The present data acquisition system of the CDF experiment has to be
upgraded for the higher luminosities expected during the Run II (1999+)
data-taking period.  The core of the system, consisting of a control network
based on reflective memories will remain the same.  The network used for data
transfers, however, will have to be changed.  We have investigated ATM as a
possible replacement technology for the current Ultranet switch.  We present
preliminary results on this new ATM-based event builder system.