The story begins by explaining the purpose of a network. The textbook explanation of what is a network goes a little something like what follows: A network is a group of connected devices that share common resources and information. I would say that the textbook said it best and will not make a second attempt at that explanation…
Now the act of sharing is to move items of relevance from one object in space to another. If a network allows for the sharing of resources and information, we stretch that understanding to mean that object A (for argument sake, your pc/laptop) needs to share the word document with your printer. Now! How this happens will blow your mind away…
Object A users the OSI Reference model to translate what you see on your word document into bits, and transmits these bits via electrical signals across a conductive material such as copper which connects object A to object B. The electrical signals can also be converted into radio waves before being transmitted out of object A. These radio waves broadcast the signals out to any device that is listening. The signal is intended for a specific device but the message is sent to any device that can listen for radio waves… The intended device will be able to rebuild the signal it receives into something that can be legible to the human eye.
The same electrical signals can also be converted into light pulses which then transmit through glass tubing from one connected device to another. This medium is called a fibre connection. Light being faster than movement of current through conductive material allows us the use of even greater speeds on our networks.
So you get the picture when two devices are connected to each other via either conductive material, radio waves or fibre, and yes, that is the simplest form of a network where two devices are able to share information with each other.
But there are more than 2 people that make use of technological devices in this great world of ours. We therefore need to expand this idea of a network to be able to connect more than two devices. We achieve this by making use of multiport devices such as hubs and switches.
A hub or a switch helps create a Local Area Network (LAN) which allows many devices to connect to one central device that is then used to pass information in the form of electrical signals from one connected device to the next. The Hub can be explained by the following analogy.
It is a hot summer’s day, there are crowds of people standing around in an open field. There is a rather large stage in the middle of the field. In the centre of the stage, there is a tall, shiny, new mic stand. Along the side of the stage, there are multiple sets of towering speakers facing all directions outwards towards where the crowds are located. You take to the stage and approach the Mic, you speak the words, “Welcome to the 2016 Olympic games”. Every single person in the crowd, roars into excitement from hearing those opening words that you just delivered from the stage.
Now to bring this analogy back home to what is a hub and how it works…
The same way that every single person in the crowd was able to listen for, and hear the message being broadcasted from the centre stage is similar to how the hub is able to transmit signals from one device to every other device connected to the hub on the LAN. When a hub receives electrical signals from a specific port on the hub, it re-generates that signal and broadcasts the same signal out to every other port on the hub. In essence every single device connected to the hub gets the same message.
The switch on the other hand works more like a mail man delivering mail to your post box. The mail man needs to know your physical address before it is able to deliver the mail to your post box. Similarly, the switch needs to know what is connected to each of its ports before it can pass an electrical signal through a specific port. The switch does behave like a hub every time it is powered on because it sends a broadcast message to all connected devices asking for the physical address of the device so that it can map the address back to a port on the switch. The physical address of a device is called the Machine Access Control address (MAC Address). The MAC address is stored in the memory of the switch once the switch learns the MAC address from the connected device.
So let us try and answer the question of, what is a network, again. The textbook meaning is still the following: A group of connected devices that share common resources and information. Breaking this down into its components looks a little something like what follows:
A group of connected devices: well, how are they all connected? One could say that it’s the copper cable that connects the devices. Yes, that will be true but that is just the physical connection. If there are more than two devices that are in this connected state, we add to the story that the network is the cable plus the device that all the cables connect into, which can either be a hub or a switch. Yes, I know some of you might argue that this is still a physical connection adding more physical devices to the story like a hub or switch. I would counter-argue at this point thou, that the switch or hub do add a logical element to the physical connection… So from breaking this down a bit, we now understand that the network is all the bits in between each device that is connected to each other. The micro freeways of the 21st century so to say, getting info bits from one device to the next.
And, why is a network important? Well, without connecting devices to each other via the network we will not be able to share common resources like office printers and fileservers and we will also have to physically approach and access each device independently to be able to view the information stored on that device.
The network makes sharing common resources and accessing information across multiple devices that much more achievable. This is why it is so important that it exists!