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.
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