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: - Identify several potential
functions of a workstation
- Identify several potential
functions of a server
- Describe the roles of equipment
in a client/server environment
- Describe the
differences between a Networking Operating System (NOS) and a
traditional operating system
- List several Windows
operating systems and their features
- List several
alternatives to the Windows operating systems and their
features
- Describe several functions of a server
- Identify network management tools
- Identify the
driving forces behind network management
- Describe the
OSI and network management model
- Describe SNMP and
CMIP
- Describe how management software gathers
information and records problems
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: - Intercepts
user data and application commands
- Decides if the
command is for the local operating system or for the NOS.
- Directs the command to the local operating system or to the
network interface card (NIC) for processing and transmission
onto the network
- Delivers transmissions from the
network to the application running on the workstation
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: - Computer-aided design
(CAD)
- Electronic circuit design
- Weather data
analysis
- Computer graphics animation
- Telecommunications equipment management
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