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- Posted on
March 16, 2005, 3:07 pm
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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?!?
Re: Min 64 bytes in data payload for Ethernet frame?!?
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
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