Most commonly refered to as a compromise between store-and-forward and cut-through switching, this method involves storing the first 64 bytes of the ethernet frame in a buffer and then forwarding it. The reasoning I find mentioned the most online goes something like:
It is because most errors occurs within the first 64 bytes of the frame
Now I have a couple of questions following this up.
What kind of errors do they have in mind? There is no FCS field in the first 64 bytes. My speculation is that since cut-through suffers mostly from the problem of runt frames caused by collisions, this will check that the frame exists atleast until 64 bytes so as to prevent a late collision.
If ethernet uses duplex which it mostly does in the modern world, why would there ever be a need to check for collisions? Wouldn't that eliminate the chances of runt frames from ever being produced?
- And finally, does fragment free by any chance relate to IPv4 fragmentation?