Ethernet Video Series


Episode 05, Segment 02 of 03

Ethernet Switches (continued)

But, consider this bigger local area network with eight computers and three Hubs. Suppose host number one (up at the top) decides to share and transmit a big file over to host number two. If itís a large file, it might tie up both hosts, and the Ethernet connections and wires in between them, for several seconds, or maybe even several minutes.

Because they are interconnected through Hub number two, and because of the way Hubs work, that  Hub is going to broadcast all of that traffic to all of the other connectors to which it is wired. This, of course, means that hosts three and four will have a difficult time using the Ethernet during that period. To make matters worse, when Hub number one receives that traffic, itís going to broadcast it out of all of its connectors. And that information will also be blasted out toward the bottom, and enter Hub number three, and of course, from there it just gets worse. Hub number three in turn broadcasts that to all of the other computers on a local area network. So the truth is, none of the other computers will be able to use the network very effectively during the entire time of this file transfer.

Now, consider the vast improvement in the performance of this network if we replace all three of those  Hubs with  Switches. In this architecture, when host number one (up at the top) transmits his large file over to host number two, the  Switch knows to send that traffic only on the appropriate wires, and the re-broadcasting and jamming of the network is minimized. The other computers are unaffected, and are able to use their Ethernet connections throughout the entire process just as if no other activity were occurring.

Episode 05, Segment 3 of  3