BASIC NETWORK


BASIC CONCEPT	NETWORK ARCHITECTURE	NETWORK TOPOLOGY

Definition Of Network.

A network is a collection of computers and mobile devices connected together via communications devices and tranmission media often wirelessly allowing computers to share resources(hardware,software,data & information).

Example of communicaton devices - modem,router,WAP,switch NIC
Example of transmission devices - twisted-pair cable,coaxial cable,fiber optic cable

Computer Networks Usage

Sharing an Internet connection among several users.
Sharing application software,printers and other resources.
Faciliting Voice over IP (VoIP),e-mail,video conferencing,messaging,and other communicatons applications.
Working collaboratively,such as sharing a company database or using collaboration tools to create or review documents.
Exchanging files among network users and over the Internet.
Connecting the computers and the entertainment devices (such as TVs,gaming consoles and stereo systems) located within a home.

DEFINITION	EXAMPLES	FUNTIONS
Comunication Devices Hardware component that enables a computer to send(transmit) and receive data,instruction and information to and from one or more computers. Or A communication device is any type of hardware capable of transmitting data,instuctions,and information between a sending device and receiving device.	Hub/Switch	A communication device that enables a computer or device that does not have built-in networking capability to access a network.
	Modem	A device that enables a computer to communicate over analog networking media such as connecting the Internet via telephone lines Wireles Modem : modem that connects tp serial port but does not connect to telephone lines.It receives through the air.
	Wireless Access Point	A device on a network that connects wireless devices to that network.
	Router	A device that connects multiple network together ; router packets to their next location in order to efficiently reach their destinstion.
	Hub	That device that provides a common central connection point for nodes on network.
	Switch	A device used to connect multipke devices on a single(typically wired) network; forward packets to only the intended recipient.
	Network Interface Cards(NIC) / Network Card	An adapter / expansion card that connect a computer to a network. Wireless network Interface Card : An expansion cards through which a computer can connect to a network that provides wireless data tranmission.
	Repeater Mobile phones Portable DVD players ,Portable media Players GPS system Satellite navigation systems Handheld computers Bluetooth	A device that enhance the weaken signal and repeat it at its original strength. These are devices that can be carried and transported easily by a person. They are used to communicate information to both the user and other people.

HUB VS SWITCH

HUB	SWITCH
Transmits signal to all other ports a computer is connected to but only the intended recipients will accept the rest will ignore. OR A device that transmits signal to all other ports a computer is connected to but only the intended recipients will accept the rest will ignore.	Transmit signal to only the intended recioients. OR A device that transmit signal to only the intended recipients.

TRANSMISSION MEDIA

The materials or substances capable of carrying one or more signals.

Physical : send signals through cable , wire or tangible materials.	Twisted-pair Cable	Physical tranmisson media which cable consisting of pairs of copper wire that are twisted together.
	Coaxial cable	Consists of a single copper wire surrounded by at least three layers : (1) an insulating material, (2) a woven or brainded metal, and (3) a plastic outer coating. OR A networking cable consisting of center wire inside a grounded,cylindrical shield, capable of sending data at high speeds.
	Fiber Optic	Physical transmission media that consists of dozens or hundreds thin strands of glass or plastic that use light to transmit signals. OR A networking cable that utilizes hundreds of thin transparent fibers over which lasers transmits data as light.
Wireless : send signals through the air or space.	Infrared	Send signals using infrared light waves from one device to another.
	Micowaves	Radio waves that provided a high-speed signal transmission using electromagnet radio wave. (P1 WiMax).
	Cellular Radio	Is a form of broadcast radio that is wide use for mobile communication.
	Broadcast radio	Distributes radio signal through the air over long distances (cities,region,country) and shorts distances (home, office).
	Communication Satellite	An earth-orbiting device that relays communications signals over long distances. OR Is a space station that receives microwave signals from an earth-based station. (Astro)
	Bluetooth	A networking standard for every short-range wireless connectios ; the devices are automatically connected once they within the allowable range.

ADVANTAGES AND DISADVANTAGES OF NETWORK

ADVANTAGES OF NETWORK	DISADVANTAGES OF NETWORK
Hardware Sharing - Network facilitate the sharing of hardware such as printer, plotters and modem	Undesirable Sharing – Viruses are easily spread over network and the Internet.
Data and information Sharing – enable many people ro access and share the same data such as database and group software development.	Security issues: a computer hacker can get unauthorized access by using different tools
Facilitate Communication – People communicate efficiently and easily via e-mail, IM, VoIP.	Network Hardware, Software and Setup Costs – Setting up a network requires an investment in hardware, software of network.
Internet Access Sharing – Small computer networks allow multiple users to share a single Internet connection.	Illegal or Undesirable Behaviour – Typical problem include the abuse of company resources, distractions that reduce productivity, the downloading of illegal or illicit material and even software piracy (abuse company production).
	Expense/cost: the initial set up costs of a computer network can be high depending on the number of computers to be connected and the number of connecting devices/expert support.