There is a small misunderstanding in BITS capabilities. When we say "bandwidth-throttling technology uses only idle bandwidth" and thus "downloads do not interfere with or slow other network activity, such as Internet browsing" the bandwidth we are talking about is the individual computer bandwidth. For example if the user is simultaneously browsing the Internet, BITS will throttle itself back to allow the user to complete his downloads so that the user experience is not affected. BITS doesn’t have information on total network usage so it will not be able to throttle the download depending on the network bandwidth.
You can limit the maximum amount of bandwidth that BITS uses by editing the local computer policy on the WSUS server or you can create a GPO on the DC to do this. Below are the steps to do this. Note that we do not officially recommend editing the Default Domain Policy, it is used below simply as an example policy.
Open the group policy you wish to edit:
Expand Administrative Templates under Computer Configuration:
Select Background Intelligent Transfer Service:
Double click Maximum network bandwidth that BITS uses:
Enable the policy and set the limits depending on what you want:
Ellis George | WSUS Support Engineer