BranchCache in Windows 7

BranchCache in Microsoft Windows 7 can be used for businesses that operate from more than one office locations. It is basically a file caching service which can automatically retrieve and distribute the local file copies between Windows 7 clients.

Infrastructure requirements for BranchCache

·         Client computers should have Windows 7 as the operating system, and BranchCache should be enabled on it.

·         Web servers and File servers should have Windows Server 2008 as the operating system, and BranchCache should be enabled on it.

BranchCache operates in either of two modes:

• Distributed Cache  –This modeuses peer-to-peer architecture and is useful for branch offices that don’t have a local server.
• Hosted Cache–This mode uses a client/server architecture. Clients upload cache contents to a Windows Server, which is called the Hosted Cache. The clients that need the same contents can retrieve it directly from the Hosted Cache.

Hosted Cache mode

The Hosted Cache acts as a storehouse of data which is downloaded from BranchCache-enabled servers at the branch office by BranchCache-enabled clients. The Hosted Cache mode does not require a dedicated server. The BranchCache feature can be enabled on any server with a Windows Server 2008 operating system that is located in a branch.
The Hosted Cache mode follows the following strategy to cache and retrieve data:

1. Requests to the content server for a file and their retrieval by the client computer are made in a similar way like how it is done without BranchCache.
2. The content server authorizes and authenticates the client, and when this is successful, the content metadata is returned from the same channel used for sending the data. 
3. Hashes in the metadata are used by the client for searching the file.
4. A Secure Sockets Layer (SSL) connection is established by the client with the Hosted Cache server, and the content identifiers can be sent over this encrypted channel. 
5. The Hosted Cache server establishes the connection with the client and retrieves the blocks which are not cached yet.
6. If the same file is requested by some other client, the content server again authorizes the user and sends content identifiers. 
7. These identifiers are used by the client for requesting the data from the Hosted Cache server, which encrypts the data and then sends it to the client.
8. The client decrypts the data, and makes sure that it is exactly similar to the block hashes that were received from the content server with the content metadata. It also ensures that the content has not been altered.

Distributed Cache mode

In this mode, the client computer retrieves the cache contents through the WAN. Then these contents are directly sent to authorized clients whenever they request. This mode is best for branch offices with less than 50-55 users.
Again, the process followed by this mode is identical to the process used by the Hosted Cache mode; the only difference is that requests for cached content are sent to the local network and a Hosted Cache server is not required.

The performance of applications is enhanced by BranchCache with one of the following protocols:

• HTTPS and HTTP – Used by browsers.
• SMB (including signed SMB traffic) - Used for shared folders.

BranchCache works only when the client requests data. It does not increase WAN utilization, being a passive cache.

Configuring the BranchCache Server

1. Start Server manager and click Add Features.
2. In the Add Features Wizard, select the BranchCache check box, and then click Next.
3. Click Install on Confirm Installation Selections window.
4. Click Close in the Add Features Wizard.
5. Expand Configuration in the left pane, and click Services.
6. In the central pane, click BranchCacheand then click Start Service.

BranchCache Client Configuration

On the Windows 7 client, you need to configure the GPO by editing the settings in the MMC.

1. Click Start and type Group Policy in the search box, then click Edit Group Policy from the search results.
2. Click Administrative Templates in Computer Configuration.
3. Click Network, and then click Branch Cache.
4. To enable, any of the given options, as shown in the screen below, double click it. For example it.

Importing the BranchCache certificate on client computers

To import the BranchCache certificate into the Trusted Root Certification Authorities certificate store for the local computer on each BranchCache client computer,perform these steps. Note: To perform these steps you should have Administrator’s account privileges, you shouls have a server in the network from where you can import the cert file:

1.       Click Start, then click Run, and then type mmc.

2.       Click Confirm Installation Selections Confirm Installation Selections from the search results.

3.       Click File, and then click Add/Remove Snap-in. The Add or Remove Snapins dialog box opens.Click Certificates, and then click Add.

4.       In the Certificates snap-in page, click Computer account, and then click Next.

5.       In Select Computer, ensure that Local computer is selected, click Finish, and then click OK. The Certificates snap-in is now added to the MMC.

6.       In the MMC, double-click Certificates (Local Computer), and then double-click Trusted Root Certification Authorities.

7.       Click Certificates.

8.       On the Action menu, click All Tasks, and then click Import. The Certificate Import Wizard opens.

9.       Click Next, thenclick Browse in the File to import. In the Open dialog box, go to the folder location where you saved the BranchCache.cert file. Select the file and then click Open.

10.   On the Certificate Import page, click Next.

11.   In Certificate Store, ensure that Trusted Root Certification Authorities is selected, and then click Next.

12.  Click Finish. An information dialog box opens and displays the message The import was successful. Click OK.

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