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Ethernet/802.3 Switches
An Ethernet switch has a similar function to a hub
(see earlier) -- switches are sometimes called "switching
hubs".
The difference is that a switch examines the MAC-level destination
address of every frame it receives, and transfers it directly to
the appropriate port, without other ports being involved in, or
aware of, the communication. Many such transfers can occur
simultaneously, which has the effect of increasing overall "system"
throughput.
NB: A switch builds a table mapping source addresses to ports
which it subsequently uses to make switching decisions. It's
obvious that switches are significantly more complex than simple
hubs, and this is reflected in their price. However, as with all
technologies, the difference is rapidly diminishing.
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