Segmenting the network into smaller subnets, prevents traffic overloading in a network.
You can also say that switch is a networking device that connects other computers, networking devices, and network segments together.
Switch is also called as multi-port bridge.
Working of switch and bridge is little bit similar to each other.
A switch is responsible for filtering, that is, transforming the data in a specific way and for forwarding packets (a piece of message being transmitted) between LAN segments.
Switch supports any packet protocol.
LANs that are segmented through switches are called Switched LANs. In the case of Ethernet LANs, they are called Switched Ethernet LANs.
Working of switch is not similar to hub, because if hub receives data on its port then hub transmits the message to all the connected devices then all the connected devices receives the message. And someone saves the message who required and other drops. Then its occur some congestion.
Whereas in case of switch, switch only transmits the data who required. In other word, switch sent the message to that person who is responsible for that particular message not to all the person.
A network switch creates a separate collision domain for its each port.
Since this is a modified version of bridge, then because in our bridges, there was two ports, and they divided network into two collision domains.
And here, we have a large number of ports, then every switch's port acts as a separate collision domain (group of network interface card where anytime collisions can occur).
For instance, if in our network, there are 4 computers connected with each other eg. computer A B, C, and D. Suppose in all four computers, let computer A transfers the data to computer B and similarly computer B also transfers the data to Computer A. The communication is only between the computer A and Computer B. When computer C and computer D also wants to communicate in between, then they can also communicate. Both the communications are separate and does not interfere with each another.
Switch works on layer 2 of OSI model.
Sometime you find a switch that works on layer 3 or on transport layer also called as layer 3 switch or multi-layer switch.
Multilayer switch also works on layer 2, layer 3, or layer 4. Therefore it also works for routing purpose.
But if we talk only about switch then switch is a device that works on data link layer or layer 2 of OSI model. And in case if we add layer 3 or multi-layer switch then it represents layer 3 switch or multi-layer switch.
Switch receives its message on its port in form of frames and transmits to device that receives the message.
Switch is essential part of all LAN network.
Now-a-day we can not think a LAN can exist without network switch.
We can see in case of mid-to-large sized LANs, there are a large number of switches that connects with each other.
We can also see switches in small offices or home offices.
Switch is an integral part of today's LAN and we can not think about LAN without switch.
Switch gives us high speed data exchange. In other word, switch works on 1000 or giga bits switch. They transfer data in giga bits.
Switch provides full-duplex communication. We have seen in earlier example, that system A directly communicate with system B and simultaneously system C directly communicate with system D.
Here latency are also very low. Switches are very fast devices.
Switch provides dedicated communication between devices in our network. We can also say that switch provides point-to-point data communication because one sender's data directly goes to one receiver.