BranchCache Technical Preview

Veröffentlicht: Februar 2012

Letzte Aktualisierung: Februar 2012

Betrifft: Windows 8 Consumer Preview

[Dieses Thema gehört zur Dokumentation der Vorabversion und kann in zukünftigen Versionen geändert werden. Leere Themen sind als Platzhalter enthalten.]

Using servers to deliver content over wide area network (WAN) connections allows organizations to store content and applications in remote datacenters. Web servers, file servers, and application servers are being moved from main offices to remote locations, and employees depend on WAN connections to access their critical data.

In Windows Server "8" Beta and Windows 8 Consumer Preview, BranchCache can optimize the bandwidth over WAN connections between content servers and remote client computers. The following sections describe the components and new features in BranchCache.

BranchCache is a WAN bandwidth optimization technology that is included in the Windows Server "8" Beta and Windows 8 Consumer Preview operating systems. To optimize WAN bandwidth, BranchCache downloads content from your content servers and caches the content at office locations, which allows client computers at office locations to access the content locally.

After a client computer has downloaded content one time, other clients that request the same content do not download it from the content servers over the WAN connection. Instead, they retrieve small identifiers, called content information, from the remote content servers. Clients use the content information to find the content in the local office. This content is cached on a computer running Windows Server or on other client computers, depending on the mode in which you have deployed BranchCache.

Hosted cache mode   When there is a server running Windows Server "8" Beta in the office location, BranchCache client computers are configured in hosted cache mode, and the server is called a hosted cache server.

Distributed cache mode   If your office does not have a server available to deploy as a hosted cache server, you can configure BranchCache in distributed cache mode on clients . In this mode, the client computers cache downloaded content and share it with other computers in the office.

When you deploy BranchCache, you can deploy three types of content servers:

  • File server   Supported file servers include computers that are running Windows Server "8" Beta or Windows Server 2008 R2 that have the File Services server role and the BranchCache for Network Files role service installed. These file servers use the server message block (SMB) protocol to exchange information. After you install your file server, you must also share folders and enable the generation of content hashes (also called content information) for shared folders. You do this by using Group Policy or Local Computer Policy to enable BranchCache.

  • Web server   Supported web servers are computers that are running Windows Server "8" Beta or Windows Server 2008 R2 that have the Web Server (IIS) server role installed, and that use Hypertext Transfer Protocol (HTTP) or HTTP Secure (HTTPS). In addition, the web server must have the BranchCache feature installed.

  • Application server   Supported application servers are computers that are running Windows Server "8" Beta or Windows Server 2008 R2 with Background Intelligent Transfer Service (BITS) installed and enabled. In addition, the application server must have the BranchCache feature installed.

BranchCache security works seamlessly with your existing network security architectures. It does not require additional equipment or complex security configuration. BranchCache encrypts cached content and content information, and it does not allow unauthorized access to files in the cache. BranchCache can speed up encrypted communication through HTTPS or IPsec without compromising security.

BranchCache does not alter any Windows authentication or authorization processes. After you deploy BranchCache, authentication is still performed by using domain credentials, and authorization with Access Control Lists (ACLs) is unchanged. In addition, other configurations continue to function as they did before the BranchCache deployment.

BranchCache security is based on content information that is created on the content servers. This metadata, which is much smaller than the size of the actual content that it represents, takes the form of a series of hashes. After the content information is created, it is used in BranchCache message exchanges rather than the actual content, and it is exchanged by using the supported protocols (HTTP, HTTPS, and SMB).

BranchCache in Windows Server "8" Beta and Windows 8 Consumer Preview provides performance, manageability, scalability, and availability improvements over BranchCache in Windows Server 2008 R2 and Windows 7. This version of BranchCache provides the following improvements.

  • Multiple hosted cache servers   In the previous version of BranchCache, you could deploy only one hosted cache server per office location. Windows Server "8" Beta provides the ability to scale hosted cache mode deployments for offices of any size by allowing you to deploy as many hosted cache servers as are needed at a location.

  • Database performance   BranchCache now uses the Extensible Storage Engine (ESE) database technology that powers Microsoft Exchange Server. This enables a single hosted cache server that is running Windows Server "8" Beta to keep up with the demands of more people while using the same hardware that is utilized for a hosted cache server running Windows Server 2008 R2. It also allows a hosted cache server to store significantly more data (on the order of terabytes), which is necessary to provide high optimization for many people.

  • Office configuration   BranchCache no longer requires office-by-office configuration. There is no requirement for a Group Policy Object for each location, which streamlines deployment. A single Group Policy Object that contains a small group of settings is all that is required to deploy BranchCache in any size organization, from a large enterprise to a small business.

  • Computer configuration   Client computer configuration is automatic. Computers can be configured through Group Policy as distributed cache mode computers by default. However, they will search for a hosted cache server. If one is discovered, clients automatically self-configure as hosted cache mode computers instead.

  • Data encryption   Cache data is kept encrypted and hosted cache servers do not require server certificates. Previously, hosted cache servers were required to have a server certificate that was issued by a certification authority (CA) that client computers at the office location trusted. BranchCache security is improved with data encryption so that additional drive encryption technologies are no longer needed to protect cached data.

  • Manageability   BranchCache is now manageable with Windows PowerShell and Windows Management Instrumentation (WMI). This enables scripting and remote management of BranchCache content servers, hosted cache servers, and client computers.

  • Preloaded content   BranchCache provides tools to manipulate data and preload the content at remote locations ahead of time.

  • Integration with file server   BranchCache is deeply integrated with the Windows-based file server, and it borrows the technology that is used to divide files into small pieces and eliminate duplicates. This increases the chance of finding duplicate pieces in independent files, resulting in greater bandwidth savings. BranchCache is also more tolerant of small changes in large files.

  • File calculations   File division calculations are performed only one time, and they can be done offline. When a client computer that is running Windows 8 Consumer Preview downloads content from a file server or web server that is running Windows Server "8" Beta and that is using disk deduplication technology, BranchCache does not spend CPU cycles calculating how to divide the content because the file server and web server have already made these calculations. Content information is calculated offline before a client computer requests a file. This provides faster performance and more bandwidth savings because content information is ready for the first client that requests the content, and the calculations have already been performed.

You can deploy BranchCache in a domain-based or non-domain based environment.

You must provide network connectivity, such as a virtual private network (VPN) or DirectAccess connection, between the content servers and office locations so that client computers can access content on the content servers.

For distributed cache mode:

You must deploy one or more content servers. For more information, see BranchCache content servers earlier in this document.

In addition, you must deploy client computers that are running Windows 8 Consumer Preview (or some editions of Windows 7). Client computers must have BranchCache distributed cache mode enabled.

For hosted cache mode:

You must deploy one or more content servers as described previously in this section. For more information, see BranchCache content servers earlier in this document.

In addition, you must deploy client computers that are running Windows 8 Consumer Preview (or some editions of Windows 7). Client computers must have BranchCache hosted cache mode enabled; and you must deploy one or more hosted cache servers.

BranchCache is supported on some editions of Windows Server 2008 R2 and Windows 7. For more information, see BranchCache on Microsoft TechNet.