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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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