Network Topology

Definition
Layout of the computers and devices in a communications network.

Different between bus, star and ring topology

BUS	STAR	RING
single central cable (backbone), to which all computers and other devices connect	computers and other devices on the network connect to a central device, thus forming a star	network travels from device to device around the entire ring, in one direction (clockwise or counterclockwise)
one device fails, only that device is affected	one device fails, only that device is affected	Failure in any cable or device breaks the loop and can take down the entire network
coaxial cable	coaxial cable	twisted pair cable

Example of  bus,star and ring topology  transfer data

LAN(Local Area Network)

-Network that connect computers and devices in a limited geographical area.

-less than 500 interconnected devices.

Example:At home,School computer,office building or closely positioned group of buildings.

Advantage and Disadvantage of LAN

Advantages	Disadvantage
Easy to share devices	Required to be on all the time
Easy to share data	Less secured
Cost of setup is low	Speed internet will be slow if all computer connect simultaneously
Sharing of resources	Area covered is limited

MAN(Metropolitan Area Network)

-Network that optimized for a large geographical area than a LAN.

Example:Traffic Light Monitoring System,Cable Network TV,Surveillance System and Building in a                  city

Advantage and Disadvantage of MAN

Advantages	Disadvantage
Shared access	Quite slow
Equal ability to go on line	It can be costly

WAN(Wide Area Network)

-Network that cover the largest geographical area.

Example:states,countries or continents.

Advantage and Disadvantage of WAN

Advantages	Disadvantage
Message can be sent very quickly	Setting up a network
Avoid older information	Security problems
Share information in large area	Maintenance problems

Network Architecture

Definition
Configuration of computers, devices and media on a network.

Type of network

Peer-to-peer
-A simple and inexpensive network that typically connects less than 10 computers.

Client server
-One or more computer act as server,and the other computer and other computer in the network         request services from the server.

Different between peer-to-peer network and client server network

Peer-to-peer	Client server
does not provide centralize data	provide centralize data
has equal responsibilities and capabilities	client request permission from the server
not need training to setup and maintenance	need training to setup and maintenance
do not need specific operating system	need specific operating system

About Computer Network

BASIC CONCEPT OF NETWORK

Collection of computers and devices connected together via communications devices and transmission media.Usually,the connections between computers in a network are made using physical wires or cables.some connections are wireless, using radio waves or infrared signals.

Applications of network:

TYPE OF APPLICATION	APPLICATION
Resource sharing	Hardware
	Software
Information sharing	Easy accessibility from anywhere
	Search capability
Communication	Email
	Message broadcast

Communication Devices

Any type of hardware capable of transmitting data, instructions, and information between a sending device and a receiving device.

DEVICES	DESCRIPTION
Dial up modem	A communication device that can convert digital signals to analog signals and analog signals to digital signals,so that data can travel along an analog telephone line.
Digital Modem(ISDN,DSL,Cable Modem)	A communication device that sends and receives data and information to and from a digital line
Wireless Modem	Some mobile users have a wireless modem that uses the cell phone network to connect to the internet wirelessy from a notebook computer, a smartphone,or other mobile device
Network Card	A communications device that enables a computer or device that does not have built-in networking capability to access a network
Wireless access point	A central communications device that allows computer and devices to transfer data wirelessly among themselves or to transfer data wirelessly to a wired network
Router	A communications device that connects multiple computers or other routers together and transmits data to its correct destination on a network
Switch	A connection device similar to a hub but more sophisticated,including functionality that allows it to control and manage data transmissions
Hub	A connection device that allows multiple connections to the network.

Transmission Media

Materials or substances capable of carrying one or more signals in a communications channel.

TYPE	EXAMPLE
Physical transmission media	Twisted-Pair Cable,Coaxial cable,Fiber-Optic Cable
Wireless transmission media	Infrared,Broadcast Radio,Cellular Radio,Microwave,communications satellite

Advantage	Disadvantage
Easy for communication	Breakdowns and Possible Loss if Resouces
Ability to share files,data and information	Expensive for the setup and maintenance
High scurity level	Security Threats
High speed	Bandwith Issues