What is TCP/IP Model and its Layers?

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What is TCP/IP Model?

TCP/IP is a (transmission control protocol/Internet protocol) that was created by the DARPA agency (Defense Advanced Research Projects Agency) in 1970. After that, it was acknowledged as a standard protocol by ARPANET (Advanced Research Projects Agency Network) in 1983. This model is described as the computer network protocol that tells how computers should be connected to the internet.

In other words, we can say that the TCP/IP model is a model that is used as a communication protocol that describes the connectivity of systems with the Internet and tells how data can be transmitted from the system to the Internet between the source and destination.

This model is very similar to the OSI model but not that much because both these model has their own specialty. In this model there are four or five layers if we include the Physical layer, we are mainly focused on four layers let see:

Application Layer
Transport Layer
Internet layer

Network Access layer

Now, let’s discuss these layers one by one:

1) Network Access Layer

This layer is the lowest layer in this model and it is a combination of physical and data link layers (As we saw in our previous blog on the OSI model). This layer contains the protocols that the computer uses to deliver the data to the other computers that are connected to the network.

In other words, the network access layer defines how the data can be used to transmit to the network physically between the systems and is known as the “Network Access interface or link layer”.

2) Internet Layer

This is the second lowest layer of the TCP/IP model and it is also known as the network layer, this is because this layer is responsible for transferring the data over the network via IP or we can say address. It provides the packets to the network node and transmits it to the destination which is known as the “Internet or network layer”.

In this layer there are some basic protocols:

I.P – I.P is an “Internet Protocol” which is used to provide the data packet from one network to another network node or we can say one computer to another computer. It is known as IP.
ARP– ARP is an “Address Resolution Protocol”, it is used to find out the MAC address of the computer system from its IP address. It is known as ARP.
I.C.M.P– ICMP is an “Internet Control Protocol”, it is an error reporting protocol that is used for handling the error over the network. It is known as ICMP.

RARP– RARP is a “Reverse Address Resolution Protocol” that is used to map the physical address into the IP address. It is known as RARP.
I.G.M.P– IGMP is an “Internet Group Management Protocol” that is used to allow several devices to share one IP address so that they all receive the same data. It is known as IGMP.

3) Transport Layer

The Transport layer just the application layer is the host-to-host layer. This layer is responsible for end-to-end communication and error-free transmission. It is known as the “Transport layer” of the TCP/IP model.

There are mainly two important protocols:

UDP– UDP is the “User Datagram Protocol”, it is an unreliable protocol that provides a connectionless service that enhances the network throughout the host-to-host transport layer. It is mainly used for broadcasting messages over the network.
TCP– TCP is a “Transmission Control Protocol”, It is a reliable protocol that is mainly used for end-to-end and error-free communication over the network. It is known as TCP.

4) Application Layer

This is the top layer of the TCP/IP model and this layer is defined as the Application, Presentation, and session layer as per the OSI model. It provides the services to the application software to run in a computer system so that users can interact with the system. It is known as “Application Layer”.

There are various protocols that are used in an application layer: