Improve WSUS Download Performance with BITS
Applies To: Windows Server Update Services, Windows Small Business Server 2011 Standard, Windows Server 2008 R2, Windows Server 2003 with SP2, Windows Server 2008 R2 with SP1
Windows Update and Microsoft Update use the Background Intelligent Transfer Service (BITS) to download updates. You can optimize download performance by configuring BITS through Group Policy. The following table shows the differences between BITS versions.
| BITS version | Included in | Can also be downloaded for |
|---|---|---|
| 4.0 | - Windows Server 2008 R2 - Windows 7 |
- Windows Server 2008 with Service Pack 2 (SP2) - Windows Vista® with Service Pack 1 (SP1) - Windows Vista with Service Pack 2 (SP2) For information about downloading BITS 4.0, see article 968929 in the Microsoft Download Center. |
| 3.0 | - Windows Server 2008 - Windows Vista |
|
| 2.5 | - Windows Server 2008 - Windows Vista - Windows XP with Service Pack 3 (SP3) |
- Windows Server 2003 with Service Pack 2 (SP2) - Windows Server 2003 with Service Pack 1 (SP1) - Windows XP with Service Pack 2 (SP2) To download BITS 2.5, see article 923845 in the Microsoft Download Center. |
| 2.0 | - Windows XP with Service Pack 2 (SP2) - Windows Server 2003 with Service Pack 1 (SP1) |
- Windows Server 2003 - Windows XP with Service Pack 1 (SP1) Warning: To obtain BITS 2.0, download the latest service pack for your operating system. Do not download BITS 2.0 directly from the Microsoft Download Center. |
In this topic:
BITS bandwidth limitations
BITS uses a computer's network adapter to measure network traffic. (BITS 3.0 can also use the Internet gateway device to monitor traffic if the computer is correctly configured.) In some cases, the network adapter does not provide an accurate measurement of network traffic. For example, if a computer has a fast network adapter that runs over a slow network connection, BITS will report an overly optimistic measurement.
Note
BITS bandwidth limitations affect the whole computer system. You cannot limit BITS bandwidth to only selected applications.
To set BITS bandwidth limitations
Log on to the computer by using an account that is a member of the local Administrators group.
Click Start, click Run, type
gpedit.msc, and then press ENTER.In the left pane of the Group Policy Management Console (GPMC), expand Computer Configuration, expand Administrative Templates, expand Network, and then click Background Intelligent Transfer Service.
In the Setting pane, double-click Limit the maximum network bandwidth for BITS background transfers.
In the top pane of the dialog box, click Enabled.
In the Options pane, set the transfer rate in kilobits per second (Kbps) that you want BITS to use. The default value is 10 Kbps.
Set the times during which you want to limit bandwidth. The default setting is from 12:00 A.M. to 12:00 A.M.
Set the limitations to use outside the designated time. The default setting is Use all available unused bandwidth.
Click OK to save the settings.
Peer caching
Peer caching is a feature of BITS that enables peer computers to share files. Peer computers are computers that have the peer caching feature enabled and that are located in the same subnet. If peer caching is enabled on a computer, Automatic Updates instructs BITS to make downloaded files available to the computer's peers.
Important
For more information about peer caching in BITS 4.0 and BITS 3.0, see Peer Caching on MSDN.
When updates are downloaded, BITS caches them. When another peer caching-enabled computer tries to download the same update, BITS sends a multicast request to all peers. If peer computers respond to the request, BITS downloads the file from the first peer computer to respond. If the download from the peer computer fails or take too long, BITS continues the download from the WSUS server or from Microsoft Update.
Peer caching can optimize bandwidth in the following ways:
Decreases the data that is transferred from the WSUS server to client computers because computers in the same subnet will usually download the updates from each other.
Decreases the data that is transferred across the WAN when some or all of the client computers of a WSUS server are located in different locations.
Decreases the data that is transferred across the Internet if WSUS client computers that are located in the same subnet are configured to download updates from Microsoft Update.
To enable peer caching
Log on to the computer by using an account that is a member of the local Administrators group.
Click Start, click Run, type
gpedit.msc, and then press ENTER.In the left pane of the Group Policy Management Console (GPMC), expand Computer Configuration, expand Administrative Templates, expand Network, and then click Background Intelligent Transfer Service.
In the Setting pane, double-click Allow BITS Peercaching.
In the top pane of the dialog, click Enabled, and then click OK.
In the Setting pane, double-click Maximum network bandwidth used for Peercaching.
In the top pane of the dialog box, click Enabled.
In the Options pane, set the maximum bandwidth in bits per second (the default is 1048576), and then click OK.
In the Setting pane, double-click Limit the BITS Peercache size.
In the top pane of the dialog box, click Enabled.
In the Options pane, set the percentage of disk space to use for the peer cache (the default is 5 percent), and then click OK.
In the Setting pane, double-click Limit the age of files in the BITs Peercache.
In the top pane of the dialog box, click Enabled.
In the Options pane, set the number of days (the default is 90), and then click OK.