Network switches

What’s a network switch ?

A switch is a device used in computer networks to connect multiple devices together within a single local area network (LAN). Its main role is to facilitate communication between different connected devices, such as computers, printers, servers, IP phones, etc.

It is a mini-computer which is made up of RAM, ROM, flash RAM, NVRAM, a microprocessor, connectivity ports and even an operating system.

How does it work ?

Now how does a switch work to transfer information from one machine to another?

Suppose we have 4 machines: A, B, C and D connected to our switch in ports 1, 2, 3 and 4 as follows:

Transmitting data from machine A to machine B happens in the following steps:

1. Machine A sends a frame to machine B


2. Once this frame arrives at port 1 (which is the one linked to A), the switch reads the source MAC address and stores it in the MAC address table


3. The switch reads the destination MAC address and looks for it in the table, if it is not in the table, it broadcasts to all the active machines connected to the switch except the source one.


4. If the port linked to the machine we want is active, it sends a response frame from which the switch reads the MAC address we were looking for (@B)


5. Once done, it records the MAC address of B in the table.