An Introduction To NetworkingAn Introduction To Networking

Computer NetworksComputer Networks

What is A NetworkA Network is a group of two or more computer systems linked together.

Objectives of Network Objectives of Network

Data Sharing

Allows groups of users to: Exchange Information Route data from user to user Use E-mail to communicate

Device SharingSharing peripheral devices Printers Scanners Fax

Networks and Standalone Computers

NetworkNetwork–A group of computers and other A group of computers and other devices connected by some type of devices connected by some type of transmission mediatransmission media–Networks enable users to share Networks enable users to share devices and data, collectively called devices and data, collectively called a network’s a network’s resourcesresources

Standalone ComputerStandalone Computer–Uses programs and data only from its Uses programs and data only from its local disks and is not connected to a local disks and is not connected to a network.network.

Sneakernet Method of sharing data by copying it to a disk and carrying it from computer to computer

FIGURE 1-1 Data sharing before the advent of networks

Local and Remote Computers

Local Computer Computer on which a user is working

Remote Computer Computer which a user controls or works on via a network connection

Computer NetworksComputer Networks

Local-Area NetworksLocal-Area Networks (LAN's): The computers (LAN's): The computers are geographically close to each other (in are geographically close to each other (in the same building). the same building). Wide-Area NetworksWide-Area Networks (WAN's): The computers (WAN's): The computers are farther apart and are connected by are farther apart and are connected by telephone lines or radio waves. telephone lines or radio waves. Metropolitan-Area NetworksMetropolitan-Area Networks (MAN's):(MAN's):Network connecting clients and Network connecting clients and servers in multiple buildings within servers in multiple buildings within limited geographic arealimited geographic area

Local Area Network (LAN)•Typically connects computer in a Typically connects computer in a single building or campus (Network single building or campus (Network of computer and other devices are of computer and other devices are confined to reliability small space) confined to reliability small space) . . • High speed networks (0.2 to 100 High speed networks (0.2 to 100 Mb/sec).Mb/sec).

Usually cover a very small area

OfficeFloorBuildingCampusLess than 10Km

Number of computers usually less Number of computers usually less than 100than 100

Classification of LAN LANs can be classified into 2 basic LANs can be classified into 2 basic typestypes Client / ServerClient / Server

In this arrangement every device has a In this arrangement every device has a distinct role. Either a Client or a Serverdistinct role. Either a Client or a Server

The client is usually a workstationThe client is usually a workstation This is what you useThis is what you use

The server is usually a dedicated device The server is usually a dedicated device designed to share resourcesdesigned to share resources

PrintingPrinting File servicesFile services Internet AccessInternet Access

Client Server Networks Servers are normally high-end Servers are normally high-end computers running a special computers running a special operation system called a NOSoperation system called a NOS NOS – Network Operating SystemNOS – Network Operating System

Windows NT ServerWindows NT Server Windows 2000 ServerWindows 2000 Server Novell NetwareNovell Netware

The NOS provides security, Backup The NOS provides security, Backup features and performance featuresfeatures and performance features

Client/Server Model

Client

ServerClient software sends requests from the user to the server

Server software responds to client requests by providing data

Client Server Networks The Client normally runs some version of DOS or Windows 95/98/NT Workstation/2000 Workstation Windows XP

In a client server network, client can not share information with other clients Client can only communicate with the server

Peer – to – Peer The second type of network is a peer – to – peer network This type of network allows workstations to communicate with other workstations

Each computer is responsible for managing its own resources and protecting them as well

Difficult network to administer

LAN Hardware LAN require special cables and devices to provide a means of communication

Cables Cabling of some sort is need to connect each of the computer together regardless of the type of network

Commonly called the Transmission Media

Other Hardware NIC – Network Interface Card

This card can be plugged into the ISA or PCI slot in the workstation or server

The NIC gives a place for you to plug the transmission media into

HUB This provides a central point to connect the other end of the cables to

Network CardNetwork Card

LAN Software As mentioned earlier, special software in needed to run a client server network

However, Windows 95/98/Me/NT/2000 contain the software needed to configure a peer to peer network

MANMAN : METROPOLITAN AREA NETWORKS

• Generally covers towns and cities (50 kms)

Medium : optical fibers cables

Wide Area Network (WAN)

• Network connecting two or more geographically distinct LANs– The Internet is an intricate and extensive WAN spanning the globe

FIGURE 1-5 A simple WAN

Generally covers large distances (states, countries, continents

WANs are often made up of LANs

Internet is example of WAN

WAN WAN