branchcache design

BranchCache Design Guide

Microsoft Corporation

Published: February, 2010

Author: James McIllece

Editor: Scott Somohano

AbstractBranchCache is a wide area network (WAN) bandwidth optimization technology that is included in

some editions of the Windows Server® 2008 R2 and Windows® 7 operating systems. To optimize

WAN bandwidth, BranchCache copies content from your main office content servers and caches

the content at branch office locations, allowing client computers at branch offices to access the

content locally rather than over the WAN.

This design guide provides information about BranchCache in both distributed cache mode and

hosted cache mode that assists you in determining the best way to deploy BranchCache on your

network.

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Contents

BranchCache Design Guide...........................................................................................................4

About this guide........................................................................................................................... 4

BranchCache Overview.................................................................................................................. 5

Key BranchCache design points.................................................................................................5

BranchCache terminology...........................................................................................................6

BranchCache installation guide................................................................................................8

Operating system versions for BranchCache..............................................................................8

Identify BranchCache Deployment Goals.......................................................................................9

Optimize wide area network performance for employees in branch offices with only client

computers.................................................................................................................................. 11

Optimize wide area network performance for employees in branch offices with server computers

.................................................................................................................................................. 12

Map Deployment Goals to a BranchCache Design.......................................................................13

Distributed cache mode design.....................................................................................................14

Hosted cache mode design..........................................................................................................16

Evaluate BranchCache Design Examples....................................................................................17

Distributed cache mode example..................................................................................................17

Hosted cache mode example.......................................................................................................19

BranchCache dual mode example................................................................................................21

Plan BranchCache Deployment....................................................................................................22

Plan content server deployment...................................................................................................22

Plan BranchCache distributed mode deployment.........................................................................23

Plan BranchCache hosted cache mode deployment....................................................................24

Deployment and migration tools and information..........................................................................26

BranchCache Design Guide

BranchCache is a wide area network (WAN) bandwidth optimization technology that is included in

the Windows Server® 2008 R2 and Windows® 7 operating systems.

To optimize WAN bandwidth, BranchCache copies content from your main office content servers

and caches the content at branch office locations, allowing client computers at branch offices to

access the content locally rather than over the WAN.

At branch offices, content is stored either on servers that are running the BranchCache feature of

Windows Server 2008 R2 or, when no server is available in the branch office, on computers

running Windows 7. After a client computer requests and receives content from the main office

and the content is cached at the branch office, other computers at the same branch office can

obtain the content locally rather than contacting the main office over the WAN link.

BranchCache increases end user productivity by improving content query response times for

clients and servers in branch offices, and can also help improve network performance by

reducing traffic over WAN links.

About this guideThis guide provides recommendations to help you plan a new deployment of BranchCache,

based on the requirements of your organization and the particular design that you want to create.

This guide is intended for use by systems and network architects and administrators, and

highlights your main decision points as you plan your BranchCache deployment.

This guide describes a set of deployment goals that are based on two primary BranchCache

designs, and the guide helps you decide the most appropriate design for your environment. You

can use these deployment goals to form one of the following BranchCache designs based on the

needs of your environment:

BranchCache distributed cache mode for small branch offices that contain only client

computers

BranchCache hosted cache mode for branch offices that contain servers in addition to client

computers

For each design, you will find guidelines for gathering required data about your environment. You

can then use these guidelines to plan and design your BranchCache deployment. After you read

this guide and finish gathering, documenting, and mapping your organization's requirements, you

will have the information necessary to begin deploying BranchCache using the BranchCache

Deployment Guide.

To learn how to deploy BranchCache, see the BranchCache Deployment Guide:

Available in Word format at the Microsoft Download Center: http://go.microsoft.com/fwlink/?

LinkId=166656

http://go.microsoft.com/fwlink/?LinkId=166656


Available in HTML format in the Windows Server® 2008 and Windows Server® 2008 R2

Technical Library: http://go.microsoft.com/fwlink/?LinkId=166639

BranchCache Overview

This topic provides key information about BranchCache, including operating system versions that

support BranchCache and BranchCache terminology. This topic contains the following sections:

Key BranchCache design points

BranchCache terminology

BranchCache installation guide

Operating system versions for BranchCache

Key BranchCache design pointsWhile you design your BranchCache solution, it is useful to remember the following key points:

BranchCache can decrease wide area network traffic between computers that are running

Windows Server® 2008 R2 and computers that are running Windows® 7.

BranchCache has two modes of operation, distributed cache mode and hosted cache mode.

When the content cache at a branch office is distributed among client computers,

BranchCache is running in distributed cache mode. When the content cache at a branch

office is hosted on a server computer, BranchCache is running in hosted cache mode.

BranchCache is installed by default on client computers running Windows® 7 Enterprise and

Windows® 7 Ultimate, however you must enable BranchCache and create firewall exceptions

to allow BranchCache traffic between client computers.

BranchCache supports the optimization of downloads over end-to-end secure transports such

as Hypertext Transfer Protocol Secure (HTTPS) and Internet Protocol security (IPsec).

To cache application and Web server content that is sent to branch offices over Hypertext

Transfer Protocol (HTTP), you must install the BranchCache feature on the application server

or Web server whose content you wish to cache in branch offices.

To cache File Server content that is sent to branch offices using the Server Message Block

(SMB) protocol, the BranchCache for network files role service of the File Server role in

Windows Server 2008 R2 must be installed and enabled.

BranchCache might not function correctly when used in combination with a hardware-based

WAN accelerator, because WAN accelerators might alter the fields and messages that are

necessary for BranchCache operation. When you deploy a WAN accelerator with

BranchCache, BranchCache might work for some protocols, but not for other protocols. For

example, some WAN accelerators cannot process server message block (SMB) 2.1, but can


process HTTP and HTTPs. Review your WAN accelerator documentation for more

information.

BranchCache is designed to prevent unauthorized access to content. Before transfer

between peers or between clients and the hosted cache server, content is encrypted by

BranchCache. Content can only be decrypted using the identifiers provided by the content

server in the main office. The content server provides identifiers only to authenticated clients

that are members of the same domain as the content server.

Distributed cache mode is best suited for small branch offices that do not contain a local

server for use as a hosted cache server. Distributed cache mode allows you to deploy

BranchCache with minimal hardware deployments in branch offices. However, if the branch

office contains additional infrastructure, such as one or more servers that are running other

workloads, deploying BranchCache in hosted cache mode might be beneficial for the

following reasons:

Increased cache availability. Hosted Cache mode increases the cache efficiency

because content is available even if the client that originally requested and cached the

data is offline. Because the hosted cache server is always available, more content is

cached, providing greater WAN bandwidth savings, and BranchCache efficiency is

improved.

Centralized caching for multiple-subnet branch offices. Distributed cache mode

operates on a single subnet. At a multiple-subnet branch office that is configured for

distributed cache mode, a file downloaded to one subnet cannot be shared with client

computers on other subnets. Because of this, clients on other subnets, unable to discover

that the file has already been downloaded, get the file from the main office content server,

using WAN bandwidth in the process. When you deploy hosted cache mode, however,

this is not the case - all clients in a multiple-subnet branch office can access a single

cache, which is stored on the hosted cache server, even if the clients are on different

subnets. If you have a multiple-subnet branch office with less than 100 users, therefore,

using hosted cache mode is recommended.

You can use the following guidelines to determine the mode in which you want to deploy

BranchCache:

For a branch office that contains less than 100 users and does not have any local servers,

use distributed cache mode.

For a branch office (either single subnet or multiple-subnet) that contains less than 100 users

and also contains a local server that you can use as a hosted cache server, use hosted cache

mode.

For a multiple-subnet branch office that contains more than 100 users, but less than 100

users per subnet, use distributed cache mode.

BranchCache terminologyThe following list provides key terminology for BranchCache. In some cases, common terms,

such as content or client computer, are provided with specific meaning in relation to

BranchCache.

Branch office. A satellite office to the main office. Branch offices contain client computers and

may also contain either client cache servers or hosted cache servers.

BranchCache-compatible protocols. Background Intelligent Transfer service (BITS), Server

Message Block 2 (SMB) protocol, Secure Hypertext Transfer Protocol (HTTPS), and Hypertext

Transfer Protocol 1.1 (HTTP) are compatible with BranchCache.

Client cache server. When BranchCache is deployed in distributed cache mode, client

computers retrieve content from main office content servers and then cache the content. When

other client computers on the same subnet request the content, the client computer that already

has the content acts as a client cache server and sends the content to the computers that request

it. All clients that download, cache, and serve content to other clients automatically act as client

cache servers.

Client computer. A computer at a branch office that is running either Windows 7 Enterprise or

Windows 7 Ultimate and that has BranchCache enabled.

Content. The files that are served to computers in branch offices by the content server.

Content information. Automatically generated metadata that is used to describe content. Also

called hashes.

Content server. Source repository, located at the main office, for the content that is accessed by

client computers in branch offices. Content may reside on either a file server with the

BranchCache for Network Files role service of the File Services server role installed, or on a

Web server or BITS-based application server with the BranchCache feature installed. Content

servers transmit content to branch offices using the BranchCache-compatible protocols.

Distributed cache mode. In distributed cache mode, branch office client computers download

content from main office content servers. The client computers then cache the content, and act as

client cache servers, providing the cached content to other client computers on request.

Distributed cache mode is especially beneficial for branch offices that do not have a local server

that can act as a hosted cache server.

Hashes. See content information.

Hosted cache mode. When BranchCache is deployed in hosted cache mode, hosted cache

servers retrieve content from client computers, cache the content, and provide the content upon

request to other client computers in the same branch office.

Hash publication. The process of generating hashes, also called content information, so that

BranchCache clients can download the content information that is stored on content servers.

Hosted cache server. When BranchCache is deployed in hosted cache mode, hosted cache

servers in branch offices cache content and provide the content on request to client computers in

the same branch office. In this mode, client computers perform the initial download of content

from content servers at the main office, and hosted cache servers later download the content

from the clients.

Main office. The office where the content servers are located.

BranchCache installation guideYou can use Server Manager in Windows Server 2008 R2 to install either the BranchCache

feature or the BranchCache for network files role service of the File Services server role,

however each use a different wizard for installation.

To install the BranchCache feature, open Server Manager, click Features, and then click Add

Features; the Add Features wizard opens, and you can install BranchCache from the list that

is provided.

To install the BranchCache for network files role service of the File Services server role,

open Server Manager, click Roles, and then click Add Roles; the Add Roles wizard opens,

and you can install the File Services role with the BranchCache for network files role

service selected.

Use the following table to determine the aspect of BranchCache that you need to install for the

functionality you require.

Functionality Computer location Install this BranchCache element

Content server (BITS

application server)

Main office BranchCache feature

Content server (Web server) Main office BranchCache feature

Content server (file server

using the SMB protocol)

Main office BranchCache for network

files role service of the File

Services server role

Hosted cache server Branch office BranchCache feature with

hosted cache mode enabled

Client cache server Branch office No installation needed; just

enable BranchCache on the

client

Operating system versions for BranchCacheFollowing is a list of operating systems that support different types of BranchCache functionality.

Operating systems for BranchCache client computer functionality:

Windows® 7 Enterprise

Windows® 7 Ultimate

Operating systems for BranchCache content server functionality:

The Windows Server® 2008 R2 family of operating systems can be used as BranchCache

content servers, with the following exceptions:

In Windows Server® 2008 R2 Enterprise Core Install with Hyper-V, BranchCache is not

supported.

In Windows Server® 2008 R2 Datacenter Core Install with Hyper-V, BranchCache is not

supported.

Operating systems for BranchCache hosted cache server functionality:

Windows Server® 2008 R2 Enterprise

Windows Server 2008 R2 Enterprise with Hyper-V

Windows Server 2008 R2 Enterprise Core Install

Windows Server 2008 R2 Enterprise Core Install with Hyper-V

Windows Server 2008 R2 for Itanium-Based Systems

Windows Server® 2008 R2 Datacenter

Windows Server® 2008 R2 Datacenter with Hyper-V

Windows Server 2008 R2 Datacenter Core Install with Hyper-V

Identify BranchCache Deployment Goals

Correctly identifying your BranchCache deployment goals is essential for the success of your

BranchCache design project. Depending on the size of your organization and the level of

involvement that you want to provide for the information technology (IT) staff in any partner

organizations, form a project team that can clearly articulate real-world deployment issues in a

vision statement. Make sure that the members of this team understand the direction in which your

deployment project must move in order to reach your BranchCache deployment goals.

When you deploy BranchCache, you have a choice between the following:

Deploy BranchCache in distributed cache mode to optimize wide area network performance

for employees in branch offices with only client computers. Distributed cache mode does not

require a server computer in each branch office; it also does not require that you purchase or

deploy server certificates.

Deploy BranchCache in hosted cache mode to optimize wide area network performance for

employees in branch offices that contain server computers. When you deploy BranchCache

in hosted cache mode, you must enroll a server certificate to hosted cache servers either by

purchasing a certificate from a third party company, such as Verisign, or by deploying your

own certification authority (CA) and enrolling server certificates to hosted cache servers.

Deploy BranchCache in both distributed cache mode and hosted cache mode. When you

deploy BranchCache in both modes, a hosted cache server is required at each branch office

where you deploy hosted cache mode. A hosted cache server is not required, however, for

branch offices where hosted cache mode is not deployed but distributed cache mode is

deployed.

For client computers, you must choose one BranchCache mode. Client computers cannot

operate in two modes at one time.

Hosted cache mode advantages

For various reasons, deploying BranchCache in hosted cache mode provides more wide area

network (WAN) bandwidth savings than distributed cache mode, even when the branch office

contains only a single subnet. In hosted cache mode, the hosted cache server is always on and

the cached content is always available to clients that request the content.

In distributed cache mode, each client computer that downloads content from the main office

content servers then acts as a client cache server, sharing the content with other client computers

so that the other computers do not have to download the same content. But client computers

power down, and portable computers might be removed from the branch office for undetermined

periods of time, and when the computers are turned off or are absent from the office, the content

that they cached is no longer available to other client computers. In this circumstance, the

requesting client computer must obtain the content from the main office content servers, which

means that the same content is downloaded more than once.

In addition, if you have subnets that contain many computers that use a wireless connection to

the local area network (LAN), distributed cache mode performance suffers because transferring

data over a wireless connection is typically slower than transferring data over a wired connection

to the LAN. In this case, if you deploy hosted cache mode with a hosted cache server that has a

wired connection to the LAN, BranchCache performance is improved.

Considerations for large branch offices

Because you can deploy only one hosted cache server per branch office, there are circumstances

where it is a good idea to choose distributed cache mode rather than hosted cache mode. If the

branch office contains more than 100 workstations and is a multiple subnet environment, a single

hosted cache server might not be able to handle the workload for the entire branch. In this case,

use distributed cache mode to distribute the caching services among many computers rather than

just one.

Deployment goals

The following table lists the main tasks for articulating, refining, and subsequently documenting

your BranchCache deployment goals.

Deployment goal tasks Reference links

Evaluate predefined BranchCache deployment

goals and combine one or more goals to reach

Optimize wide area network performance

for employees in branch offices with only

Note

Deployment goal tasks Reference links

your organizational objectives. client computers

Optimize wide area network performance

for employees in branch offices with server

computers

Accomplish both goals above by deploying

BranchCache in both distributed cache

mode and hosted cache mode.

BranchCache dual mode example.

Map one goal or combine predefined

BranchCache deployment goals to an existing

BranchCache design.

Map Deployment Goals to a BranchCache

Design

Optimize wide area network performance for employees in branch offices with only client computers

A connection between the main office and each branch office must exist before you

deploy BranchCache.

This deployment goal is recommended for branch offices that do not contain server computers.

When you deploy BranchCache for employees in branch offices that contain only client

computers:

Employees with the correct security permissions that are using computers running

Windows 7 and that have BranchCache enabled can access content on your content servers

at the main office; they can also access content that is cached locally by their computer and

other computers at their branch office.

Server computers are not required at the branch office to cache content, because the content

is cached on client computers that are running Windows 7.

Depending on the types of content servers that you have deployed, employees can access

many types of content at the local branch office rather than over the wide area network

(WAN) link to the main office. This includes Web server content, files on a SharePoint server,

training videos, software installation files (such as software patches and antivirus program

signature updates), and file shares.

Due to reduced usage of the WAN, employees might see reduced application response times

and improved application performance.

The following components are required for this deployment goal.

Important

Content server. One or more content servers that are running Windows Server 2008 R2 and

are located in the main office. Content servers can be file servers, application servers, or

Web servers.

Client computers. One or more client computers that are running Windows 7 and are

located in one or more branch offices.

Client cache servers. Each client computer automatically becomes a client cache server

when it obtains content from a content server and then caches the content for distribution to

other client computers on request.

Group Policy BranchCache object. To enable BranchCache on Windows 7 client

computers using Group Policy, you must first create a Group Policy object (GPO) that will

carry the BranchCache configuration.

Group Policy client computer firewall configuration. The client firewall must be configured

to allow incoming HTTP and WS-Discovery traffic on computers that use distributed cache

mode.

Free hard disk space on client computers. Free hard disk space on client computers at

branch offices must be greater than the sum of the content plus the content information that is

generated by the content servers. Content information is small in comparison to the actual

content; you must reserve one byte of disk space for every 2,000 bytes of content that might

be cached by client computers.

Optimize wide area network performance for employees in branch offices with server computers

A connection between the main office and each branch office must exist before you

deploy BranchCache.

This deployment goal is recommended for branch offices that contain one or more server

computers. When you deploy BranchCache for employees in branch offices that contain client

computers and one or more server computers:

Employees using computers that are running Windows 7 and that have BranchCache

enabled can access content on your content servers at the main office; they can also access

content that is cached locally by the hosted cache server at their branch office.

Free hard disk space is required on the hosted cache server, but no additional hard disk

space is required on client computers, because BranchCache content is located on the

hosted cache server rather than on client computers.

Depending on the types of content servers that you have deployed, employees can access

many types of content at the local branch office rather than over the wide area network

(WAN) link to the main office. This includes Web server content, files on a SharePoint server,

Important

training videos, software installation files (such as software patches and antivirus program

signature updates), and file shares.

Due to reduced usage of the WAN, employees might see reduced application response times

and improved application performance.

The following components are required for this deployment goal.

Content server. One or more content servers that are running Windows Server 2008 R2 and

are located in the main office. Content servers can be file servers, application servers, or

Web servers.

Hosted cache server. A hosted cache server must be installed at each branch office, and

must be running Windows Server 2008 R2 with the BranchCache feature installed and

enabled.

Free hard disk space on the hosted cache server. Free hard disk space on hosted cache

servers at branch offices must be greater than the sum of the content plus the content

information that is generated by the content servers. Content information is small in

comparison to the actual content; you must reserve one byte of disk space for every 2,000

bytes of content that might be cached by the hosted cache server.

Certification authority. A certification authority (CA) must be used to enroll or autoenroll

server certificates to hosted cache servers.

CA certificate. The certificate of the CA must be present in the Trusted Root Certification

Authorities certificate store on client computers. This certificate allows client computers to

trust the hosted cache server when retrieving content from the server.

Copy of the Web server certificate template. Using the Certificate Templates Microsoft

Management Console (MMC) snap-in, you can configure a copy of the Web server certificate

template for autoenrollment, allowing you to automatically issue, or enroll, a certificate to

hosted cache servers that is based on the copy of the Web server certificate template.

Hosted cache server certificate. This certificate is issued by the CA to the hosted cache

server, and is based on the Web server certificate template. The hosted cache server uses

the certificate to prove its identity to client computers.

Client computers. One or more client computers that are running Windows 7 and are

located in branch offices.

Group Policy BranchCache object. To enable BranchCache on Windows 7 client

computers using Group Policy, you must first create a Group Policy object (GPO) that will

carry the BranchCache configuration.

Group Policy client computer firewall configuration. The client firewall must be configured

to allow incoming HTTP and WS-Discovery traffic on computers that use distributed cache

mode.

Map Deployment Goals to a BranchCache Design

After you finish reviewing the existing BranchCache deployment goals and you determine which

goals are related to your specific deployment, you can map those goals to a specific

BranchCache design. For more information about BranchCache predefined deployment goals,

see Identify BranchCache Deployment Goals.

Use the following table to determine which BranchCache design maps to the appropriate

combination of BranchCache deployment goals for your organization. This table refers only to the

two primary BranchCache designs as described in this guide. However, you can create a hybrid

or custom BranchCache design by using a combination of the BranchCache deployment goals to

meet the needs of your organization.

BranchCache deployment goal Distributed cache mode

design

Hosted cache mode design

Optimize wide area network

performance for employees in

branch offices with only client

computers

Yes No

Optimize wide area network

performance for employees in

branch offices with server

computers

No Yes

Accomplish both goals above by

deploying BranchCache in both

distributed cache mode and

hosted cache mode.

Yes Yes

For information on deploying both distributed cache mode and hosted cache mode, see

BranchCache dual mode example.

Distributed cache mode design

With the distributed cache mode design of BranchCache, users in branch offices can quickly

access locally cached content despite not having a server installed in the branch office. Client

computers obtain content from main office content servers over wide area network (WAN) links

and then cache the content to share with other client computers upon request. Typically, you

Note

deploy this design when you do not have servers in branch office locations and do not want to

incur the expense of deploying new servers.

The Main office in the illustration above contains three types of content servers to demonstrate

that you can deploy all three types of content servers on the same network if you want to;

however to deploy BranchCache, only one content server is required.

Branch office 1 in the illustration above contains domain member client computers. These

computers are automatically configured for BranchCache by domain Group Policy, which is

configured on the AD DS domain controller, and which is applied to the computers when domain

Group Policy is refreshed, such as when a user logs on to the computer or when the gpupdate

command is run.

Branch office 2 in the illustration above contains non-domain member client computers. Because

these computers are not joined to the domain, domain Group Policy cannot be applied to the

computers and they cannot be automatically configured.

Hosted cache mode design

With the hosted cache mode design of BranchCache, employees in branch offices can quickly

access content that is cached on a local hosted cache server. Client computers obtain content

from main office content servers over wide area network (WAN) links, and then the content is

cached on the hosted cache server. The hosted cache server then provides the content to other

client computers upon request.

The Main office in the illustration above contains three types of content servers to demonstrate

that you can deploy all three types of content servers on the same network; however to deploy

BranchCache, only one content server is required. In addition, the main office contains a

certification authority (CA) that enrolls certificates to the hosted cache servers that are located in

branch offices. Also in the main office is an Active Directory Domain Services domain controller;

BranchCache domain member client configuration is created in domain Group Policy.

Branch office 1 in the illustration above contains domain member client computers. These

computers are automatically configured for BranchCache by domain Group Policy, which is

configured on the AD DS domain controller, and which is applied to the computers when domain

Group Policy is refreshed, such as when a user logs on to the computer or when the gpupdate

command is run. This branch office also contains a hosted cache server that has enrolled a

server certificate from the main office CA.

Branch office 2 in the illustration above contains non-domain member client computers. Because

these computers are not joined to the domain, domain Group Policy cannot be applied to the

computers and they cannot be automatically configured. In addition, this branch office contains a

non-domain member hosted cache server that has been manually configured and to which a

server certificate has been manually enrolled using the Certificates Microsoft Management

Console (MMC).

Evaluate BranchCache Design Examples

The following BranchCache design examples illustrate how you can use BranchCache to

optimize wide area network (WAN) bandwidth for branch offices using distributed cache mode,

hosted cache mode, or both modes.

Distributed cache mode example

Hosted cache mode example

BranchCache dual mode example

Distributed cache mode example

In this example, BranchCache is deployed in distributed cache mode at a main office and a single

branch office. This example depicts the following two stage process:

The branch office client computer Client 1 seeks and obtains content from the main office

content server.

Another client computer in the same branch office, Client 2, seeks the same content that was

originally obtained by Client 1. In this case, Client 2 obtains the content from Client 1 instead

of over the wide area network link from the main office content server.

At the outset of the process, the employee using the computer Client 1 attempts to access

content that is stored on a BranchCache-enabled content server.

The content that the employee wants to access can be on any of the three types of

content servers – a Web server, a BITS-based application server, or a file server.

In the following illustration, Client 1 seeks and obtains content from the main office content server.

Note

The numbers in the illustration above correspond to the following actions:

1. Client 1 sends a request for content to the main office content server. In this request, Client 1

indicates that it is BranchCache-capable.

2. The content server obtains previously generated content information from a local cache and

sends it to Client 1.

3. Client 1 uses the content information and sends a multicast message to all computers on the

subnet requesting the content; no computers have the content, however, because none of

them has previously downloaded the content from the main office.

4. Client 1 requests the content from the main office content server.

5. Client 1 receives content from the content server and stores the content in its cache.

In the following illustration, Client 2 seeks and obtains content from Client 1.


1. Client 2 sends a request for content to the main office content server. In this case, Client 2

seeks the same content that Client 1 has already obtained.



3. Client 2 uses the content information and sends a multicast message to determine if any

clients in the branch office have already cached the content. Client 1 sends a response

stating that it has the content.

4. Client 2 requests the content from Client 1, connects to Client 1, and downloads the content.

Hosted cache mode example

In this example, BranchCache is deployed in hosted cache mode at a main office and a single

branch office. This example depicts the following two stage process:

The branch office client computer Client 1 seeks and obtains content from the main office

content server, and then advertises the content to the hosted cache server in the branch

office. The hosted cache server downloads the content from Client 1 and adds the content to

its cache.

Another client computer in the same branch office, Client 2, seeks the same content that was

originally obtained by Client 1. In this case, Client 2 obtains the content from the local hosted

cache server instead of over the wide area network link from the main office content server.

At the outset of the process, the employee using the computer Client 1 attempts to access

content that is stored on a BranchCache-enabled content server.

The content that the employee wants to access can be on any of the three types of

content servers – a Web server, a BITS-based application server, or a file server.

In the following illustration, Client 1 seeks and obtains content from the main office content server,

and then the hosted cache server obtains the content from Client 1 and caches the content.


1. Client 1 sends a request for content to the main office content server. In this request, Client 1

indicates that it is BranchCache-capable.



3. Client 1 requests the content from the hosted cache server in the branch office, and the

hosted cache server informs Client 1 that it does not have the content in its cache.

4. Client 1 requests the content from the main office content server.

5. Client 1 receives content from the main office content server.

6. Client 1 advertises the content to the hosted cache server in the branch office; the hosted

cache server connects to the client and downloads the content to store in its cache.

In the following illustration, Client 2 seeks and obtains content from the hosted cache server.

Note


1. Client 2 sends a request for content to the main office content server. In this case, Client 2

seeks the same content that Client 1 has already obtained.



3. Client 2 uses the content information and sends a request to the hosted cache server for the

content. The hosted cache server sends a response stating that it has the content.

4. Client 2 connects to the hosted cache server and downloads the content, using the content

information that it received from the main office content server to verify the data.

BranchCache dual mode example

In this example, BranchCache is deployed at one main office and two branch offices. The branch

office deployments are:

In branch office 1, BranchCache is deployed in distributed cache mode and client computers

cache content they have downloaded from the main office content server.

In branch office 2, BranchCache is deployed in hosted cache mode and a hosted cache

server caches content that client computers have downloaded from the main office content

server.

In the following illustration, BranchCache is deployed in both modes.

For more detail on how distributed cache mode and hosted cache mode work, see

Distributed cache mode example and Hosted cache mode example.

Plan BranchCache Deployment

You can use the following topics to plan BranchCache deployment.

Plan content server deployment

Plan BranchCache distributed mode deployment

Plan BranchCache hosted cache mode deployment

Plan content server deployment

When you deploy BranchCache, you must deploy at least one type of content server in your main

office. The content servers you deploy can be new servers upon which Windows

Server® 2008 R2 is installed, or they can be content servers that already exist that are running

other operating systems.

Note

If the content servers are running other operating systems, you must upgrade the servers to

Windows Server 2008 R2 or install a new server running Windows Server 2008 R2 and then

migrate the content from the old server to the new server.

To plan for content server deployment, take the following actions:

Evaluate each content server and document the following state and required actions as

required to create your deployment plan:

If the content server is running Windows Server 2008 R2 and BranchCache is already

installed and configured in accordance with the instructions in the BranchCache

Deployment Guide, no action is needed.

If the content server is running Windows Server 2008 R2 and BranchCache is not already

installed and configured, then BranchCache must be installed and configured using the

instructions in the BranchCache Deployment Guide.

If the content server is not running Windows Server 2008 R2 and the hardware meets the

minimum hardware requirements for Windows Server 2008 R2, determine whether to

upgrade the server to Windows Server 2008 R2 or migrate the server to another

computer that is running Windows Server 2008 R2. After you upgrade or migrate the

server, BranchCache must be installed and configured using the instructions in the

BranchCache Deployment Guide.

If the content server is not running Windows Server 2008 R2 and the hardware does not

meet the minimum hardware requirements for Windows Server 2008 R2, migrate the

server to another computer that is running Windows Server 2008 R2. After you migrate

the server, BranchCache must be installed and configured using the instructions in the

BranchCache Deployment Guide.

If you are removing or adding content servers, or if you do not already have a content backup

plan in place, create or revise your content backup plan.

For assistance with server migration and upgrades, see Deployment and migration tools and

information

Plan BranchCache distributed mode deployment

When you deploy BranchCache in distributed cache mode, you must deploy client computers in

branch offices. These client computers must be running either the Windows® 7 Enterprise or the

Windows® 7 Ultimate operating system.

To plan for client computer deployment, take the following actions as required to create your

deployment plan:

1. Evaluate each client computer in each branch office and document the following actions:

a. If the client computer is running either the Windows® 7 Enterprise or the Windows® 7

Ultimate operating system, and if BranchCache is already configured in accordance with

the instructions in the BranchCache Deployment Guide, no action is needed.

b. If the client computer is running either the Windows® 7 Enterprise or the Windows® 7

Ultimate operating system but BranchCache is not configured, you must configure

BranchCache in accordance with the instructions in the BranchCache Deployment Guide.

c. If the client computer is not running either the Windows® 7 Enterprise or the Windows® 7

Ultimate operating system and the client computer hardware meets the minimum

hardware requirements for one of these operating systems, determine whether you want

to upgrade the computer or migrate the client to another computer. After you upgrade or

migrate the computer, you must configure BranchCache in accordance with the


d. If the client computer is not running either the Windows® 7 Enterprise or the Windows® 7

Ultimate operating system and the client computer hardware does not meet the minimum

hardware requirements for one of these operating systems, you must migrate the client to

another computer that does meet the minimum hardware requirements for the respective

operating system. After you migrate the computer, you must configure BranchCache in

accordance with the instructions in the BranchCache Deployment Guide.

2. Identify non-domain member client computers and plan to manually configure them in


3. Examine your domain Group Policy configuration and plan on enabling BranchCache client

configuration in Group Policy for domain member client configuration in accordance with the


4. If you are using DirectAccess, plan on creating Internet Protocol security (IPsec) rules that

allow inbound and outbound BranchCache traffic on client computers in accordance with the


5. Compare free disk space on client computers to the total amount of disk space it takes to

store your source content on content servers in the main office. Ensure that the free hard disk

space on clients at each branch office is sufficient to cache all of the main office content

server data. Note cases in which you must increase the number or size of hard disks per

client computer so that you can upgrade the hardware.

For assistance with client migration and upgrades, see Deployment and migration tools and

information

Plan BranchCache hosted cache mode deployment

When you deploy BranchCache in hosted cache mode, you must deploy client computers and

one server computer, the hosted cache server, in each branch office.

The hosted cache server must be running one of the following operating systems:

Windows Server® 2008 R2 Enterprise

Windows Server 2008 R2 Enterprise with Hyper-V

Windows Server 2008 R2 Enterprise Core Install

Windows Server 2008 R2 Enterprise Core Install with Hyper-V

Windows Server 2008 R2 for Itanium-Based Systems

Windows Server® 2008 R2 Datacenter

Windows Server® 2008 R2 Datacenter with Hyper-V

Windows Server® 2008 R2 Datacenter Core Install with Hyper-V

If the server computer in each branch office is not running one of these operating systems, you

must plan to upgrade the computer or to migrate the server to another computer, depending on

hardware requirements and your resources.

In addition, compare the free hard disk space to the amount of hard disk space that will be

required to cache all of the content on all of your content servers, and ensure that the hosted

cache server has sufficient free disk space to store all of the content.

The hosted cache server can serve purposes in addition to hosting the BranchCache

content. For example, if the server you want to use as a hosted cache server is also a

domain controller, a DHCP server, or is performing other services for your branch office

network, you can still use it as a hosted cache server. Just ensure that the computer

hardware is sufficient to serve all purposes for which the server is intended.

The client computers must be running either the Windows® 7 Enterprise or the Windows® 7

Ultimate operating system.

To plan for client computer deployment, take the following actions as required to create your

deployment plan:

1. Evaluate each client computer in each branch office and document the following actions:

a. If the client computer is running either the Windows® 7 Enterprise or the Windows® 7

Ultimate operating system, and if BranchCache is already configured in accordance with

the instructions in the BranchCache Deployment Guide, no action is needed.

b. If the client computer is running either the Windows® 7 Enterprise or the Windows® 7

Ultimate operating system but BranchCache is not configured, you must configure

BranchCache in accordance with the instructions in the BranchCache Deployment Guide.

Note

c. If the client computer is not running either the Windows® 7 Enterprise or the Windows® 7

Ultimate operating system and the client computer hardware meets the minimum

hardware requirements for one of these operating systems, determine whether you want

to upgrade the computer or migrate the client to another computer. After you upgrade or

migrate the computer, you must configure BranchCache in accordance with the


d. If the client computer is not running either the Windows® 7 Enterprise or the Windows® 7

Ultimate operating system and the client computer hardware does not meet the minimum

hardware requirements for one of these operating systems, you must migrate the client to

another computer that does meet the minimum hardware requirements for the respective

operating system. After you migrate the computer, you must configure BranchCache in


2. Identify non-domain member client computers and plan to manually configure them in


3. Examine your domain Group Policy configuration and plan on enabling BranchCache client

configuration in Group Policy for domain member client configuration in accordance with the


4. If you are using DirectAccess, plan on creating Internet Protocol security (IPsec) rules that

allow inbound and outbound BranchCache traffic on client computers in accordance with the


Deployment and migration tools and information

The following links and information are provided to assist you in preparing to deploy

BranchCache.

BranchCache Deployment Guide

To learn how to deploy BranchCache, see the BranchCache Deployment Guide:

Available in Word format at the Microsoft Download Center: http://go.microsoft.com/fwlink/?

LinkId=166656

Available in HTML format in the Windows Server® 2008 and Windows Server® 2008 R2

Technical Library: http://go.microsoft.com/fwlink/?LinkId=166639

Microsoft Assessment and Planning Toolkit: http://go.microsoft.com/fwlink/?LinkID=117991

The Microsoft® Assessment and Planning (MAP) Toolkit makes it easy to assess your current IT

infrastructure and determine the right Microsoft technologies for your IT needs.

MAP is a powerful inventory, assessment, and reporting tool that can securely run in small or

large IT environments without requiring the installation of agent software on any computers or

devices. The inventory and assessment capabilities provided by this Solution Accelerator can





significantly simplify the planning process for migrating your laptops, desktops, and server

computers to Windows® 7, Windows Server 2008 R2, Windows Server 2008, Windows Vista®

and Microsoft Office 2007. The server virtualization scenarios help you identify underutilized

resources and the hardware specifications needed to successfully consolidate your servers using

Microsoft Hyper-V technology. Additionally, the toolkit can help you identify unmanaged assets,

Microsoft SQL Server® components and virtual machines in your environment

Microsoft Application Compatibility Toolkit 5.5: http://go.microsoft.com/fwlink/?LinkID=23302

The Microsoft Application Compatibility Toolkit (ACT) version 5.5 contains the necessary tools

and documentation to evaluate and mitigate application compatibility issues before deploying

Windows 7, Windows Vista, a Windows Update, or a new version of Windows® Internet

Explorer® in your environment.

Windows User State Migration Tool (USMT) Version 3.0.1: http://go.microsoft.com/fwlink/?

LinkId=167867

Microsoft® Windows® User State Migration Tool (USMT) version 3.0.1 migrates user files and

settings during deployments of Windows XP and Windows Vista. USMT captures files and

settings from the source computer and then migrates them to a new Windows installation.

The Windows Automated Installation Kit (AIK) for Windows 7: http://go.microsoft.com/fwlink/?

LinkId=167870

The Windows Automated Installation Kit (Windows AIK) is a set of tools and documentation that

support the configuration and deployment of Windows operating systems. By using Windows AIK,

you can automate Windows installations, capture Windows images with ImageX, configure and

modify images using Deployment Imaging Servicing and Management (DISM), create Windows

PE images, and migrate user profiles and data with the User State Migration Tool (USMT).

Windows AIK also includes the Volume Activation Management Tool (VAMT), which enables IT

professionals to automate and centrally manage the volume activation process using a Multiple

Activation Key (MAK).

Microsoft Deployment Toolkit (MDT) 2010: http://go.microsoft.com/fwlink/?LinkID=110477

Microsoft Deployment Toolkit 2010 is the newest version of Microsoft Deployment Toolkit, a

Solution Accelerator for operating system and application deployment. MDT 2010 supports

deployment of Windows 7 and Windows Server 2008 R2 in addition to deployment of Windows

Vista, Windows Server 2008, Windows Server 2003, and Windows XP.

Migrate Server Roles to Windows Server 2008 R2: http://go.microsoft.com/fwlink/?

LinkId=167873

Migration documentation and tools ease the process of migrating server roles, operating system

settings, and data from an existing server that is running Windows Server 2003, Windows Server

2008, or Windows Server 2008 R2 to a computer that is running Windows Server 2008 R2.









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