How Does the Internet Work? | What is the Internet's mechanism of operation?

Where to Begin? Internet Addresses

Because the Internet is a global network of computers, each computer connected to the Internet must have a unique address. Internet addresses are in the form nnn.nnn.nnn.nnn, were and must be a number from 0 - 255. This address is known as an IP address. (IP stands for Internet Protocol; more on this later.)

The image below shows two computers connected to the Internet, one with an IP address of 1.2.3.4 and the other with an IP address of 5.6.7.8. The Internet is depicted as a semi-abstract item in the middle. (As the specifics of the Internet are revealed in this work, the Internet component of Diagram 1 will be explained and redrawn multiple times.)

Diagram 1

When you use an Internet Service Provider (ISP) to connect to the Internet, you usually are given a temporary IP address for the duration of your dial-up session. If you connect to the Internet through a LAN, your computer may have a permanent IP address or receive a temporary one from a DHCP (Dynamic Host Configuration Protocol) server. In any event, your computer has a unique IP address if it is linked to the Internet.

Protocol Stacks and Packets

As a result, your machine is online and has a unique address. How does it communicate with other computers on the Internet? As an illustration, consider the following: If your IP address is 1.2.3.4, and you wish to send a message to the computer 5.6.7.8, you can do so. "Hello, computer 5.6.7.8!" is the message you want to send. The notice must, of course, be forwarded across whatever wire connects your computer to the Internet. Assume you've dialed into your ISP from your house and the message needs to be sent over the phone http://line.As a result, the notification must be converted from alphabetic text to electrical signals, sent via the Internet, and then returned to alphabetic text. How does one go about doing this?

A protocol stack is used to do this. To communicate on the Internet, every computer requires one, which is usually incorporated into the operating system (i.e., Windows, Unix, etc.). Because of the two main communication protocols used on the Internet, the protocol stack is the TCP/IP protocol stack.

If we followed the path taken by the message "Hello computer 5.6.7.8!" from our computer to the computer with the IP address 5.6.7.8, it would look like this:

Diagram 2

1. The message would begin at the top of your computer's protocol stack and work its way down.
2. If the message to be sent is lengthy, each stack layer it goes may divide it up into smaller data chunks. This is because data is transferred in digestible bits through the Internet (and most computer networks). These data chunks are known as packets on the Internet.
3. The packets would then go to the TCP layer after passing through the Application Layer. A port number is assigned to each box. Ports will be discussed later, but suffice to state that numerous programs may deliver messages utilizing the TCP/IP stack. Because the message will be received on a particular port, we need to know which application on the destination computer needs to receive it.

1. The packets then travel to the IP layer after passing through the TCP layer. This is where each packet's destination address, 5.6.7.8, gets received.
2. Our message packets are now ready to be sent across the Internet because they have port numbers and IP addresses. The hardware layer is responsible for converting our message's alphabetic text into electronic signals and transmitting them across the phone line.
3. Your ISP has a direct link to the Internet on the other end of the phone line. The ISP's router examines each packet's destination address, which determines where it should be sent. Another router is frequently the packet's next stop. Later, we'll talk about routers and Internet infrastructure.
4. The packets eventually make it to computer 5.6.7.8. The boxes begin at the bottom of the TCP/IP stack on the destination machine and work their way up.
5. All routing data contributed by the transmitting computer's stack (such as IP address and port number) is taken from the packets as they progress up the stack.
6. The packets have been reassembled into their original form when the data reaches the top of the stack, "Hello computer 5.6.7.8!"

Networking Infrastructure

So now you know how packets travel from one computer to another over the Internet. But what's in-between? What makes up the Internet? Let's look at another diagram:

Diagram 3

Diagram 1 has been redrawn in greater detail. The physical connection to the Internet Service Provider via the phone network may have been obvious, but what happened after that may require some explanation.

For dial-in subscribers, the ISP maintains a pool of modems. This is controlled by a computer (typically a dedicated one) that directs data from the modem pool to a backbone or dedicated line router. Because it serves network access, this system is referred to as a port server. In most cases, billing and usage data are also gathered here.