Internet

What is Internet ? 

Evolution of the Internet

ADVANTAGES AND DISADVANTAGES OF INTERNET

Comparison of Internet, Extranet and Intranet

NETWORK ARCHITECTURE

Definition: The configuration of computers, devices and media on a network.

Catogeries of Network Architecture

Category	Client/Server	Peer-to-Peer
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	For medium and large network	For small network fewer than 10 computers.
Operating System	Needs a specific operating system such as Windows Server 2008.	Does not need a specific operating system.
Training	Needs training	Does not need training
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

NETWORK TOPOLOGY

Topology	Ring Topology	Bus Topology	Star Topology
Definition	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 (backbone) , to which all computers and other devices connect.	All the computers and other devices on the network connect to a central device, thus forming a star.
Advantages	1. Transmission of data is simple as packets travel in one direction only. 2. Cabel faults are easily located, making troubleshooting easier.  3. All devices in ring topology share the network resources fairly.	1. Inexpensive and easy to install. 2. Other devices can be attached or detached without disturbing the network.  3. Failure of one device usually does not affect the rest of the network.	1. If one decive fails, nly that device is affected.  2. Devices can be added or removed from network with no distruption.  3. Easy to troubleshoot and isolate problem.
Disadvantages	1. A failure in any cable or device breaks the loop and can take down entire network.  2. Data packets must pass through every computer, thus make it slower.  3. More difficult to install than a bus network.	1. There might be disruption when computer or other devices are added or removed  2. The break in the cable (backbone) will prevent all systems from accessing the network.  3. It is difficult to identify the problem if the entire of network shut down.	1. If the hub or switch fails, the entire of network will be inoperated. 2. Requires more cables than most of the other topologies. 3. More expensive because of the cost of hub/switch.

COMPARISON LAN, MAN AND WAN

CRITERIA	LAN	MAN	WAN
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
EXAMPLES	-Network inside the computer lab	-Surveillance system	-Car Navigation System
	- Network around school	-Traffic light monitoring system.	-Video conference
	-Network inside your home	- Cable Network TV	-Intelligent Transportation System
	LAN's example can be an office whose different departments such as personnel, accounting etc are located in the same building and connected via bus topology using Ethernet cards.	Example of MAN is bank whose different branches in a city like Kuala Lumpur are connected using public telephone exchange and the system are connected with each other using LAN within each branch and different branches are connected using modem and bridges.	WAN's example is the connection of various branches of American Insurance Group at different countries. These branches are linked using microwave satellite communication system or internet connection. Each branch has its own LAN circuit.
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

COMPUTER NETWORK

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

Communication Device & Transmission Media

Communication Devices

- A communication  device is any type of hardware capale of transmitting data, instructions, and information between a sending device and receiving device.

Devices	Description
Dial-up Modem	A communications 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 communications 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 wirelessly from a notebook computer, a smart phone, or other mobile device.
Network Card	Sometimes called a network interface card, is 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 computers and devices to transfer data wirelessly among themselves or to transfer data wirelessly to a wired network .
	*Wireless access points have high-quality antennas for optimal signals.
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 and substance capable of carrying one or more signals in a communications channels. 

Types of tranmission media :

1. Physical Transmission Media/Guided Media/Wired

• Twisted-pair cable, Coaxial Cable, Fibre-Optic Cable 

2. Logical Transmission Media/Unguided Media/Wireless

• Infrared, Broadcast Radio, Cellular Radio, Microwave, Communications Satellite

1. Physical Transmission Media
Twisted Pair Cable	•Twisted-pair cable consists of one or more twisted-pair wires bundled together.
	•Widely used transmission media for network cabling and telephone systems.
Coaxial Cable	Consists of a single copper wire surrounded by at least three layers:
	1.An insulating material
	2.A woven or braided metal
	3.A plastic outer coating .
Fiber optic	A transmission media that uses glass or plastic fiber to carry light (laser) signals.