Starting with this blog post we are going to talk about Computer Networking. Basically we’ll have a look at how computer networks work by understanding their elements (the network devices – Routers and Switches). Let’s jump in!

What is a Computer Network?

A computer network is a group of devices (PCs, Laptops, Servers, Smartphones, etc.) interconnected that can communicate (exchange information) with each other. These devices are interconnected by special network equipment such as: Routers and Switches.

1) Network Types

Networks can be of several types:

  • LAN – Local Area Network – Your home network
  • MAN – Metropolitan Area Network – extended network, on the surface of a city
  • WAN – Wide Area Network – multiple networks (LANs) of an organization interconnected
  • WWAN World Wide Area Network – the Internet
  • WLAN – Wireless LAN – the your wireless network from home (aka. Wi-Fi)


2) Network Components

A network is composed of:

  • End-device (PC, Laptop, Smartphone, Servers etc.)
  • Switch interconnects multiple end-devices within a network (LAN)
  • Router  – interconnects multiple networks (thus forming a WAN)
  • Firewall – protects our network from potential cyber-attacks from the Internet
  • Transmission medium – copper cable (current), light impulses (fiber optic), wireless (radio waves)


Now, let’s dive in a little deeper and talk about the network components that are listed above. The first and most basic components of a network are the end-devices:


Generally, we are the ones that have a terminal device (end-device) component. Each of us has a Laptop, tablet or smartphone with which we connect to the Internet. This connection can be made with 1 or more transmission media (current, light impulses, radio waves).

When we connect with our smartphones to the Internet, we will most likely use the wireless connection. If we use a Laptop, we can connect it either wirelessly or through a network cable (UTP).

Figure 1

We use Fiber optic when we want to connect multiple network or server equipment (eg. switch – switch, server – switch). The reason is simple: a Fiber Optic connection can be much faster than UTP (cable) or Wireless. We can transfer more data (10, 40, 100 Gbps throughput) on a longer range (1 – 5 km or miles).

Also, fiber optics is now being used regularly when connection a home user to the Internet. The main reason for this is the fact that fiber optics can transfer data at a longer distance (1 – 5 miles/km as I said before) which is way, way more than the classic UTP cable that caps out at 100 meters !


A Switch is a network device that interconnects multiple end-devices (PCs, laptops, printers, IP phones, Servers,, etc.) in the same Local Area Network (LAN).

It is well known for its high port density (generally 24, 48 or even more) capable of speeds between 1 Gbps and 10 Gbps (or even 40 Gbps) per port. The switch uses MAC addresses as a way of identifying the end-devices connected to the network (we will talk in more detail in Chapter 2).

Here is an image with a Cisco Switch:

Figure 2


       A Router is a network device that has the role of interconnecting multiple networks (LANs) thus forming a larger network (WAN – Wide Area Network). The Router is the device that connects us to the Internet. It handles packet delivery to the destination network.

The Router achieves this by using IP addresses in order to identify the source and the destination devices (we’ll talk more about IP addresses in Chapter 3)

Compared to the Switch, the Router has way fewer ports (between 2 to 5) at similar speeds (100 Mbps – 10Gbps, depending on the model).

Bellow you can see a Cisco Router:

Figure 1.3

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