9.5 Microsegmentation of a Network
9.5.1 LAN segmentation using switches
An advantage of a switch over a hub is that a switch allows for a dedicated path between two devices on the switch as shown in Figure . This means that pairs of devices on the same switch can communicate in parallel with a minimum number of collisions. When two or more devices attempt to send to the same device on a switch port, a collision does not occur. Instead one frame will be sent out the switch port to the destination, while the other one will be held in the switches memory or buffer. This is very common when multiple clients are sending information to the same server.

Note: On a switch, each switch port creates a separate collision domain.

In Figure , Host A is sending a frame to Host D, at the same time Host B is sending a frame to Host C. Within the switch, Hosts A and D are communicating in parallel with Hosts B and C, giving two different dedicated paths between senders and receivers. There are no collisions are occurring in this example.

However, as shown in Figure , a collision may occur if the switch is forwarding a frame at the same time the host on that port is sending a frame towards the switch. This is assuming the switch and host are operating in half-duplex.