Creating Diskless Workstations

Remote booting is the process of booting a client machine from the server. That is, the operating system is loaded from the server’s hard disk instead of the client. The benefit of this is that client machines don’t need a separate hard disk of their own. However, for remote boot to work on diskless workstations, client machines should have a network card with a compatible BOOT ROM. This is used to retrieve startup and configuration information, like the IP address, default gateway, etc, from the server when the client machine starts. The BOOT ROM you select depends on your remote boot process. RPL and PXE are two better known protocols used in BOOT ROMs. In this article, we’ve used a network card with a PXE boot ROM.

Before going any further, let’s first take a look at how remote booting works. 

How it works

When you start your client machine, the BOOT ROM in your network card is initialized. It then issues a

DHCP/BOOTP request for receiving an IP address and other configuration information from the server. If your server is able to identify the MAC address of your client’s network card, it sends back a

DHCP/BOOTP reply with relevant information, such as an IP address for the client machine, a subnet mask, default gateway if defined, and IP address of the Boot and Login server. After receiving this information, the BOOT ROM downloads the boot image file from the boot server using TFTP (Trivial File Transfer Protocol). TFTP is used to transfer files between the server and the client machines. After downloading the image file, the client machine boots from the image file and loads whatever operating system is present on it.

There are several utilities for remote booting. In this article we have used a utility called 3Com Virtual LAN Drive to remote boot and install Win 98 on a diskless workstation from a Windows 2000 server. It also worked fine on a Windows NT server, for which you need to install Service Pack 3 or above. We used an Intel 82559 chip-based network adapter with

PXE-compatible BOOT ROM.

The 3COM Virtual LAN Drive software lets you create a virtual hard disk for your client machine on the server. Client machines can then use this virtual drive as a local hard drive. The 30-day trial version of this software is available on the accompanying PCQuest CD. It can also be downloaded from

www.3com.com/vld.

Step-by-step installation 

Before a client can remote boot an operating system, it needs to obtain an IP address from the server. This can be done either through DHCP or BOOTP protocol. Check which of these protocols your client’s network adapter supports. BOOTP is an older protocol similar to

DHCP, but limited in certain features. The DHCP server in Windows 2000 can be configured to assign IP addresses using either or both of these protocols. Our network card worked fine with a DHCP server, so we configured it in Windows 2000. 

Install Windows 2000 or NT server if you haven’t already and assign it a static IP address. Next, set up the DHCP services on the server. In Win NT, you can add this service by opening up network properties from the control panel. In Windows 2000, go to Start>Administrative Tools and select the Configure your server option. Here, choose the DHCP server.

Ensure that this server has enough hard-disk space for storing all the client image files. This will depend upon the number of clients logging in, and the applications they’ll be running. Next install the 3Com Virtual LAN drive software. This software consists of several components: a PXE server, TFTP server, BOOTP server, Login services, and I/O services. You’ll have to configure each of these for remote booting to work. So, let’s start configuring them.

1. Step: Configuring PXE Server

To configure the PXE server, double click the 3COM PXE applet from the Control Panel. Here, you’ll find a Data File text box. By default, the software uses a file called BOOTPTAB in the

C:\TFTPBOOT directory. This file will contain the MAC and IP address and the boot image file being assigned to a client. Next, select Proxy DHCP option, if your DHCP server is located on a different machine. If it’s on the same machine, then don’t select this option. Next click the Network Adapters tab. This will show you the IP address of your server. Click the check box next to the IP address to bind your PXE server with the network adapter card. If you have multiple network adapters, then check the appropriate one.

2. Step: Configuring TFTP Server

To configure the TFTP server, open it from the Control Panel. This contains five tabs. Go to the File Transfer tab and select the directory

C:\TFTPBOOT and check the Transmit secure mode option. Now go to the Network Cards tab and select the IP address of the server to bind the TFTP server with the network adapter. 

Finally, start both TFTP and PXE services from the Control Panel by right-clicking their icons and selecting Start.



Next, you need to configure the I/O services, Virtual Login Services, the Administrator and the Boot- strap file. The I/O service is used to read and write requests from the client machine to the virtual drive. The login service is used to validate logon requests. The BootStrap file has all the configuration information required by the client BOOT ROM and finally, the Administrator is used to create client boot records and assign the boot image file to it. 

3. Step: Configuring IO Service

Before you configure the Virtual LAN drive I/O service, you first have to create a directory to store all your virtual hard-disk image files. For this, format the drive or partition on which you wish to create this directory. The software requires you to format it in the NTFS file system. Now open the I/O Service Preferences from Start>Programs>3Com Virtual LAN Drive and in the Virtual disks directory select the directory you just created. Again bind the IP address of the server to the I/O Service. There’s a port number specified here. Leave this to default.