The origin of the Ethernet symbol
Ethernet recently turned 35, and it struck me as amusing that its original icon is still prolific in so many network diagrams. Pictured below is one of the first drawings of an Ethernet segment by Bob Metcalfe, courtesy of Charles Spurgeon's Ethernet website.
Indeed, the original Ethernet implemented a shared coaxial cable (thicknet), which end hosts connected to via vampire taps. Hence the half-duplex bus. I'm too young to have had the [mis]fortune of working with original Ethernet myself, but its progression over the decades has always fascinated me.
You'd think that such a concept would be long forgotten in the realm of modern local area networks, those which employ full-duplex switching at speeds exponentially faster than their predecessors. Yet, the symbolism lives on: the following stencil comes stock with Microsoft Visio 2007.
If you're interested as I am in how Ethernet functions, check out Ethernet: The Definitive Guide by Charles Spurgeon.
About the Author
Jeremy Stretch is a freelance networking engineer, instructor, and the maintainer of PacketLife.net. He currently lives in Fairfax, Virginia, on the edge of the Washington, DC metro area. Although primarily an R&S guy, he likes to get into everything, and runs a free network training lab out of his basement for fun. You can contact him by email or follow him on Twitter.