Assess Existing Network Infrastructure

The impact that RIS-based operating system installations have on your network varies with the demand for RIS services. When large scale installations are in progress, your network carries a heavy load because multiple simultaneous operating system image downloads create significant increases in network traffic. For this reason, it is ne 11111r1718l cessary to assess whether your network can support the speed and traffic volumes that permit RIS-based operating system installations in a reasonable amount of time.

To facilitate the assessment of your network, consider drawing a Visio diagram of the network. You can consult Active Directory and your DHCP scopes when determining the organization of the subnets and domains for your diagram.

Use the following guidelines to verify network requirements to support RIS-based operating system installations:

Network Topology. Determine if your network topology can support a data transmission rate of at least 10 megabits per second (Mbps), but preferably 100 Mbps. To support the minimum recommended transmission rate, you need a 10 Mbps Ethernet network with supporting transmission media. For a 100 Mbps transmission rate, you need a minimum of a Fast Ethernet network with Category 5 UTP cable.

You also need to determine if the network adapters of your RIS servers and clients can support the minimum data transmission rate.

Number of Servers. Estimate how many RIS servers you need, based on the number of RIS clients in your organization. A single RIS server can use network pipes and allow 75 simultaneous instances of a Riprep or Risetup image to the equivalent number of clients. If you attempt to use a single RIS server to provide service to more than 75 clients, all subsequent PXE client requests for RIS service are ignored. If clients reboot after a TFTP time-out initiated by the RIS server, they are unable to obtain a client connection to that RIS server.

Firewall. Assess your need for a firewall. Because PXE does not provide any inherent security mechanisms, ensure that you have a correctly configured firewall for your network to prevent unauthorized access to your RIS server. For more information about RIS server security, see "Planning RIS Server Security" (ACIRIS_05.doc) on the Windows Server 2003 Deployment Kit companion CD (or see "Planning RIS Server Security" on the Web at https://www.microsoft.com/reskit).

Disk Image Transfer Time. You must have a network connection to every RIS client computer. Ethernet local area networks (LANs) and Token Ring LANs are well suited for distributing disk images across a network. Wide area networks (WANs) are generally not fast enough, unless the LAN segments that make up the WAN are connected with a fast T-carrier service (T2 or higher). Digital subscriber line (DSL), cable modem, Integrated Services Digital Network (ISDN), and dial-up modem connections are not suitable for network distribution of RIS images.

Table  . shows connection speeds and image transfer times for various network connections. Image transfer times are based on optimum network speeds only and are calculated for a 2.5 GB disk image. File server performance is not factored into the disk image transfer times. You can use Table  . as a rough guide to help you determine whether your network is a suitable for RIS-based installations.

Table  .    Approximate Image Transfer Times for RIS-Based Installations

Network Component Requirements. Your network configuration must include a Windows Server 2003-based server, the DHCP service, DNS, and Active Directory. It is unnecessary for the RIS server to be the sole DNS/DHCP server or the domain controller.

For this part of your planning process, use job aid "Planning the RIS Network Configuration" (ACIRIS_04.doc) on the Windows Server 2003 Deployment Kit companion CD (or see "Planning the RIS Network Configuration" on the Web at https://www.microsoft.com/reskit) to indicate your decisions to:

Render a network structure diagram.

Upgrade your network components, including installation and configuration of a firewall.

In the job aid, also record your image transfer time requirements and include the personnel you want to assign to upgrading or other tasks.

Other network-related factors you should evaluate include:

The network installation point for RIS servers.

The redirection of RIS client requests.

The role of routers in forwarding client DHCP requests.