Networking Basics: Part 2 - WHAT IS A TCP/IP and OSI???????
Tags: networking, network, internet, devops
Published: 2023-11-02 11:30:00

Wassupppp Nerds, Hope you guys are doing fine. As promised today we will understand deeply what is TCP/IP and OSI and more important than that why do we need a protocol to work can't we have different rules for different networks. We'll also see today how these TCP/IP and OSI emerged and also even though we use TCP/IP as the standard protocol today, why we always talk about OSI. There is only one pre-requisite for this blog that you must've read my last blogs of the computer networking series so that you get the context. You can read them [here](https://dev.to/bhavesh_yadav/series/25215).

SO LETS GET STARTEDDD!

In the realm of networking, two most important models or we can say protocols, TCP/IP and OSI, act as the bedrock of data transmission, ensuring seamless connectivity and reliable communication across networks. In this in-depth blog, we will delve into the necessity of these models, trace their historical significance, comprehend their individual components, and explore their interplay within the networking ecosystem.

# Why Do We Need TCP/IP and OSI Model:

To truly appreciate the significance of TCP/IP and OSI models, is important to understand their origins. In the 1960s, the Advanced Research Projects Agency (ARPA), a U.S. Department of Defense agency, embarked on the ambitious task of connecting various computers to build a robust network. This endeavor led to the development of the Advanced Research Projects Agency Network (ARPANET), a precursor to the internet. However, a challenge arose: as there was not only ARPA in the market there were computers from the other companies too, like IBM show and they had their own rules and protocols of the network then how can diverse computer systems from different manufacturers will communicate effectively. This necessitated the establishment of standardized models, such as TCP/IP and OSI, ensuring seamless interoperability. These models created  a standard in the networking field and everyone has to use them in order to communicate in the network.


## The Rise and Significance of OSI Model:

In the late 1970s, the International Organization for Standardization (ISO) introduced the OSI (Open Systems Interconnection) model with the objective of standardizing network protocols and advancing interoperability. The OSI model comprises seven distinct layers, each assigned specific responsibilities during the transmission of data. These layers are: Physical, Data Link, Network, Transport, Session, Presentation, and Application.

## The Emergence of TCP/IP

The landscape of networking, prior to standardized models, was occupied by several proprietary protocols, including IBM's Systems Network Architecture (SNA). However, as ARPANET gained popularity, a new set of protocols called TCP/IP (Transmission Control Protocol/Internet Protocol) emerged as a flexible, scalable, and robust solution. The importance and need of TCP/IP was largely driven by its simplicity, efficiency, and widespread adoption worldwide, ultimately becoming the de facto standard for internetworking. And this TCP/IP is infact OSI model only, you can think of it has OSI model but without the Session and Presentation layer, or we can say that the application layers combines the application, presentation and session layer in TCP/IP.

However, despite its comprehensive design and lofty ambitions, the OSI model did not attain the same level of dominance as TCP/IP. Instead, TCP/IP emerged triumphant due to its operational efficiency, practicality, and widespread acceptance in the networking community. But even though we use TCP/IP today but whenever we learn networking we always talk and understand in the terms of OSI model as TCP/IP and OSI are same but OSI is just a more descriptive one and it explain things a lot better on the other hand TCP/IP who is just doing the same job as OSI but is more easier to implement in the real world, the OSI model's layered approach and systematic declaration of functionalities have endured, making it a crucial framework for understanding networking protocols.

# Unraveling the Layers of TCP/IP and Their OSI Equivalents:

To comprehend how TCP/IP and OSI interrelate, let's explore the equivalent layers and their responsibilities:

1. **Physical Layer (OSI) ↔ Network Interface Layer (TCP/IP)**:
The Physical Layer focuses on the transmission of raw bit streams over physical media, encompassing cabling, connectors, and signaling like switches and hubs we talked about in our previous blogs. Its counterpart in TCP/IP, the Network Interface Layer, handles the physical transmission and network access, including Ethernet or Wi-Fi protocols.

2. **Data Link Layer (OSI) ↔ Internet Layer (TCP/IP)**:
The Data Link Layer ensures reliable data transfer over the physical layer, incorporating error detection and correction mechanisms. The Internet Layer in TCP/IP, responsible for packet routing and addressing, facilitates IP (Internet Protocol) communication, enabling seamless data delivery across networks.

3. **Network Layer (OSI) ↔ Transport Layer (TCP/IP)**:
The Network Layer provides logical addressing, routing, and path determination to facilitate end-to-end communication. By contrast, the Transport Layer in TCP/IP, consisting of protocols like TCP (Transmission Control Protocol) and UDP (User Datagram Protocol), guarantees reliable, orderly, and error-free data transfer between network hosts.

4. **Transport Layer (OSI) ↔ Application Layer (TCP/IP)**:
The Transport Layer within the OSI model ensures transparent, reliable, and robust end-to-end delivery of data and handles various functions such as segmentation, flow control, and error recovery. In TCP/IP, the Application Layer provides services that allow applications to access the network, encompassing protocols like HTTP, FTP, SSH, and DNS.

The layers above the Transport Layer in the OSI model (Session, Presentation, and Application) are conceptually integrated into the Application Layer in TCP/IP, where the diverse set of applications interact with the network services.

Conclusion:

TCP/IP and OSI models continue to be the pillars of modern networking, shaping the way data is transmitted across networks globally. While TCP/IP emerged as the dominant force due to its simplicity, efficiency, and widespread adoption, the OSI model's layered approach and conceptual framework remain invaluable in comprehending the underlying principles of network protocols. Together, these models have paved the way for seamless communication, enabling the interconnection of people, devices, and systems across the world.

Gaining a comprehensive understanding of TCP/IP and OSI empowers individuals to grasp the intricacies of networking, unravel the mysteries of data transmission, and navigate the ever-expanding digital landscape. With that lets meet in our next blog.

Happy Networking