Sonia Manoubi
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[ Devops : Back to Basics ] : The Network Layer

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[ Devops : Back to Basics ] : The Network Layer

Sonia Manoubi's photo
Sonia Manoubi
·Feb 11, 2022·

3 min read

Table of contents

  • The Network Layer
  • Conclusion

This article is part of a serie called [ Devops : Back to Basics ] where i document what i'm learning on my journey to become a Devops Engineer from my current position as a Backend Engineer.

The Network Layer

On a local area network or LAN, nodes can communicate with each other through their physical MAC addresses. This works well on small scale because switches can quickly learn the MAC addresses connected to each other ports to forward transmissions appropriately. But MAC addressing isn't a scheme that scales well, every single network interface on the planet has a unique MAC address and they aren't ordered in any systematic way. There is no way of knowing where on the planet a certain MAC address might be at any one point in time, so it's not ideal for communicating across distances.

IP addresses

IP addresses are a 32 bit long numbers made up of four octets, and each octet is normally described in decimal numbers. This format is known as dotted decimal notation.

ipv4-5bdcc3d4c9e77c0051c98cca.png

The important thing to know for now is that IP addresses are distributed in large sections to various organizations and companies instead of being determined by hardware vendors. For example IBM, which owns every single IP that has the number 9 as the first octet. At a very high level, this means that if an Internet router needs to figure out where to send a data packet intended for the IP address 9.0.0.1, that router only has to know to get it to one of IBMs routers.

You can find here the list of how ip adresses are distributed.

It's important to understand that IP addresses belong to the networks, not the devices attached to those networks. So your laptop will always have the same MAC address no matter where you use it, but it will have a different IP address assigned to it at your work than it would when you're at home.

IP address classes

IP addresses can be split into two sections, the network ID and the host ID.
Earlier we mentioned that IBM owns all IP addresses that have a nine as the value of the first octet in an IP address.
If we take an example IP address of 9.100.100.100, the network ID would be the first octet, and the host ID would be the second, third and fourth octets. The address class system is a way of defining how the global IP address space is split up.

ip adress class@2x.png

Routers

Routers are networking devices operating at layer 3 or a network layer of the OSI model.
They are responsible for receiving, analyzing, and forwarding data packets among the connected computer networks.
When a data packet arrives, the router inspects the destination address, consults its routing tables to decide the optimal route and then transfers the packet along this route

ARP (address resolution protocol)

Address Resolution Protocol (ARP) is a protocol that connects an ever-changing Internet Protocol (IP) address to a fixed physical machine address, also known as a media access control (MAC) address, in a local-area network (LAN).

1625683953964.webp

Conclusion

That's it !

Don't hesitate to comment to point out some mistakes or make some precisions.

As i said in the beginning, i am still studying these concepts :)

See you in the next one ! 🤖🤖🤖

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