TCP/IP: What It Is & How It Works

Network protocols are necessary for data transmission and networking over different devices. One of the most common protocols is the TCP/IP framework, which builds connections through our internet. In fact, if you check email, watch Netflix, or stream music from Spotify, you’re relying on TCP/IP in the background. 

In this article, you’ll learn about the TCP/IP protocol layers and how they function.

What is the TCP/IP model?

The TCP/IP model (Transmission Control Protocol/Internet Protocol) is a foundational Internet and network communication framework. The Department of Defense developed this in the 1970s to maintain reliable and secure communication across different networks. 

TCP/IP transmits data in packets. These packets are routed from sender to receiver and reassembled at the destination. In this process, we can break it into two actions:

• TCP provides reliable data delivery.
• IP handles addressing and routing packets across networks.

TCP/IP framework vs. OSI reference models

The OSI (Open Systems Interconnection) reference model is often compared with TCP/IP. Why? Because it also implements network communications but with a different architecture. 

OSI standardizes the functionality of a telecommunication or computing system regardless of its underlying internal structure and technology. Whereas TCP/IP is more practical and streamlined because it focuses on actual processes involved in data transmission over the internet.

Here’s how these two frameworks differ:

Main applications of the TCP/IP model

The TCP/IP framework uses other protocols like HTTP, SSL, and IMAP to establish connections between different applications and devices. These protocols help TCP/IP to function properly across its diverse applications. 

Here are some common applications of the TCP/IP framework:

Web browsing

TCP/IP allows computers to access websites using HTTP or HTTPS. 

Suppose you want to visit a website on Google. You type that website’s domain address into your browser’s search bar. TCP/IP will ensure your request travels safely across the internet to Google's servers in packets. This process allows you to browse the web smoothly.

Email exchange

TCP/IP lets you send and receive emails via protocols like SMTP, POP3, and IMAP.  SMTP sends your email, while POP3 and IMAP receive and read emails. These protocols work to deliver these messages after they are routed accurately. 

File transfer

If you've ever downloaded a file from the internet or uploaded pictures to a cloud service, you've used FTP. Through protocols like FTP, TCP/IP transfers files between computers. These protocols maintain data integrity and security during the transfer process.

Remote access

TCP/IP supports remote connections to networks or computers via protocols like SSH and Telnet. These protocols secure command execution and data access over the internet. SSH and Telnet are like your secure keys to another computer or network from anywhere in the world. 

Streaming services

Did you know that what you watch on Netflix and what you listen to on Spotify rely on TCP/IP streaming protocols? 

These services rely on TCP/IP because it is designed to support streaming content for video and audio via secured protocols. They manage data transmission rates and network congestion so you can enjoy a smooth playback. 

The 5 layers of the TCP/IP 

TCP/IP framework is divided into four or five primary layers. Every layer performs a different function, and here’s how each works to ensure efficient data transmission.

1) Application layer

The Application layer directly interacts with end-user software. It's where network applications can access network services. This layer includes protocols that define the standards and communication methods between network devices and applications. 

Each protocol serves a specific purpose. Here’s a quick breakdown of the protocols of the application layer:

• HTTP (HyperText Transfer Protocol) helps users access and view web pages during web browsing.
• SMTP (Simple Mail Transfer Protocol) delivers messages from one server to another.
• FTP (File Transfer Protocol) transfers files between computers on a network and makes it easy to upload or download files.
• DNS (Domain Name System) translates human-friendly domain names (www.google.com) into IP addresses that computers use to identify each other on the network.

2) Transport layer

Transport layers ensure that data sent by an application over the network arrives safely and correctly at the destination. The transport layer works around two main protocols:

• TCP (Transmission Control Protocol) provides reliable, ordered, and error-checked data between applications.
• UDP (User Datagram Protocol) manages a simpler and faster data exchange without establishing a connection—mostly used in streaming.

3) Internet layer

The Internet layer sends packets across multiple networks to reach their final destinations. These protocols work together to traverse data through the complex web of networks.

The internet layer is directly linked with internet connections and operates through three main protocols:

• IP (Internet Protocol) is the primary protocol to define IP addresses to route data packets across the Internet.
• ICMP (Internet Control Message Protocol) reports errors. For example, it informs the network when a service is unavailable or a router cannot be reached.
• ARP (Address Resolution Protocol) translates IP addresses into physical MAC addresses to send data to the correct device on a local network.

4) Network interface layer

The network interface layer physically transfers data packets over the network. It transmits data over the network medium regardless of its src and ensures the packets reach their destination safely. This layer is used in your computer’s network card, cables, and switches that connect your devices.

The main protocols the network interface layer uses are:

• Ethernet defines the physical and data link layers for LAN communication.
• Token Ring circulates the network and allows devices to send data.

5) Data link layer

The data link layer is usually a part of the network interface layer. It controls the physical layer's communication between devices on the same network. It deals with protocols that operate at the link level — handling communication between adjacent network nodes.

Here are the most commonly used data link layer protocols:

• PPP (Point-to-Point Protocol) enables communication between two points. It’s used for internet connections over dial-up modems or DSL.
• Wi-Fi is a wireless version of Ethernet that connects devices without cables within a local area network.

Pros and cons of TCP/IP models

Since TCP/IP has become a universal standard protocol for internet connections, here’s a quick analysis of the pros and cons of TCP/IP models:

Other common Internet protocols

Apart from the core protocols within the TCP/IP, there are a few additional protocols. Here’s how each of them works:

• HTTPS (Hypertext Transfer Protocol Secure) adds a layer of security to web browsing by encrypting data exchanged between the web browser and server.
• SSL/TLS (Secure Sockets Layer/Transport Layer Security) encrypts data sent over the internet and secures your transactions, data transfers, and logins conducted over the websites.
• DHCP (Dynamic Host Configuration Protocol) automatically assigns IP addresses and other network configuration parameters to devices on a network.
• SNMP (Simple Network Management Protocol) allows network administrators to monitor network performance, find and solve network problems, and plan for network growth.
• SSH (Secure Shell) provides network encryption and security while logging into systems, executing commands remotely, and transferring files.

Reliable data transmission through TCP/IP framework

The TCP/IP framework is behind many daily network activities, such as web browsing, email exchange, file transfers, and streaming services. Despite some challenges, like security vulnerabilities and potential inefficiencies, the TCP/IP framework remains integral to network communication.