The internet is a worldwide, open communication network. It originates from the American ARPAnet (Advanced Research Project Agency Network) from 1969, and it uses a special communication protocol called IP (Internet Protocol). Data networks to many companies, schools and universities are connected to this network, making it grow larger and larger. Many individuals are also connected from their homes, who becomes a part of this whole network as well.
These kinds of networks are also known as “IP Networks“. It’s important in the networks that the different computers and machines speak the same language and has the same rules for communication, also known as “protocols”. But before we go further into that, let’s talk about how the internet and the “IP Network” are built up.
When we take a look at the whole communication network, we can see that there are a lot of different machines such as PCs, Laptops and other computers use. All these machines we call for “hosts“. These hosts are divided into two groups called “Clients” and “Servers“. The communication on the internet is started by the client machines asking the server machines to do various services. The most common application on the internet today is web (World Wide Web). The user instructs the web client/reader/browser which website to visit with the subdomain “www“, and the server responds with the website and sends the page you’re looking for. However, it is purely a personal preference to use “www” on your own website. There are other services that are made custom for the website and functions just as good.
Internet and other IP networks are actually called Internetworks. Think of it as a network of networks. The name of the internet is actually an abbreviation of the internetwork because it consists of many different networks, which then consists of many different machines.
In order for these machines to talk to each other on different networks, they are connected together with “routers“. These devices can route traffic from one network to another, such as requests, or getting an answer from a request back. The machines that are surfing on the internet all have a globally unique address for this. This enables the routers to use their routing tables to know where to send the information. The global unique addresses and the tables are something we will talk more about later.
Today’s internet is also a quite large network. If we had a random communication with each other through the routers, it would be quite frustrating. We wouldn’t know which route to take and it would be chaotic. This is why our networks are built up in a hierarchy, forcing messages to move up and down in a systematic order to create a more fixed and reliable environment. This way we can send our texts over to you in a very far distance away, and you being able to read it right now.
At the highest level, there are international “backbone” networks. On the level beneath, we can find national backbones and on the lowest level, we have company networks or ISPs (Internet Service Provider) for example. This hierarchical structure doesn’t follow any specific pattern. Big companies will typically want to have their own backbone network, and international ones as well, and these will both be standing at a high level in the hierarchy. However, even if the company’s backbone is at a very high level, that doesn’t necessarily mean they want to handle your request for reading Facebook in the morning. This creates a more complex structure. More about this topic comes later in the series.
The last aspect with the internet’s structure for this time: when you surf online on your computer at home, you don’t necessarily utilize your own internet cable for this case. You could also be using the telephone line or the TV cable. How does this work? It has to do with the “access“. What’s common with these access methods is that they transport information from and to the ISP. The ISP then takes care of the continuation of those signals. However, the development of these access technologies have gone off with a storm lately, and using the telephone line is what most people prefer anymore. We will talk about the different ways of delivering signals and access methods later in the series as well.
picture 1: Self-made
picture 2: https://www.signupto.com/wp-content/uploads/2016/07/Client-server.png
picture 3: https://www.valuewalk.com/wp-content/uploads/2014/06/Political-hierarchy.jpg
Next in the series: https://x9security.com/networking-2-the-network-infrastructure/