BranchCache
is a new technology that has been introduced in Windows Server 2008 R2
and Windows 7, BranchCache allows an organization with slower links
between offices to cache data so downloads between offices do not have
to occur each time a file is accessed.
For example, say John comes
into work and logs in to the network. John accesses the corporate
website and downloads a media file that takes four minutes to download.
With BranchCache enabled, when Judy comes into work and connects to the
corporate website and tries to download the same media file, the file
will be cached from the previous download, and Judy will have immediate
access to the file.
There are two types of BranchCache configurations that you can set up—distributed cache mode and hosted mode:
Distributed Cache Mode
In the distributed cache mode configuration, all Windows 7 client
machines cache the files locally on the client machines. So in the
preceding example, after John downloaded the media file, Judy would
receive the cached media file from John's Windows 7 machine.
Hosted Mode
In the hosted mode configuration, the cache files are cached on a local
(within the site) Windows Server 2008 R2 machine. So in the preceding
example, after John downloaded the media file, the cached file would be
placed on a Windows Server 2008 machine by default and all other users
(Judy) would download the media file from the Windows Server 2008 R2
machine.
1. Distributed Cache Mode Requirements
If you decide to
install BranchCache in the distributed cache mode configuration, a
hosted cache server running Windows Server 2008 R2 is not required at
the branch office. To set up distributed cache mode, the client machines
must be running either Windows 7 Enterprise Edition or Windows 7
Ultimate Edition.
The Windows 7 machines would
download the data files from the content servers at the main branch
office, and then these Windows 7 machines become the local cache
servers. To set up distributed cache mode, you must install a Windows
Server 2008 R2 content server at the main office first. After the
content server is installed, physical connections (WAN or VPN
connections) between the sites and branch offices must be established.
Client computers running
Windows 7 have BranchCache installed by default, but you must, however,
enable and configure BranchCache and configure firewall exceptions.
Complete Exercise 1 to configure BranchCache firewall rule exceptions.
On a domain controller, click Start => Administrative Tools => Group Policy Management. This opens the Group Policy Management console. In the Group Policy Management console, expand the following path: Forest Domains =>
Group Policy Objects. Make sure that the domain you choose contains the
BranchCache Windows 7 client computer accounts that you want to
configure. In
the Group Policy Management console, right-click Group Policy Objects
and select Create And Link Group Policy Here. Name the policy BranchCache Client and press Enter. Right-click BranchCache Client and click Edit. The Group Policy Management Editor console opens. In
the Group Policy Management Editor console, expand the following path:
Computer Configuration ^Policies ^-Windows Settings ^Security Settings
^Windows Firewall with Advanced Security ^-Windows Firewall with
Advanced Security => LDAP => Inbound Rules. Right-click Inbound Rules and then click New Rule. The New Inbound Rule Wizard opens. In
Rule Type, click Predefined, expand the list of choices, and then click
BranchCache— Content Retrieval (Uses HTTP). Click Next. In Predefined Rules, click Next. In
Action, ensure that Allow The Connection is selected, and then click
Finish. You must select Allow The Connection for the BranchCache client
to be able to receive traffic on this port. Now
to create the WS-Discovery firewall exception, right-click Inbound
Rules, and click New Rule. The New Inbound Rule Wizard opens. In Rule Type, click Predefined, expand the list of choices, and then click BranchCache— Peer Discovery (Uses WSD). Click Next. In Predefined Rules, click Next. In Action, ensure that Allow The Connection is selected, and then click Finish. In
the Group Policy Management Editor console, right-click Outbound Rules,
and then click New Rule. The New Outbound Rule Wizard opens. In
Rule Type, click Predefined, expand the list of choices, and then click
BranchCache— Content Retrieval (Uses HTTP). Click Next. In Predefined Rules, click Next. In Action, ensure that Allow The Connection is selected, and then click Finish. Create
the WS-Discovery firewall exception by right-clicking Outbound Rules,
and then click New Rule. The New Outbound Rule Wizard opens. In Rule Type, click Predefined, expand the list of choices, and then click BranchCache— Peer Discovery (Uses WSD). Click Next. In Predefined Rules, click Next. In Action, ensure that Allow The Connection is selected, and then click Finish.
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Now that you have looked at the distributed cache mode configuration, let's take a look at the hosted mode configuration.
2. Hosted Mode Requirements
To set up a hosted mode
BranchCache configuration, you must first set up a Windows Server 2008
R2 hosted cache server at the main and branch offices. You also need
Windows 7 Enterprise or Windows 7 Ultimate computers at the branch
offices.
The Windows 7 machines
download the data from the main cache server, and then the hosted cache
servers at the branch offices obtain a copy of the downloaded data for
other users to access.
Your network infrastructure
must also allow for physical connections between the main office and the
branch offices. These connections can be VPNs or some type of WAN
links. After these requirements are met, your cache server must obtain a
server certificate so the client computers in the branch offices can
positively identify the cache servers.
Exercise 2
walks you through the process of installing the BranchCache feature on a
Windows Server 2008 R2 machine. To accomplish this exercise, you must
be logged in to the Windows Server 2008 machine as an administrator.
Open the Server Manager by clicking Start => Administrative Tools => Server Manager. In Server Manager, right-click Features and then choose the Add Feature link. The Add Features Wizard starts. Select the BranchCache check box and click Next. At the Confirm Installation Selections screen, click Install. After the BranchCache feature installs, click Close. In the Server Manager left window pane, double-click Configuration and then click Services. In the Services detail pane, double-click BranchCache. The BranchCache Properties dialog box appears. Click the General tab and then click Start. Click OK.
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Make sure to repeat this
exercise on all branch office cache servers. Now one of the requirements
for BranchCache was a physical connection between the main office and
the branch offices. In the next section, you will look at configuring
DirectAccess.
