TCP/IP Model in Networking

TCP/IP Model helps you to determine how a specific computer should be connected to the internet and how data should be transmitted between them. It helps you to create a virtual network when multiple computer networks are connected together. The purpose of TCP/IP model is to allow communication over large distances.

Transmission Control Protocol/Internet Protocol is referred to as TCP/IP. In order to provide a very stable, end-to-end byte stream over an unstable internetwork, the TCP/IP stack was particularly created as a model.

TCP Characteristics

Here, are the essential characteristics of TCP IP protocol:

  • Support for a flexible TCP/IP architecture
  • Adding more system to a network is easy.
  • In TCP IP protocols suite, the network remains intact until the source, and destination machines were functioning properly.
  • TCP is a connection-oriented protocol.
  • TCP offers reliability and ensures that data which arrives out of sequence should put back into order.
  • TCP allows you to implement flow control, so sender never overpowers a receiver with data.

Four Layers of TCP/IP model

In this TCP/IP tutorial, we will explain different layers and their functionalities in TCP/IP model:

TCP/IP Conceptual Layers
TCP/IP Conceptual Layers

The functionality of the TCP IP model is divided into four layers, and each includes specific protocols.

Each layer of the TCP/IP server architecture is defined in accordance with a particular purpose that it is intended to carry out. The data is transmitted cooperatively between these four TCP/IP layers as it moves from one layer to another.

  • Application Layer
  • Transport Layer
  • Internet Layer
  • Network Interface

Application Layer

The highest level of the OSI model, the application layer, communicates with an application software. The OSI layer closest to the end user is the application layer. It indicates that users can communicate with other software applications over the OSI application layer.

To implement a communicative component, the application layer communicates with software programs. The application program’s interpretation of the data is always outside the OSI model’s purview.

Example of the application layer is an application such as file transfer, email, remote login, etc. 

Following are the main protocols used in the application layer:

  • HTTP: HTTP stands for Hypertext transfer protocol. This protocol allows us to access the data over the world wide web. It transfers the data in the form of plain text, audio, video. It is known as a Hypertext transfer protocol as it has the efficiency to use in a hypertext environment where there are rapid jumps from one document to another.
  • SNMP: SNMP stands for Simple Network Management Protocol. It is a framework used for managing the devices on the internet by using the TCP/IP protocol suite.
  • SMTP: SMTP stands for Simple mail transfer protocol. The TCP/IP protocol that supports the e-mail is known as a Simple mail transfer protocol. This protocol is used to send the data to another e-mail address.
  • DNS: DNS stands for Domain Name System. An IP address is used to identify the connection of a host to the internet uniquely. But, people prefer to use the names instead of addresses. Therefore, the system that maps the name to the address is known as Domain Name System.
  • TELNET: It is an abbreviation for Terminal Network. It establishes the connection between the local computer and remote computer in such a way that the local terminal appears to be a terminal at the remote system.
  • FTP: FTP stands for File Transfer Protocol. FTP is a standard internet protocol used for transmitting the files from one computer to another computer.

Transport Layer

Data transit from a process on a source system machine to a process on a destination system is provided by the transport layer, which builds on the network layer. It preserves the quality of service features and is hosted over one or more networks.
It establishes the rate and amount of data that should be transmitted. The messages obtained from the application layer are built upon in this layer. It makes sure that data units are provided in the correct order and without errors.
Through flow control, error control, and segmentation or de-segmentation, the transport layer aids in your ability to manage a link’s dependability.
Additionally, the transport layer provides confirmation of a successful data transmission and, in the absence of any faults, delivers the subsequent data. TCP is the best-known example of the transport layer. 

Important functions of Transport Layers:

  • It divides the message received from the session layer into segments and numbers them to make a sequence.
  • Transport layer makes sure that the message is delivered to the correct process on the destination machine.
  • It also makes sure that the entire message arrives without any error else it should be retransmitted. 

The two protocols used in the transport layer are User Datagram protocol and Transmission control protocol.

  • User Datagram Protocol (UDP)
    • It provides connectionless service and end-to-end delivery of transmission.
    • It is an unreliable protocol as it discovers the errors but not specify the error.
    • User Datagram Protocol discovers the error, and ICMP protocol reports the error to the sender that user datagram has been damaged.
    • UDP consists of the following fields:
      Source port address: The source port address is the address of the application program that has created the message.
      Destination port address: The destination port address is the address of the application program that receives the message.
      Total length: It defines the total number of bytes of the user datagram in bytes.
      Checksum: The checksum is a 16-bit field used in error detection.
    • UDP does not specify which packet is lost. UDP contains only checksum; it does not contain any ID of a data segment.
TCP/IP model
TCP/IP model

  • Transmission Control Protocol (TCP)
    • It provides a full transport layer services to applications.
    • It creates a virtual circuit between the sender and receiver, and it is active for the duration of the transmission.
    • TCP is a reliable protocol as it detects the error and retransmits the damaged frames. Therefore, it ensures all the segments must be received and acknowledged before the transmission is considered to be completed and a virtual circuit is discarded.
    • At the sending end, TCP divides the whole message into smaller units known as segment, and each segment contains a sequence number which is required for reordering the frames to form an original message.
    • At the receiving end, TCP collects all the segments and reorders them based on sequence numbers. 

Internet Layer

The second TCP/IP layer of the TCP/IP model is known as the internet layer. A network layer is another name for it. This layer’s primary task is to deliver packets from any network and any computer such that, regardless of the path they take, they always reach their destination.

With the aid of multiple networks, the Internet layer provides a practical and procedural mechanism for moving variable-length data sequences from one node to another.

Message delivery at the network layer does not give any guaranteed to be reliable network layer protocol.

Layer-management protocols that belong to the network layer are:

  1. Routing protocols
  2. Multicast group management
  3. Network-layer address assignment. 

Following are the protocols used in this layer are:

IP Protocol: IP protocol is used in this layer, and it is the most significant part of the entire TCP/IP suite.

Following are the responsibilities of this protocol:

  • IP Addressing: This protocol implements logical host addresses known as IP addresses. The IP addresses are used by the internet and higher layers to identify the device and to provide internetwork routing.
  • Host-to-host communication: It determines the path through which the data is to be transmitted.
  • Data Encapsulation and Formatting: An IP protocol accepts the data from the transport layer protocol. An IP protocol ensures that the data is sent and received securely, it encapsulates the data into message known as IP datagram.
  • Fragmentation and Reassembly: The limit imposed on the size of the IP datagram by data link layer protocol is known as Maximum Transmission unit (MTU). If the size of IP datagram is greater than the MTU unit, then the IP protocol splits the datagram into smaller units so that they can travel over the local network. Fragmentation can be done by the sender or intermediate router. At the receiver side, all the fragments are reassembled to form an original message.
  • Routing: When IP datagram is sent over the same local network such as LAN, MAN, WAN, it is known as direct delivery. When source and destination are on the distant network, then the IP datagram is sent indirectly. This can be accomplished by routing the IP datagram through various devices such as routers.

ARP Protocol

  • ARP stands for Address Resolution Protocol.
  • ARP is a network layer protocol which is used to find the physical address from the IP address.
  • The two terms are mainly associated with the ARP Protocol:
    • ARP request: When a sender wants to know the physical address of the device, it broadcasts the ARP request to the network.
    • ARP reply: Every device attached to the network will accept the ARP request and process the request, but only recipient recognize the IP address and sends back its physical address in the form of ARP reply. The recipient adds the physical address both to its cache memory and to the datagram header

ICMP Protocol

  • ICMP stands for Internet Control Message Protocol.
  • It is a mechanism used by the hosts or routers to send notifications regarding datagram problems back to the sender.
  • A datagram travels from router-to-router until it reaches its destination. If a router is unable to route the data because of some unusual conditions such as disabled links, a device is on fire or network congestion, then the ICMP protocol is used to inform the sender that the datagram is undeliverable.
  • An ICMP protocol mainly uses two terms:
    • ICMP Test: ICMP Test is used to test whether the destination is reachable or not.
    • ICMP Reply: ICMP Reply is used to check whether the destination device is responding or not.
  • The core responsibility of the ICMP protocol is to report the problems, not correct them. The responsibility of the correction lies with the sender.
  • ICMP can send the messages only to the source, but not to the intermediate routers because the IP datagram carries the addresses of the source and destination but not of the router that it is passed to.

The Network Interface Layer

This tier of the TCP/IP model’s four layers is known as the Network Interface Layer. Network access layer is another name for this layer. You can use it to specify the specifics of how data should be transmitted across the network.

It also includes how bits should optically be signaled by hardware devices which directly interfaces with a network medium, like coaxial, optical, coaxial, fiber, or twisted-pair cables.

A network layer is a combination of the data line and defined in the article of OSI reference model. This layer defines how the data should be sent physically through the network. This layer is responsible for the transmission of the data between two devices on the same network.

Differences between OSI and TCP/IP models

Difference between OSI and TCP/IP model

Here, are some important differences between the OSI and TCP/IP model:

OSI Model TCP/IP model
It is developed by ISO (International Standard Organization) It is developed by ARPANET (Advanced Research Project Agency Network).
OSI model provides a clear distinction between interfaces, services, and protocols. TCP/IP doesn’t have any clear distinguishing points between services, interfaces, and protocols.
OSI refers to Open Systems Interconnection. TCP refers to Transmission Control Protocol.
OSI uses the network layer to define routing standards and protocols. TCP/IP uses only the Internet layer.
OSI follows a vertical approach. TCP/IP follows a horizontal approach.
OSI model use two separate layers physical and data link to define the functionality of the bottom layers. TCP/IP uses only one layer (link).
OSI layers have seven layers. TCP/IP has four layers.
OSI model, the transport layer is only connection-oriented. A layer of the TCP/IP model is both connection-oriented and connectionless.
In the OSI model, the data link layer and physical are separate layers. In TCP, physical and data link are both combined as a single host-to-network layer.
Session and presentation layers are not a part of the TCP model. There is no session and presentation layer in TCP model.
It is defined after the advent of the Internet. It is defined before the advent of the internet.
The minimum size of the OSI header is 5 bytes. Minimum header size is 20 bytes.

Most Common TCP/IP Protocols

Some widely used most common TCP/IP protocol are: 


Transmission Control Protocol is an internet protocol suite which breaks up the message into TCP Segments and reassembling them at the receiving side. 


An IP address, sometimes referred to as an Internet Protocol address, is a numerical designation. Each device linked to a computer network that makes use of the IP for communication has one assigned to it. Its routing capability enables internetworking and, in essence, creates the Internet. A virtual connection between a source and a destination can be created using IP and TCP together.


The World Wide Web’s cornerstone is the Hypertext Transfer Protocol. It’s used to move files like webpages and other types of resources from the HTTP server or web server to the HTTP client or web client. You utilize a web client every time you use a web browser like Firefox or Google Chrome. The transmission of web pages that you request from distant servers is made easier via HTTP.


SMTP stands for Simple mail transfer protocol. This protocol supports the e-mail is known as a simple mail transfer protocol. This protocol helps you to send the data to another e-mail address. 


SNMP stands for Simple Network Management Protocol. It is a framework which is used for managing the devices on the internet by using the TCP/IP protocol. 


DNS stands for Domain Name System. An IP address that is used to identify the connection of a host to the internet uniquely. However, users prefer to use names instead of addresses for that DNS. 


TELNET stands for Terminal Network. It establishes the connection between the local and remote computer. It established connection in such a manner that you can simulate your local system at the remote system. 


FTP stands for File Transfer Protocol. It is a mostly used standard protocol for transmitting the files from one machine to another. 

Advantages of the TCP/IP model

Here, are pros/benefits of using the TCP/IP model:

  • It helps you to establish/set up a connection between different types of computers.
  • It operates independently of the operating system.
  • It supports many routing-protocols.
  • It enables the internetworking between the organizations.
  • TCP/IP model has a highly scalable client-server architecture.
  • It can be operated independently.
  • Supports a number of routing protocols.
  • It can be used to establish a connection between two computers. 

Disadvantages of the TCP/IP model

Here, are few drawbacks of using the TCP/IP model:

  • TCP/IP is a complicated model to set up and manage.
  • The shallow/overhead of TCP/IP is higher-than IPX (Internetwork Packet Exchange).
  • In this, model the transport layer does not guarantee delivery of packets.
  • Replacing protocol in TCP/IP is not easy.
  • It has no clear separation from its services, interfaces, and protocols. 

Similar Posts

Leave a Reply

Your email address will not be published. Required fields are marked *