Ethernet Defined

- History, the origin of the word, and Ethernet Versions -

Since the inception of the first Ethernet (Experimental Ethernet)  .  .  .  the 2.94 Gbps Xerox standard, a flurry of standards development began.  It was viewed as a sort of oasis, capable of yielding vast treasures.  The entire world was in desperate need of high-speed networking, and Ethernet fit the bill.

The term Ethernet - and the first "Experimental Ethernet"

The roots of this word are very, very odd indeed !!   If one looks up the word ether in Webster's - there are several definitions :

Ether /\E"ther\, n. [L. aether]/

1. Any of a class of organic compounds in which two hydrocarbon groups are linked by an oxygen atom.
2. A volatile, highly flammable liquid, C₂H₅OC₂H₅, derived from the distillation of ethyl alcohol with sulfuric acid and used as a reagent and solvent. It was formerly used as an anesthetic. Also called diethyl ether, ethyl ether.
3. The medium contained in the regions of space beyond the earth's atmosphere.  An all-pervading, infinitely elastic, massless medium formerly postulated as the medium of propagation of electromagnetic waves.

Many people are familiar with the second definition, since all auto-parts stores sell bottles of the stuff - which is used to help start your car on a cold morning (it's twice as explosive as gasoline).  But it is the 3rd definition that interested a young, 25 year-old Xerox Engineer in 1971. 

The 3rd definition is more vague.  It is an old concept, where physicists "thought that" the universe is filled with a ubiquitous substance called Ether.  It was estimated that 80% of the outer-space void is filled with this substance.  Furthermore, this medium has an effect on light and electromagnetic waves where it bends and guides the waves as they travel through.  Due to this property, Physicists later began calling the substance luminiferous ether.  Little did they know, that term would later be dissected to represent the most common network standard in the world.

The Engineer  .  .  .  Bob Metcalfe  .  .  .  had been working to improve an existing radio network called "Aloha" - which connected several Hawaiian islands together via a single RF channel.  (see "Interview with Bob Metcalfe")

The half-duplex network was problematic, in that each station had to wait their turn to transmit, and had not real way of knowing whether the channel was available.  So Metcalfe augmented the protocol, adding the now infamous CSMA/CD contention rules for listening (CS - Carrier Sense), allowing many stations to use one channel (MA - Multiple Access), and the ability to detect if the data sent by one station is blocked because another station sent data at the same time (CD - Collision Detection).  Instead of confining the medium to radio waves, Metcalf put together a cabled system of computers on a 2.94 Mbps bus.  

He initially had penciled in his first concept of the whole idea and it was saved somehow - here is the actual sketch !!

Metcalfe wanted to make it clear to the world, that just like luminiferous Ether, his new 2.94 Mbps network could propagate data through a medium to any connected destination (i.e. any computer)  .  .  .  the name EtherNet was born !!

Xerox immediately began work on Metcalf's original "Experimental Ethernet" network, and later, along with Intel  and was i

Ethernet Versions

This original Ethernet, today, is called "Experimental Ethernet".  It is not in use anywhere, but is thought to be the only Ethernet by purists.  However, as many standards have been developed that are based on Experimental Ethernet  -  the technical community has accepted the term Ethernet for ALL OF THEM.  Therefore, Ethernet can be used to name any of the following: