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Metcalfe had worked on this problem in grad school, where he discovered that with the right packet-queuing algorithms, you could reach 90 percent efficiency of the potential traffic capacity. While this primitive form of packet collision avoidance worked relatively well, Abramson's original design showed that ALOHAnet would reach its maximum traffic load at only 17 percent of its potential maximum efficiency. The nodes would rebroadcast these "lost in the ether" packets after waiting a random interval of time. Unlike ARPANET, in which communications relied on dedicated connections, ALOHAnet used shared UHF frequencies for network transmissions.ĪLOHAnet addressed one important issue: how the technology coped when a collision happened between packets because two radios were broadcasting at the same time. ALOHAnet was used for data connections between the Hawaiian Islands. In particular, Metcalfe looked to Norman Abramson's 1970 paper about the ALOHAnet packet radio system.
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He used previous work for his inspiration.
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Metcalfe didn't try to create his network from whole cloth. The network had to connect hundreds of computers simultaneously and be fast enough to drive what was (for the time) a very fast laser printer. They only wanted to enable PARC's Xerox Alto-the first personal workstation with a graphical user interface and the Mac's spiritual ancestor-to connect and use the world's first laser printer, the Scanned Laser Output Terminal. His creation, Ethernet, changed everything.īack in 1972, Metcalfe, David Boggs, and other members of the PARC team assigned to the networking problem weren't thinking of changing the world.
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But then Robert "Bob" Metcalfe was asked to create a local-area network (LAN) for Xerox's Palo Alto Research Center ( PARC). In the 1960s and 1970s, networks were ad hoc hodgepodges of technologies with little rhyme and less reason. We plug a cable jack into the wall or a switch and we get the network.
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