OVERVIEW OF THE INTERNET

What is the ineternet ?

The Internet is a worldwide collection of networks that links millions of businesses, government agencies, educational institutions, and individuals.

EVOLUTION OF THE INTERNET 

ADVANTAGES AND DISADVANTAGES OF THE INTERNET 

INTERNET
ADVANTAGES	DISADVANTAGES
Software Downloads: You can freely download software like utilities, games, music, videos, movies, etc from the Internet.	Virus threat: Computers attached to Internet are more prone to virus attacks and they can end up into crashing your whole hard disk.
Online Services: •       Perform all your transactions online. •       Can book tickets for a movie, transfer funds, pay utility bills. •       Make a hotel or flight reservation right from your home.	Social Disconnect: •       People now only meet on social networks. •       More and more people are getting engaged with virtual world and drifting apart from their friends and family.
E-mail: People can sent messages. It is delivered instantly to people anywhere in the world, unlike traditional mail that takes a lot of time.	Dangers involved when children using the Internet : When children talk to others online, they do not realize they could actually be talking to a harmful person. Plus, there are thousands of pornographic sites on the Internet that can be easily found.
Information resources: Can find any information on almost any kind of subject that you are looking for by using search engines like Google, Yahoo, MSN, etc.	Theft of Personal information: Your personal information such as your name, address, credit card, bank details and other information can be accessed by an irresponsible people for their own benefit.

INTRANET 

An intranet is a private network that is contained within an enterprise. It may consist of many interlinked local area networks and also use leased lines in the wide area network. Typically, an intranet includes connections through one or more gateway computers to the outside Internet. The main purpose of an intranet is to share company information and computing resources among employees. An intranet can also be used to facilitate working in groups and for teleconferences.

INTRANET
ADVANTAGES	DISADVANTAGES
Commercial or confidential data is kept secure within the organization	High financial cost incurred by the company when initially implementing the intranet
Email remain private and may also be encrypted	Connections between an intranet and the Internet potentially compromises security, by allowing virus infections or system hacking.
High bandwidth. No connection limits unlike the Internet.	Staff needs training to ensure workers know how to use the system effectively.
Reliable. The company will have dedicated IT personnel to keep things running smoothly.	Information overload is another disadvantage because it reduces productivity.

EXTRANET

-An extranet is the portion of a company’s network that allows customers or suppliers of a company to accesS parts of an enterprise’s intranet.

-An extranet provides a secure, physical connection to the company’s network.

    

EXTRANET
ADVANTAGES	DISADVANTAGES
Exchange large volumes of data using electronic data interchange (EDI)	Extranets can be expensive to implement and maintain within an organization (e.g., hardware, software, employee training costs), if hosted internally rather than by an application service provider.
Share product catalogs exclusively with trade partners	Security of extranets can be a concern when hosting valuable or proprietary information.

CLASSIFICATION OF NETWORK

CRITERIA	LAN (LOCAL AREA NETWORK)	WAN (WIDE AREA NETWORK)	MAN (METROPOLITAN AREA NETWORK)
AREA OF COVERAGE	Network cover limited geographical area such as closely positioned group of buildings network , network at home, network inside computer laboratory and network in office building  .	A high speed network that connects Local Area Networks in a Metropolitan Area such as a  cities or town.	Network cover large geographical  area  such a countries ,the  continents or the world
NETWORK SIZE	Small size ( in a building)	Larger size ( in a cities or campus)	Largest size (different states or countries)
SPEED	Fastest in data transferring and access time	Slower in data transferring and access time	Slowest  in data transferring and access time
COMMUNICATION DEVICES	Connected using modems, hubs, switch , router	- Connected using modems, hubs, switch , router	The connection is made via satellite communication link or via internet
COST	Less costly setup and maintenance	More costly setup and maintenance	Costliest setup and maintenance
NETWORK OWNERSHIP	Private – owned, controlled and manage by a single person or organization	Private - owned and operated by a single entity such as a government or large corporation	Not owned up any one organization but exist under collective or distributed ownership

NETWORK TOPOLOGY

A network topology refers to the layout of the computers and devices in a communications network.

(Physical and logical)

PHYSICAL TOPOLOGY - The arrangement of a cabling 

LOGICAL TOPOLOGY - The path that data travels between computers on a network

CATEGORY	STAR TOPOLOGY	RING  TOPOLOGY	BUS TOPOLOGY
DEFINITION	All the computers and other devices on the network connect to a central device, thus forming a star.	On a ring network,  a cable forms a closed loop (ring) with all computers and devices arranged   along the ring.	A bus network consists of a single central cable (backbone), to which all computers and other devices connect.
ADVANTAGES	·         If one device fails,only that device is affected. ·         Devices can be added or removed from network with no disruption. ·         Easy to  troubleshoot and isolate problem	·         Transmission of data is simple as packets travel in one direction only. ·         Cabel faults are easily located, making troubleshooting easier. ·         All devices in ring topolgy share the network resources fairly.	·         Inexpensive and easy to install. ·         Other devices ca be attached or detached without disturbing the network. ·         Failure of one device usually does not affect the rest of the network
DISADVANTAGES	·         If the hub or switch fails, the entire network will be inoperabled. ·         Requires more cables than most of the other topologies ·         More expensive because of the cost of hub/switch	·         A failure in any cable or device breaks the loop and can take down entire network. ·         Data packets must pass through every computer, thus make it slower. ·         More difficult to install than a bus network	·         There might be disruption when computer or other devices are added or removed. ·         The break in the main cable (backbone) will prevent all systems from accessing the network. ·         It is difficult toidentify the problem if the entire network Shut down.

NETWORK ARCHITECTURE

NETWORK ARCHITECTURE ?
The configuration of computers, devices and media on a network.

PEER-TO-PEER NETWORK ARCHITECTURE

• A simple, inexpensive network that typically connects fewer  than 10 computers.
• Each computer, called a peer, has equal responsibilities and capabilities.
• Sharing hardware (such as a printer), data or information with other computers on the peer-to-peer network.
• Each computer stores files on its own storage devices. Thus, each computer on the network contains both the server operating system and application software.
• All computers on the network share any peripheral device(s) attached to any computer.
• Peer-to-peer networks are ideal for very small businesses and home users.
• Some operating systems, such as Windows, include a peer to-peer networking utility that allows users to set up a peer-to-peer network.
• Peers are both suppliers and consumers of resources.
• Each node is a computer on the network which acts and communicates with other Peers to make a portion of their resources, such as processing power, disk storage or network bandwidth.
• Directly available to other network participants, without the need for central coordination by servers or stable hosts.

CCJ       CLIENT/SERVER NETWORK ARCHITECTURE

C

•One or more computers act as a server, and the other computers on the network request services from the server.

•Server, sometimes called a host computer, controls access to the hardware, software, and other resources on the network and provides a centralized storage area for programs, data and information.

•The clients are other computers and mobile devices on the network that rely on the server for its resources.

•

•For example, a server might store a database of customers. Clients on the network (company employees) access the customer database on the server.

     

CATEGORY	CLIENT SERVER	PEER TO PEER NETWORK
DEFINITION	One or more computers act as a server, and the other computers on the network request services from the server.	Each computer, called a peer, has equal responsibilities          and    capabilities, sharing hardware (such as a printer), data, or information with other computers on the peer-to-peer network.
SIZE	Needs a specific operating system such as Windows Server 2008.	Does not need a specific operating system.
TRAINING	Needs training	Does not need training
OPERATING SYSTEM	Needs a specific operating system	Does not need a specific operating system.
SET UP	More difficult to set up	Easy to set up
INSTALLATION	More expensive to install	Less expensive to install
IMPLEMENTATION	Big corporations or organizations with high security data	Small businesses and home users