Controlling Network Traffic in Windows 7

In corporate networks you can use Differentiated Services Code Point (DSCP) values to prioritize traffic for best performance of the most important traffic.  However, if you manage a small network and your perimeter devices do not support DSCP, there is an alternative method known as traffic throttling which allows you to specify the amount of bandwidth a specific application can consume. Traffic throttling does not have any network infrastructure requirements.

Remember, that when setting up traffic throttling on individual Windows 7 computers you need to calculate the aggregate bandwidth used by all computers to make better use of your overall bandwidth. For instance, if you have five computers and want to allow half of your 1,000 Kbps (1 Mbps) link to be used for browsing then, you must configure the QoS policy to throttle web browsing traffic at 100 Kbps for each of the five computers. This will total to 500 Kbps of web browsing traffic on your network, when all five computers are hitting their maximum allowable threshold.

To configure Traffic Throttling, open the Local Group Policy Editor snap-in, by typing gpedit.msc in the Start search text box and press enter. Go to Computer Configuration\Windows Settings\ Policy-based QoS node or the User Configuration\Windows Settings\Policy-based QoS node and follow these steps:

  1. Right-click the Policy-based QoS node and click Create New Policy as shown below:
  2. The Policy-based QoS Wizard appears. On the Create A QoS Policy page, specify a name for the policy. Then, a throttle rate (which Windows will use to restrict outgoing bandwidth usage) as needed – Notice that the throttle rate must be entered in kilobytes per second (KBps) or megabytes per second (MBps). For instance, 16KBps would translate to 128 Kbps
  3. Click Next
  4. On the This QoS Policy Applies To page, select one of the following options: All Applications, Only Applications With This Executable Name, or Only HTTP Server Applications Responding To Requests For This URL. If you are specifying an application, Windows will apply throttle rate to network traffic generated by that application. For instance, check Only Applications With This Executable Name and type C:\Program Files\Internet Explorer\iexplore.exe
  5. Click Next.
  6. On the Specify The Source And Destination IP Addresses page, you can configure the policy to apply to traffic between any two computers – QoS policies apply only to outgoing traffic, so the computer to which you’re applying the policy will always be identified by the source address, and the remote computer or network will always be identified by the destination address. In our case, you can use the default settings.
  7. On the Specify The Protocol And Port Numbers page, you can prioritize traffic based on TCP or UDP port numbers. For instance, to throttle all outgoing Web requests, you can select TCP, select To This Destination Port Number Or Range, and then specify port 80. (The HTTP protocol uses TCP port 80.)
  8. Click Finish.

Note: It is recommended not to use traffic throttling to limit the bandwidth of every application or protocol; instead, use traffic throttling to limit only traffic from low-priority applications, such as network backups or the downloading of large updates.