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========
Ethernet
========
.. warning:: Under progress!
History
=======
Bob Metcalfe first described the ethernet system in a memo while working at
the Xerox Palo Alto Research Center in 1973 ([oreilly]_). It was based on
the earlier *Aloha* system developed by Norman Abramson at the University of
Hawaii. *Aloha* was a radio network for inter-island communications.
Structure
=========
Data Frames
~~~~~~~~~~~
The frame format is the same for ethernet systems of any speed.
==================== ===========
Section Size (bits)
==================== ===========
Preamble 64
Destination Address 48
Source Address 48
Type Length 16
Data 46 to 1500
Checksum 32
==================== ===========
.. topic:: Preamble
The preamble originally served as a "warm up" period for hardware to
stabilize and prepare for the rest of the frame.
.. topic:: Source and Destination addresses
Manufacturers are given a 24 bit id (first half), and are expected to
ensure the uniqueness of the second half of each device's address.
The IEEE-SA (Standards Association) delegates addresses.
.. topic:: Checksum
The checksum (or Frame Check Sequence) is a Cyclic Redundancy Checksum.
.. [oreilly] `Ethernet: The Definitive Guide`:title:, by Charles Spurgeon.
O'Reilly, 2000
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