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BranchCache supports the same network protocols that are commonly used in enterprises—HTTP(S)
and SMB—so that any applications based on these network protocols will automatically benet from the
technology. Examples of these applications include Microsoft Ofce SharePoint 2007, Internet Explorer,
CopyFile, and others. For example, Windows Media Player uses the HTTP protocol so internal training
videos can be cached and viewed more efciently by branch ofce users. BranchCache also supports
network security protocols (such as SSL and IPSec), helping ensure that only authorized PCs can access
requested data.
To implement BranchCache, you need to install Windows Server 2008 R2 on the remote le servers, Web
servers, and optionally the branch ofce server on which the cache is hosted.
Transparent Caching
Before Windows 7, client PCs always retrieved the le from the server computer to open a le across a
slow network—even if the client PC had recently read the le. With transparent caching in Windows 7,
client PCs cache remote les more frequently, which helps reduce the number of times a client PC has to
retrieve the same data from a server computer.
The rst time a user opens a le in a shared folder, Windows 7 reads the le from the server computer
and then stores it in a cache on the PC’s hard disk. For any subsequent times a user reads the same
le, Windows 7 retrieves the cached le from the hard disk instead of the server computer. Windows 7
always contacts the server computer to make sure the cached copy is up-to-date. The cache is never
accessed if the server computer is unavailable, and updates to the le are always written directly to
the server computer.
By default, transparent caching is not enabled on fast networks. You can use Group Policy to enable
transparent caching to improve the efciency of the cache and to save disk space on the client.
You can also congure the amount of disk space the cache uses and prevent specic le types from
being synchronized.
As the feature name implies, transparent caching is invisible to users, which makes it seem more like they
are on the same LAN as the server computer. In addition, transparent caching helps reduce bandwidth
utilization across WAN links.
Windows 7 for IT Pros: Make People Productive Anywhere
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