WHAT IS A COMPUTERNETWORK?• A Computer network is a number ifcomputers interconnected by one ormore transmission paths.• The transmission path often is thetelephone line, due to its convenienceand universal preserve.
DATA COMMUNICATION• Data Communication is theexchange of data (in the form of Osand 1s) between two devices viasome form of transmission medium(such as a wire cable).
TYPES OF DATACOMMUNICATION• Data Communication is considered• Local – if the communicating device are in• the same building.• Remote – if the device are farther apart.
THE DIFFERENCE BETWEEN DATA ANDINFORMATION• Data: is a representation of facts, conceptsand instructions presented in a formalizedmanner suitable forcommunication, interpretation or processingby human beings or by automatic means.• Information: is currently assigned to data bymeans by the conventions applied to thosedata.
FUNDAMENTAL CHARACTERISTICSOF DATA COMMUNICATION• The effectiveness of a data communicationsystem depends on three characteristics.• 1. Delivery: The system must deliver data tothe correct destination.• 2. Accuracy: The system must deliver dataaccurately.• 3. Timeliness: The system must deliver datain a timely manner.
THE MESSAGEThis is the information (Data)to be communicated; it may beanimage, text, number, Audio, orVideo.
THE SENDERThe sender is device or person thatsends the data. It can be sent using acomputer, telephone, or camera.
THE RECEIVERThe receiver isdevice or personthat receives thedata. It can bereceived whether byusing atelephone, computer, television.
Transmission mediaThe physical path by which massagetravel from source to destination(sender to receiver) example -twistedpair, coaxial cable, fiber optic, radiowaves.
ProtocolA protocol is set of rules that governdata communication. It provideagreement between sender andreceiver devices
SYNTAXStructure or format of the data;for example, fist 8bits areflag, 2nd 8bits are destinationaddress, other 32 bits formassage and last 8bits are forsource address
SEMANTICSthis refers to the meaning of eachsection of bits, how the particularpattern to be interpreted is and whataction to be taken. For example10101010, pattern as a flag (start ofdata stream)
TIMINGwhen the data sending ,how fastthey can send for example senderis send data at 100 mbpsspeed, receiver is receive data at10 mbps what will happen, datawill be lost !
IN DATA COMMUNICATION FOUR BASICTERMS ARE FREQUENTLY USED• In data communication four basic terms are frequentlyused. They are:• Data : A collection of facts in raw forms that becomeinformation after processing.Signals : Electric or electromagnetic encoding of data.• Signaling : Propagation of signals across a communicationmedium.• Transmission : Communication of data achieved by theprocessing of signals.