network connections. There are two very important things to note:

  1. All settings are lost on Reboot
  2. All settings are lost when the user logs on or off

Q & A

If you find this useful, drop me a line.