a data switch is configured to communicate data messages in the form of multibit data unit segmented into a plurality of multibit data subunits . the data switch includes at least two separate , parallel switching units , each having a plurality of ports to communicate the multibit data subunits . hardwired or software implemented prioritization logic provides for the initiations of transfer of data messages between the ports in response to a category of the data messages . a memory is used to store a history of prior data message transfers so that least recently transferred message types are serviced prior to those most recently switched . so as to reestablish synchronization between the parallel switching units , such as loss of a data subunit , a controller responds to a reset condition by temporarily suspending communications between affected ones of the ports and clearing the history so to recommence lock - step operations of the units .