A multisite topology is typically found in large, geographically dispersed organizations in which the costs of bandwidth and network resources are higher than the management costs associated with maintaining a server at each deployment site. Multisite topologies help make bandwidth consumption more efficient by placing servers closer to the clients serviced by WDS. Each WDS instance runs WDS services and has access to a centralized image store. If client deployments take place over a wide area network (WAN) connection, you should ensure that enough bandwidth is available for deployments.

A multisite topology relies heavily on File Replication Services (FRS) to copy images between WDS servers. Because WDS isn’t cluster-aware, the WDS servers don’t act in conjunction with one another. However, you can manage disparate WDS servers from a single WDS management console.
The typical scenario for a multisite topology involves prestaging and assigning clients to their nearest or local WDS server (known as a referral server).

Prestaging clients
Prestaging clients enables you to specify client settings such as the server that should respond to a deployment request, the boot image, user credentials, and other items. To add a prestaged client, right-click Active Directory Prestaged Devices in the WDS MMC snap-in and select Add Device to launch the Add Prestaged Device Wizard.
The Add Prestaged Device Wizard begins with a dialog box to enter the device name and the device ID. The Device ID is an identifier (GUID, UUID, or MAC address) that enables the WDS server to identify the client when it asks for its deployment (see Figure 1-6).

Configuring multisite topology and distribution points

FIGURE 1-6 Prestaging a client in WDS.

Clicking Next brings up the dialog box in Figure 1-7. This dialog box enables you to set the boot information, including the referral server from which the client obtains its installation information. You also can override the server’s default PXE Prompt Policy here so that you can deploy servers without needing to press F12 on the server itself to start a PXE boot. The boot image can also be chosen in this dialog box.

Configuring multisite topology and distribution points

FIGURE 1-7 Choosing boot information for this prestaged client in WDS.

Clicking Next reveals a dialog box in which you can specify the unattended file, as well as create a new unattended installation file (see Figure 1-8).

Configuring multisite topology and distribution points

FIGURE 1-8 The Client Unattend dialog box enables you to specify an unattended installation file or create a new one.

Clicking Create New reveals the Create Client Unattend dialog box in Figure 1-9. This important dialog box includes areas to specify the disk partitions for the client, the language to use, and the install image to use for the client.

Configuring multisite topology and distribution points

FIGURE 1-9 The Create Client Unattend dialog box enables you to specify a good deal of information about the client to be deployed.