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Part 1: CCNA Training: What is a network

Posted: October 21st, 2016

Intro to Networking

What is a network?

How would you answer this? What would you say if you were asked to explain “what is a network” in your job interview?

To put it simply a network is a collection of devices that move parcels of information from A to B.

Do not think of a network as any more complex than this statement and you will find that networking is a complete doddle, I promise.

Of course there will be those who will think that I am trying to down play the sometimes complex nature of networks, sure, yes networks can be complex but only in the sense that there may be many components involved, but If you take each individual component and examine it as a single standalone function or item then the whole will make more sense and will appear far less complex. Than before. It’s a case of study each tree to understand the forest.

Hubs and the physical layer, the very basics toe in the water time

In the beginning the way in which computers were connected to one another was very primitive compared indeed to today’s methods.

Image a long electrical wire like a clothes line with shorter lengths of wires hanging down, at the end of each of these hanging wires you would find that there was a computer attached. That’s it, that’s the way the earliest networks were put together, they were very simple and very crude, but since that was the only method to connect computers together that was fine.

figure-1

At some point someone looked at this “clothes line” network and decided it was too messy having this long length of cable snaking around the building so they decided to get a cardboard box and stuff the cable into the box with holes in the box to run the cables down to the computers, so now instead of a network which resembles a centipede we now have a network which resembles a box with lots of wires coming out of it, like in the picture below.

This type of network is referred to as a “Star Topology”

figure-2

If you were to remove the box you would see only the wires, it would resemble the picture below

figure-3

So in effect the “clothes line” network and the “box” network are one and the same, the major difference is that the “box” is more than a box it has the ability to amplify any data it receives and repeat the data out to all connected computers, this box has a name, and it is called a hub.

Hubs are very simple devices, they were used to connect multiple machines in an office network. One machine has something to say it will parcel it up into a little package called a “Frame” places it onto the wire, and once on the wire all connected “live” computers will receive a copy of the “Frame” even if they are not the intended recipient