Packets are parts of a file that range between 1, and 1, bytes. Packets have headers and footers that tell computers what's in the packet and how the information fits with other packets to create an entire file.
Each packet travels back up the network and down to your computer. Packets don't necessarily all take the same path -- they'll generally travel the path of least resistance. That's an important feature.
Because packets can travel multiple paths to get to their destination, it's possible for information to route around congested areas on the Internet. In fact, as long as some connections remain, entire sections of the Internet could go down and information could still travel from one section to another -- though it might take longer than normal. When the packets get to you, your device arranges them according to the rules of the protocols.
It's kind of like putting together a jigsaw puzzle. The end result is that you see this article. This holds true for other kinds of files as well. When you send an e-mail, it gets broken into packets before zooming across the Internet. Phone calls over the Internet also convert conversations into packets using the voice over Internet protocol VoIP. We can thank network pioneers like Vinton Cerf and Robert Kahn for these protocols -- their early work helped build a system that's both scalable and robust.
That's how the Internet works in a nutshell. As you look closer at the various devices and protocols, you'll notice that the picture is far more complex than the overview we've given. It's a fascinating subject -- learn more by following the links on the next page. Sign up for our Newsletter! Mobile Newsletter banner close. Mobile Newsletter chat close. Mobile Newsletter chat dots. Mobile Newsletter chat avatar.
Mobile Newsletter chat subscribe. Internet Basics. How does the Internet work? A Matter of Protocols " ". The Internet is a global entity -- you could call it the largest machine on Earth. Packet, Packet, Who's Got the Packet? The internet is composed of computer networks that allow users to access information from other computers provided that they have permission to do so.
What are the main features of the internet? One of the main features of the internet is accessibility. Anyone with access to a computer and a broadband connection can gain access to the internet without restriction. The internet also happens to be low cost and compatible with most platforms.
How does data move through the Internet? Data is chopped into packets. This is where each packet receives it's destination address, 5. Now that our message packets have a port number and an IP address, they are ready to be sent over the Internet. The hardware layer takes care of turning our packets containing the alphabetic text of our message into electronic signals and transmitting them over the phone line. On the other end of the phone line your ISP has a direct connection to the Internet.
The ISPs router examines the destination address in each packet and determines where to send it. Often, the packet's next stop is another router. More on routers and Internet infrastructure later. Eventually, the packets reach computer 5. As the packets go upwards through the stack, all routing data that the sending computer's stack added such as IP address and port number is stripped from the packets. When the data reaches the top of the stack, the packets have been re-assembled into their original form, "Hello computer 5.
But what's in-between? What actually makes up the Internet? Let's look at another diagram: Diagram 3 Here we see Diagram 1 redrawn with more detail. The physical connection through the phone network to the Internet Service Provider might have been easy to guess, but beyond that might bear some explanation. The ISP maintains a pool of modems for their dial-in customers. This is managed by some form of computer usually a dedicated one which controls data flow from the modem pool to a backbone or dedicated line router.
This setup may be refered to as a port server, as it 'serves' access to the network. Billing and usage information is usually collected here as well. From here the packets will usually journey through several routers and over several backbones, dedicated lines, and other networks until they find their destination, the computer with address 5. But wouldn't it would be nice if we knew the exact route our packets were taking over the Internet?
As it turns out, there is a way This one is called traceroute and it shows the path your packets are taking to a given Internet destination. Like ping, you must use traceroute from a command prompt. In Windows, use tracert www. From a Unix prompt, type traceroute www.
Like ping, you may also enter IP addresses instead of domain names. Traceroute will print out a list of all the routers, computers, and any other Internet entities that your packets must travel through to get to their destination. If you use traceroute, you'll notice that your packets must travel through many things to get to their destination. Most have long names such as sjc2-core1-h These are Internet routers that decide where to send your packets.
Several routers are shown in Diagram 3, but only a few. Diagram 3 is meant to show a simple network structure. The Internet is much more complex. Internet Infrastructure The Internet backbone is made up of many large networks which interconnect with each other. These networks peer with each other to exchange packet traffic. NAPs were the original Internet interconnect points. Below is a picture showing this hierarchical infrastructure. Diagram 4 This is not a true representation of an actual piece of the Internet.
None of the physical network components are shown in Diagram 4 as they are in Diagram 3. This is because a single NSP's backbone infrastructure is a complex drawing by itself. Most NSPs publish maps of their network infrastructure on their web sites and can be found easily. To draw an actual map of the Internet would be nearly impossible due to it's size, complexity, and ever changing structure.
Does every computer connected to the Internet know where the other computers are? Do packets simply get 'broadcast' to every computer on the Internet? The answer to both the preceeding questions is 'no'.
No computer knows where any of the other computers are, and packets do not get sent to every computer. The information used to get packets to their destinations are contained in routing tables kept by each router connected to the Internet.
Routers are packet switches. A router is usually connected between networks to route packets between them. Each router knows about it's sub-networks and which IP addresses they use. The router usually doesn't know what IP addresses are 'above' it. Examine Diagram 5 below. The black boxes connecting the backbones are routers. Under them are several sub-networks, and under them, more sub-networks.
Nothing, so let's do that. Such a network comes very close to what we call the Internet, but we're missing something. We built that network for our own purposes. There are other networks out there: your friends, your neighbors, anyone can have their own network of computers. But it's not really possible to set cables up between your house and the rest of the world, so how can you handle this? Well, there are already cables linked to your house, for example, electric power and telephone.
The telephone infrastructure already connects your house with anyone in the world so it is the perfect wire we need. To connect our network to the telephone infrastructure, we need a special piece of equipment called a modem. This modem turns the information from our network into information manageable by the telephone infrastructure and vice versa. So we are connected to the telephone infrastructure. The next step is to send the messages from our network to the network we want to reach.
An ISP is a company that manages some special routers that are all linked together and can also access other ISPs' routers. So the message from our network is carried through the network of ISP networks to the destination network. The Internet consists of this whole infrastructure of networks.
If you want to send a message to a computer, you have to specify which one. Thus any computer linked to a network has a unique address that identifies it, called an "IP address" where IP stands for Internet Protocol. It's an address made of a series of four numbers separated by dots, for example: That's perfectly fine for computers, but we human beings have a hard time remembering that sort of address.
To make things easier, we can alias an IP address with a human readable name called a domain name. For example at the time of writing; IP addresses can change google. So using the domain name is the easiest way for us to reach a computer over the Internet. As you might notice, when we browse the Web with a Web browser, we usually use the domain name to reach a website.
Does that mean the Internet and the Web are the same thing?
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