An Overview of a BranchCache Implementation

Last time, I wrote about the new BranchCache capability in Windows 7 and Server 2008 R2. Today I'll give you an overview on how to go about setting it up. (You’ll find details on these steps online in various TechNet docs on Microsoft’s website, but it’s useful to understand the big picture before you start drilling down to the specifics.) Your first decision is whether to use hosted mode or distributed mode. My preference is for hosted mode, but if you have a small branch (fewer than 50 systems) and only one subnet, you can use distributed mode and avoid tasking a server to be the cache point. If you choose distributed mode, you can use the netsh command to change the default setting of 5% of the hard disk size as the upper limit on the cache size for any one Windows 7 client. If you use hosted mode, you have to install the BranchCache feature using the Server Manager console on both the central office server and the branch office cache host. (If the central office system is already set up to be a file server, you can just install the role service titled “BranchCache for Network Files.”) The central-office system's BranchCache functionality is turned on through its local Group Policy Object. The location is Computer Configuration, Policies, Administrative Templates, Network, Lanman Server, and Hash Publication for BranchCache. With this policy, you can choose to allow BranchCache to publish content metadata for all file shares on the server, or only for those that have been specially tagged. (You can tag the shares that you want to participate in BranchCache using the Share and Storage Management console on the file server.) You’ll need to set up the cache host server with a certificate, because the clients use TLS when talking to the caching server. Import the certificate with the Certificates MMC snap-in, and associate it with BranchCache using the netsh command. Finally, you have to ensure that TCP ports 80 and 443 are open on the caching server. On the client side, BranchCache is turned off by default. You can turn it on through Group Policy, which is the preferred method (Computer Configuration, Policies, Administrative templates, Network, and BranchCache) - or you can use the netsh command, for example if you're only configuring a single machine. Either way, you also need to specify whether you want the clients to use distributed or hosted mode. You can check the status of your client BranchCache status with the command “netsh branchcache show status all” after you’re done configuring the clients.