When revising the work,.SE logos terney.info graphic elements shall be removed from the processed version. They are protected by law and are not covered by. The Internet has changed the world and, with everything from blogs to podcasts , Internet phones - Selection from How the Internet Works, Eighth Edition. In this lesson, we will give a brief overview of the internet, and we will The internet is the largest computer network in the world, connecting.
|Language:||English, Spanish, French|
|Distribution:||Free* [*Registration Required]|
A slightly technical whitepaper explaining what makes the Internet tick. Now you know how the Internet works. But how long will it stay this way? The version of. CS, Stanford University. How the Internet Works. (in about an hour). Nick McKeown. Professor of Electrical Engineering and Computer Science, Stanford. The Internet works because every computer connected to it uses the same set of rules why the Internet is sometimes described as a network of networks.
It does not go into great depth, but covers enough of each area to give a basic understanding of the concepts involved. For any unanswered questions, a list of resources is provided at the end of the paper. Any comments, suggestions, questions, etc. 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. This address is known as an IP address. IP stands for Internet Protocol; more on this later. The picture below illustrates two computers connected to the Internet; your computer with IP address 1.
The Internet is represented as an abstract object in-between.
As this paper progresses, the Internet portion of Diagram 1 will be explained and redrawn several times as the details of the Internet are exposed. HTML has, almost since the beginning of websites, been one of the main languages used to communicate information, particularly for the creation of websites.
You can view the code on most webpages by using the view source option in your browser. Most of what you will see is HTML, since dynamic sites hide their real code when displayed that way for security reasons. Details on the current version of HTML 4.
The code of dynamic sites is usually a portal to a database. What that means is that they are requests, or questions, that can be answered by a database, which is where the real data is displayed. The form will send that information to a database, and tell it to store it on a particular part of the database with tags for your name, address, password, etc. When you click login, the page will send a request to the database that asks if that person exists in the database. The database will search for it and if it finds that information if will reply that is does and give you access to your information on the site.
You may have seen the term "XML. What is XML and how do you use it? XML is a markup language that is mostly used to structure documents and transfer data between applications. It is also a language that can be used very effectively for transfer of information between databases because it is so configurable. With Flash, people can create sites with moving elements, music and action script which only require one plugin download to be viewed. It was widely adopted and by it had over million users.
Its plugin can be found on most computers with Internet access. It is a platform that has been used for many web and non-web applications, such as games and applications. Much like Flash, it requires software to be downloaded to your computer in the form of a plugin.
Ajax was coined in by Jesse James Garrett. What Ajax does is basically load information on a page without the need to click on links and reload pages like HTML does.
This helps make web pages more interactive, and feel less like a series of documents. Pop up using Ajax. Bubble appears when mouse is over the link. Who runs the Internet? No one organization controls the Internet; instead, a variety of international organizations work to make it what it is. It is a venue for discussions about the direction of the Internet on a global level. Basically they specify the standards that browsers use when supporting particular languages.
It is responsible for coordinating IPs and registries and regulates how they work together. If the message to be sent is long, each stack layer that the message passes through may break the message up into smaller chunks of data. This is because data sent over the Internet and most computer networks are sent in manageable chunks.
On the Internet, these chunks of data are known as packets. Each packet is assigned a port number.
We need to know which program on the destination computer needs to receive the message because it will be listening on a specific port. 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.