An Introduction to TCP/IP

TCP/IP , or Transmission Control protocol/Internet Protocol, is literally the backbone of internet and network communication. The concepts of TCP/IP are difficult to grasp without previous experience, so don’t be dismayed if it doesn’t click instantly. To better help you out, we’ll start from the very beginning- with a definition of just what a network is.

Networks, Protocols, and Suites, Oh My!

A network is simply a collection of computers or similar devices that can communicate over a transmission medium. Don’t worry- that is just a fancy phrase that usually refers to Ethernet cable and other connective wire. You can see a basic network in the diagram below- odds are you’ve already seen something similar.


Simple enough, isn’t it? Just three computers linked together for communication. Sadly, it is a little more complex than that. To actually send any data from one computer to another we need to make use of a network protocol. A network protocol is a set of common rules that defines how data should be sent. These protocols ensure that a message sent from one computer will reach the next, and that it is interpreted correctly. These many different protocols make up TCP/IP, which is referred to as a protocol suite.

But why do we need a special suite? Back when TCP/IP wasn’t around, there were many different proprietary protocols. Since many different companies developed different protocols, many networks just weren’t compatible. Without a common suite like TCP/IP, the internet would not be possible.

A Brief History of TCP/IP

Now that we have a basic understanding of what TCP/IP is for, let’s review how it came to be. Believe it or not, TCP/IP was developed way back in the 1960’s by the United States Department of Defense. Its original designers had a problem- networks at the time were very small and incompatible. Proprietary protocols were in wide use, contributing to the compatibility problem.

In the early days, it was believed that relying on networks could be a disastrous idea. If a particular network node were to be destroyed for any reason, it would likely bring the entire network down. Since a missile or bomb could literally make any point on a network a target, a decentralized system was needed. The goal was to create a network that didn’t depend on other parts of the network to operate- one of the key features of TCP/IP. Review the diagram below for a visual representation of what happens if a computer fails on a centralized network. As you can see, both right and left computers have lost connection to the central computer, since the middle computer is down.


To actually provide a decentralized network, two important features of TCP/IP are used. Instead of one computer having authority over others, computers generally operate as equals. Dynamic routing is another feature that ensures decentralization. If computers are connected through multiple paths, computers will check for alternative routes if one seems to be down. In the above image, we could achieve dynamic routing by connecting both left and right computers to the first centralized computer- this enables us to completely bypass the downed middle computer.

This ambitious project was initially named ARPANET after the Defense Department’s Advanced Research Projects Agency (ARPA). A few years later, research institutions wanted in on the protocol system too. This is the start of what became the foundations of the internet.

Soon after, we had another networking concept arise- the Local Area Network, or LAN. These networks were the solution for offices and institutions to share resources with ease. The first LAN connections were crippled from today’s standards- they lacked internet access. The advent of the gateway enabled protocols to be translated for LAN connections to access the internet- and the popularity of TCP/IP exploded from there.

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