It should be noted that the 53-byte size of an ATM-
cell is due to the dumbest
compromise in the
history of telecommunication.
53 bytes is the sum of 48 bytes
payload and 5 bytes
overhead.
The
telephony people involved with the ATM negociations wanted a 32 byte payload, because low payload means low transmission delay (You don't have to wait for a
zillion bytes prior to send, you don't have to wait for a zillion bytes prior to send to the
DAC).
The data people trusted the technology, and didn't want to waste 5 bytes every 32 payload bytes. So they wanted twice as much payload per cell.
The fighting was ended when they decided to make everybody happy : they took the mean between 32 bytes and 64 bytes and chose to use 48 bytes, which is a pleasure to
implement, especially in
hardware.