Member Avatar for Joey_Brown

Hello.
I have a question regarding ethernet frame size.
So I understand that the maximum SDU size for the frame is 1500 Bytes, and the header size is 18 Bytes
(MAC Dest, MAC Sour, EtherType & FCS).
That makes 1518 Bytes.
So how come the wikipedia entry for Ethernet Frame adds The Preambule with SFD (8 Bytes) , and IPG (with min of 12 Bytes)
to the overall size. Their size is 1538 Bytes.
Which one is correct then? I've always thought that Preambule, SFD and IPG are related to the frame (they are added on the PHY layer),
but are not considered part of the frame and are definitely not added to the overall frame size.

Thanks

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Member Avatar for rubberman

The actual ethernet frame size is 84-1542 octets (bytes) in size. Here is a wikipedia article about it: http://en.wikipedia.org/wiki/Ethernet_frame

The last 12 bytes is taken up with the interframe gap, so the actual data packet, including the CRC is 1530 bytes in length.

Edited by rubberman
Member Avatar for Joey_Brown

Thanks, will look into it

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