Dr. Metcalfe??™s
first Ethernet design allowed this configuration to operate at a speed of 2.94 Mbps,17
using a new algorithm known as Carrier Sensing Multiple Access/Collision Detection
15 Ether is actually derived from the lumeniferous ether that, at one time, supposedly surrounded the
Earth and served as the medium for electromagnetic radiation. It also signifies that Ethernet can be
used to connect any computer, not just the Alto brand computers used.
16 This figure was drawn by Dr. Metcalfe at the National Computer Conference in 1976.
17 This speed was apparently chosen because it was derived from the system clock of the Alto computers
that were being interconnected.
Ethernet: From LAN to the WAN 11
(CSMA/CD).18 This protocol not only enabled the relatively high speed of communication
but also dramatically improved the transmission efficiency over the shared media in
the LAN by up to 80 percent when compared to the existing methods19 and hence, was
deemed a great success.
The CSMA/CD Ethernet
At the time, the big challenge was to minimize the number of collisions that occurred
when several computers interconnected over a shared coaxial cable tried to communicate
with each other.
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