TCP/IP Model

What Does TCP/IP Do?

TCP/IP facilitates reliable data transmission between devices over networks. TCP (Transmission Control Protocol) ensures data integrity by breaking information into packets, numbering them, and reassembling them in the correct order upon arrival. IP (Internet Protocol) handles addressing and routing, ensuring that packets reach the intended destination efficiently. Together, TCP/IP enables smooth communication across different devices and networks, supporting essential services like web browsing, emails, and file transfers. It provides a standardized communication method, making the internet accessible and functional for billions of users worldwide.

How Does the TCP/IP Model Work?

The TCP/IP model works by dividing data into packets before transmission. The Application layer processes user data, while the Transport layer (TCP) ensures reliable delivery by segmenting data and managing retransmissions. The Internet layer (IP) assigns addresses and routes packets efficiently across networks. Finally, the Network Access layer handles physical data transmission via wired or wireless mediums. Upon reaching the destination, packets are reassembled in the correct order to restore the original message. This layered approach ensures accurate and efficient communication across diverse networks, making the internet functional and scalable.

Functions of TCP/IP model

The layers are as follows:

1. Process/Application Layer
2. Host-to-Host/Transport Layer
3. Internet Layer
4. Network Access Layer 

Application Layer

• In the TCP/IP paradigm, the application layer is the uppermost layer.
• It is in charge of high-level protocols and symbolic concerns.
• The user may interact with the program via this layer.
• When one application layer protocol wishes to connect with another, it sends its information to the transport layer.
• In the application layer, there is some uncertainty. Except for those that interface with the communication system, no application may be deployed within the application layer. For instance, a text editor cannot be regarded as an application layer protocol. Still, a web browser interacts with the network via the HTTP protocol, an application layer protocol.

Example: When you open a web browser to visit a website, the browser communicates with the web server using the HTTP protocol in the application layer.

The following are the most common application layer protocols:

• Hypertext Transfer Protocol (HTTP) is a protocol for transferring data over the internet. We can use this protocol to access data via the internet. It transfers data in a variety of forms, including plain text, audio, and video. Because it's efficient enough to employ in a hypertext environment with frequent leaps from one page to the next, it's dubbed a hypertext transfer protocol.
• SNMP stands for Simple Network Management Protocol. It is a framework that uses the TCP/IP protocol stack to manage devices over the internet.
• SMTP stands for Simple mail transfer protocol. 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.
• Domain Name System is the abbreviation for DNS. An IP address is a number that is used to identify a particular host's internet connection. People, on the other hand, prefer to use their names rather than their addresses. As a consequence, the Domain Name Mechanism (DNM) is the system that converts a name into an address.
• TELNET stands for Terminal Network and is an acronym for it. It creates a connection between the local and distant computers so that the local terminal seems to be a remote terminal.
• FTP stands for File Transfer Protocol. FTP (File Transfer Protocol) is a common internet protocol for transferring data from one computer to another.

You can also read about the network models in computer network and Subnetting in Computer Networks

Transport Layer

The transport layer ensures that data is transferred reliably and accurately between devices. It provides mechanisms for flow control, error correction, and data segmentation.
Protocols used in this layer include TCP (Transmission Control Protocol) and UDP (User Datagram Protocol).

Example: When you download a file, TCP ensures the file's integrity by confirming all data packets have arrived correctly. If any packets are lost or corrupted, TCP retransmits them.

User Datagram Protocol (UDP)

• It offers apps with complete transport layer functions.
• It establishes an active virtual circuit between the sender and receiver during the connection.
• The User Datagram Protocol detects the issue, and the ICMP protocol notifies the sender that the user datagram has been damaged.
• The following are the fields that makeup UDP:
  The address of the application software that created the message is the source port address.
  The address of the application program that receives the message is the destination port address.
  The total length (in bytes): The entire amount of bytes in the user datagram is specified here.
  A checksum is a 16-bit field used to detect data flaws.
• UDP does not specify how a packet is lost. There is no data segment ID in UDP; it just has a checksum.

Protocol for Controlling Transmission (TCP)

• It provides entire transport layer services to applications.
• It creates a virtual circuit between the sender and receiver that stays active during the connection.
• TCP is a trustworthy protocol since it detects mistakes and retransmits the corrupted frames. Consequently, all segments must be received and acknowledged before the transmission is considered complete and a virtual circuit is erased.
• TCP divides the whole message into smaller pieces known as segments at the transmitting end. Each segment carries a sequence number used to reorder the frames to reassemble the original message.
• TCP reorders all segments according to the sequence numbers at the receiving end.

You can read related articles such as Congestion Control in Computer Networks here.

Internet Protocol Layer

This layer performs comparable responsibilities to the OSI Network layer. It defines the protocols that control logical data transmission throughout the whole network. The primary protocols discovered at this layer are as follows:

• The Internet Protocol (IP) is responsible for transmitting packets from a source host to a destination host based on the IP addresses in the packet headers.
• IPs are divided into two categories: IPv4 and IPv6. The majority of websites now utilize the IPv4 protocol. However, as IPv4 addresses grow limited concerning users, IPv6 is becoming increasingly popular.
• The Control Message Protocol (ICMP) abbreviation is Internet Control Message Protocol. It is stored within IP datagrams and is responsible for providing hosts with network issues.
• The acronym for Address Resolution Protocol (ARP) is Address Resolution Protocol. Its purpose is to identify the hardware address of a host-based on a given IP address. The four types of ARP are reverse ARP, proxy ARP, gratuitous ARP, and inverse ARP.

Also see, Message Switching in Computer Networks.

Example of ARP: If you send data to another computer within the same network, ARP will convert the IP address of that computer into its corresponding MAC address for communication.

Network Access Layer

• The network layer is the lowest in the TCP/IP paradigm.
• The OSI reference model defines a network layer as a combination of the Physical and Data Link layers.
• It defines how data should be physically sent via a network.
• This layer is largely responsible for data transport between two networked devices.
• This layer performs functions such as encapsulating IP datagrams into network frames and converting IP addresses to physical addresses.
• This layer uses Ethernet, token ring, FDDI, X.25, and frame relay protocols.

Example: When you connect to the internet using an Ethernet cable, the network access layer defines how data is packaged into Ethernet frames and transmitted over the physical cable.

Recommended Topic, Internal and External Fragmentation and Basic Networking Commands

TCP/IP protocol suite

The TCP/IP protocol suite is a set of communication protocols that enable data transmission across computer networks, including the Internet. It consists of four layers:

1. Application Layer – Handles high-level protocols like HTTP, FTP, and DNS.
2. Transport Layer – Ensures reliable communication using TCP and fast, connectionless transmission with UDP.
3. Internet Layer – Manages addressing and routing through IP, ICMP, and ARP.
4. Network Access Layer – Defines how data is physically transmitted over Ethernet, Wi-Fi, and other link-layer technologies.

This suite powers global networking by providing scalability, interoperability, and reliability.

Why TCP/IP Model Does Not Have Physical Layer

The TCP/IP model does not have a separate Physical Layer because it was designed to be an open, flexible model that can work with different underlying network technologies. Instead of defining hardware-level specifications like cables, signals, and connectors, TCP/IP includes these functions within the Network Access Layer (which combines the Physical and Data Link layers from the OSI model). This allows TCP/IP to operate across various types of networks, including Ethernet, Wi-Fi, fiber optics, and satellite links, without being tied to any specific physical technology.

Difference Between TCP/IP and OSI Model

The TCP/IP model and the OSI model are both conceptual frameworks for networking, but they differ in structure, functionality, and real-world implementation. Here’s a comparison:

Advantages of the TCP/IP Model

• TCP/IP supports large and small networks, making it ideal for the internet and enterprise systems.
   
• It allows different types of devices and operating systems to communicate seamlessly.
   
• It ensures data integrity by retransmitting lost packets and maintaining proper sequencing.
   
• It efficiently routes data across multiple networks, optimizing performance.
   
• It follows global standards, making it universally accepted for communication.
   
• It enables various applications like web browsing, emails, and file transfers.

Disadvantages of the TCP/IP Model

• The model is complex to set up and manage, requiring expertise in networking.
   
• TCP’s error-checking and congestion control add extra processing and transmission delays.
   
• Some functions in TCP/IP overlap between layers.
   
• The model lacks built-in encryption, requiring additional security protocols.
   
• Modifying or replacing core protocols can be challenging due to widespread adoption.
   
• It requires more bandwidth and processing power, which may impact performance on low-end devices.

Frequently Asked Questions

What exactly is a network?

According to Merriam Webster, a network is an informal organization or affiliation of various elements such as people, computers, radio stations, etc.
Domino's Pizza, for example, has 1232 locations throughout India. As the name implies, a computer network is a collection of peripherals or computers linked together and sharing a common communication channel to exchange various data and information.

What is the significance of a computer network?

Have you heard of the Internet, often known as the NET? I'm guessing you have since read this article on Coding Ninjas Studio while browsing the web. However, have you considered the Internet? The Internet connects all various network-enabled devices and allows them to share data and information, making computer networks an essential element of our lives and technical interviews.

What are the differences between nodes and links?

Any device that interacts in a network is referred to as a node. A node is a point of intersection in a network. It can send and receive data and information inside a network. Nodes include computers, laptops, printers, servers, modems, and other devices.
The connection between two nodes in a network is known as a link, sometimes known as an edge. It describes the kind of connection between the nodes (wired or wireless) as well as the protocols that enable one node to communicate with another.

Conclusion

This article discussed the introduction to the TCP/IP model briefly discussing each layer i.e. Network Access Layer, Internet Protocol Layer, Transport Layer, and Application Layer along with their responsibilities in detail.

Recommended Readings:

• OSI v/s TCP/IP Model
• TCP v/s UDP
• Network Types
• Asynchronous Data Transfer
• Addressing Modes in Computer Architecture
• Go-Back-N ARQ Protocol
• HDLC Protocol
• Register in Computer
• Stop and Wait Protocol 

I hope that you have gained some insight into this topic of Modulation and if you want to learn more then you can refer to this guided path for Computer Networks.

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