Content Overview The first PCs were designed as standalone desktop systems. The operating system (OS) software allowed one user at a time to access files and system resources. The user had physical access to the PC. As PC-based computer networks gained popularity in the workplace, software companies developed specialized network operating systems (NOS). Developers designed NOS to provide file security, user privileges, and resource sharing among multiple users. The explosive growth of the Internet compelled developers to build the NOS of today around Internet-related technologies and services like the World Wide Web. Within a decade, networking has become of central importance to desktop computing. The distinction between modern desktop operating systems, now loaded with networking features and services, and their NOS counterparts has blurred. Now, most popular operating systems, such as Microsoft Windows 2000 and Linux, are found on high-powered network servers and on the desktops of end users. Knowledge of different operating systems will ensure that the correct operating system is selected to offer all the necessary services. UNIX, Linux, Mac OS X, and several Windows operating systems will be introduced. Effective management of LANs and WANs is the key element to maintaining a productive environment in the networking world. As more services become available to more users, the performance of networks suffer. Network administrators, through constant monitoring, must recognize and be able to rectify problems before they become noticeable to the end users. Various tools and protocols are available to monitor the network on a local and remote basis. A comprehensive understanding of these tools is critical to effective network management. Students completing this module should be able to:
Content 6.1 Workstations and Servers 6.1.1 Workstations A workstation is a client computer that is used to run applications and is connected to a server from which it obtains data shared with other computers. A server is a computer that runs a network operating system (NOS). A workstation uses special software, such as a network shell program to perform the following tasks: Some Windows operating systems may be installed on workstations and servers. The NT/2000/XP versions of Windows software provide network server capability. Windows 9x and ME versions only provide workstation support. UNIX or Linux can serve as a desktop operating system but are usually found on high-end computers. These workstations are employed in engineering and scientific applications, which require dedicated high-performance computers. Some of the specific applications that are frequently run on UNIX workstations are included in the following list: Most current desktop operating systems include networking capabilities and support multi-user access. For this reason, it is becoming more common to classify computers and operating systems based on the types of applications the computer runs. This classification is based on the role or function that the computer plays, such as workstation or server. Typical desktop or low-end workstation applications might include word processing, spreadsheets, and financial management. On high-end workstations, the applications might include graphical design or equipment management and others as listed above. A diskless workstation is a special class of computer designed to run on a network. As the name implies, it has no disk drives but does have a monitor, keyboard, memory, booting instructions in ROM, and a network interface card. The software that is used to establish a network connection is loaded from the bootable ROM chip located on the NIC. Because a diskless workstation does not have any disk drives, it is not possible to upload data from the workstation or download anything to it. A diskless workstation cannot pass a virus onto the network, nor can it be used to take data from the network by copying this information to a disk drive. As a result, diskless workstations offer greater security than ordinary workstations. For this reason, such workstations are used in networks where security is paramount. Laptops can also serve as workstations on a LAN and can be connected through a docking station, external LAN adapter, or a PCMCIA card. A docking station is an add-on device that turns a laptop into a desktop.
Content 6.1 Workstations and Servers 6.1.2 Servers In a network operating system environment, many client systems access and share the resources of one or more servers. Desktop client systems are equipped with their own memory and peripheral devices, such as a keyboard, monitor, and a disk drive. Server systems must be equipped to support multiple concurrent users and multiple tasks as clients make demands on the server for remote resources. Network operating systems have additional network management tools and features that are designed to support access by large numbers of simultaneous users. On all but the smallest networks, NOSs are installed on powerful servers. Many users, known as clients, share these servers. Servers usually have high-capacity, high-speed disk drives, large amounts of RAM, high-speed NICs, and in some cases, multiple CPUs. These servers are typically configured to use the Internet family of protocols, TCP/IP, and offer one or more TCP/IP services. Servers running NOSs are also used to authenticate users and provide access to shared resources. These servers are designed to handle requests from many clients simultaneously. Before a client can access the server resources, the client must be identified and be authorized to use the resource. Identification and authorization is achieved by assigning each client an account name and password. The account name and password are then verified by an authentication service to permit or deny access to the network. By centralizing user accounts, security, and access control, server-based networks simplify the work of network administration. Servers are typically larger systems than workstations and have additional memory to support multiple tasks that are active or resident in memory at the same time. Additional disk space is also required on servers to hold shared files and to function as an extension to the internal memory on the system. Also, servers typically require extra expansion slots on their system boards to connect shared devices, such as printers and multiple network interfaces. Another feature of systems capable of acting as servers is the processing power. Ordinarily, computers have a single CPU, which executes the instructions that make up a given task or process. In order to work efficiently and deliver fast