Windows Server 2008 R2 and BranchCache

Driven by challenges of reducing the costs and complexity of Branch IT, organizations are seeking to centralize applications. However, as organizations centralize applications, the dependency on the availability and quality of the wide-area network (WAN) link increases. The increased utilization of the WAN link is a direct result of centralization, as is the degradation of application performance. Recent studies have shown that despite the reduction of costs associated with WAN links, WAN costs are still a major component of enterprises’ operational expenses.

BranchCache in the Windows 7 and Windows Server 2008 R2 operating systems can help increase network responsiveness of centralized applications when accessed from remote offices, giving users in those offices the experience of working on your local area network. BranchCache also helps reduce WAN utilization.

When BranchCache is enabled, a copy of data accessed from intranet Web and file servers is cached locally within the branch office. When another client on the same network requests the file, the client downloads it from the local cache without downloading the same content across the WAN.

BranchCache can operate in one of two modes:

• Distributed Cache. Using a peer-to-peer architecture, Windows 7 client computers cache copies of files and send them directly to other Windows 7 client computers, as needed. Improving performance is as easy as enabling BranchCache on your Windows 7 client and Windows Server 2008 R2-based computers. Distributed Cache is especially beneficial for branch offices that do not have a local server.
• Hosted Cache. Using a client/server architecture, Windows 7 client computers cache content to a computer on the local network running Windows Server 2008 R2, known as the Hosted Cache. Other clients who need the same content retrieve it directly from the Hosted Cache. The Hosted Cache computer can run the Server Core installation option of Windows Server 2008 R2 and can also host other applications.

The following diagram illustrates these two modes:

BranchCache can improve the performance of applications that use one of the following protocols:

• HTTP and HTTPS. The protocols used by Web browsers and many other applications, such as Internet Explorer or Windows Media, among others
• SMB (including signed SMB traffic). The protocol used for shared folders

BranchCache only retrieves data from a server when the client requests it. Because it is a passive cache, it will not increase WAN utilization. BranchCache only caches read requests and thus will not interfere with a user saving a file.

BranchCache improves the responsiveness of common network applications that access intranet servers across slow links. Because it does not require any infrastructure, you can improve the performance of remote networks simply by deploying Windows 7 to client computers, deploying Windows Server 2008 R2 to server computers, and enabling BranchCache.

BranchCache works seamlessly alongside network security technologies, including SSL, SMB Signing, and end-to-end IPsec. You can use BranchCache to reduce network bandwidth utilization and to improve application performance, even if the content is encrypted