Data communication:-

Data communication is the process of exchanging data or information.

In the case of computer networks, this exchange takes place between the two devices in the transmission medium.

fig 1:data communication

Components of Data Communication:-

Message:-data.
Sender:-sending the data.
Receiver:-A receiver is a device by which a sender wants to communicate data.
Transmission medium:-This is the way the message travels from the sender to the receiver. It can be wired or wireless and has many sub-types.

Computer Networks:-

Computer Networks are used for data communication. A computer network is a collection of nodes. A node can be any device capable of sending or receiving data. Nodes need to be connected via communication links.

protocol:-

It agrees with the set of rules used by the sender and the recipient to Communicate data.

A protocol is one of the components of a data communications system. Communication cannot take place without protocol. A protocol defines what should be communicated, how it should be communicated, and when to notify.

Computer networks are operated by network models. The most popular are the OSI and TCP / IP models. This blog gives an Understanding of OSI and TCP/IP Reference Modes.

Both TCP/IP and OSI models are commonly used when referring to protocols at various layers. These two protocols describe how devices connect to the Internet and how data is transmitted between those devices.

This blog gives an Understanding of OSI and TCP/IP Reference Modes.

Before going OSI model see this figure:

fig 2: sending and receiving post

The post works in a step-by-step process. The network models also work same type step by step process

OSI model:-

fig 3: OSI

It is a network model that defines protocols for network Communications. It was developed to allow systems with different platforms to communicate with each other. Platform means hardware, software, or operating system. It has 7 layers as follows:

On the sender side

application layer:- End-user application, converts UI to data.
Presentation layer:- encryption, serialization of the data, and sending it to the bottom layer.
session layer:- Maintaining the connections, Opening connections, Keeping connections, Closing connections, and sending them to the bottom layer.
Transport layer:- Manages data transfers, checks whether transferred data, is the same data received or not, converts data to segments, and sends it to the bottom layer.
Network layer:- converts segments to packets, adds IP address to the packet and sends it to the bottom layer.
data link layer:-converts packets to frames, Add mac address to frames and sends it to the bottom layer.
physical layer:- converts frames to bits, encodes the signal, transmits it into bytes (8 bits), and transmits them in certain modes of transport (electricity, waves, light, etc).

On the receiver side,

the other accepts the electrical signal received by the physical layer.

physical layer:- decodes the signal, transmits it into bits, converts bits to frames, and sends it to the top layer.
data link layer:-open the frames, check the mac address, converts frames to packets, and sends them to the top layer.
Network layer:- open the packets, converts packets to segments, and send them to the top layer.
Transport layer:- Manages data transfers, checks transferred data, the same data received or not, and sends it to the top layer.
session layer:- Maintaining the connections, Opening connections, Keeping connections, Closing connections, and sending them to the top layer.
Presentation layer:- Decryption, Deserialization of the data, and sending it to the top layer.
application layer:- End-user application, converts data to UI form.

Explain

Application layer:-

The application layer maintains the foundation used by almost all end-user applications. Provide an interface between the user and network application to gain access to the network. Access messages sent by the user and files transferred over the network or perform other network-related tasks. Web browsers, email clients, and file transfer apps are implemented by interacting with application layer protocols.

Presentation layer-

The responsibility of the presentation layer in the OSI model is to translate or format the data for the application layer and is also responsible for encrypting and decrypting data.

This layer performs three main functions:

Encryption and Decryption:-You do not want to keep your data public, so it should encrypt your data.
Serialization and Deserialization:-It means 'translation', We "want to translate" our data so that our application can understand it.
Compression:- this is lossless compression which means that no information is lost during the process.

Session layer:-

Maintaining connections between client and server, It's used for Opening connections, Keeping connections alive, and Closing connections.

Transport layer:-

It is one of the main protocols in TCP / IP and OSI networks. Manages data transfers and checks transferred data, the data received is the same, ensures reliable transport of packets from source to destination

There are two types of transmission:- TCP and UDP

Transmissions Control Protocol (TCP) is a connection-oriented protocol used by computers to communicate over the Internet.

TCP provides error-checking and guarantees data delivery packets are delivered in the order they were sent.

TCP is best suited for applications requiring high reliability where timing is less of a concern.

● World wide web (HTTPS, HTTP), Secure Shell (ssh), File Transfer Protocol (FTP), Email (SMTP, IMAP/POP)

TCP guarantees data delivery, TCP provides data in order and there is no data corruption.

If data is not delivered, TCP will resend the data and Three-way handshakes are a must

User datagram protocol (UDP) is a connectionless protocol that works just like TCP but assumes that error-checking and recovery services are not required. Instead, UDP continuously sends datagrams to the recipient whether they receive them or not.

UDP is best suited for applications that require speed and efficiency.

Streaming videos, Online games, and Live broadcasts.
It is faster than TCP.
UDP is connectionless, there is no three-way handshake.
UDP sends the data one time
It doesn’t guarantee data delivery, Not necessarily in-order delivery.

Network Layer:-

The network layer is responsible for sending the packets from network to network. Moves data between and through other networks.it is responsible for the correct addressing and delivery packets of the data.

The main task of the network layer is to identify the network on which the data should be transmitted. It's called a packet.

segments to packets.
Adds the IP address to the packet.
Determines the best path for the packet(routing).

DataLink layer:-

The data link layer is made up of two parts: MAC and LLC.

Logical Link Layer (LLC) - This layer provides flow control, acknowledgment, and error management in case of any error.

Media Access Control (MAC) - This layer is responsible for the connection to the physical media(eg cable). A unique ID number based on your network card is called the MAC address.

Headers are attached to the packet sent from the network layer and the MAC address of the source and destination on that packet.

The data is now called the frame.

Physical Layer:-

The physical layer also deals with the encoding of the bits streamed into signals. Data can be transferred in many ways, such as radio waves or light.

Converting these layer frames to bytes (8 bits) and transmitting them in certain modes of transport (electricity, waves, light, etc).

fig 4 OSI

The protocols that make up the TCP / IP protocol suite can also be explained in terms of the OSI reference model. In the OSI model, the network access layer and the application layer of the TCP / IP model are further subdivided to describe the isolated functions that must occur in this layer

fig 5: OSI and TCP/IP

TCP/IP Model:-

TCP / IP means Transmission Control Protocol and Internet Protocol. This network model is also used in the current Internet architecture. Almost all networks in use today the TCP / IP model. This model is the same as the OSI model.

fig 6: TCP/IP

Application Layer:-

The application layer is a combination of application, presentation, and session layers. Here, the data is formatted, converted, encrypted, decrypted, and set to the user.

Transport Layer:-

the already discuss the transport layer in the OSI model and this layer is also the same as that.

Network or Internet Layer:-

This layer is compatible with the network layer of the OSI model.

Network Access Layer:-

This layer is a combination of the physical and data link layers of the OSI model.

Similarities

Both models depend on the layered architecture.

Both models convert raw data into packets and reach their destination.

both same but there are some differences in TCP/IP and OSI.

Data communication-Osi - Tcp/Ip models