data communication & networks

Ayesha Khalil

Data communication

& Networks

What is Data?Data consist on raw facts and figures.by using an object data can be easily get. while information is process foam of data. data is not certain while information is certain.

Data

process

information

Electronically transmission of data from one place to another place by using a medium is called data communication.

There are three components of data communication

Data communication

Sender

Medium

receiver

The way of transmission of data from one place to other is called data transmission mode

There is three transmission modesSimplex ModeHalf duplex ModeFull duplex Mode

Data Transmission Modes

Data Transmission Modes

Simplex

mode

• Data can flow only in one direction• Not moved in both direction.one way street• Not perform both action either send or receive data• Direction of flow not changes

Half duple

x

• Data can flow in both directions but not at same time• One way at one time• Device with half duplex mode can send and receive data but not at same time

Full duple

x

• Data can flow in both directions simonstenously• Fast speed and time is not waited

Direction of data flow

Simplex

Half Duplex

Full Duplex

Foams of Data Transmission

Digital Data Transmission Analogue Data transmission

Digital signals are transmitted in sequence of voltage

They represented in binary foams

Continues in foam of wave and this wave is called carrier wave

The number of wave repeats during a specific time is known as frequency.

The height of carrier wave is called amplititude

AsynchronousTransmission

Data is transmitted character by characterThere is regular gap between characters in data transmission

synchronousTransmission

Saved data is transmitted block by blockNo Gap in dataThat’s why it is faster

Types of Data Transmission

A computer network is a set of two or more computers connected through to share information and other resources through cables, satelite,or telephone cables.

There is three types of networks LAN(local area networks) WAN(wide area networks) MAN(metropoletin area networks)

Networks

Networks• Most common type of networks• Used in relatively small areaLan

• Cover large area• Consist two or more lanWan• Covers geographical area• Wan include two or more lan but

cover small area then wanMan

Network TopologiesThe physical layout or the way in which network connection are made is called network topologies.

Bus topology

Ring topology

Star topology

consists of a single cable—called a bus— connecting all nodes on a network without intervening connectivity devices

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Bus Topology

each node is connected to the two nearest nodes so the entire network forms a circleone method for passing data on ring networks is token passing

Ring topology

Star topology

Every node on the network is connected through a central device

Questions???