Learning Networking Basics - 1

And I decided to learn networking fundamentals

Why ?

When I was working at YoupiLab as embedded software developer, my CEO told me multiple times that I need to learn networking basics that its a great part in IT. Now that I’m working as backend developer at Uptimise, my Lead told me that if I want to advance in the field I need to be comfortable with Networking.

In fact, I don’t know too much about networking besides the fact that I can access my React application locally on localhost (127.0.0.1) and that generally, I need the IP address + Port to access an application, like 127.0.0.1:3000 for a React app 😅 (shame).

As I was interested in system programming, I thought, why not learn networking programming (system) at the same time? So I started this month with the Networking Basics by Cisco Academy.

First Steps

The course seems good, with around 17 chapters, and the first 4 are about generalities (I’m at chapter 5). It provides good information to conceptualize what networking is, with the support of Cisco Packet Tracer to design networks.

These insights made me realize some things I did in the past but didn’t really understand because I searched “How to” on Google. It’s not bad, but now, I’m gradually understanding why some things are done in certain ways.

For example:

• On a router (even a wireless router), there is a built-in switch that allows devices to connect to the local network (LAN).

• The ports usually colored in yellow or orange on a router are for LAN, and the usually blue port (one) is for the internet or Wide Area Network (WAN). That’s why when we want a device to be wired to the router, we connect it to the yellow ports through these (you know) cables with multiple colors.

Basics right ? Yes, that’s why the course is named so.

There is an analogy that I get at this point that helps me remember all of these terms (IP address, LAN, WLAN, Gateway, Subnet Mask, Router, ISP, …):

The IP addresses for the end devices can range from 192.168.0.2 - 192.168.0.254. Each device will get a unique IP address in the same network.

The subnet mask is used to differentiate the host and the network ID portion of the IP address. You can relate the IP address to your street address. The subnet mask defines the length of the street name. The network part of the address is your street, 192.168.0. The house number is the host port of the IP address. For the IP address 192.168.0.2, the house number is 2 and the street is 192.168.0. If there is more than one house on the same street, for example, house number 3, will have an address 192.168.0.3. The maximum number of houses on this street is 253, ranging from 2 to 254.

The default gateway is analogous to the street intersection. The traffic from the 192.168.0 street has to exit through the intersection to another street. Another street is another network. In this network, default gateway is the wireless router that directs the traffic from the local network to the cable modem, and the traffic is then sent to the ISP.

From Networking Basics by CISCO Academy.

I understand that the default gateway that we read when doing Router config is the Router IP address, simple !

Conclusion

The first 4 chapters may seem boring because the general info is already known, but from chapter 5, it starts to get really technical. As Linux networking is built on top of this knowledge, I hope at the end of the course to be able to understand more about Linux networking.