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.