title: error handling in Ethernet
body: <p>Standard Ethernet has no error correction. If FCS doesn't check out fine, the frame is dropped with no further effort.
  Ethernet doesn't notify the switch at the other end of the link that it 
  is dropping the packet, something like ICMP of IP, neither does it ask for retransmission.</p>
  
  <p>Isn't that a bit odd? One would have guessed a retransmission mechanism right when an error comes up-- before it propagates, without burdening the higher levels with overhead due to this.</p>
  
  <p>In TCP for instance, a packet loss in Ethernet layer is likely to cause 
  destination buffer overflows due to gaps in the byte sequence, and from there retransmission of dropped segments due to this lack of buffer space, which is a much bigger waste of resources than fixing it right at the link layer. </p>
  
  <p>TIA. </p>
  
  <p>//=================================</p>
  
  <p>EDIT:</p>
  
  <p>The Q here is: </p>
  
  <p>Why doesn't Ethernet have a retransmission mechanism when there is a CRC error? That is, 
  when the receiving switch sees an error on the frame, why doesn't the it 
  ask the sending switch at the other end of the link to retransmit the frame? Or doesn't even just notify the sender? </p>
  
  <p>Ethernet is just dropping the packets whenever there are such errors. Without any retransmission or notification, the packet loss won't be discovered 
  until some other control mechanism in an upper layer protocol. </p>
  
  <p>Wouldn't it be a sound logic to make Ethernet at least notify the sender? Is retransmission overhead the only reason for 
  not having an elaborate error handling?</p>