title: Why is the Frame Check Sequence at the end of an Ethernet frame and not somewhere else
body: <p>An Ethernet Frame Check Sequence is always appended to the end of a frame in the Data Link Layer. Why is it appended to the end of the frame and not somewhere else?</p>
  
  <p>I thought about it and think it might have something to do with how e.g. CRC-checksums are calculated and that it's easier performed by hardware if the structure of a frame is header+payload+crc rather than header+crc+payload.</p>
  
  <p>CRC performs an XOR division of the form (data+padding)/divisor, and for the final frame the padding is replaced by the remainder. The receiver then calculates (data+remainder)/divisor and accepts the frame if the result is 0.</p>