PRESENTATION ON

NETWORKING

SUBMITED BY: SUBMITED TO: Chandra prakash Hitesh MahapatraRajendra soni (faculty)Virender bhati

2 Cont…

Certificate

This is to certify that this report is entitled to introduction to an NETWORKING, is an original work of name, & name. It is further certified that we have done our work under guidance & supervision to the best of our knowledge. We have done this by consulting various sources related to topic.

Name NameDirector (faculty)

Date: name (GL)

3 Cont…

Acknowledgement

Presenting the project report in present form, be sincerely feel to acknowledge many individuals who have contributed to the development of this project report we would like to thank the entire NIIT faculty for their invaluable help.

A special thanks to Miss Nidhi Bhatia (GL) & Mr. Hitesh Mahapatra (faculty) who gave their valuable time and efforts for our report preparation.

We are certain that this report will satisfy every bodiesexpectations.

Chandra prakash GandhiRajendra soniVirender bhati

4 Cont…

Table Of Contents

What is Computer Network?........................................................................... 5Overview of a Network .................................................................................... 6Communication processors ........................................................................... 7Communication media .................................................................................... 9Telecommunication software ....................................................................... 11Types of networks......................................................................................... 14LOCAL AREA NETWORK (LAN):-................................................................. 15History of LAN: .............................................................................................. 16LAN TRANSMISSION METHODS:................................................................. 20METROPOLITAN AREA NETWORK (MAN):................................................. 21WIDE AREA NETWORK (WAN):.................................................................... 21WAN TECHNOLOGIES: ................................................................................. 22WIRELESS NETWORKING:........................................................................... 23NETWORK ARCHITECTURE:........................................................................ 24NETWORK PROTOCOLS: ............................................................................. 25NETWORK DEVICES: .................................................................................... 26Software ......................................................................................................... 28INTERNET: ..................................................................................................... 30History of internet : ....................................................................................... 31INTRANET & EXTRANETS: ........................................................................... 32METHODS OF INTERNET CONNECTIVITY: ................................................. 33BENEFITS OF A COMPUTER NETWORK: ................................................... 34

5 Cont…

What is Computer Network?

End users need to communicate electronically in today’s world. People need to

exchange data and information electronically with one another. A good communication

system is a must for every organization. Organizations depends on interconnected

networks of computers to service their information procession needs. We live in a

networked or connected world. A network is a group of two or more computer systems

linked together.

Stand-alone personal computers gave users the ability to create and save

documents, spreadsheets, and other type of data formats. However, this was not

adequate for large companies. The stand-alone computer was not enough for the

following reasons:

Small hard drive capacities

Resources like data, printers, and CD-drive could not be shared with other

computers

To address these problems, networks were born. Whenever we speak about

network, it refers to inter-connection of several devices. For example in a telephone

network, various telephones are interconnected. The same is true with a computer

network. All forms of telecommunications now rely heavily on computers and

computerized devices.

A computer network is a set of computers connected to each other.

6 Cont…

Overview of a Network

Generally a communications network is any arrangement where a sender

transmits a message to a receiver over a channel consisting of some type of medium. A

network consists of five basic components:

Terminals: Terminals include video display terminals and other end user

workstations. Any input/output device that uses a network to transmit or receive data is

a terminal. This includes microcomputers, telephones, fax machines etc.

Telecommunication Processors: These are devices, which support data

transmission and reception between terminals and computers. These devices such as

Modems, Message Switchers, Multiplexers and front-end processors, perform a

variety of control and support Functions in a network. For example, they convert data

from digital to analog and back, code and decode data, and control the accuracy and

efficiency of the flow of data between computers and terminals in a network.

Telecommunications Channels and Media: The media over which

data are transmitted and received are called telecommunication channels;

Telecommunication channels use combinations of media, such as Twisted-pair Wire,

Coaxial Cables, Fiber Optic Cables, Microwave Systems and Communication

satellite systems to interconnect the other components of a network.

Computer: Network interconnects computers of all sizes and types so that

they can carry out their information processing assignments. For example, a mainframe

7 Cont…

computer may serve as a host computer for a large Organization’s

network, assisted by minicomputers acting as network servers for smaller networks

consisting of end user microcomputer workstations.

Telecommunication Software: Consists of programs that reside in host

computer systems, communication control computers and end user computers. This

controls the telecommunication activities of the computer systems and manages the

functions of networks.

The telecommunication software provides several major functions such as Access

control, Transmission control, Network control, Error control and Security

control.

No matter how large and complex the real world networks may appear to be these five

basic categories of components must be at work to support a network.

Communication processors

Communications processors resemble computer CPUs in that they have similar

circuitry, have memories and can be programmed but their purpose is limited to enhance

data communications between two points. Communication processors include the

following: modems, message switchers, multiplexers, concentrators and controllers and

front end processors.

8 Cont…

1. Modems: Modems are the most common type of communications processors.

They convert the digital singals from a computer or transmission terminal at one

end of a communications link into analog signals, which can be transmitted over

ordinary telephone lines. A modem at the other end of the communication line

converts the transmitted data back into digital form at the receiving terminal. The

process is known as modulation and demodulation, and the world modem is a

combined abbreviation of these two words. Modems come in several forms

including small stand-alone units. Plug in circuit boards, and microelectronic

modem chips.

2. Message switchers:- A message switcher is a processor that receives data

message from terminals, determines their destination, and routes them one at a

time to the CPU. It distributes the message coming from the CPU to the

appropriate terminal.

The advantage of message switcher is that it reduces long distance

transmission costs, since only a single line is needed. Although only one terminal

at a time can communicate with the CPU, messages switchers are efficient, with

low speed terminals that are intermittently used at remote sites.

3. Multiplexers, concentrators and controllers:- Like message switchers, a

multiplexer allows several terminals to use one line to communicate with the

CPU. However, it allows the terminate to sent their message simultaneously. A

multiplexer, in other words collects messages from various senders, put them in

9 Cont…

order, and transmits them along a broadband channel at very high speeds to the

receiver.

4. front end processros: A front end processor is located at the site of the CPU or

the host computer and its purpose is to relieve the central computer free for

processing applications programs. Here we can see that communication

processing and data processing equipments are nearly alike. Indeed front-end

processors are Computers they have some identical circuitry and perform many of

the operations that data processing equipment performs. The only difference

between the two kinds of equipments is in their purpose.

Communication media

Channels also called communication lines or links are the means by which data is

transmitted between the sending and receiving devices in a network. A channel makes

use of a variety of media. These include twisted-pair wire, coaxial cables and fiber

optic cables, all of which physically link the devices in a network. Channels also

included microwave systems, communications satellite systems and cellular radio, all of

which use microwave and other radio waves to transmit and receive data.

1. Twisted-pair wire:- This is the oldest and still most common transmission line

and consists of copper wires twisted into pairs. These lines are used in established

10 Cont…

communications networks throughout the world for both voice and data

transmission.

2. Coaxial cable:- Coaxial cable consist of a sturdy copper or alumimium wire

wrapped with spacers to insulate and protect it. The insulation minimize the

interference and distortion of the signals the cable carries.

Group of coaxial cables may be bundled together in a big cable for ease of

installation. These high quality lines can be placed underground and laid on the

floors of lakes and oceans. They allow high-speed data transmission.

3. Fibre optic cables:- Fibre optic cables consisting of one or more hair thin

filaments of glass fiber wrapped in a protective jackets. They can conduct light

pulses generated by lasers at transmission rates as high as 2 billion bits per

second. This is about ten times greater than coaxial cables and 200 times better

than provide substantial size and weight reduction as well as increased speed and

greater carrying capacity. A half inch diameter fiber optic cable can carry up to

50,000 channels, compared to about 5,500 channels for a standard coaxial cable.

4. Microwave systems:- Terrestrial (earth bound) microwave systems transmit

high-speed radio signals in a line-of-sight path between relay stations spaced

approximately 25 to 35 miles apart.

Because the waves cannot bend with the curvature of the earth, they are

relayed via antennas usually placed on top of buildings, towers, hills and

11 Cont…

mountain peaks. Microwave transmission consists of high frequency radio waves

that travel in straight lines through the air rather than through wires.

5. Communications satellites:- Communications satellites in space orbiting 22,000

miles above the earth are also used as microwave relay stations because they

rotate at the precise point and speed above the equator that makes them appear

stationary to microwave transmitters on the ground. Among the dozens of

satellites now orbiting the earth and handling voice, video and data

communications are those launched by INTELSAT, short for international

Telecommunications satellite consortium. INTELSAT began with the Early Bird

satellite in 1965 and now forms a worldwide communications system for over

100 countries. It accounts for most long-distance international communications.

Telecommunication software

Software is a virtual component of all telecommunications networks. Communications

controls software includes programs stored in the host computer as well as programs in

the front-end computers and other communications processors. This software controls

and supports the communications occurring in a telecommunications network.

Telecommunications software packages for large computer networks are frequently

called telecommunications monitors or teleprocessing (TP) monitors. Local Area

Networks (LANs) rely on software called network operating systems. Many

communications software packages are also available for microcomputers.

12 Cont…

Functions of Telecommunication software:- Telecommunication software

packages provide a variety of communication support services. The number and type of

terminals, Computers, and communication processors and communications activities

involved determine the capabilities of the programs required. The telecommunication

software provides several major functions such as:

Acess control:- This function establishes the connection between terminals and

computers in a network. The software works with a communications processor

(such as a modem) to connect and disconnect communication links and

established parameters such as transmission speed, mode, and direction. This

function may also involve automatic telephone dialing and redialing, logging on

and off with appropriate account numbers and security code, and automatic

answering of telephone calls from another Computer.

Transmission control:- This function allows computers and terminals to send

and receive commands, messages, data, and programs. Some error checking and

correction of data transmission may also be provided. Data and programs are

usally transmitted in the form of files, so this activity is frequently called file

transfer.

Network control :- This function manages communications in a network.

Software determines transmission priorities, route message, polls terminals in the

13 Cont…

network and forms waiting lines (queues) of transmission requests. It also logs

statistics of network activities and resource usage and detects and corrects errors.

Error control :- Error control involves detection and correction of transmission

errors. Errors are usally caused by distortions in the communication channel, such

as line noise and power surges. Communications software and processors control

errors in transmission by several methods, including parity checking. Besides

parity bits, additional control codes are usually added to the message itself. These

specify such information as the destination of the data, their priority, and the

beginning and end of the message, plus additional error detecting information.

Most error correction methods involve retransmissions. A signal is sent back to

the Computer or terminal to retransmit the previous message.

Security control :- Security control protects a communications network from

unauthorized access. Access control software and other types of programs restrict

access to data and the computing resources in the network. This restriction

usually involve control procedures that limit access to all or part of a network by

various categories of users. Automatic disconnection and call back procedures

may also be used. Data transmission can be also be protected by coding

techniques called encryption. Data is scrambled in to a coded form before

transmission and decoded upon arrival.

14 Cont…

Types of networks

There are many different types of networks. However from an end user’s point of view

there are two basic types :-

Local Area Networks (LANs) :- The Computers are geographically close

together (that is, in the building).

Wide Area Networks (WANs) :- The Computers are farther apart and are

connected by telephone lines or radio waves

Categorization of networks: In addition to these types, the following

characteristics are also used to categorize different types of networks.

Topology :- Topology of a network refers to the geometric arrangement of a computers

systems on the network. Common topologies include a bus, star, and ring.

Protocol :- The protocol defines a common set of rules and signals that computers on

the network use to communicate. One of the most popular protocols for LANs is called

Ethernet. Another popular LAN protocol for PCs is the IBM token-ring network.

Architecture :- Networks can be broadly classified as using either peer-to-peer or

client/server architecture.

Computers on a network are sometimes called nodes. Computers and devices that

allocated resources for a network are called servers.

15 Cont…

CLASSIFICATION:-

Based on the distance covered by a computer network, a network can be

classified as Local Area Network (LAN), a Metropolitan Area Network (MAN), and a

Wide Area Network (WAN). We will now discuss these in more details.

LOCAL AREA NETWORK (LAN):-

A Local Area Network or LAN is a group of computers in a localized area. The term-

localized area can refer to a small room, twenty feet by ten feet, or to a factory spanning

several acres. Another widely accepted definition states that a LAN is a computer

network confined to a building or a cluster of buildings. A LAN is a network that is

installed for the exclusive use of a particular office or a factory of an organization. You

will rarely come across two or more organizations in an office complex sharing a LAN.

LANs are restricted in size.

Most LANs connect workstations and personal computers. Each node

(individual computer) in a LAN has its own CPU with which it executes programs, but

it is also able to access data and devices anywhere on the LAN. This means that many

users can share expensive devices, such as laser printers, as well as data. Users can also

use the LAN to communicate with each other, by sending e-mail or engaging in chat

sessions.

16 Cont…

There are many different types of LANs – token-ring networks, Ethernets, and

ARC nets being the most common for PCs. Most Apple Macintosh networks are based

on Apple’s AppleTalk network system, which is built into Macintosh computers.

LANs are capable of transmitting data at very fast rates, much faster than data

can be transmitted over a telephone line; but the distances are limited, and there is also a

limit on the number of computers that can be attached to a single LAN.

History of LAN:

In the 1980s, there were large room-sized mainframe computers that had special

terminal displays and keyboards. An example of a mainframe was the IBM S/370 or

IBM System/3, which was commonly running a traditional business application like

payroll or inventory. These “dumb terminals” were of a single fixed function and often

required special wiring required months of programming. Very little off-the-shelf

software was available and most programs were custom-written, often tailored to

accommodate the proprietary terminals.

With the arrival of the 1970s came the mini-computer, which made use of a

standard terminal interface and a slow, but cheap, ASCII serial connection. While the

terminals were dropping in size and price, they still relied completely on the mini-

computer for any intelligence. Unfortunately, the cabling for the mainframe terminals

was different from the cabling for the mini-computers.

The personal computer came on the scene in 1980 with the Apple II and then

into the business world with the IBM PC in 1981. Wildly popular software programs,

often referred to as “killer apps” were VisiCalc and WordStar. Sharing of these

17 Cont…

spreadsheet and document files was accomplished by taking the diskette from machine

to machine, a process jokingly referred to as “sneaker-net.” Not only was this method

inefficient, it created version control problems. When there were several copies of a file

floating around, it was difficult to establish which one was the official version when

updates occurred.

Wide Area Networks were still in place for the mini and mainframes, and the

new PCs could emulate those older WAN protocols for sharing files. The PC could

emulate a fixed function terminal and be able to run VisiCalc as well. It was the best of

both worlds. However, there was still no central repository for files.

Eventually, Novell and Microsoft independently came up with the idea of

LANs to connect the PCs together. Because disks and printers were so expensive at that

time, the original intent of a LAN was to allow users to share disk and printer resources.

As a result, the first LANs were designed simply to avoid transportation of newly

created files via diskettes from one computer to another. Later, PC LANs improved to

the point where they were no longer dependent on mainframe and mini computers. As

LANs continue to desktop, they share more kinds of resources and more kinds of data.

LAN TOPOLOGIES:

Topology is a term that refers the shape of the network and the layout of cabling from a

bird’s eye view, much as a floor plan identifies the layout of offices and hallways in a

building. Common topologies include star, ring and bus.

18 Cont…

Theoretically, any kind of cable medium could be wired together to create an infinite

variety of network layouts. But, in fact, certain implementations of topology have

become more popular while other implementations have simply never caught on.

Consider some of the most common types of LAN topology.

As we seen earlier, topology is the geometric arrangement of the Computers in a

network. Common topologies include star, ring and bus.

Star Network: The Star network is frequently used to connect one or more

small computers or peripheral devices to a large host computer or CPU. Many

organizations use the star network or a variation of it in a time-sharing system, in which

several users are able to share a central processor.

In a time sharing setup, each terminal receives a fixed amount of the central

CPU’s time, called a time slice. If you are sitting at a terminal and cannot complete your

task during the time slice, the computer will come back to you to allow you to do so.

Actually, because the CPU operates so much faster than terminals, you will probably

not even notice that the CPU is away.

If the user wants to send a document or message to a user at another computer,

the message is routed through the central communications controller. Another common

use of the star network is to connect several microcomputers to a mainframe computer

that allows access to an organization’s database.

Ring Network: The ring network is a local area network whose topology is

a ring-can be as simple as a circle or point-to-point connections of computers at

dispersed locations, with no central host computer or, communications controller. That

19 Cont…

is, all of the nodes are connected in a closed loop. Messages travel around the ring, with

each node reading those messages addressed to it. One of the advantages of ring

networks is that they can span larger distances than other types of networks, such as bus

network, because each node regenerates messages as they pass through it.

Bus Network: Bus network are similar to ring networks except that the ends

are not connected. All communications are carried on a common cable or bus and are

available to each device on the network.

Mesh Topology: The Mesh topology is a variation of the bus, in which all

devices are connected to one another in a daisy-chain fashion, as opposed to connecting

in sequence to a single network cable. Each node is capable of transmitting, receiving,

and routing data to other nodes on the network.

Tree Topology: The Tree topology is essentially a hybrid of the bus and star

layouts. The basic topology is similar to that of a bus, with nodes connected in sequence

to a linear central cable. But tree networks may have “branches” that contain multiple

workstations that are connected point-to-point in a star-like pattern. Signals from a

transmitting node travel the length of the medium and are received by all other nodes.

LAN APPLICATIONS:

Software applications are programs designed for the end user (spreadsheets, games,

graphics). Sharing of application is one of the most important reasons for installing

LANs. Specialized applications include:

20 Cont…

Vertical applications are specific to a particular industry (medical,

government, education, etc.).

Strategic applications are vital to business operations, including Oracle, SAP,

and Lotus Notes.

Vestigial applications refer to critical business applications that pre-date the

LAN, such as MINX.

LAN TRANSMISSION METHODS:

LAN data transmissions fall into three classifications:

In a uni-cast transmission, a single packet is sent from the source to a

destination on a network. First the source node addresses the packet by using the

address of the destination node. The package is then sent onto the network, and finally,

the network passes the packet to its destination.

A Multicast transmission consists of a single data packet that is copied and

sent to a specific subset of nodes on the network. First the source node addresses the

packet by using multicast address. The packet is then sent into the network, which

makes copies of the packet and sends a copy to each node that is part of the multicast

address.

A Broadcast transmission consists of a single data packet that is copied and

sent to all nodes on the network. In this type of transmissions, the source node addresses

the packet by using the broadcast address. The packet is then sent onto the network,

which makes copies of the packet and sends a copy to every node on the network.

21 Cont…

METROPOLITAN AREA NETWORK (MAN):

A MAN covers an area larger than LAN, but it uses the LAN technology to connect the

computers. It covers an area of a state or a city and includes tow or more LANs. For

example, an organization may have two offices in different parts of the city. The

computers in each of these offices can be connected through cables and will form a

LAN. Connecting the two LANs will result in a MAN. There are three important

features, which discriminate MANs from LANs or WANs:

The network size falls intermediate between LANs and WANs. A MAN

typically covers an area of between 5 and 50 km diameter. Many MANs cover an area

equivalent to the size of a city, although in some cases MANs may be as small as a

group of buildings or as large as the North of Scotland.

A MAN often acts as a high-speed network to allow sharing of regional

resources (similar to a large LAN). It is also frequently used to provide a shred

connection to other networks using a link to a WAN.

WIDE AREA NETWORK (WAN):

In a WAN, computer networks located in different countries and continents can be

connected to share information. A WAN covers an Area larger than MAN. A WAN

uses telephone cables and satellites for communication. For example, the computer

network of an organization with the head office at U.S.A. connects to the networks of its

branches in Hong Kong. This forms a WAN. The largest WAN in existence is the

Internet.

22 Cont…

WAN TECHNOLOGIES:

A WAN is a data communications network that covers a relatively broad graphics area

and that often uses transmission facilities provided by common carriers, such as

telephone companies.

Point-to-point Links: A point-to-point link provides a single, pre-established

WAN communication path from the customer premises through a carrier network, such

as Telephone Company, to a remote network. Point-to-point lines are usually leased

from a carrier and thus are often called leased line. For point-to-point lines, the carrier

allocates pairs of wire and facility hardware to your line only. These circuits are

generally priced based on bandwidth required.

Circuit Switching: Switched circuits allow data connections that can be

initiated when needed and terminated when communication is complete. This works

much like a normal telephone line woks for voice communication. Integrated Services

Digital Network (ISDN) is a good example of circuit Switching.

Packet Switching: Packet Switching is a WAN technology in which users

share common carrier resources. Because this allows the carrier to make more efficient

use of its infrastructure the cost to the customer is generally much better than with

point-to-point lines. In a packet switching setup, networks have connections into the

carrier’s network, and many customers share the carrier’s Network.

23 Cont…

WIRELESS NETWORKING:

A wireless LAN (WLAN) is a flexible data communication system implemented as an

extension to, or as an alternative for, a wired LAN within a building or campus Using

electromagnetic waves, WLANs transmit and receive data over the air, minimizing the

need for wired connections. Thus, WLANs combine data connectivity with user

mobility, and, through simplified configuration, enable movable LANs.

Wireless LAN market is rapidly approaching billion of rupees in revenues.

Applications for wireless LANs.

Wireless LANs frequently augment rather than replace wired LAN networks often

providing the few meters of connectivity between a backbone network and the mobile

user. The following list describes some of the many applications made possible through

the power and flexibility of wireless LANs:

Doctors and nurses in hospitals are more productive because hand held or

notebook computers with wireless LAN capability deliver patient information

instantly.

Consulting or accounting audit engagement teams or small workgroups increase

productivity with quick network setup.

Training sites at corporations and students at universities use wireless

connectivity to facilitate access to information, information exchanges, and

learning.

24 Cont…

Networks managers installing networked Computers in older buildings find that

wireless LANs are a cost-effective network infrastructure solution.

Retail store owners use wireless networks to simply frequent network

reconfiguration.

Trade show and branch office workers minimize setup requirement by installing

preconfigured wireless LANs needing no local MIS support.

Warehouse worker use wireless LANs to exchange information with central

database and increase their productivity.

Network managers implement wireless LANs to provide backup for mission

critical applications running on wired networks.

Senior executives in conference rooms make quicker decision because they have

real time information at their fingertips.

NETWORK ARCHITECTURE:

The term architecture can refer to either hardware or software, or a combination of

hardware and software. The architecture of a system always defines its broad outlines,

and may define precise mechanism as well.

Open Architecture: An open architecture allows the system to be connected

easily to devices and programs made by other manufactures. Open architecture use off-

the-shelf components and conform to approved standards. A system with a closed

25 Cont…

architecture, on the other hand, is one whose design in proprietary, making it difficult to

connect the system to other systems.

Peer-to-peer architecture: This is a type of network in which each

workstation has equivalent capabilities and responsibilities. This differs from

client/server architecture in which some workstations are dedicated to serving the

others.

Peer-to-peer networks are generally simpler and less expensive.

Client/Server Architecture: This is a network architecture in which each

computer or process on the network is either a client or a server. Servers are powerful

computers or processors dedicated to managing disk driver’s printers, or network traffic.

Clients are less powerful PCs or workstations on which users runs application.

NETWORK PROTOCOLS:

A protocol is an agreed-upon format for transmitting data between two devices. The

protocol determines the following:

1. The type of error checking to be used.

2. Data compression method, if any.

3. How the sending device will indicate that it has finished sending a message.

4. How the receiving device will indicate that it has received a message.

26 Cont…

There are a variety of standard protocols from which programmers can choose. Each has

its own particular advantage and disadvantages; for example, some are simpler than the

others, some are more reliable, and some are faster.

From a user’s point of view, the only interesting aspect about protocols is that your

computer or device must support the right ones if you want to communicate with other

computers. The protocol can be implemented either in hardware or in software. Some of

the popular protocols are TCP/IP, HTTP, FTP, SMTP, POP, Token-ring, Ethernet,

Kermit, MNP, etc.

NETWORK DEVICES:

Network Interface Cards (NICs): The Network Interface Card (NIC) is a

circuit board that is physically installed within an active network node, such as a

computer, server, or printer. The NIC is an adapter that controls the exchange of

information between the network and the user. Newer NICs are increasingly pre-

installed and have the ability to automatically configure to match the speed of the

network to which they are connected.

Hub, Switch, and Router: Most network equipment manufactures offer hub,

switch, or router as their main products. This is because these are the devices needed to

set up an Ethernet network in today’s UTP cabling and star topology environment.

While most people has heard about them, there are still many who don’t fully

27 Cont…

understand the differences between these devices. To understand their functions, it is

necessary to look into the OSI model.

Switches are a fundamental part of most networks. They make it possible for

several users to send information over a network at the same time without slowing each

other down. Just like routers allow different networks to communicate with each other,

switches allow different nodes of a network to communicate directly with one another in

a smooth and efficient manner.

Router is generally an OSI layer 3 devices. Routers use IP address instead of

MAC address for the destination of a data packet. Therefore, it is hardware independent

and gives network designer more flexibility. A router can divide network into different

subnets, thus making Internet sharing possible. Nevertheless, because routers use

software method to control the network traffic, they are generally slower than switches.

Therefore, the use of routers for most business is limited to Internet connection sharing

through NAT routers.

Repeaters: Repeaters work at the physical level. They are not intelligent

workers, which means that they do not perform switching or routing functions. A

repeater’s main task is to boost the signal it receives from one segment of a network for

transmission on a different segment. Generally, a repeater is used to extend a segment of

a network.

Firewall: Firewall can take a variety of forms, from physical devices to

software. A firewall will operate at either the Network Layer or at the Application

Layer. At the Network layer, the firewall is transparent to the user. That is to say that a

28 Cont…

user will not log into the firewall or give passwords to get through. This type of firewall

will not be transparent when it refuses a user request!

Software

In addition to hardware’s importance in construction a network, software plays a crucial

role in the network’s function.

This section is not meant to cover network operating system in depth, nor are the

operating systems covered here are the only systems available. Many networks consist

of a variety of different Computers and operating systems. The task of a network

operating system is to give all of these various components the tools they need to

communicate directly with other host and resources on the network.

Novell:

Netware 5 compatibility, IP and IPX protocol integration, most current version of NDS,

IP and Z.E.N. works ready client software, a three user demonstration copy of Netware

5 , the Z.E.N. works starter pack, five user version of Oracle8, supports network access

for remote employees, Netscape FastTrack Server for NetWare, Netscape

Communicator, Multi-protocol Router(v3.2), Perl (v5.1) and NetBasic (v6) scripting

tools, integrated with all reliability updates, year 2000 compatible.

29 Cont…

TCP/IP

Unlike a packaged network operating system, the TCP/IP protocol suite is the standard

protocol suite that allows internet access. Sometimes this collection of protocols is

called a TCP/IP stack. All internet compatible NOS’s include a TCP/IP suite.

TCP/IP software is normally included with UNIX installations. Most versions of the

UNIX operating system (including the different distribution on Linux) have everything

needed to use a UNIX Computer as a network server or client.

Windows NT / 2000

Windows NT 4.0 provides traditional network services, web, ftp, DNS, POP mail and

gopher servers. NT supports files haring for DOS, Windows, UNIX and Macintosh and

includes TCP/IP protocols and NetBEUI protocols.

Optionally, Backoffice a server suite, includes NT server, firewall, cache, database,

internet mail, small business, legacy integration, intranet, remote authentication, and

secure business servers, network resource prioritization and usage statistics tools, and a

web editing package.

Windows NT Server 4.0 requires either an Intel 486/33 or higher CPU, and 125 MB

hard drive space, or a RISC processor compatible with NT and 160 MB of space.

Additionally, 16 MB of memory, a CD-ROM and VGA video are required.

30 Cont…

INTERNET:

The Internet is made up of millions of computers linked together around the world in

such a way that information can be sent from any computer to any other 24 hours a day.

These computers can be in homes, schools, universities, government departments, or

business small and large. They can be any type of computer and be single personal

computers or workstations on a school or a company network. The Internet is often

described as ‘a network of networks’ because all the smaller networks of organizations

are linked together into the one giant network called the Internet. All computers are

pretty much equal once connected to the internet, the only difference will be the speed

of the connection which is dependent on your Internet Service Provider and your own

modem.

The Internet is a loose amalgam of thousands of computer networks reaching

millions of people all over the world. Although its original purpose was to provide

researchers with access to expensive hardware resources, the Internet has demonstrated

such speed and effectiveness as a communications medium that it has transcended the

original mission. It has, in recent years, grown so large and powerful that it is now an

information and communication tool you cannot afford to ignore.

Today the Internet is being used by all sorts of people and organizations

newspapers, publishers, TV stations, celebrities, teachers, librarians, hobbyists, and

business people for a variety of purposes, from communicating with one another to

accessing valuable services and resources. You can hardly pick up a newspaper or

magazine without reading about how the Internet is playing a part in someone’s life a

project or discovery.

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History of internet :

The internet universe was created by an unassuming bang in 1969 with the birth of

ARPANET, an experimental project of the U.S. Department of Defense Advanced

Research Projects Agency (DARPA). It is a humble mission, to explore experimental

networking technologies the would link researchers with remote resources such as larg

computer systems and database. The success of ARPANET helped cultivate numerous

other networking initiatives, which grew up intertwinded, 25 years later, these have

evolved into an ever expanding, complex organism comprising tens of millions of

people and tens of thousands of networks.

The internet is habited by millions of regular folks “non-techies” who use it daily to

communicate and search for information in 1992. it’s important to understand the

significance of the internet’s growth and popularity. In one sense it could be compared

to the proliferation of fax machines in the late 1980’s. Similarly stand-alone computers

are useful, but their potential is limited by isolated applications – word processors and

spreadsheets, for example -- and the amount of money you have to spend on disk drives

and CD-ROMS. A mere direct full time or dial-up connection to the worldwide internet

gives you access to more info-goods, services, and people than you’ll ever find on your

own isolated computer or local-area network.

32 Cont…

How large is the internet? According to the internet society (ISOC), a professional

organization of internet developers, influencers and users as of spring 1994, the internet

reaches 69 countries directly and 146 via email gateways, and consisted of 23,659

networks and 2.217 million Computers.

INTRANET & EXTRANETS:

The newest type of network to be used within an organization is an intranet or an

internal web. Intranets are patterned after the Internet. Such networks enable computers

or networks of any type to communicate easily. The hardware and the software needs

are same as that for an Internet, specifically TCP/IP protocols and server and browser

software used for the World Wide Web.

With an intranet all of the organization’s computers-whether they are stand

alone systems connected to the mainframe, or part of LAN or WAN-can communicate

with each other. There is no need to adjust a network when a new user joins in. This

capability allows for growth without pain

and flexibility without sacrifice.

Users can put the information on the web pages on the intranet, and all

interested parties can access the information, read it and download it without wasting

the paper to copy it, or time to make copies and circulate them.

33 Cont…

The difference between intranets and extranets is that an intranet is meant for

the use within an organization, whereas in an extranet, an external user connects to the

organization’s intranet through the Internet gateway and would be able to use the

intranet as if he is a physical user on the network. These days it is called as Virtual

Private Network. Using VPN client software, an extranet user connects to the company

intranet through a secured connection through the Internet.

METHODS OF INTERNET CONNECTIVITY:

There are several methods of connecting to Internet for the home and small network

users. However, the most popular methods are following:

Dial-up

Internet Connection Sharing

Dial-up:

In a dial-up connection, you can connect to Internet using the telephone line and

modem. All Windows operating systems support the feature of dial-up connection. You

need to just configure modem and dial-up connection in your operating system.

34 Cont…

Internet Connection Sharing:

In a home network, a computer having Internet connection can share its connection

services with other computers using the Internet connection sharing ICS Feature. The

computer providing the services of Internet connection is called connection-sharing

computer.

BENEFITS OF A COMPUTER NETWORK:

Computer Networks do not just form a network of computers. They also form

a network of people. An office with diverse departments and employees working on

various jobs can be made to function as a single unit by creating a network. Here are

some of the benefits of the computer network.

1. Resource Sharing: Using a network, you can share expensive resources like

laser printers, modem, graphic devices, and data storage units. This enables several

users to access these resources simultaneously. You can store software and programs at

a Resource sharing allow organizations to purchase sophisticated and faster equipment.

2. Data Sharing: Computer networks enable data sharing that is faster and more

efficient than using devices such as floppies and compact disks.

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3. Communication: Another use of a network is that it can help you make the

computer perform like an office intercom. You can use the computer to flash messages

on the screen of other computers in the office. This would save employees the time

spent in going to someone in another department or on another floor to deliver a

message or a memo. This also reduces the need for face-to-face meetings and circulation

of memos among employees.

4. Security: The computer is capable of storing a fair amount of information, but it

is not a very secure place to store data. Using a network, users can store their files on a

computer that is a part of the network. A network has built-in security features such that

it would be virtually impossible for anyone to access these files.

5. Expanded computer Usage: A network is very accommodating. When

employees are transferred between departments or machines moved to different

locations, new machines can be added or existing ones removed. A network ensures that

a user faces minimum inconvenience.

Although a network is not the only solution for an office to share computing

power, it helps combine the power of computers in single location as well as maintain

their independence. It makes an office a more compact setup and increases its

efficiency.

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