April 9, 2020

What is Switch? What does it do?

Switches used in computer networks can be used for more than one computer, printer, etc. it is a network device that allows them to communicate with each other.

What is the Switch Used in Computer Networks?

Switches used in computer networks allow multiple computers or other devices to communicate. The most basic working principle of the switches is to filter and transmit IP packets to the target computer.

Switches record the MAC addresses and IP addresses of the computers on the network to this table using the MAC address table (CAM table). The computer that will send a file for the first time will need to write the MAC address and IP address of the target computer into the IP Package. If the packet sending computer does not know the MAC address of the target computer, it broadcasts an ARP (Address Resolution Protocol) to the network environment.

As a result, the MAC address information of the target computer is obtained and written to the MAC address table. In subsequent new packet transmissions, it sends directly to the target computer without broadcasting ARP.

The switches also start working as soon as the power cord is plugged in. It has multiple ports and uses the CSMA / CD mechanism to prevent Collision states.

Switch
Switch

 Which Layer Works Switches?

A LAN is created using switches, and these LANs can be separated from each other by Routers. The switches operate on the 2nd and 3rd layers of the OSI model.

Layer 2 Switching

The 2nd layer switches are hardware-based and all ports on the switch transmit packets according to the cable speed. It transmits IP packets using the MAC address table.

Layer 2 switches can only send IP packets to computers in the same IP block.

Layer 2 Switching
Layer 2 Switching

Layer 3 Switching

Layer 3 switches use both hardware-based switching and hardware-based routing. The 3rd layer switching takes place with the integrated circuit ASIC hardware. Also, Frame transmission and Packet transmission are transmitted using ASIC hardware.

Layer 3 switches can also transmit packets to different IP blocks. We can also think of the 3rd layer switches as a Router. Layer 3 switches store source and destination routing information in the cache after the first routing. In the next packet transmissions, it does not need to redirect and retrieves this information from its cache and transmits it quickly.

With this cache feature, layer 3 switches are more efficient than Routers.

Layer 3 Switching
Layer 3 Switching

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