Switches are Layer 2 (Network Layers) used to connect the hosts in LAN. Generally the main use of switch is to connect multiple number of computers and to enable communication between them in a same network. Now let us take a basic example to understand how does communication take place through switch.
As shown in above figure, two computers are connected to a switch(more number of computers can also be connected depends on the number of ports in switch). Now if PC-1 wants to communicate with PC-2, then same like hub, PC-1 don’t know the IP Address or MAC Address of PC-2. So what it will do is it will send one broadcast message to all the hosts connected to switch. But here in our case only two hosts are connected. So, the message sent by PC-1 to switch will be broadcasted by switch to the PC-2. So, PC-2 will come to know the IP Address and MAC Address of PC-1 and it will send ARP to the PC-1. This how they both got the information they needed to communicate with each other and they can start communication.
Now suppose if PC-1 wants to send message for the second time to PC-2, then switch will not broadcast the message to other hosts connected to the switch. So it means that switch creates only one Broadcast Domain.
Now assume that one more host is attached to the switch after these two hosts and if PC-1 wants to communicate to that new host, then switch will not broadcast the message to PC-2(as it is known to PC-1 by its IP and MAC), but it will directly send message to the new host connected. This is how it breaks the Collision Domain.
Now suppose if PC-1 wants to send message for the second time to PC-2, then switch will not broadcast the message to other hosts connected to the switch. So it means that switch creates only one Broadcast Domain.
Now assume that one more host is attached to the switch after these two hosts and if PC-1 wants to communicate to that new host, then switch will not broadcast the message to PC-2(as it is known to PC-1 by its IP and MAC), but it will directly send message to the new host connected. This is how it breaks the Collision Domain.
Advantages of Switch over Hub
- Switches creates only one broadcast domain and no collision domain while Hub creates one broadcast domain as well as one collision domain for each host.
- Traffic reduces while using switch while it increases while using Hub.
- More number of Host can be connected(Maximum 48).
Important Note: Switches creates only one Broadcast Domain and no Collision Domain
Point Level Switches
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