Before we get into the simplified explanation of Transmition Control Protocol, here’s a more technical breakdown. TCP is a “standard that defines how to establish and maintain a network conversation via which application programs can exchange data.”
- Working together with the IP (Intern Protocol) to form TCP/IP, TCP establishes a connection that allows the Application Layer to send packets.
- These packets are delivered to another application by the IP layer or Network Layer
- The size of the packets sent across the connection are regulated by TCP.
- Lost or damaged packets are fixed by TCP and sent to the destination by the IP Layer once more.
- The network layers in which TCP does its active work, as assigned by Open Systems Interconnection, are the Transport Layer and Sessions Layer.
- Once communication ceases, TCP closes the connection.
We can rephrase the technical explanation by imagining a Medieval pizza delivery system. For the sake of simplicity and fun, let’s pretend that pizza was invented in the middle ages.
Here are some facts
- There are two dukes(Duke Blue and Duke Red) that are currently waging war against one another.
- Their castles(Castle Blue and Castle Red) are on opposite ends of a ten mile stretch of land.
- The only road that one can take to reach one castle or the other is Duke’s Way. The road is closed and is guarded by men who only allow messengers through.
Now we’ll explain
A citizen of Red Castle(client) sends a messenger(HTTP/DNS/SMTP) to order pepperoni pizza(data) from Bobby(server), a renown pizza maker in Blue Castle.
The messenger(HTTP/DNS/SMTP) gains approval from the guards(TCP) who then open up the road(IP).
Bobby(server) receives the order from the messenger(HTTP/DNS/SMTP). Bobby makes the pizza and gives it to the messenger(HTTP/DNS/SMTP).
The messenger(HTTP/DNS/SMTP) then travels across the still open road(IP) and delivers the pizza(data) to the Red Castle citizen(client).
The guards(TCP) close the road(IP) after the messenger(HTTP/DNS/SMTP) delivers the pizza(data).