What is TCP/IP Model? Layers in TCP IP Model | Scaler Topics

Introduction

TCP/IP stands for Transmission Control Protocol/Internet Protocol and is a suite of communication protocols that makes data exchange between two devices possible. TCP/IP specifies how data should be packetized, addressed, transmitted, routed, and received on a network by providing end-to-end communication. As compared to the OSI model, which is a theoretical model, TCP/IP is an application and practical model.

Scope

• This article provides an overview of the TCP/IP model in computer networks, its various functionalities, and its advantages and disadvantages.
• This article covers all the theoretical aspects of the TCP/IP protocol suite and does not cover the comaprison with OSI model.

TCP/IP started as one of many internet protocols created by DARPA (the Defense Advanced Research Projects Agency in the United States) in the 1970s. The TCP/IP model was later adopted as the standard protocol for ARPAnet, the modern internet’s predecessor. TCP/IP is now the international standard for internet communication.

What is TCP/IP Model?

The TCP/IP model is created to allow communication over long distances possible between two devices. It also assists in how the data between two devices is transmitted over the internet. TCP/IP specifies how the data should be packetized, addressed, transmitted, routed, and received on a network by providing end-to-end communication. The TCP/IP model consists of 4 layers, i.e., the application layer, transport layer, network layer, and data link layer. Each layer is responsible for a particular task strictly according to the protocols.

TCP specifies how applications will establish communication channels across a network. It also controls how a message is split into multiple data packets, sent over the internet, and reassembled in order at the destination address. IP specifies how each packet should be addressed and routed to ensure that it arrives at its destination. To identify where the message should be forwarded, each gateway computer on the network verifies this IP address.

Highlights:

• The TCP/IP model allows communication over long distances between two devices.
• TCP handles the flow of data and also handles errors in data transmission, while IP provides a unique address to each device in the network.

How does the TCP/IP protocol work?

Whenever we send things like a simple text message, a file, or a video message over the internet, the TCP/IP model divides the data into packets, according to four-layered architecture. The data goes in order from the sender’s side, and on the receiver’s side, it follows the reverse order and is finally reassembled.

TCP/IP is based on the client-server communication model, which means that a user of a first computer (the client) sends a service request to a second network computer or web hosting provider(server), such as forwarding a Web page. TCP/IP also uses point-to-point communication, which means that data is sent from one host computer to another within a defined network border. In TCP/IP model, each client request is unique and unrelated to previous ones. Hence, it is called stateless and being stateless allows network channels to be used indefinitely.

Because the entire process is standardized, the TCP/IP model works. Without standardization, communication would go haywire, and fast internet service relies on efficiency. The TCP/IP model provides both efficiency and standardization. The TCP/IP model is the most effective way to send internet data because it is the global standard.

Highlights:

• According to four-layred architecture, the TCP/IP model divides the data into packets.
• The TCP/IP model provides both efficiency and standardization, and it is one of the biggest reason why the TCP/IP model always work.

Layers in TCP/IP Model

The TCP/IP model generally consists of four essential layers

1. Application Layer
2. Host-To-Host Layer/Transport Layer
3. Internet Layer/Network Layer
4. Network Access Layer/Link Layer

Since TCP/IP is a implemementable model, it can be further classified into a five-layer model in which the data link layer and the physical layer are separated from the Link layer. It is done to achieve the client’s requirement with efficiency. To understand better, let’s have a look at the diagram given below, which compares four-layer and five-layer TCP/IP Models with the standard OSI Model.

This article will focus on the four-layer TCP/IP model and discuss all layers of the TCP/IP.

The 4 Layers of the TCP/IP Protocol Suite

The four layers of the TCP/IP protocol suite are defined below.

1.Application Layer

This layer performs the functions of the top three layers of the OSI model, i.e., Application, Presentation, and Session Layer. It is responsible for node-to-node communication and controls user-interface specifications. Its protocols include HTTP, Post Office Protocol 3, Simple Mail Transfer Protocol, and File Transfer Protocol. At the application layer, the payload is the actual application data. Some of the protocols of the application layer are described below.

• HTTP:- It stands for Hypertext transfer protocol. This protocol enables us to access data via the internet. It sends data in plain text, audio, and video formats. It’s called a hypertext transfer protocol because it’s efficient enough to use in a hypertext environment where there are rapid jumps from one document to another.
• TELNET:- It establishes a connection between the local and remote computers in such a way that the local computer seems to be a remote terminal.
• SMTP:-The Simple Mail Transfer Protocol (SMTP) is the TCP/IP protocol that handles e-mail. The data is sent to another e-mail address using this protocol.
• FTP:- The FTP (File Transfer Protocol) is a standard internet protocol for transferring data from one computer to another.

2.Host-to-Host/Transport Layer

This layer is similar to the OSI model’s Transport layer. It specifies how much data should be sent, when, and where at what rate. The message from the application layer is built upon this layer. This layer ensures that data units are supplied in a timely and error-free manner. Through error control, flow control, and segmentation or de-segmentation, the transport layer helps to control the link’s reliability. The transport layer also acknowledges the successful data transmission and sends the next data if no errors occur. The two important protocols present in this layer are

• Transmission Control Protocol (TCP):-It is known for offering error-free and reliable communication between end systems. It does data segmentation and sequencing. It also features an acknowledgment feature and uses a flow control method to govern data flow. It is a very effective protocol, but it has a lot of overhead because of these features. Increased overhead translates to higher costs. TCP uses three-way handshaking to establish and acknowledge the connection between the two devices.
• User Datagram Protocol (UDP):-On the other side, it doesn’t have any of these properties. If your application does not require dependable transmission, one must use this protocol because it is relatively cost-effective. UDP is a connectionless protocol, so it does not provide assurance of data delivery.

3.Internet Layer

This layer is also known as the network layer. The Internet layer’s primary function is to send packets from the source or computer to their destination, regardless of their route. The Internet layer or Network Layer provides a functional and procedural means for sending variable length data sequences between nodes across multiple networks. Message delivery at the Internet layer does not guarantee reliable network layer protocol. The main protocols lie in the layer are

• IP:-

  The Internet Protocol (IP)

  is in charge of sending packets from a source host to a destination host based on the IP addresses in the packet headers. There are two variations of IP are IPv6 and IPv4.

• ARP:-

  Address Resolution Protocol (ARP)

  is a protocol for resolving conflicts between computers. Its task is to determine a host’s hardware address from an IP address. ARP’s primary function is to convert 32-bit addresses to 48-bit addresses and vice versa. ARP is necessary because IP addresses in IP version 4 (IPv4) are 32 bits long, but MAC addresses are 48 bits long.

4.Network Access Layer/Link Layer

Network access or Link layer specifies the physical transmission of data over the network. This layer handles data transmission between two adjacent devices on the same network. It also determines how bits should be optically signalled by hardware devices that interface directly with a network media such as coaxial, optical, fiber, or twisted-pair cables.

Highlights:

• Application Layer is responsible for node-to-node communication and controls user-interface specifications. HTTP, SMTP, TELNET, etc., are some of its essential protocols.
• Host-To-Host Layer specifies how much data should be sent, when, and where at what rate. TCP and UDP are two significant protocols of this Layer.
• The Internet layer’s primary function is to send packets from the source or computer to their destination, regardless of their route. IP and ARP are two significant protocols of this layer.
• Network Acess Layer handles data transmission between two adjacent devices on the same network.

Uses Of TCP/IP Model

The various uses of the TCP/IP Model are described below.

1. It provides a suite of communication protocols that allows data exchange between two devices possible or in general we can say that it makes the internet possible.
2. We all are aware of the importance of text communication in today’s environment. For text communication, flow control and error control are mandatory because the text message’s size is minimal, and it must be delivered with minimal error to the right person. A small mistake in the text message can change the meaning of the whole message. So TCP/IP model handles the following operations to ensure the transition between sender and receiver is in order and error-free. Examples of text communication are WhatsApp, Instagram, Google Chat, and iMessage.
3. Internet banking is possible due to this model because it provides reliability, efficiency, and security, making it possible for users to use such facilities online.
4. Online gaming and video streaming are also possible because TCP/IP model provides flexibility in choosing connection-oriented or connectionless transmission. Due to this flexibility, broadcasting sports and events over a mass audience is possible.
5. TCP/IP provides various functions like DNS, DHCP, Virtual Private Networking, Piggybacking, Error control, etc. This feature allows end-user to use the internet without fear of losing their privacy and integrity.

Advantages of TCP/IP Model

1. It’s a set of open protocols. As any one institution does not own it, it can be used by anybody or any group.
2. It’s a client-server architecture and highly scalable. It allows the addition of new networks without disrupting existing services.
3. It’s an industry-standard model that can be used to solve real-world networking problems.
4. It is interoperable, allowing two different systems to communicate via a heterogeneous network.
5. It assigns a unique IP address to each device in a network such that each device has its own unique identity over the internet.
6. It is challenging for humans to remember the numerical values compared to alphabetical names. So to solve this, TCP/IP models also provide DNS service to provide resolution between alphabetical domain names and IP addresses.

Disadvantages of TCP/IP Model

1. The concepts like “services,” “interfaces,” and “protocols” are not distinguished. As a result, describing new technologies in new networks is not appropriate.
2. This model was created to be used in wide-area networks. It is not designed for tiny networks such as LANs and PANs (pervasive area networks) (personal area networks).
3. It’s not generic. As a result, it can’t represent any protocol stack other than TCP/IP. It cannot, for example, define a Bluetooth connection.
4. It is not easy to replace protocols.

Conclusion

• TCP/IP stands for

  Transmission Control Protocol/Internet Protocol

  and is a suite of communication protocols that makes data exchange between two devices possible.

• TCP specifies how applications establish communication channels across a network and manages flow control and error control. It also has an acknowledgment function which increases the overall reliability.
• IP specifies how each packet should be addressed and routed to ensure that it arrives at its destination.
• There are generally four layers in TCP/IP protocol, but it extends to five in some cases.
• The four layers of the TCP/IP are the

  application layer

  ,

  transport layer

  ,

  network layer

  , and

  data link layer

  .

• TCP/IP has various real-life applications such as broadcasting, Internet banking, online gaming, etc.