Managing BITS

Windows 7 includes Background Intelligent Transfer Service (BITS) 3.5. BITS is a file-transfer service designed to transfer files across the Internet using only idle network bandwidth. Unlike standard Hypertext Transfer Protocol (HTTP), File Transfer Protocol (FTP), or sharedfolder file transfers, BITS does not use all available bandwidth, so you can use BITS to download large files without affecting other network applications. BITS transfers are also very reliable and can continue when users change network connections or restart their computers.

In Windows 7, BITS can take advantage of BranchCache to reduce wide area network (WAN) bandwidth utilization.

BITS Network Protocol

BITS uses HTTP to transfer files in the same way as a Web browser. However, unlike standard HTTP transfers, BITS transfer speed is carefully throttled. Using the HTTP protocol enables BITS to work through proxy servers, to authenticate both clients and servers, and to provide encryption using Secure Sockets Layer (SSL) certificates. If you want to explicitly allow or block BITS transfers at your firewall, create filters for the HTTP or Hypertext Transfer Protocol Secure (HTTPS) protocol and the source or destination networks. For example, you can limit HTTP communications so that Windows 7 clients can connect only to your WSUS server.

BITS File Storage

Because updates can be very large and have the potential to affect network performance, Windows Update uses BITS to download updates from Microsoft Update or from a WSUS server. Additionally, custom applications can use BITS to transfer files. To use BITS, the Background Intelligent Transfer Service must be running.