Welcome back to your free Windows 7 training course. In this video I will look at BranchCache
It is not uncommon for companies to have branch offices connected to a central
office. Internet speed and connections are getting better, but sometimes you may find
that the link between head office and a branch office to be quite slow and may even be unreliable.
This especially may be the case when you are dealing with links that travel half away across
the world. BranchCache works by caching files on the
local network after they have been copied over the wide area network. If anther computer
requests a file that has been cached, the file is copied over the local area network
rather than the wide area network. This helps reduce the amount of traffic traveling over
your wide area networks. In order to start using BranchCache you require
Windows 7 Enterprise or Ultimate edition and also Windows server 2008 R2. Once you have
configured BranchCache to operate it will automatically by default kick in when the
round trip latency from your client to server exceeds 80 milliseconds. If you have a high
speed link that has low latency, BranchCache even when configured correctly may never operate.
To change this, you need to change the default latency.
BranchCache can operate in two different modes. The first most is hosted mode. Hosted
mode requires Windows server 2008 R2 at each branch location. The data when transferred
across the network is encrypted with SSL encryption so the server also requires a SSL certificate.
The advantage of hosted mode is that BranchCache is always available assuming the server
is always on. The way hosted mode works is like this. When
a client attempts to access a file across the wide area network the round trip is calculated.
If it is greater than the default 80 milliseconds, that is the time take from the client computer
to the WAN to the server and back again, the file is automatically cached with BranchCache.
If anther computer on the local network now attempts to access the same file across the
wide area network, the client can instead access the file from the cache on the local
server. When the file request comes through, the server will first check over the WAN link
to see if the file has changed since it cached it and if not will transfer the file to the
client from its cache. This saves the file having to be copied over the WAN link a second
time. If you don't have Windows server 2008 R2
at each branch office, you can use the second mode called distributed cache mode. In this
mode each widows 7 computer has its own cache. When a file is copied over the network it
is stored on the local computer. If anther Windows 7 computer wants the same
file, it will send a broadcast on the network asking the other computers if one of them
has it. If one of the computers does, the file will be transferred from that computer
rather than using the wide area network. In order to start using BranchCache it needs
to be set up. This can be done through group policy or using NetSH. If you use group
policy the settings are found in computer configuration, administrative templates, network
and than BranchCache. There are five settings for BranchCache found
in group policy. The first "Turn on BranchCache" when enabled simply turns on
BtanchCache. If you do not configure this setting BranchCache will not operate regardless of
what you set the other settings to. The next setting "Set BranchCache distributed
cache mode" configures BranchCache to run in distributed mode. If you want to run
BarnchCache to run in distributed mode you simply need to enable this setting.
The next setting "set BranchCache hosted cache mode" configures BranchCache to run
in hosted mode. Once you enable this setting you need to also configure which server
BranchCache will contact to download data. The next setting "configure BranchCache
for network files" determines the latency time that will be used with BranchCache.
The default is 80. Remember this setting is the round trip value. That is the time taken
from the client computer across the WAN and back again. If you want to enable BranchCache
to always operate set this value to zero. If you want to stop BranchCache from operating
then set the value really high. The last setting "set percentage of disk
space used for client computer cache" is the percentage of hard disk space that
BranchCache will use to store files. The default is 5 percent. This is worked out from the
total hard disk space not the available free space.
In a large enterprise environment you are most likely going to use group policy to configure
BranchCache. However there is also a number of NetSH commands that you can use
to configure BranchCache. The first command I want to look at is the
NetSH BranchCache show status command. When this command in run from a command prompt,
this will show that current status of the service that runs BranchCache and the service
mode BranchCache is running in. Service mode being weather BranchCache is in hosted mode
or distributed mode. BranchCache is currently not configured.
If I want to configure BranchCache to run in hosted mode, I would run the command
BranchCache set service mode equals hosted client. Following this I need to enter in the server
by typing location equals the BranchCache server in this case fs1.training.local.
Notice when this command is run it also starts the BranchCache service and configures the
firewall. This means you could configure your Windows 7 client to start using BranchCache
with one command. If you want to configure BranchCache to run in distributed mode. It
is a simply matter of running the same command again but this time change the mode to distributed.
Notice that this time I do not need to add the location parameter because distributed
mode does not use a server. The next command sets the cache size that
will be used with BranchCache. The amount is in bytes so this example sets the cache
to 20 megabytes. You can also set the size based on the disk size. To do this use the
size parameter followed by percent equals true.
Once you configure BranchCache you will probably want to get some statistics to see if it is
working. To do this run the command show local cache. This will show you how the cache is
configured, where it is stored and how much cache is currently in use.
If you find that the cache never seems to get used, you may need to reduce the latency
value that BranchCache is working on. If you set the value to zero, BranchCache will
cache all files. If you simply want to confirm it is working set the value to zero. Later
on you can increase the value. If you use NetSH you will not need to configure
the firewall. If however you use group policy you will need to configure the firewall either
manually or through group policy. BranchCache needs certain ports open which can change
depending on which mode it is running in. The first port that needs to be opened is
port 80 for inbound and outbound traffic. This is regardless of which mode you use.
If you decide to use distributed mode you require UDP port 3702 open for inbound and
outbound traffic. If you decide to use hosted mode you only require TCP port 443
for outbound traffic. When used correctly, BranchCache should help
to take some load off your wide area networks which should hopefully give your end users
a better experience. In the next video I will look at BitLocker. BitLocker is a system
in Windows 7 that allows you to encrypt your hard disk protecting it from theft.
For the rest of this free training course on Windows 7, please check out our web page
or are you tube channel. Thanks again for watching.