COMMUNICATION AND

COMPUTER NETWORK

Computer network

A network consists

of multiple computers

connected to each

other to share

data and resources.

Network types :

1. Local Area Network (LAN).

2. Wide Area Network (WAN ).

Computer network

1 -Local Area Network -LAN

When the network computers are located in the same general area, such as the same building or a department, it is called a Local Area Network

1 -Local Area Network -LAN

Client / Server Network :

There is a central computer called a server which stored all Data and software programs so that other computers (Client) can use it .

Peer-To-Peer Network :Individual computers share data directly with others computers , does not use a server. It is less expensive than Client / Server Network .

Clients and Nodes

Clients — computers on a network not being used as servers .

Nodes — any devices attached to the network through a hub .

A Typical Network LayoutIn a typical network layout, the client or user computers are connected to a hub, which is also connected to the server.

Client or user computers

Data and programs are stored on the server. All clients can access data and pro-grams through the server and can access the printer attached to the server.

Hub

Network Hub

2- Wide Area Network -WAN This network spread

over a wider region such as

a city, state, or country. Many WAN use satellite

communication and telephone network . Bank ATM . Internet .

graphical representation of the Internet

The Internet

The Internet evolved from a government research project in the late 1960’s called ARPANET that enabled the military and scientists around the world to share information.

Today it is the largest network in the world. It is used daily by millions of computer users. It has become a critical and valuable

business tool used by businesses of all sizes.

Intranets It is a network for the exclusive use of a

business or university and contains company information.

information on the network is not accessible to outside users .

Advantage :Reliability and security .internal controls access .

Extranets

Allow outside users to access a company’s Intranet - internal information system .

Access is tightly controlled and its reserved for supplier and customers .

EXPANSION OF NETWORK

o Hub : a distributor that has a lot of ports which connect computers .

o Switchers : like a hup , but it transmits packet to its destination .

o Routers : choose the best path to transmit the packet .

o Bridge : use to connect two similar LANs.o Repeaters : repeats signals that travels via

long distances .

Transmission Media

Transmission Media : are used to send data over the network .

1- Wired media : Twisted pairs . Coaxial . Fiber optics .

Coaxial

Twisted pairs

Fiber optics

Transmission Media

Transmission Media : are used to send data over the network .

2- Wireless media :1. Radio waves .

2. Microwaves .

3. Satellite .

Electronic Communication

Has made the Internet, e-mail, online shopping, and other processes possible.

There are four components of electronic communication:

1. Sender: The computer sending a message.2. Receiver: The computer receiving the message.3. Channel: The media that carries the message.4. Protocol: The rules that govern the processing

of a message between computers.

Electronic Communication Components

Computer A sends a message to Computer B.

The message travels via the channel, following the rules defined by the protocol being used so that each computer can understand the message.

Electronic Communications

Examples of Electronic Communications

Examples of Electronic Communications

Computers in Our Future Will be more powerful and less

expensive . Almost every type of job will

somehow involve a computer . More people will work full-time

or part-time from home . Wireless and mobile devices are

becoming the norm.