3.1 Network Basic ( Classification of Network )

Networks typically are classified as

 ☻ LOCAL AREA NETWORK  ( LAN )

•A local area network (LAN) is a network that connects computers and devices in a limited geographical area

•A wireless LAN (WLAN) is a LAN that uses no physical wires

Advantages

•Easy to share devices(printers, scanners, external drives)

•Easy to share data (homework, pictures)

•Cost of LAN Setup is low.

Disadvantages 

•Power - a good LAN is required to be on all the times.

•Security - each computer and device become another point of entry for undesirables.

•if all computers running at once, can reduce speed for each.

•Area covered is limited

☻ METROPOLITAN AREA NETWORK ( MAN )\

•    A metropolitan area network (MAN) is a high-speed network that connects local area networks in a metropolitan area such as a city or town and handles the bulk of communications activity across that region.

❤  Type of MAN

✿  Campus Area Network (CAN)

•A campus network is a computer network made up of an interconnection of local area networks (LAN's) within a limited geographical area. 

•In the case of a university campus-based campus network, the network is likely to link a variety of campus buildings including; academic departments, the university library and student residence halls.

Advantages

•efficiency and shared access.

•All the computer-owning residents of the area have equal ability to go on line. 

Disadvantages

•it can be costly (hardware, software, support, etc.).

•security problems

•As the network consists of many computers over the span of a city, the connection can lag or become quite slow.

 ☻ Wide Area network ( WAN )

A wide area network (WAN) is a network that covers a large geographic area (such as a city, country, or the world) using a communications channel that combines many types of media such as telephone lines, cables, and radio waves.

 The Internet is the world’s largest WAN

Advantages

•increased efficiency, ease of communication, and lowered costs. 

Disadvantages

•security problems

•training costs

•maintenance problems. Large enterprises will dedicate personnel to maintaining their WAN.

How Are LAN, MAN, and WAN Different

Network Basic

Basic Concept of Network

A network is a collection of computers and devices connected together via communication devices and transmission media 

Computer Comunication

process in which two or more computers or devices transfer data, instructions and information

Communications System

• sending device : initiates an instruction to trasmit data, instruction and information
• communication device : connects the sending device to a communication channel
• communication channel / transmission media : which the data, instructions or information travel
• communication device : connects the communicatin channel/transmission media to a receiving device
• receiving device : accepts the transmission of data, instruction or information  

 Communication device : 

• hub
• switch
• router
• network interface card (NIC)

Transmission media :

• telephone line
• cable tv
• power line
• fiber optic
• satellite
• radiowave
• microwave

Network 

A network is a collection of computers and devices connected together via communication devices and transmission media.

Advantages of network :

• facilitating communication
• sharing hardware
• sharing software
• sharing data and information
• transfering funds

Disadvantages of network :

• viruses
• network failure
• slow service
• cost
• expert support required

Network Architecture

Network architecture is the design of computers and media on a network
Types of network architecture :  

• peer-to-peer (P2P)
• client server 

Peer-to-peer

• a collection of computers and other devices to share resources where computer have equal capabilities and responsibilities

Client Server 

• one or more computers act as a server and the other computers on the network request services from the server.
• Client : a host computer that supply/provide resources to client on the network
• Server : other computer and devices that request resources from the server on the network  

Network Topology

A network topology refers to the layout of the computers and devices in a communication network
Divided into :

• physical : the arrangement of a cabling
• logical : the path that data travels between computers on a network

Types of network topology :

• bus network
• star network
• ring network

Bus Network Topology

Physical :
consists of a single central cable (backbone) to which all computers and other devices connect

Logical :

• transmit data, instruction and information as a series of signal
• those signal are sent as electrical pulses that travel along the cable in all directions
• each devices is connected through T-connector
• a terminator is required at each end to prevent the signal from bouncing back 

Advantages :

• inexpensive and easy to install
• other devices can be attached and detached at any point without disturbing the network
• failure of one device dows not affect the network

Disadvantages :

• there's a disruption when other devices are added or removed
• difficult to identify the problem if the network is shut down

 

Star Topology

Physical :
All computers and other devices on the network connect to a central device thus forming a star

Logical :

• two types of central device that provide central connection point to all the devices on the network are hub and switch  
• all data that transfers from one divice to another passes through the hub or switch

Advantages :

• affect the whole network if one device fails
• other device can be added or removed from the network with no disruption
• easy to troubleshoot problem

Disadvantages :

• hub or switch fail, the entire network will fail
• requires more cable 
• more expensive because of the cost of the hub/switch

 

Ring Topology

Physical :
A cable forms a closed loop (ring) with all computers and devices arranged along the ring

Logical :

• data travels from one device to device around the ring in one direction
• token passing is the method for sending data around the ring
• each device takes a turn sending information through the use of a token
• only the device with the token is allowed to send data while the othe device must wait for their turn

Advantages :

• transmission of data is simple as it travel in one direction
• troubleshooting is easier
• the use of token enable all devices to share the network resources fairly

Disadvantages :

• a failure in any cable or device will breaks the loop and take down the entire network
• slower because data packets must pass throuh every computer 
• more difficult to install  

 

     
   
   

 
 
 

Network Basic

Learning Outcome :

• Basic Concept of Network

• Network Architecture

• Network Topology

• Classification of Network

Application Software

Application software consists of programs designed to make users more productive and assist with personal tasks.           
Types of software :

• Open source software

- Created by unpaid volunteers 
- Freely
- Examples : Shareware , Freeware , Web application

• Proprietary software

- Privately owned and limited to a specific vendor of computer model
- Paid / license

Web Browser

• Allows user to access and interact with software from any computer or device that is connected to the Internet
• Example :

- Google chrome
- Firefox
- Opera

Word Pracessing

• Allows users to create and manipulated documents
• Example :

- Microsoft Office Word
- OpenOffice.org Writer

Spreadsheet

• Allows users to organize data in rows amd columns and perform calculations
• To create personal profiles, budget summaries, income statement or calculate students marks.
• Example :

- Microsoft Office Excel

- OpenOffice.org Calc

Presentation

• Allows users to create visual aids for presentations to communicate ideas, messages and other information to a group
• To create a presentation for teaching, marketing or tourist information
• Example :

- Microsoft Office PowerPoint

- OpenOffice.org Impress

Database

• Collection of data organized in a manner that allows access, retrieval and use of that data 
• Allows user to create, access and manage a database
• To create student database, employees database or book database
• Example :

- Microsoft Office Access

- OpenOffice.org Base

^__^ TQ

System Software-Utility Program

Utility Program is a system software that allows a users to perform maintenance-type task.


File Manager 

• utility that performs functions related to file management       

- displaying a list of file
 -organizing files in folders

-copying, renaming, deleting, moving, and sorting files and folders  

-creating shortcuts

Disk Cleanup

• utility searches for and removes unnecessary files   

 -downloaded program files  

-temporary internet files         

-deleted files                   

-unused program files

Compression Tools

• shrinks the size of a file(s)

 -compressing files frees up room on the storage media 

 -two types of compression 

 LOSSY

 LOSSLESS
-sometimes are called zipped files
 -can be uncompressed 
-eg: WinZip, WinRAR, PKZIP


Anti-Virus Program
Virus- a potentially damaging computer program that affects a computer negatively 

A WORM copies itself repeatedly in memory or over a network.
A TROJAN HORSE within or looks like a legitimate program
An ANTIVIRUS PROGRAM protects a computer against virus 
eg: Avira Antivirus, Kaspersky Antivirus, Norton Antivirus

Spyware Remover
Spyware- a program placed on a computer without the user's knowledge that secretly collects information about the user
SPYWARE REMOVER- detects and deletes spyware and other similar program
eg: Spyware Doctor, Spyware remover, Spyware Blaster

Disk Defragmenter 

• reorganizes the files and unused space on a computer's hard disk so that the operating system accesses  the data more quickly and program runs faster 

eg: MyDefrag, Defraggler

Backup and Restore Utility

BACKUP UTILITY- allows users to copy files to another storage medium
RESTORE UTILITY- reverses the process and returns backup files to their original form 
eg: Backup PC, Bacula


Adware Remover 

ADWARE- displays an online advertisement  in a banner or a pop-up window
ADWARE REMOVER- a program that detects and deletes adware 
eg: Ad-Aware 

Filters 

• remove or block certain items from being displayed 

eg: Web Filtering Software, Anti-spams Programs

Media Player

• allows user to view image and animation, listen to audio, and watch video files on user's computer 

Disc Burning Software

• writes texts and graphics on a recordable or rewritable  optical disc 

Image Viewer and Uninstaller 
IMAGE VIEWER- allows users to display, copy and print the contents of the graphics file 
UNINSTALLER- removes a program, as well as any associates entry in files 

Screen Saver and Personal Firewall

SCREEN SAVER- show a moving image or blank screen if no activity occurs
PERSONAL FIREWALL- detects and protects personal computer from unauthorized intrusions

Search Utility

• program that attempts to locate a file ion computer based on criteria specify 

PC Maintenance Utility 

• identifies and fixes operating system problems, detects and repairs disk problems and includes the capabilities of improving a computer performances 

System Software - Operating System

Computer Software

   ☺   Software, also called a program, tells the computer what task perform and how to perform them

☺System software consists of the programs that control or maintain the operations of the computer and its devices

- Operating Systems

- Utility Programs

❀ Operating Systems

An operating system (OS) is a set of programs containing instructions that work together to coordinate all the activities among computer hardware resources

•Start and shut down a computer

•Provide a user interface

•Manage programs

•Manage memory

•Coordinate tasks

•Configure devices

•Establish an Internet connection

•Monitor performance

•Provide utilities

•Automatically update

•Control a network

•Administer security

✵ Operating System Functions

1.Start and Shut Down a Computer

❃ The process of starting or restarting a computer is called booting

2. Provide a User Interface

✿ A user interface controls how you enter data and instructions and how information is displayed on the screen

✿ 2 types of user interface:

üGraphical user interface (GUI)

•With a graphical user interface (GUI), you interact with menus and visual images

üCommand-line

•With a command-line interface, a user uses the keyboard to enter data and instructions

3. Manage Programs

❦ How an operating system handles programs directly affects your productivity

❦ An OS manages multiple programs & processes while you use the computer

•Single user and multiuser

•Single tasking and multitasking

•Foreground and background

•Preemptive multitasking

•Multiprocessing

4. Manage Memory

✰ Memory management optimizes the use of RAM

✰ Operating System allocates data and instructions to memory while they are being processed, monitors the content of memory and release from memory when the processor no longer requires them

5. Coordinate Tasks

• The operating system determines the order in which tasks are processed

6. Configure Devices

7. Establish an Internet Connection

•Operating systems typically provide a means to establish Internet connections

8. Monitor Performance

•A performance monitor is a program that assesses and reports information about various computer resources and devices

9. Provide Utilities

•Operating systems often provide users with the capability of:

10. Automatically Update

•Automatic update automatically provides updates to the program

11. Control a Network

•Some operating systems are designed to work with a server on a network

•A server operating system organizes and coordinates how multiple users access and share resources on a network

•A network administrator uses the server operating system to:

–Add and remove users, computers, and other devices

–Install software and administer network security

12.Administer Security

•Establish permissions to resources

•Define who & when they can access certain resources

•By setting user account

•Each user has a user account

–A user name, or user ID, identifies a specific user

–A password is a private combination of characters associated with the user name