The main disadvantage of using this device is its negative impact on network performance, resulting from the fact that any incoming signal on any of its ports is re-created and sent out on any connected ports.?
Hub is used to connect devices in a network. It is also called a dumb device because it broadcasts the signals or messages on any of its ports to all other ports.
For example a message has to be sent to a computer. Lets name that computer H. Hub will send that message to all connected ports on the hub not just considering that specific port of computer H.
So hub is an unintelligent device which is not able to distinguish between devices and sends a messages to every port irrespective of which the destination host is.
Now when the destination computer H responds to that message this too goes to all other ports on hub.
This has a negative effect on network's performance as it might result in collisions between data packets.
The bandwidth of hub is shared by all the devices connected to it. When a source host is sending a large amount of data to destination, it will take all the bandwidth which leads to slow network performance and access in other connected computers .
The network speed and performances reduces as more devices are added.