Min 64 bytes in data payload for Ethernet frame?!?

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I was wondering if this was a typo, or if this is what Cisco documents: in
Todd Lammle's CCNA deluxe edition 2005, the Ethernet frame - data payload
part - the size is said to be between 64-1500 bytes, when, as far as I
remember, I thought that the min OVERALL size of an Ethernet frame is 64
bytes ==> minus MACs (12 bytes), minus length/type field (2 bytes), minus
FCS (4 bytes) ==> 46 bytes min data payload. Am I missing something here?!?

TIA,
C


Re: Min 64 bytes in data payload for Ethernet frame?!?


C,
The 64-1500 you mentioned must be a typo.  As I understand it you have a
correct read on the specs and the normal Ethernet payload is 46-1500.  With
the addition of the 18 bytes for addressing, Ethertype and CRC, the frame
outside dimensions are 64-1518 (anything shorter than 64 defined as either a
runt or a fragment).

The above numbers normally assume that the 8 bytes of preamble and start
frame delimeter are not counted as part of the frame dimension.

There is a nice graphic at
http://www.erg.abdn.ac.uk/users/gorry/course/lan-pages/mac.html

FWIW,
Robert
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