My internal training in the next version of SharePoint has sparked some intriguing thoughts around what will be possible in the near future to help our customers in situations where bandwidth constraints are making SharePoint performance less than optimal.
I have searched high and low, internally and our external sources (TechNet, MSDN), for any SharePoint specific information in regards to Branch Cache. There is a good white paper here; http://technet.microsoft.com/en-us/library/ff468721(WS.10).aspx on setting up a lab to test Branch Cache. The lab in this white paper is a good start on how to setup a lab where you can test the functionality of Branch Cache for SharePoint as it has steps on configuring IIS 7.5 for Branch Cache, which would be the same as setting up SharePoint for Branch Cache.
There are a few things I would like to add to the information given in the white paper though.
When testing the speed of downloading documents from the SharePoint server on client machines there is a very easy way to visualize the difference between a slower WAN type connection and the cached document download. Turn on bandwidth connection limits in IIS for the web application you are testing caching on (Figure 1). While testing, I set the Maximum Bandwidth (Bytes/second) to 57344; which is 50KB a second, or about the same as the old 56K MODEM days (Figure 2). For a multi megabyte file, you can see in the IE download window that without caching the file transfers at about 50KB (Figure 3).
The first time the document is downloaded from the SharePoint server, you will see the speed is about the same as the IIS web application bandwidth setting. Downloading the same file again, you should see that the file is downloaded much faster than the first time. This is the Branch Cache version of the file being downloaded. I could not snap a screenshot of the second download as the 3.5MB file completed too fast (under a second!).
To rerun the test on the same client run the following command to clear out the Branch Cache files on all of client computers.
NETSH branchcache flush
That’s it for now, the white paper above has some more information on how to use Performance Monitor to monitor Branch Cache usage and find out exactly how many bytes you are saving. So now when SharePoint 2010 is released you can rejoice in your new found SharePoint speed!