Windows Server 2008 R2 Unleashed (182 page)

balancing and ensures that users get connected to the correct Remote Desktop session.

However, the RD Connection Broker also supports load balancing and session state

management for session-based desktops, virtual desktops, and RemoteApp programs

accessed by using RemoteApp and Desktop Connection.

NOTE

When the RD Connection Broker role service is installed, the RD Web Access role ser-

vice is also installed.

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To track user sessions in a load-balanced RD Session Host server farm, an RD Connection

Broker server stores information in its local database for each and every session. This

session information includes where the session resides, its state, the session ID, and the

username associated with the session. Using this information, the RD Connection Broker

redirects users with an already existing session to the correct RD Session Host server or

virtual desktop.

With RD Connection Broker Load Balancing, users with existing sessions are still redi-

rected to those sessions if they attempt to reconnect to them. However, for new session

connections, the RD Connection Broker will attempt to distribute the session load

between more-powerful and less-powerful servers in the farm based on an assigned server

weight value and which server has the least load.

To configure RD Connection Broker Load Balancing, an administrator must create an A or

AAAA record for each RD Session Host in a farm. The hostname for the record is then set

to the farm’s name and the IP address to the RD Session Host server that is being added.

The RD Connection Broker then uses round-robin DNS to distribute a user’s initial

connection to an RD Session Host server farm. After the user has connected and authenti-

cated to the initial RD Session Host server, that server then queries the RD Connection

Broker for where to redirect the user to. The final RD Session Host server that is returned

from the RD Connection Broker is based on the following two decisions:

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. Does the user have an existing session? If so, redirect that user to the RD Session

Host server where that session exists.

. If the user doesn’t have an existing session, which RD Session Host server has the

least load? Redirect that user to the RD Session Host server with the least load.

CAUTION

RD Connection Broker Load Balancing does not work with Windows Server 2003

Terminal Servers, but does with work Windows Server 2008–based Terminal Servers.

In addition, there are also a couple of features that allow an administrator some control

over the two previously listed decision paths. First, as mentioned, server weight can be

assigned to each RD Session Host server that has been added to the RD Connection

Broker. Configuring a server weight allows differences in load to be spread across RD

Session Host servers that might not have the same hardware configuration. Less-powerful

RD Session Host servers would then have a lower weight and fewer sessions, whereas

more-powerful RD Session Host servers would have a higher weight and more sessions.

Second, an administrator can also configure an RD Session Host server to act as a dedi-

cated redirector. A dedicated redirector is an RD Session Host server that is configured to

process initial session requests, but does not accept any user sessions. By using a dedicated

Understanding Remote Desktop Services

937

redirector(s), the time associated with the initial connection into a farm and the resulting

redirection is decreased, which results in faster logon times.

NOTE

By default, RD Connection Broker Load Balancing has a limit of 16 maximum pending

logon requests per RD Session Host server. The limit is in place to prevent RD Session

Host servers from becoming overwhelmed with logon requests either when they are

coming back online or being added into a farm.

Windows System Resource Manager

Windows System Resource Manager (WSRM) is a feature in Windows Server 2008 R2 that

allows administrators to control how resources are allocated to applications, services, and

processes. When being used in conjunction with Remote Desktop Services, WSRM allows

administrators to precisely control the amount of resources each user or session is allowed

to consume on an RD Session Host server. By limiting resources a session or user can use,

an administrator can reduce the chances of a user maxing out an RD Session Host server’s

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resources, which might impact other users on that server.

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Using Network Load Balancing (NLB)

Since Windows 2000 Server Terminal Services, Terminal Services nodes could be “clus-

tered” using Network Load Balancing (NLB) to split the client load across several servers.

With the introduction of RD Connection Broker Load Balancing, this clustering technique

is no longer the only method by which to facilitate RD Session Host load balancing. As a

general recommendation, RD Connection Broker Load Balancing should be used for RD

Session Host server farms that need to facilitate load balancing.

NOTE

Do not confuse NLB-based clustering for Windows Server 2008 RD Session Host

servers with the use of Microsoft Cluster Service (MSCS). It is recommended that you

don’t cluster your RD Session Host servers using MSCS. Clustering does not support

memory failover for a node. In the event of a failover, information in memory is lost.

RD Licensing

In addition to purchasing a Windows Server 2008 R2 server license, administrators must

also have the correct number of Windows Server client access licenses (CALs). When utiliz-

ing Remote Desktop Services functionality, an additional set of Terminal Services client

access licenses (TS CALs) or Remote Desktop Services client access licenses (RDS CALs) is

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needed for each user or device. For certain types of deployments, RDS External Connector

or Service Providers License Agreement (SPLA) licenses can be purchased as well.

NOTE

New CALs are not required to deploy Windows Server 2008 R2 Remote Desktop

Services. Both Windows Server 2008 TS CALs and Windows Server 2008 R2 RDS

CALs provide access to Remote Desktop Services. However, Windows Server 2008 SP2

is required to install RDS CALs on a TS licensing server. Therefore, Microsoft recom-

mends installing and using a Windows Server 2008 R2–based RD licensing server.

Understanding Remote Desktop Services License Types

The following Remote Desktop Licensing types are available for use:

.
RDS Device CAL—
This CAL type permits one device (used by any user) to utilize

Remote Desktop Services functionality on any server.

.
RDS User CAL—
This CAL type permits one user (using any device) to utilize

Remote Desktop Services functionality on any server.

.
RDS External Connector—
Using this type of license allows for multiple external

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users to access a single Remote Desktop server; when multiple servers are being used,

additional RDS External Connectors and Windows Server External Connectors must

be purchased.

.
Service Providers License Agreement (SPLA)—
Using this type of license provides

a service provider with a more flexible and robust licensing solution when hosting

Remote Desktop Services to a number of different organizations and end users.

NOTE

Any combination of RDS Device CALs and RDS User CALs can be simultaneously used.

Understanding Remote Desktop Services Client Access Licensing Mode

When using RDS CALs (Per-User or Per-Device modes), a separate RDS CAL is required for

each user or device that is accessing Remote Desktop Services. CALs may be reassigned

from one user or device to another. This assignment can be either permanent or tempo-

rary, depending on the need at the time.

Understanding Virtual Desktop Infrastructure (VDI) Licensing

To correctly license a VDI environment also requires the purchase of licenses for both the

Windows operating system being used for the virtual machine(s) and the

infrastructure/management components needed for an end-to-end VDI deployment.

To license Windows as a guest operating system for any VDI environment, regardless of

the choice of infrastructure or hypervisor vendor, a Virtual Enterprise Centralized Desktop

(VECD) licensing agreement must be purchased. This agreement is available both for client

Understanding Remote Desktop Services

939

devices that are covered by Software Assurance (VECD for SA) or just VECD for devices

such as thin clients.

To license the rest of a VDI environment requires using one of two paths. The VDI infra-

structure components can be licensed using RDS CALs, whereas the VDI management

components are separately licensed. Or, the environment can be licensed using either

Microsoft Virtual Desktop Infrastructure Standard Suite or the Microsoft Virtual Desktop

Infrastructure Premium Suite. Both suites are volume license offerings that combine the

products for an optimum VDI experience in a value package.

Understanding New RD Licensing Features

The new features that have been introduced in Windows Server 2008 R2 for the RD

Licensing role service are discussed in the following sections.

Automatic License Server Discovery No Longer Supported for Remote Desktop Servers

In

previous versions of Windows Server, the licensing server was automatically discovered on

the network. In Windows Server 2008 R2, automatic discovery is no longer supported.

Instead, administrators must now specify the name of a licensing server to use for each RD

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Session Host server.

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Changes to the Licensing Tab in Remote Desktop Server Configuration

When configuring

an RD Session Host server, an administrator can use the Licensing tab in the Remote

Desktop Server Configuration tool to specify the licensing server. When using this tab, a

licensing server can be chosen from a list of servers that have been registered as a service

connection point in Active Directory or can be manually defined by entering its name.

For cases where more than one license is added, an RD Session Host server will attempt to

contact licensing servers in the order in which they appear in the Specified License

Servers box.

The Manage RDS CALs Wizard

A new wizard has been introduced in the RD Licensing

Manager, which allows the following tasks to be performed:

. Migrate RDS CALs from one licensing server to another.

. Rebuild the RD Licensing database.

It is important to understand that the Manage RDS CALs Wizard can only be used against

licensing servers running Windows Server 2008 R2. Therefore, if a licensing server is not

running Windows Server 2008 R2, the original CALs on that server should be manually

removed as part of the migration process to a Windows Server 2008 R2 licensing server.

CAUTION

When rebuilding the RD Licensing database, all RDS CALs are deleted and, therefore,

will need to be reinstalled.

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CHAPTER 25

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Service Connection Point Registration

While installing the RD Licensing role service, the

licensing server will attempt to register itself as a Service Connection Point (SCP) in Active

Directory. Once registered, the licensing server will then show up as a known licensing

server in the Remote Desktop Server Configuration tool’s Licensing tab. If Active Directory

is not available during the role service installation, or the SCP registration fails, an admin-

istrator must manually register the licensing server by using Review Configuration in the

RD Licensing Manager.

RemoteApp and Desktop Connection

Windows Server 2008–based Terminal Services introduced a new feature called RemoteApp

(TS RemoteApp) or “Seamless Windows.” This feature allows applications that are accessed

through Terminal Services to appear as if they are running locally on an end user’s

machine. By using this feature, a user would run their remote application side by side

other applications allowing them to minimize, maximize, and resize the application

window as if it were a location application. In addition, if a user were to launch more

than one RemoteApp, each RemoteApp would reuse the existing Terminal Services session.

In Windows Server 2008 R2 Remote Desktop Services, the RemoteApp feature has been

expanded to include the ability to group and personalize RemoteApp programs, session-

based desktops, and virtual desktops while making them available to users on the

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Windows 7 or Windows Server 2008 R2 Start menu. As a result, the expanded RemoteApp

feature has been renamed to RemoteApp and Desktop Connection.

To deploy RemoteApp and Desktop Connection, an administrator must first deploy and

configure both the RD Connection Broker and the RD Web Access role services. Then,

once RemoteApp programs have been defined on a source, administrators can use the

Remote Desktop Connection Manager tool to configure virtual desktops or define which

RemoteApp sources will be used for RemoteApp and Desktop Connection.

Once configured by and deployed by administrators, users on Windows 7 or Windows