To determine the net data rate (rate at which actual data bits are
transmitted), you need to consider four parameters: maximum input data rate
(ATM rate), frequency of data bursts, duration of each data burst, and the
overhead on each cell.  Use 5- byte overhead for the 53-byte cell.  You do
not need to worry about the frequency and the duration of the bursts as they
could be balanced to achieve the maximum output data rate, determined by the
token rate.