Understanding Network Protocols and Data Communication

hello everyone welcome back to the course on computer networks today we shall see Network protocols and

communication before we step into the topic we shall understand what are the things we are going to learn today today

we will be learning about data communication data flow what are the importance of protocol in computer

network understand guys protocols are very important in computer network and what are the elements will also be

addressed in today's session now we shall see what is data communication data communications are the exchange of

data between two nodes if there are two nodes they are going to exchange data via some form of link or transmission

medium in this case the transmission medium is the cable we have seen data communication it means two nodes are

going to exchange data data flow means the data is going to flow from one node to another node and there are three

different flows simplex half-duplex full duplex we shall see all these three data flows in detail firstly the simplex it

is always a unidirectional communication one node can transmit and other will receive for example keyboards just take

a keyboard is connected to a CPU keyboard is going to give data to the CPU whereas CPU is not going to give any

data to the keyboard likewise our traditional monitors I am NOT talking about our touch monitors are traditional

monitors whatever the data is there in the CPU that is going to be given to the monitor and monitor is not going to give

any information to the CPU in both the cases the data or the communication is always unidirectional coming to the half

duplex the communication is in both directions it means it can send as well as it can receive but not at the same

time the very important part about half duplex is that the communication can happen in both directions but not at the

same time if one device is sending the other device can receive and not at the same time both sending and receiving can

happen example walkie talkie in a walkie talkie we can talk as well as we can but we can't talk and listen at the same

time now we shall see what is full-duplex or simply duplex in the previous case that is the half duplex

communication happened in both directions but not at the same time whereas in full duplex communication can

happen in both directions simultaneously it means devices can send or receive data at the same time example telephone

line we can talk as well as listen simultaneously in a telephone line now we shall see an example for simplex

communication now this computer is sending data in only one direction so this is simplex if both sending and

receiving can happen but not at the same time if you observe now sending is happening now receiving is happening but

not at the same time this is sending and this is receiving this is not happening at the same time so this comes under

half-duplex and full-duplex mode of communication both sending and receiving can happen at the same time if both

sending and receiving can happen simultaneously then we call as full duplex we will now see what are

protocols any communication scheme whether it is a postal communication or a whatsapp communication or SMS way of

communication we always have certain things in common they are source or sender destination or the receiver

Channel or media any communication will definitely have these things source or the sender destination or the receiver

channel or the media and this communication will always be governed by certain protocols so protocols are rules

that governs all the methods of communication what if there are no protocols if this guy speaks at high

speed which this destination cannot handle this communication becomes useless so they have to mutually agree

upon certain rules what if this blue guy speaks in the language which this guy cannot understand

he may be grammatically correct but still there is no use in this communication again what if this blue

guy keeps on talking at a high speed at the same time not at all giving any room for this guy to respond so these are

example situations where the communication goes chaos or messy so definitely there is a need for protocols

because a protocol is a set of rules that governs data communication simply speaking protocol is a rule that governs

data communication protocol determines what is communicated in the network how it is communicated in the network and

when it is communicated in the network before going into the network communication let's talk about the

protocols in the human communication in human communication definitely there should be sender and a receiver there

may be a single receiver or a group of receivers and this human communication can be effective only when this

communication involves common language and grammar otherwise communication will not be perfect and speed and timing of

delivery of speech is also very important in human communication and if this guy wants to ensure whatever he has

talked is understandable by this guy he should get confirmation or the acknowledgement from the receiver that

is the destination only then human communication can be effective we have just seen what is human communication

why do we need protocols in human communication now we shall see why do we need protocols in network communication

say if there is a sender and there is a receiver and this communication can be effective when these protocols are

addressed properly the message should be encoded formatted and encapsulated in such a way that the destination can

understand timing is also very important in network communication the size is also very important because the link

cannot carry big data if this is a low capacity link then this link cannot carry big data if there is a very big

data in the sender side it cannot send that big data on a very small link so it has to be handled

appropriately at the same time the delivery option should also be dealt whether the message is only for one

destination or some group of destinations on all the day nations in the network that should also

be dealt in the protocol spot so a protocol defines message encoding message formatting and encapsulation

message timing message size and the delivery that is what we exactly call as elements the elements of protocol are

message encoding message formatting and encapsulation message timing message size and message delivery options we

shall see each of this element in a detailed manner message encoding means the source that is the source computer

generates a message it gives that message to the encoder in order to generate signals once the data

is converted into signals now it is given to the transmitter for transmission you may be getting confused

why we need encoder here because we have two kinds of transmission medium one is a wired medium another one is a wireless

medium the source have to understand to which medium it is connected to if it is a wired medium the data have to be

converted into signals in order to facilitate the data transmission on a wired medium if it is a wireless medium

the sender have to encode the data in the form of waves because this is a wireless medium we can't send signals we

have to send waves and once the data is sent through the transmission medium the receiver receives the data and D course

it decoding means understanding it after understanding it properly it means the message has reached the

destination this is what message encoding is all about the sender sends the data the sender creates the data and

encodes the data and finally the transmitter sends the data through the transmission medium this transmission

medium takes the data to the receiver the receiver after receiving the data it decodes the data and after proper

decoding it means the message has reached the destination this is what message encoding is all about we shall

see the second element of the protocol that is the message formatting and encapsulation both sender and receiver

must mutually agree upon certain formats which we call as formatted at the same time when the receiver receives some

data it should identify who has sent this data we are going to add some information

with the data in order to identify the sender and the receiver so we are not going to just send data assets we are

going to encapsulate certain things like the source information and the destination information with the data so

that the right sender and the receivers are identified and the third element in the protocol part is message sizing if

there is a very big message to be communicated to the destination human breaks the message into smaller parts or

sentences say if this guy has a very big content to be sent so what he does he breaks the message into smaller parts or

sentences likewise our computer should also do that if the capacity of the link is very small but the data to be

transmitted is very big this computer should break this big message into smaller units which this

transmission medium can handle this is what message sizing and this is one of the thing a protocol should do and

message timing is the fourth element of protocols and message timing deals with flow control and response time mode

let's first talk about flow control let's assume this guy is very fast the sender is very fast and the receiver is

slow since the sender is very fast it can send data at high speed what about the receiver he can't handle that speed

if there is no flow control mechanism he can keep so on sending data but he cannot receive that data so the entire

communication will become useless it is the responsibility of the protocol to provide flow control mechanism at the

same time the sender is sending some data and the receiver has to acknowledge the data when the acknowledgement is

sent back to the sender the sender can understand that the data is received by the destination if the acknowledgement

is not received the sender have to wait for a certain period of time after the expiry of the time the sender will

retransmit the same so that we can ensure guaranteed delivery and it is the responsibility of the protocol to tell

how much time this computer should wait for an acknowledgment and we have the last element of the protocol and may say

delivery options there are three delivery options one unique - multicast 3 broadcast unicasting means

one sender and one receiver it means this sender is going to send data to exactly one receiver in the

network if the sender is sending the data to exactly one destination it is called as unicasting if the sender sends

the data to set of receivers but not to all then this is multicast in broadcasting means the sender sends the

data to all the participants in the network then we call us broadcasting and that's it guys now we shall just

recapture what we have seen today we have seen what is data communication that is the exchange of data between

nodes and we have also seen what is data flow and we have seen the three data flows simplex half-duplex and

full-duplex we have also seen the role of protocols in computer networks not only in computer networks even in real

time protocols has a very important role to play with and we have also seen what are the elements of protocols there are

five elements of protocols message encoding message formatting and encapsulation message size message

timing and finally the delivery options I hope the session is informative thank you all

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